Ron Maillet, General Manager of SyBridge Technologies in Fitchburg, Massachusetts, is an injection molding expert who started as an apprentice nearly forty years ago in Fitchburg, Leominster, Clinton, and surrounding areas. 

For the past twenty-four years, Maillet has been working in the same building, in many roles and increasing responsibilities, and even through ownership changes. Now in the leadership role at SyBridge Technologies-Fitchburg, he helps oversee a well-established apprenticeship program with students from Montachusett Regional Vocational Technical School (“Monty Tech”) to learn the art, science, and craft of mold-making. 

“It’s fitting that this area would be home to a thriving apprenticeship program in plastics and mold-making,” said Maillet. “One hundred years ago, Foster Manufacturing – famous for Foster Grant glasses – pioneered plastics and injection molding five miles away in Leominster,” said Maillet. The industry has had a presence here ever since.  

SyBridge Technologies in Fitchburg has partnered with Monty Tech for seven years, bringing students into apprenticeship programs and then on into full employment. All the students that have started as apprentices under Maillet are either still in apprenticeship or are now employed by SyBridge, a testament to the staying power of the training and the industry. 

Kim Curry, Coordinator of Co-operative Education and Placement for Monty Tech, explained the breadth of the apprenticeship program. Monty Tech serves 18 cities and towns in the area and offers 21 vocational programs, including “Advanced Manufacturing.”  For a student to be considered for the co-operative education program, the student must be a junior, maintain grades of 75 or better, and be free of any discipline issues. The co-operative education program has seen a steady growth in interest from students since 2018. 

“It’s been a great partnership between SyBridge and Monty Tech,” said Curry. “When I do site visits there, I see my former students in mentorship and supervisor roles—and it is such a delight!” 

First comes the blueprint 

Every SyBridge apprentice starts in the same way Maillet began: reading a blueprint. From the blueprint, they sort out the cuts and angles, note the dimensions and tolerances, and then schedule the order of each process. The apprentice then moves to a manual milling machine, where they install the tools, calculate cutting speeds, and make their first test cuts.  

“I started reading blueprints,” said Jake Rickan, a 2023 graduate from Monty Tech who recently signed on as an employee of SyBridge. Rickan became interested in tool design and machine tech during his exploratory section in school, where he learned about different functional areas. He had been tinkering with after-market car parts, which involved machining, and the work of the apprenticeship program “caught his eye.” 

“I had always been infatuated with machining,” said Jake. His parents were both educators, but for Jake, machine technology and the finished, machined piece of steel has its own appeal. “It’s very cool to see the finished piece and be like, ‘Hey, I’m the one who did that,’” said Rickan. 

Step by step through the apprenticeship 

“Once they show us they’ve [mastered a particular skill], then we move them on to the next stage,” said Maillet, “For instance, after showing they can run the manual machines, we move them to milling equipment with numerical controls. Then they start programming with computers; using 3D files created by our engineers, they start actually cutting steel.” Eventually, they get to the 16-tool changer and the higher-end work. And then on to another department. 

Along the way, apprentices meet with both the experienced staff at SyBridge and with Monty Tech faculty to review expectations. Each step of advancement through the apprenticeship comes only after demonstrating the ability to perform previous steps.  

“Students record each of the skills they learn every day,” said Maillet. Those records become a valuable reference document throughout their journeys as apprentices, and as they move into full-time employment. 

The Monty Tech/SyBridge apprenticeship program enrolls one student per year. The program alternates weeks students spend attending school and working at SyBridge, so skills can be reinforced in both the apprenticeship program and classes. 

“It’s cool to be able to come to the workplace and say, ‘Oh, what they’re teaching us [at school] is actually very useful,’” said Rickan.  

Learning outside the lecture hall 

One of the highlights of the apprenticeship program is that former students pass on the skills and habits they have learned to newer students. Students share the tacit knowledge they pick up from experienced mold-makers and machinists, like securing workpieces, locating the zero point (starting position) on the workpiece, and keeping their work area very clean. This is especially important for the precision work that SyBridge is known for; starting with a clean mill ensures debris from previous jobs will not alter tolerances for the next job. 

“We have a very strong emphasis on making sure the part [in process] falls within certain tolerances,” said Rickan. In addition to setting up the workspace properly and having the specialized equipment required for precise tolerances, “we need to know how to get the part within those tolerances.” 

Toward expertise that invents tomorrow’s tooling  

Maillet likes to say that while most people divide an inch into quarters, eighths, and sixteenths, he and the highly specialized journeymen machinists at SyBridge divide an inch into 10,000 sections.  Here, tools are regularly manufactured with .0002” tolerances (as compared to a standard sheet of printer paper which is about 20 times thicker at .004”). Observing and maintaining tolerances is critical to any machined part moving forward. That ability to work with very tight tolerances is an uncommon one; it’s also why the new apprentice enters the program only after being vetted by Monty Tech staff and instructors. Throughout their program, class subjects dovetail with real-world experience at SyBridge to reinforce skills that will prove useful over a lifetime.  

Training students with experienced machinists has proven to be very productive for Maillet. Maillet noted that when he ran an ad for an experienced machinist, “90% of people don’t even know what a machinist is.” Meanwhile, Monty Tech (which is half a mile from SyBridge) has 25 potential students who are already interested and poised to learn new machinist skills. The bottom line is that Maillet can train and then hire experienced workers right into his shop —resulting in a scenario that benefits the students and the company.  

“As an industry, we are actually in a time of rebuilding our skills here in the US,” said Maillet. “Tooling and mold-making were strong in the 1980s and 1990s, but then moved offshore for a lot of years.” After COVID-19 and the renewed focus on supply chain management, Maillet noted that interest in skilled mold and tool making had surged.  

Rebuilding the craft of injection mold tooling means students remain in the community, earn a good salary, and help advance the art and science of mold-making. 

The post Apprenticeship Program Serves Students and the Tooling Community appeared first on SyBridge Technologies.

Acrylic, also known as plexiglass or polymethyl methacrylate (PMMA), and polycarbonate are both lightweight, transparent plastics suitable for manufacturing parts via CNC machining. Acrylic is known for its strength and transparency, making it an excellent alternative to standard glass, whereas polycarbonate is incredibly tough and impact resistant, making it ideal for applications that require clarity as well as increased durability, such as safety glass.

While acrylic and polycarbonate are similar in many respects, there are some important differences between these two common materials that can make one better suited for a particular application over the other, or impact the machining process and thus lead time and cost. In this article, we’ll go over what you need to know about machining acrylic and polycarbonate so that you can select the best manufacturing option for your project and create designs that work with the material you choose.

Machining Acrylic and Polycarbonate: What You Need to Know

When it comes to machining acrylic, cast acrylic is often a better choice than extruded acrylic, as the latter is more likely to crack or chip during the machining process. This means that the toolpath strategies sometimes need careful selection to avoid chipping the part. Additionally, since acrylics aren’t very heat resistant, it’s necessary to use a sharp cutting tool in order to obtain a smooth surface finish. Acrylic’s low melting point means that it will also be necessary to use a lower cutting feedrate than other plastics during machining, since higher feedrates will generate more friction and heat, and potentially ruin your part. If necessary, acrylic may be kept in a freezer before machining to ensure that it remains as cool as possible.

With its toughness and impact resistance, polycarbonate is better for machining and is particularly well-suited to CNC milling. However, when machining polycarbonate, the sharpness of the cutting tool is still important, as polycarbonate sheets can melt if too much heat builds up during the machining process. Since polycarbonate is less likely to chip than acrylic, it tends to be easier to machine and allows for more standard toolpath strategies to be used. In addition, because there is a higher temperature working range, more aggressive strategies can be used with a smaller chance of causing issues, potentially saving time and money.

Applications for Acrylic and Polycarbonate

Both acrylic and polycarbonate are lightweight, machinable, and have unique characteristics that make them suitable for an array of applications across industries.

Acrylic is a popular material within the automotive, construction, and aerospace industries, and is often used for things like dry boxes, lenses, radiation shields, and desiccators. Additionally, its transparency, strength, and high impact resistance make it a great alternative to glass, and you can commonly find it used in greenhouses, aquariums, terrariums, security barriers, and more.

Like acrylic, polycarbonate is popular in the automotive, aerospace, and construction industries, but its resistance to heat and strong dimensional stability make it very popular in the medical industry, as polycarbonate parts can withstand limited autoclaves and irradiation sterilization. Among its more common applications, polycarbonate is often used for point-of-purchase retail displays, face shields, architectural features, clear manifolds, bulletproof windows, and much more.

Pros and Cons of Using Acrylic for Your Parts

Acrylic offers a range positive attributes, including:

• Transparency: Acrylic can allow up to 92% of light to pass through it, making it more transparent than some grades of glass and most other thermoplastics. It can also be colored without sacrificing its transparency, though it’s possible to manufacture more opaque acrylic parts, as well.
• Strength: Acrylic is much stronger and more impact resistant than glass. Most grades of acrylic are four to eight times stronger than glass.
• Environmental resistance: Acrylic is naturally resistant to scratches, weathering, and UV radiation, making it ideal for outdoor applications.
• Chemical resistance: Acrylic is resistant to many chemicals, including alkalis, detergents, cleaners, and dilute inorganic acids.
• Moisture absorption: Acrylic has low moisture absorption, which allows it to retain its dimensions when used in outdoor applications.
• Compatibility with coatings: Acrylic parts can be coated with anti-static, hard coat, or non-glare layers in order to improve their surface quality, extend their lifespan, and ensure they meet specific requirements.
• Affordability: Despite its strength, durability, and clarity, acrylic remains relatively inexpensive to manufacture and machine. For comparison, polycarbonate is about 35 – 40% more expensive.
• Color: Acrylic is available in a wide range of colors.

CNC machining acrylic is not without its disadvantages. As previously noted, acrylic is more susceptible to cracking and chipping than polycarbonate, and it’s slightly more difficult to machine, since it will lose structural integrity and begin melting at temperatures over 160°C. When designing acrylic parts for CNC machining, you’ll need to remember that relatively low melting point because it makes the material more susceptible to deformation during the manufacturing process. To avoid the risk of melting, and to achieve a quality surface finish, using a proper feed rate and pass depth is crucial. Similarly, to reduce chatter and achieve quality cuts, acrylic parts should be machined using tools with a short flute length and a cutting depth roughly half the diameter of the bit.

Your product’s intended use will also determine whether acrylic is the best option for your project. For example, acrylic’s extreme biocompatibility makes it a good option for bone implants, dentures, or other skin-contact applications; similarly, its resistance to weather, UV radiation, and scratching make it a good fit for parts which will be used outdoors. On the other hand, acrylic might not be the best choice for food containers that will be exposed to high temperature environments, such as dishwashers or microwaves, since acrylic parts will only maintain their dimensions up to 149°F (65°C), at which point they begin to soften. 

Pros and Cons of Using Polycarbonate for Your Parts

The positives of using polycarbonate include:

• Transparency: Polycarbonate is a naturally transparent thermoplastic that can transmit light just as effectively as glass, making it ideal for lenses, lighting, and bulletproof glass. Like acrylic, polycarbonate can be colored without sacrificing its transparency.
• Variety: There are several formulations of polycarbonate on the market, including glass-filled and FDA-compliant variants, so it’s likely that you’ll be able to find one that meets your project’s needs.
• Strength and impact resistance: Polycarbonate has a tensile strength around 200 times that of glass, and is highly resistant to impact. Accordingly, it’s often used in bullet-resistant glass and protective gear.
• Shrinkage and dimensional stability: Polycarbonate will maintain its dimensions under most conditions, and has a low shrink rate of 0.6 – 0.9%.
• Environmental resistance: Polycarbonate is naturally resistant to UV radiation and can withstand varying moisture levels and fluctuating temperatures, which makes it an excellent material for outdoor applications and eyewear.
• Chemical resistance: Polycarbonate is resistant to many chemicals, including diluted acids, oils, waxes, aliphatic hydrocarbons, alcohols, and greases.
• Moisture absorption: Polycarbonate has slightly lower moisture absorption compared to acrylic.
• Compatibility with coatings: Like acrylic, polycarbonate components can be coated with anti-static, hard coat, and non-glare layers. Polycarbonate is also compatible with UV and anti-fog layers.
• High machinability: Since it’s so durable and tolerant to heat, polycarbonate is easier to machine than acrylic.

While polycarbonate has many positive attributes, there are some disadvantages to using polycarbonate for a CNC machining project, including its high cost and its susceptibility to denting. Additionally, since polycarbonate scratches easily, it’s more likely to require finishing, which is complicated by the fact that only certain finishing processes, such as vapor polishing and coating, work with polycarbonate parts.

Additionally, it’s important to note that polycarbonate parts are also prone to developing sinks or voids in thicker sections. To prevent this, it’s best to break thicker elements down into smaller, thinner sections to be assembled later. It’s easy to remember this tip by keeping costs in mind — machining a thick part out of a single block of polycarbonate will typically be more expensive than working with smaller pieces due to the cost of the raw materials and the machining time.

Finishing Options for Acrylic and Polycarbonate

There are several finishing options available for acrylic and polycarbonate, including some that will help your parts look and feel ready for end-use applications and even improve clarity:

• As-machined finish: The standard and most economical finish, ‘as-machined’ or ‘as-milled’ means that no additional post-processing is applied to the part. As-machined parts have tight dimensional finishes and may represent a faster, more affordable manufacturing option. In some cases, as-machined parts may have small but visible surface tool marks, blemishes, or scratches.
• Bead blasting: An economical finish that creates a uniform appearance, bead blasting tends to leave a dull or satin finish and is effective for removing tool marks and surface blemishes.
• Vapor polishing: This finishing option uses solvent vapor to transform matte or opaque surfaces into smooth, high gloss, or optically clear surfaces. Vapor polishing is often used on parts where rough surfaces are unacceptable or where clarity is paramount. 

With sufficient care during the cutting process, machined surfaces of acrylic and polycarbonate parts will typically be translucent, but can become nearly opaque if the material melts. Should melting occur, it may be possible to address surface opacity with post-processing options such as vapor polishing. However, it’s worth noting that as-machined finishes for acrylic and polycarbonate parts will not be optically clear, although it may be possible to achieve optical clarity if diamond tooling is used, but this must be specifically requested during the quoting process, as it will significantly add to cost.

Bottom line: Comparing Acrylic and Polycarbonate for Machining

Special care should be taken with designs that include machined acrylic due to the increased likelihood of stress cracking. With this in mind, it’s advisable to use razor-sharp cutting tools to avoid melting the acrylic or causing cracking; diamond cutters yield the best surface finish, though carbide cutters are much more affordable. It will also be necessary to use a relatively fast feed rate to prevent the acrylic from melting, but remember that going too fast can cause extreme cutting pressure and breakage.

While polycarbonate is generally better suited to machining thanks to its rigidity, toughness, durability, and higher melting point, the trade-off is that polycarbonate is less transparent than acrylic. However, if you need to create specific-use parts, such as protective gear, fuse boxes, or large, tough components, transparency may not be an issue. On the other hand, if you’re designing a product for which transparency is a top priority, taking the extra effort to machine acrylic may be worth it.

Bringing Your Part Designs to Life with SyBridge

Selecting a suitable material for your manufacturing project can be the difference between success and failure. While we’ve explored the positives and negatives of acrylic and polycarbonate, it’s worth remembering that they’re not your only options. Numerous CNC machining materials may be compatible with your part’s design and intended application, and choosing the right one can be a complicated process. 

Fortunately, a manufacturing partner like SyBridge can reduce that complexity and address the challenges certain materials present. Beyond helping you decide whether acrylic, polycarbonate, or another material will work best for your part, our team can offer access to the tools and expertise you’ll need to ensure production runs as smoothly and cost-efficiently as possible. And getting your project started is simple: just create an account and upload your designs to get a quote for your parts instantly. Or, to learn more about how we can make your project possible, contact us today.

The post Key Differences for Acrylic and Polycarbonate Machining appeared first on SyBridge Technologies.

Since its development in the mid-20th century, polycarbonate (PC) has been an increasingly popular material in manufacturing. Today, around 2.7 million tons of polycarbonates are produced each year globally. Over the years, various companies have created different formulas for polycarbonate, so there are several industry grades of polycarbonate to choose from. Some forms have more glass fiber reinforcement, while others have additives like ultraviolet stabilizers for protection against long-term sun exposure.

Strong and versatile, this amorphous thermoplastic is resistant to heat, impact, and many chemicals. As such, polycarbonate is ideal for components that need to be tough or repeatedly sterilized and is often used in the automotive and medical industries.

How Polycarbonate is Manufactured

Each company manufactures polycarbonates slightly differently, but polycarbonate materials have traditionally been created via the condensation polymerization of bisphenol A and carbonyl chloride. However, many companies have started to use diphenyl carbonate instead because carbonyl chloride is extremely toxic.

Regardless of whether carbonyl chloride or diphenyl carbonate is used, a bisphenol A solution in sodium hydroxide is required and then mixed with the carbonyl chloride or diphenyl carbonate solution in an organic solvent so polymerization can take place. When the polycarbonate forms, it will initially be in a liquid state. The solution will be evaporated to form granules, or ethanol will need to be introduced to precipitate the solid polymer.

Once created, polycarbonate is often sold in rods, cylinders, or sheets and can be used in various manufacturing processes. Polycarbonate is compatible with thermoforming, extrusion, and blow molding, but it’s most often used with injection molding. After all, as a thermoplastic, polycarbonate can be melted, cooled, and reheated without burning or significant degradation, making it an ideal injection molding material.

During injection molding, polycarbonate needs to be processed at a high temperature and injected into the mold with high pressure because polycarbonate is quite viscous. The melt temperature should be between 280°C and 320°C, and the mold temperature should fall between 80°C and 100°C. However, those numbers can vary depending on the grade of polycarbonate being used. For example, a high-heat polycarbonate will require a melt temperature between 310°C and 340°C and a mold temperature between 100°C and 150°C, whereas a PC-ABS (polycarbonate/acrylonitrile butadiene styrene) blend’s melt temperature only needs to be between 240°C and 280°C and its mold temperature can fall as low as 70°C and up to 100°C.

Properties and Mechanical Specifications of Polycarbonate Material

While there are several grades of polycarbonates, each with their own molecular mass, structure, and properties, all polycarbonates have a few things in common.

For one, they are known for their toughness and high impact resistance. As a result, polycarbonate is often used for applications that require reliability and high performance.

Despite their toughness and strength, polycarbonates are light weight, allowing for extensive design possibilities and relatively easy installation when compared to other materials.

Polycarbonates are also very resistant to heat and flames. A polycarbonate can maintain its toughness in temperatures up to 140°C, which means polycarbonate parts can withstand repeated sterilization. Polycarbonates also have light transmittance rates above 90% and good chemical resistance against diluted acids, oils, greases, aliphatic hydrocarbons, and alcohols.

A polycarbonate’s properties depend on its molecular mass and structure, so each material is slightly different. To give you an idea of what you can expect, here are some typical key characteristics and specifications:

• Specific gravity: 1.21
• Melt temperature: 295 – 315°C
• Mold temperature: 70 – 95°C
• Heat deflection temperature: 137°C at 0.45 MPa
• Tensile strength: 61 MPa
• Flexural strength: 90 MPa
• Shrink rate: 0.5 – 0.7%
• Rockwell hardness: 118R

As you can see, polycarbonate manufacturing has plenty to offer. However, there are a few things you’ll want to be aware of before selecting this material for a project. For example, its mechanical properties can degrade after prolonged exposure to water over 60°C. Polycarbonate is also susceptible to scratching, more costly to manufacture than many other materials, and vulnerable to diluted alkalis and aromatic and halogenated hydrocarbons. Additionally, the polycarbonate formulations without UV stabilizers can sometimes yellow over time when exposed to UV rays.

Common Uses of Polycarbonates in Everyday Life

Polycarbonate’s toughness and high impact resistance make it a popular material choice for automotive industry manufacturers, particularly when it comes to parts that must be clear or translucent and are subject to frequent impact, such as headlight and turn signal lenses.

In the medical industry, polycarbonate can be found in everything from incubators to dialysis machine housings. After all, polycarbonate is tough, resistant to heat, dimensionally stable, and able to withstand sterilization via FDA-approved methods including autoclaves and irradiation. Polycarbonate can be used in blood filters, reservoirs, and oxygenators, as well as surgical instruments. Plus, given its transparency, polycarbonate enables doctors to more easily monitor blood and track the administration of fluids.

Polycarbonate is also a material of choice in many household appliances, such as mixers, hair dryers, refrigerators, and electric razors. Other common uses for polycarbonate include exterior lighting fixtures, machinery guards, protective gear, bullet-proof glass, fuse boxes, television housings, roofing, skylights, greenhouses, suitcases, eyeglasses, and beverage containers, such as baby bottles, sippy cups, and refillable water bottles.

Getting Started With Polycarbonate

Polycarbonate is a strong and impact-resistant thermoplastic that’s used across a variety of industries. However, there are several different kinds of polycarbonate on the market, each with its own characteristics. Working with an experienced manufacturing partner like SyBridge can make all the difference for product teams who are unfamiliar with polycarbonate or are looking to manufacture parts and products with materials that may be more suitable for a specific application. Want to see if polycarbonate is the right material for your next project? Create an account and upload your part files or contact us today to get started.

The post Know Your Materials: Polycarbonate (PC) appeared first on SyBridge Technologies.

Traditional metal surface finishing is the process of using an abrasive paste, wool berets, and polishing sponges to finish the surface of a metal part or component after it has been machined. The goal of polishing is to remove scratches, nicks, and other surface defects created during the machining process, while also improving the shine and appearance of the surface.

However, polishing metal parts serves more than a purely aesthetic purpose. Many metal surfaces will tarnish with time, typically as a result of exposure to oxygen, high temperatures, and use. The reflective surface achieved through metal polishing not only improves the aesthetics of the part, but helps to prevent contamination caused by corrosion, oxidation, and other forms of quality degradation.

There are three primary types of metal polishing in use today — mechanical, chemical, and electropolishing — and each offers advantages and drawbacks that must be taken into consideration. If you’re not sure of the differences between these three metal surface finishing techniques, or which one is best suited for your project, this article will help.

Mechanical polishing

The mechanical polishing process involves using physical tools and abrasives to remove grinding lines, scratches, pits, and other flaws from the metal surface. Common materials used include abrasive media, flat wheels, sandpaper, wool berets, polishing sponges, and more. For ultra-precise polishing, turntables capable of high-speed rotation and other specialized auxiliary tools may be necessary. Sometimes manufacturers use mechanical polishing as a preliminary step before electropolishing.

While mechanical polishing is precise and produces high-quality surface finishes, it is a specialized process that requires a skilled and knowledgeable technician in order to achieve the best results.

Chemical polishing

In contrast to mechanical polishing, the chemical polishing process obtains a smooth surface finish by immersing the workpiece in a chemical solution, which dissolves surface layers of the metal. This process smoothes and polishes micro-roughnesses on the workpiece’s surface, leaving behind a mirror-like finish free of burrs, vapor stains, and microscopic particles. Chemical polishing results in the formation of passivation layers, meaning that the metal is so free of debris and convex surface defects that it can be considered frictionless.

Electropolishing

The electropolishing process is similar to chemical polishing in that the part or component is immersed in a chemical solution. The key difference is that electropolishing applies an electric current to the workpiece’s surface that dissolves its metal ions into the electrolytic medium. The addition of an electric current allows for greater control over the amount of surface metal removed, which can be as little as microns of material.

Electropolishing is also an ideal fit for processing fragile parts or those with complex geometries that may be difficult to polish through other means. The process also produces passivation layers on the surface of the metal.

Pros and cons of metal surface finishing techniques

Mechanical polishing produces superior surface finishes with high brightness and aesthetic appearance. Surfaces that have been mechanically polished are also typically easier to clean. However, mechanical polishing is highly labor-intensive, can’t be used with fragile or complex parts, and may produce inconsistent or short-lived gloss if not performed properly. Mechanically polished parts are also more susceptible to corrosion.

Chemical polishing, on the other hand, can be used to polish workpieces and components with complicated shapes. It’s a highly efficient process, allowing for multiple workpieces to be polished simultaneously, and typically requires less investment in specialized equipment.

Chemical polish produces good corrosion resistance but can lead to inconsistent brightness across the surface of the workpiece. The chemical polishing solution can also be hard to heat to the proper temperature, is difficult to adjust and regenerate, and may emit harmful substances as part of the process.

Electrochemical polishing creates a smooth, bright, and long-lasting luster that is resistant to corrosion and wear and has consistent coloration throughout the part. Electrochemical polishing is low pollution and low cost but typically involves large equipment investment and additional, complex steps before the process can be performed.

If you’re trying to weigh the pros and cons of electropolishing vs mechanical polishing, there are a few things to keep in mind. Due to its speed and affordability, electropolishing is more often used for rapid prototyping. Polished metal that goes through the electropolishing process is highly lustrous, which makes it easier to visually identify any remaining surface defects. While mechanical polishing can achieve extremely high-resolution surface finishes, doing so is labor-intensive and requires highly skilled operators.

In addition, mechanically polished parts may not be usable in high-purity applications, as abrasives and other compounds may become embedded within the material of the part, which can also negatively impact the workpiece’s mechanical strength. Physical and chemical methods of polishing can result in the impregnation of particles or other contaminants in the surface, which limits cleanliness. The criterion for cleanliness is dependent on the application, but this can be a significant drawback for mechanical and chemical polishing. In applications where cleanliness is critical, like medical devices, electropolishing is often preferable for this reason.

Get started with metal surface finishing

Metal surface finishing techniques help ensure that workpieces and part components have strong, lustrous surfaces that are free of imperfections. Mechanical, chemical, and electrochemical polishing processes have different benefits and drawbacks, so it’s critical that product teams choose the right technique for a given project. SyBridge Technologies brings extensive experience to the table, including guidance and insight into choosing the best metal polishing finish for your parts. Contact us today to get started.

The post Comparing Different Types of Polishing Surface Finishes appeared first on SyBridge Technologies.

Polyethylene is a thermoplastic with a variable crystalline structure. This popular material is used in everything from shopping bags, to pipes, to prostheses and other medical devices. With several grades, types, and formulations of polyethylene available, it’s essential to learn about each material’s properties, advantages, and disadvantages before deciding which type to use for your product. Here’s everything you need to know about ultra high molecular weight polyethylene (UHMW or UHMWPE) from its molecular structure to its many uses.

What is UHMW?

An extremely dense form of polyethylene, UHMW is a semi-crystalline thermoplastic composed of long chains. UHMW forms when ethylene molecules bond, and the resulting UHMW molecules are much longer than the molecules found in other forms of polyethylene thanks to the presence of metallocenes. These compounds can serve as a catalyst and usually consist of positively charged metal ions located between negatively charged cyclopentadienyl anions.

With compression molding, sintering, ram extrusion, or gel spinning, UHMW can be produced as a sheet, rod, strip, or tube. Though the polymerization of UHMW wasn’t commercialized until the 1950s, it was quickly recognized as a versatile material suitable for many applications.

UHMW’s Properties and Mechanical Specifications

UHMW plastic is very strong thanks to each molecule’s impressive length and high molecular orientation. In fact, UHMWPE fibers are among the strongest and lightest on the market today. UHMW is tough, slick, and durable with high tensile strength. It’s also highly resistant to corrosive chemicals, wear, abrasion, impact, moisture, and cold temperatures.

As the name suggests, UHMWPE has a very high molecular weight between 3.1 and 100 million grams per mole. Some of UHMW’s mechanical properties include:

• Tensile strength, yield: 18.9 – 5800 psi
• Tensile strength, ultimate: 2030 – 102000 psi
• Flexural strength at yield: 2000 – 5800 psi
• Flexural modulus: 58.0 – 210 ksi
• Compressive strength: 580 – 12000 psi
• Compressive modulus: 42.0 – 100 ksi
• Hardness, shore D: 57 – 120

When considering using UHMW plastic for your next project, you should know that UHMWPE fibers are less resistant to heat than other high-strength plastics. UHMW polyethylene fibers have a melting point between 144 °C and 152 °C and shouldn’t be used for extended periods at temperatures above 80 °C to 100 °C. Also, even though UHMW plastic is known for its ability to withstand cold temperatures, it will become brittle at temperatures below -150 °C (or -240 °F).

Popular UHMW Applications

Due to its strength and durability, UHMW is often used in belt scrapers, chain guides, idler rollers, sprockets, packaging machinery components, and gears. Other UHMW plastic uses include bearings, conveyor systems’ star wheels, guard rails, and food processing machining parts.

UHMWPE’S strong and light fibers make it an ideal material for body armor. It provides increased ballistic protection and resistance to cuts while remaining comfortable to wear. Many prostheses also contain UHMW due to its biocompatibility, strength, and wear resistance. UHMW’s abrasion and moisture resistance make it a popular choice for building docks, and its resistance to cold temperatures makes it an ideal material for snowplow blades, snowmobile skis, skid steers, and truck bed liners.

Why Choose UHMW?

It’s challenging for many product teams to decide between HDPE and UHMWPE. After all, high-density polyethylene (HDPE) and ultra high molecular weight polyethylene (UHMWPE) are both linear versions of polyethylene plastic that are affordable as well as resistant to abrasion, chemicals, and impact.

HDPE is well suited for use in fuel tanks, piping, and outdoor furniture, and unlike UHMW, it is ideal for injection molding. However, it may crack under stress. In contrast, UHMW is incredibly dense and strong — in fact, its strength rivals steel. UHMW’s combination of high tensile strength, wear resistance, impact resistance, and self-lubrication make it an ideal material for industrial applications as well as high-performance equipment.

Getting Started With UHMW

UHMWPE is a strong, water-resistant, and biocompatible plastic that’s suitable for a wide range of applications, from docks to orthopedic implants. It’s highly versatile, durable, and easy to fabricate, making it an ideal choice for many projects. Working with an experienced manufacturing partner when selecting materials can simplify the process and elevate your final product.

When you partner with SyBridge, we’ll work with you and offer in-depth information to help you navigate the manufacturing process. Backed up by years of manufacturing experience with a wide range of materials, we can guide you to the best material that will help you achieve your manufacturing goals. Ready to get started? Contact us today.

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Polyoxymethylene (POM), more commonly known as acetal or its branded name Delrin®, is an engineering plastic offering low friction, high stiffness, and excellent dimensional stability. Polyoxymethylene is a category of thermoplastics and includes many different formulations of the material, all of which vary slightly. As such, it’s important to learn as much as you can about each type before choosing one for your next project.

Delrin® is a semi-crystalline engineering-grade thermoplastic widely used to create highly precise parts. In general, Delrin® provides impressive dimensional stability and sliding properties. It’s known for its high strength, wide operating temperature range (-40°C to 120°C), and excellent mechanical properties. Here’s everything you need to know about this material, from how it’s made to its best-fit applications.

Inside the Polyoxymethylene Production Process

Acetal was first discovered by German chemist Hermann Staudinger in 1920 before it was commercially synthesized by research chemists at DuPont, the original manufacturers of  Delrin® plastic, in 1956. Like all other plastics, acetal is created by distilling hydrocarbon fuels down into lighter groups called “fractions,” which can then be combined with other catalysts via polymerization or polycondensation to produce a finished plastic.

To make an acetal homopolymer like Delrin®, anhydrous formaldehyde must be generated by causing a reaction between aqueous formaldehyde and alcohol to form a hemiformal. The hemiformal is then heated to release the formaldehyde, and the formaldehyde is polymerized by anionic catalysis. The resulting polymer is stabilized when it reacts with acetic anhydride, which creates polyoxymethylene homopolymer.

Acetal comes in many different commercial varieties and formulations, each with its own advantages and disadvantages. For example, Delrin® 500 is medium-viscosity, all-purpose polyoxymethylene that has a good balance of flow and physical properties. It can be used to produce parts via CNC machining and injection molding and is frequently used to manufacture mechanical parts, fuel systems, and fasteners. Delrin® 1700P, on the other hand, is a very low- viscosity, fast-molding resin that is best suited for parts with complex shapes, thin walls, long flow paths, or multi-cavity tools. It also offers the best molding thermal stability for deposit-free molding in demanding conditions.

Since there are dozens of different formulations of acetal, it’s important to do your research and make sure your prospective plastic offers all of the properties you need for your application.

Delrin® Plastic Properties and Mechanical Specifications

Acetal’s excellent mechanical properties make it extremely versatile, offering a unique blend of properties that you won’t find in most metals or other plastics. Delrin® plastic is strong, rigid, and resistant to impact, creep, abrasion, friction, and fatigue. It’s also well known for its excellent dimensional stability during high-precision machining. Acetal can also stand up to moisture, gasoline, solvents, and a wide range of other neutral chemicals at room temperature. From a design standpoint, parts made with extruded POM naturally have a glossy surface finish.

Since acetal is compatible with CNC machining, injection molding, extrusion, compression molding, rotational casting, and more, product teams are free to choose the manufacturing process that works best for their budget and their needs. However, it’s worth noting that Delrin® plastic is typically very challenging to bond.

Acetal material properties vary by formulation, but the mechanical properties for Delrin® 100 NC010, one of the most popular formulations, include:

• Tensile modulus: 2900 MPa
• Yield stress: 71 MPa
• Yield strain: 26%
• Density: 1420 kg/m3
• Charpy notched impact strength, +23°C: 15 kJ/m2
• Coefficient of linear thermal expansion, normal: 110 E-6/K
• Water absorption: 0.9%

Delrin® does have a few limitations. For instance, even though Delrin® is resistant to many chemicals and solvents, it’s not very resistant to strong acids, oxidizing agents, or UV radiation. Prolonged exposure to radiation can warp the color and cause the part to lose its strength. Also, this material isn’t readily available in a flame-retardant grade, which limits its utility for certain high-temperature applications.

Why Choose Delrin® Plastic?

These limitations notwithstanding, there are many reasons to choose acetal over other materials. When compared to other plastics, acetal offers better creep, impact, and chemical resistance, better dimensional stability, and higher strength. It also has a lower coefficient of friction.

Acetal outpaces certain metals as well. Parts built with this material have a higher strength-to-weight ratio, better corrosion resistance, and offer more opportunities for part consolidation. You can build thinner and lighter parts faster and at a lower price point with acetal than with a comparable metal.

Delrin® plastic can be found in almost every major manufacturing sector. In the automotive industry, common applications include heavy load-bearing gears, fuel system components, loudspeaker grilles, and safety system components like seatbelt hardware. Delrin® can also be found in all-purpose industrial equipment like bearings, gears, pumps, and meters. In the consumer goods and appliances space, this material can be used to make anything from zippers and pens to knife handles and lawn sprinklers.

Getting Started With Delrin®

There’s a lot for product teams to love about Delrin®. It’s strong, stable, versatile, and its excellent mechanical properties make it a good choice for a wide variety of applications in a number of industries. However, with dozens of different formulations of acetal on the market, it can be very challenging to determine which one might be the best fit for your unique project. A seasoned manufacturing partner can help demystify the material selection process.

When you partner with SyBridge, you partner with a team of on-demand manufacturing experts who have years of experience helping product teams navigate material selection. We’re well-versed in the wide range of materials that can be used for both traditional and additive manufacturing — including Delrin®. Once you’ve selected the Delrin® formulation that’s the right fit for your application, our team of experts can help facilitate the entire manufacturing process — from design and prototyping to production and fulfillment. With a full suite of manufacturing services including CNC machining and injection molding, SyBridge can bring your vision to life quickly and easily. Contact us today to get started.

The post Know Your Materials: Delrin (Polyoxymethylene) appeared first on SyBridge Technologies.

PEEK was first conceived in 1978 — relatively recently by manufacturing standards — as a high-temperature resistant material for cable insulation. Over the past 50 years, PEEK has developed into one of the most widely used materials for high-performance applications.

In fact, PEEK is one of the most commonly manufactured polyaryletherketones (or PAEKs) for large-scale production runs. To make the most out of this versatile and adaptable material, engineers and product teams should familiarize themselves with the properties, characteristics, and limitations of PEEK.

What is PEEK?

PEEK is a polymer created by step-growth polymerization, in which the polymer chain doubles with each polymerization step. This material boasts incredible electrical resistance along with heat resistance, wear resistance, and fatigue resistance. PEEK is also creep-resistant, meaning it will retain its shape in harsh environments and high temperatures, and when placed under mechanical stress. Along with being tough, PEEK is lightweight and easy to manufacture.

Since PEEK is physically light yet highly resistant to corrosive substances, it is well-suited for a variety of manufacturing methods. PEEK can be processed using injection molding or additive manufacturing, where its high melting point permits faster feeds and speeds. PEEK can also be manufactured via CNC machining. Across manufacturing methods, PEEK offers repeatability and accuracy component-to-component and can produce parts with tight tolerances.

Pure, unfilled PEEK is quite durable on its own, but PEEK is also often reinforced with carbon or glass fibers to become less brittle. Glass-filled PEEK offers more stiffness than unfilled PEEK and is often used in the oil and gas industries to ward off poor reactions to steam, chemicals, and high temperatures.

One disadvantage of glass-filled PEEK is its tendency to wear down mating parts. Carbon-filled PEEK has increased compressive strength, which dramatically lowers its expansion rate and supports better wear-resistance and load-carrying capabilities. Carbon-filled PEEK also has more thermal conductivity, increasing a part’s lifespan and performance.

Properties and Mechanical Specifications of PEEK

PEEK was developed as a high-heat-resistant plastic and only melts at an extremely high temperature. PEEK also releases very low smoke and toxic gas emissions when exposed to fire, reducing hazards when near flame or extreme heat. This makes PEEK an excellent choice for manufacturing methods that require heating and melting, like injection molding.

Some other mechanical specifications for pure, unfilled PEEK include:

• Tensile strength: 14,000 psi
• Tensile modulus: 590,000 psi
• Water absorption: 0.50% over 24 hours
• Melting point: of 343°C (nearly 650°F)
• UL 94 V-0 flammability rating: (0.059″ thickness)

PEEK is also highly chemical-resistant and abrasion-resistant, and can maintain its shape throughout continuous exposure to hot water or steam. PEEK is also biodegradation-resistant and can survive extreme natural conditions, like intense environments and temperatures.

Key Considerations for Manufacturing With PEEK

PEEK is a very adaptable material, but there are a few engineering considerations to keep in mind to ensure the best results. For instance, even though PEEK is very heat-resistant, it doesn’t dissipate heat well and must be cooled during machining to prevent breakage or deformation. This can be achieved by using standard liquid coolants, but doing so can affect biocompatibility. In cases where PEEK products require direct human contact, pressurized air is the better alternative for cooling PEEK.

A mold temperature of 160°C to 190°C (320°F to 374°F) is recommended when using PEEK, as this will help minimize warping and yield optimal crystallization. When utilizing PEEK for additive manufacturing, the printing nozzle temperature should be 360°C to 400°C (680°F to 752°F) with a heated bed of 120°C (248°F).

Other considerations include:

• Lower elongation: Since PEEK has lower elongation than other plastics, it can crack if you drill into it deeply. Special handling is often required to minimize heat cracks and other internal stress damage.

• Susceptibility to cracking: Annealing is also required when using PEEK. This process helps reduce the chance of stress surface cracks and deformation, which PEEK is prone to during machining. Depending on how much PEEK will be machined, multiple annealing stages could be necessary.
• Tool choice: Oftentimes, you can machine PEEK with silicon carbide cutting tools. Diamond tools might be required when using carbon-filled PEEK or when trying to achieve tight tolerances. Also, ensure your cutting tools were not previously used on metals to avoid contamination.

Popular PEEK Applications

There are three main industries that utilize PEEK components — the industrial sector, the healthcare sector, and the food and beverage industry.

Industrial Applications

Industrial-grade PEEK is inherently pure and supports high mechanical and chemical stability. This minimizes contamination and maximizes safety efforts for chemical and energy applications, as well as for components in the automotive, aerospace, and electronics industries. PEEK can even outperform metals, such as stainless steel, when it comes to industrial wheels and pumps.

Medical Applications

PEEK can create components for the healthcare industry such as orthopedic devices and spinal fusion devices. PEEK can also be used for dental implants, healing caps, and more when manufactured with biocompatible methods.

Food and Beverage Applications

PEEK was recently approved by the US Food and Drug Administration (FDA) for safe human contact when properly prepared. Now, PEEK is finding its way into the food and beverage industry for use in components like cookware, beverage dispensers and nozzles, and processing applications.

Why Choose PEEK?

PEEK can be melt-processed without creating corrosive gasses, making it extremely safe and effective to use with injection molding and additive manufacturing. PEEK’s high melt point also opens it up to CNC machining possibilities, as fast-moving tools can cut PEEK without causing any melting.

Manufacturing PEEK using any of these methods results in good mechanical performance and consistency between parts. PEEK can also support complex designs and geometries with additive manufacturing — in fact, PEEK offers a significantly higher tensile strength and tensile modulus than polyethersulfone (PES), a primary material competitor.

PEEK is more heat resistant than PES and polyphenylene sulfide (PPS), another material product teams often swap out for PEEK. While PES can be used up to 220ºC and PPS can stand continuous use up to 250ºC, PEEK doesn’t even begin to melt at these temperatures.  PEEK offers similar water and chemical resistance to PPS while boasting increased temperature control, resulting in total outperformance across high-heat applications.

Getting Started With PEEK

PEEK is a relatively new polymer that offers incredible heat resistance, electrical resistance, and corrosion resistance. Along with its durability, PEEK is lightweight and incredibly processable, allowing for accurate and consistent production runs even when using tight tolerances. Product teams must perform their own research in order to determine if PEEK is the right material for a particular part, but making these decisions is far simpler with the help of a trusted manufacturer.

At SyBridge, we’re dedicated to helping you reach your manufacturing goals. Our expert manufacturing team has experience with a wide breadth of material types and manufacturing methods. If you think PEEK is the right material for your upcoming project, we’ll guide you through the entire manufacturing process from material selection to launch. Contact us today.

The post Know Your Materials: Polyetheretherketone (PEEK) appeared first on SyBridge Technologies.

Engineering plastics, a group of plastics that have better mechanical and thermal properties than other plastics, are often used as replacements for traditional engineering materials such as wood, metal, or rubber. Two of the most commonly used engineering plastics are acetal (known by many names like Delrin and POM) and nylon, which both offer low coefficients of friction and excellent durability. These two materials can also be used for many of the same applications, such as bearings, bushing, and high-performance gears.

Since there’s so much overlap between nylon and acetal, it can be difficult to grasp the key differences between the two and choose one over the other. Here’s everything product teams need to know about nylon and acetal, plus how they can determine which is better for their project.

Overview of Nylon Plastic

Like other plastics, nylons are made by distilling hydrocarbon fuels. There are two main processes by which nylons are created — polymerization and polycondensation. Polycondensation involves the reaction of a diamine with dicarboxylic acids and results in the formation of a more biodegradable nylon. Polymerization, on the other hand, involves reacting amine monomers with carboxylic acid.

Nylon’s semi-crystalline structure provides a high level of stiffness, strength, chemical resistance, and heat resistance. For these reasons, nylon is ideal for applications involving friction, such as gears or bearings. However, nylon tends to absorb moisture from its surroundings, which can have a negative impact on a part’s stability and functionality, and it isn’t inherently resistant to UV light. Luckily, the use of preconditioning treatments can mitigate both of these effects and reduce damage.

The numerous types of nylon are all identifiable by number. The three most common types of nylon are Nylon 6, Nylon 66, and Nylon 12, and the physical and chemical properties of nylon will vary by type. Some key mechanical specifications for unreinforced Nylon 6, for example, include:

• Water Absorption: 1.900%, 24 hrs @ 73.4°F (23°C)
• Tensile Strength: 76 MPa
• Flexural Strength: 110 MPa
• Flexural Modulus: 2965 MPa
• Hardness: 116, Rockwell R
• Melting Temperature: 428°F (220°C)

Nylon is highly valued for its strength and versatility, as well as its natural low-friction properties. It can be shaped into filaments, fibers, films, and sheets, and it’s compatible with a range of manufacturing processes, including injection molding, CNC machining, and 3D printing. For these reasons, nylons are often used from prototyping to high volume serial production. Nylons are also used across a variety of industries for a wide range of applications. Nylon film is often used for food packaging, nylon parts frequently replace aluminum components in engines, and nylon is often used for electrical applications like cable ties, insulators, and switch housings.

Overview of Acetal Plastic

There are two main types of acetal — homopolymers and copolymers. Homopolymers and copolymers have different chemical compositions, are used for different applications, and require different manufacturing processes. Homopolymer acetal is produced by reacting aqueous formaldehyde with alcohols to form hemiformal, then distilling this mixture and polymerizing it with catalysts. Acetal copolymer manufacturing is more complex and involves converting formaldehyde to trioxane, which is then distilled and polymerized with catalysts.

Homopolymers tend to be stiffer and harder with a more slippery texture. Copolymers, on the other hand, have better dimensional stability and greater resistance to chemicals. Both types of acetal are favored for applications that require strong resistance to abrasion, water, and chemicals, as well as low friction. Some of these applications include gears, zippers, consumer electronics, plastic furniture, and medical supplies.

Other common applications for acetal include mechanical gears, electrical insulation, housing parts, automotive parts like power windows and door locks, food industry materials like food conveyors, and more. However, unlike nylon, acetal isn’t particularly compatible with 3D printing. For this reason, it’s not used for prototyping to the extent that nylon is.

Acetal plastic material properties vary by type, but its typical mechanical and physical properties include:

Homopolymer Acetal

• Water Absorption: 0.25%, 24 hrs @ 73.4°F (23°C)
• Tensile Strength: 10,000 psi
• Flexural Modulus: 420,000 psi
• Coefficient of friction: 0.20

Copolymer Acetal

• Water Absorption: 0.20%, 24 hrs @ 73.4°F (23°C)
• Tensile Strength: 9,800 psi
• Flexural Modulus: 370,000 psi
• Coefficient of friction: 0.21

Acetal is highly favored for its high strength, low friction properties, and excellent wear properties in both hot and cold environments. What’s more, because it’s easy to machine, it tends to be an excellent material choice for applications that require tight tolerances.

Getting Started with Acetal and Nylon

Nylon and acetal are versatile thermoplastics that are both excellent choices for many projects. However, despite the similarities between the two, they’re not the same material and should not be conflated. Nylon is an abrasion-resistant material that’s particularly compatible with 3D printing. Acetal, on the other hand, is more resistant to moisture and exceptionally compatible with CNC machining. Product teams must always do their due diligence to ensure the plastic they’re choosing for the project is truly the right fit. Luckily, an experienced partner can help make the material selection process a breeze.

When product teams partner with SyBridge, they’re partnering with a team of experienced on-demand manufacturing experts with a strong track record of success bringing products to life. With expertise in both traditional and additive manufacturing methods, our team of designers, engineers, and advisors can guide you through the entire manufacturing process, from material selection to the finished product. Contact us today to get started.

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Aluminum is a lightweight yet incredibly strong metal, making it an excellent choice for many applications in the automotive, aerospace, and electronics industry. Along with its durability and physical lightness, aluminum is corrosion-resistant due to a strong layer of oxide film covering its surface.

Since aluminum easily forms compounds with other chemical elements, a large number of aluminum alloys have been developed over the years. To create an aluminum alloy and improve certain qualities of base aluminum, you must add a chemical element to pure aluminum. This requires a thorough mixing of these elements — such as magnesium, silicon, zinc, or copper — with aluminum while the metal is molten. These elements can increase aluminum’s strength, density, workability, electrical conductivity, and more.

Aluminum alloys can vary significantly depending on their composition and tempering. To prevent confusion, aluminum alloys are named and categorized according to an aluminum alloy numbering system. These systems help designers and engineers familiarize themselves with various alloys, their characteristics, and common applications. This helps product teams choose the right aluminum alloy and manufacturing method for a particular part.

Wrought Aluminum Series Numbers

The Aluminum Association established the wrought alloy description system in 1954. When the system was first implemented, it listed 75 chemical compositions — today, there are more than 530 registered active chemical elements, and this number continues to grow.

The wrought aluminum series names elements with four numerical digits where the first digit represents the principal alloying element, the second digit indicates a modification of a specific alloy, and the third and fourth digits are arbitrary numbers assigned to specific alloys in the series.

Here are the primary alloying agents in the wrought aluminum series:

1xxx — 99.000 Minimum Aluminum

It’s impossible for aluminum to be 100% pure, but aluminum in this wrought series category contains at least 99% aluminum. For all intents and purposes, 1xxx alloys are considered pure aluminum. Notably, this alloy is the exception to the wrought series naming rule — in 1xxx alloy names, the last two digits stand for the minimum percentage of aluminum above 99. For example, Alloy 1350 consists of at least 99.50% aluminum.

Pure aluminum has great corrosion resistance and workability, plus high electrical and thermal conductivity. For this reason, this alloy is often used for electrical and chemical applications. Pure aluminum is not very strong and is seldom used for structural applications, but strain hardening can moderately increase material strength.

2xxx — Copper

This wrought series alloy offers high strength and performance over a wide range of temperatures and is regularly used in aerospace applications. One well-known aircraft aluminum alloy is Alloy 2024. However, some copper aluminum alloys are susceptible to heat and stress corrosion cracking and are considered non-weldable, whereas other 2xxx alloys can be welded using the right methods. 2xxx decreases the elongation and tensile strength of aluminum and doesn’t offer as good corrosion resistance as other alloys in the wrought series.

3xxx — Manganese

3xxx aluminum alloys were first used only in pots and pans, but are now widely used in heat exchanger components for vehicles and power plants. With good temperature stability and corrosion resistance, alloys in this category are suitable for use in extreme conditions. 3xxx also allows for good formability and workability. 3003 is a popular manganese alloy used for moderate strength applications that require complex shapes.

4xxx — Silicon

Silicon reduces aluminum’s melting point and improves its fluidity when molten. For this reason, 4xxx alloys are often used in fusion welding wire and as brazing alloys. Silicon on its own is non-heat-treatable, but a number of 4xxx alloys respond well to heat treatments thanks to added copper or magnesium.

5xxx — Magnesium

Aluminum alloys in this category are easily weldable and widely used for applications in shipbuilding, transportation, bridge building, and construction. 5xxx alloys offer good corrosion resistance in marine environments and have the highest strength of all non-heat-treatable alloys. However, 5xxx alloys with more than 3 to 3.5% magnesium are not recommended for elevated temperature service above 65.6°C (150°F) due to the possibility of stress corrosion cracking.

6xxx — Magnesium and Silicon

6xxx alloys usually consist of around 1.0% magnesium and silicon each, which produces magnesium-silicide. Magnesium-silicide can support solution heat treatments that improve strength, formability, and corrosion resistance. This wrought series number is used throughout the welding fabrication industry, primarily incorporated into structural components and extrusions.

These alloys are sensitive to solidification cracks, which means they should not be welded without filler materials — oftentimes, 6xxx is welded with 4xxx or 5xxx filler materials to increase weldability. A major magnesium-silicide alloy is 6061, which is one of the most versatile heat treatable aluminum alloys.

7xxx — Zinc

This wrought series number contains some of the highest strength aluminum alloys that are best-suited for high-performance applications in competitive sporting equipment or the aircraft and aerospace industries. Zinc additions range from 0.8 to 12% in 7xxx alloys and can be coupled with smaller percentages of magnesium, copper, and chromium for heat treatability.

Like 2xxx, 7xxx contains alloys both suitable and non-suitable for welding — one commonly welded alloy is 7005, which is primarily used with 5xxx alloy fillers. One of the highest-strength aluminum alloys available is 7075, which is often used in air-frame structures and for other high-stress applications.

Considerations for the Wrought Aluminum Series

It’s important to note which aluminum alloys are heat treatable and which are non-heat-treatable. This will help product teams determine appropriate applications for specific aluminum alloys, and protect components from high temperatures when necessary.

• 2xxx, 6xxx, and 7xxx series alloys are heat treatable.
• 1xxx, 3xxx, and 5xxx series wrought aluminum alloys are non-heat-treatable and only allow for strain hardening.
• 4xxx series contains some heat-treatable alloys, but mostly non-heat-treatable alloys. However, most 4xxx non-heat-treatable alloys can respond to heat treatments when mixed with other heat-treatable alloys.

In the United States, we mainly use the wrought aluminum alloy series, but there are other aluminum naming and organization systems, including the cast aluminum alloy series. Cast aluminum series numbers look similar to the numbers above. The cast aluminum series uses a 3-digit number and one decimal place (xxx.x), where the first digit (Xxx.x) indicates the principal alloying element.

Understanding Aluminum Alloys and Tempers

Tempers indicate whether an aluminum alloy has undergone any processing to increase mechanical properties like tensile strength, hardness, or heat resistance. Tempers are shown in the wrought aluminum series as a tagged-on letter after an alloy number, e.g. 3003-H.

Strained-Hardened Tempers (-H)

The addition of an “-H” after alloys 1xxx, 3xxx, 5xxx, and sometimes 4xxx indicates that the alloy has been strained-hardened since they cannot be heat treated. The number immediately following the H indicates its processing:

• H1 — Strain-hardened
• H2 — Strain-hardened and partially annealed
• H3 — Strain-hardened and stabilized
• H4 — Strain-hardened and lacquered or painted

Strained hardened aluminum alloys are followed by two numbers, where the second number indicates a scale designation ranging from 0 (fully annealed, softest) to 8 (hardest). For example, Aluminum 5052-H32 has been strained-hardened plus stabilized and is relatively soft.

Thermal and Heat-Treated Tempers (-T)

The addition of a “-T” after alloys 2xxx, 6xxx, 7xxx, and some 4xxx indicates that the alloy has been heat-treated, rapidly cooled or quenched, or precipitation hardened. The number following the T indicates which thermal process it has undergone.

• T1 — Cooled from an elevated temperature and naturally aged
• T2 — Cooled from an elevated temperature, cold-worked, and naturally aged
• T3 — Solution heat-treated, cold-worked, and naturally aged
• T4 — Solution heat-treated and naturally aged
• T5 — Cooled from an elevated temperature and artificially aged
• T6 — Solution heat-treated and artificially aged
• T7 — Solution heat-treated and stabilized
• T8 — Solution heat-treated, cold-worked, and artificially aged
• T9 — Solution heat-treated, artificially aged, and cold-worked
• T10 — Cooled from elevated temperature, cold-worked, and artificially aged

Precipitation hardened or heat-treated alloys sometimes contain an additional digit, which indicates specific end properties such as stress relief by stretch (-T51) or compression (-T52).

Reading the Wrought Aluminum Series With SyBridge

While it is important to be familiar with the aluminum alloy numbering system, we don’t expect you to know all aluminum alloys by heart. To ensure you’re choosing the right aluminum alloy for your project’s application, enlist the help of a seasoned manufacturing partner.

SyBridge can help you understand the aluminum alloy wrought series and determine the best possible aluminum alloy for a given part. Our team of expert manufacturers has in-depth industry knowledge and experience, which we’ll dedicate to making your next project a success. Contact us today to begin your aluminum alloy journey.

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Polyethylene (PE) was discovered just before the turn of the 20th century and instantly became an industry favorite. Thanks to its affordability, machinability, and compatibility with other materials, polyethylene is still a staple in the manufacturing industry. PE is widely used across consumer goods, medical devices, and industrial applications such as tanks and pipes.

There are many forms of polyethylene, broken down by three main chemical structures — branched versions, linear versions, and cross-linked polyethylenes. High-density polyethylene (HDPE) and low-density polyethylene (LDPE) are the two most common kinds of PE. This low-density polyethylene vs. high-density polyethylene “Know Your Materials” guide provides everything you need to know about these two materials, so you can decide which type of polyethylene is best for your next project.

High-Density Polyethylene (HDPE)

HDPE is a type of polyethylene with a linear structure. Since its molecules are packed together tightly, HDPE is an incredibly strong polyethylene with high tensile strength, rigidity, and impact resistance. HDPE is also resistant to chemicals and can be UV-resistant. Along with its durability, HDPE is quite a versatile material and easy to fabricate.

Due to its malleability and dimensional stability, HDPE is often used in outdoor furniture and equipment, including structures like playgrounds. HDPE is also used in industrial applications, such as pipe flanges and chemical tanks, as well as consumer goods like food and beverage bottles, cutting boards, and even toys.

Here are a few key mechanical and chemical properties of high-density polyethylene:

• Melting point: 135°C (275°F)
• Tensile strength: 4,000 psi
• Tensile elongation: 600 psi
• Flexural modulus: 200,000 psi
• Water absorption: 0.10% over 24 hour immersion

Some disadvantages of HDPE include a susceptibility to stress cracking under intense pressure and low-to-moderate heat resistance. There is also a risk of shrinkage while molding HDPE and for this reason, HDPE is best suited for CNC machining and additive manufacturing. Processing HDPE with CNC machining is especially popular, as this manufacturing method can yield tight tolerances.

One massive benefit to HDPE is its recyclability and reusability. Recycled HDPE is often just as versatile and weldable as new or “virgin” HDPE, making recycled HDPE an excellent material choice for reducing your ecological footprint.

Low-Density Polyethylene (LDPE)

LDPE is a branched version of polyethylene, meaning its molecules are more loosely packed. As a result, LDPE is less dense than other linear polyethylenes like HDPE. This doesn’t mean LDPE isn’t strong, though.

Along with boasting impact resistance, LDPE is also stain-resistant, electrically insulating, and waterproof. LDPE is also naturally transparent and reflects light well. Some other mechanical low-density LDPE properties include:

• Melting point: 115°C (239°F)
• Tensile strength: 1,400 psi
• Tensile elongation: 500 psi
• Flexural modulus: 30,000 psi
• Water absorption: 0.10% over 24 hour immersion

Common LDPE consumer components include grocery bags, plastic film or wrap, flexible packaging material, and food and beverage containers. LDPE is also used in medical device manufacturing for orthotics and prosthetics.

Design teams should be mindful of some of LDPE’s limitations — LDPE is more prone to stress cracking than HDPE, less heat resistant than HDPE, and highly permeable to gases like carbon dioxide. LDPE is also highly flammable, which greatly limits its use in high-temperature applications.

One upside to LDPE’s lessened heat resistance is its low melting point, which improves heat sealing. This makes LDPE easy to process using injection molding, which opens up many manufacturing possibilities in this realm.

Differences Between HDPE and LDPE

High-density polyethylene and low-density polyethylene are two common polyethylenes with differing structures but similar properties. HDPE has a linear structure and is opaque, while LDPE is a transparent branched version of PE. Both materials have excellent strength and weldability, boasting impact and chemical resistance alongside malleability and manufacturability.

While LDPE and HDPE can both be processed using injection molding and additive manufacturing, LDPE is best suited for injection molding whereas CNC machining HDPE can help achieve tight tolerances. It’s up to product teams to do their research and determine which material is best suited for their upcoming project. A trusted manufacturing partner can help you make these decisions confidently.

SyBridge can help you understand the key differences between HDPE and LDPE, as well as choose between many other manufacturing materials. Our team of manufacturing experts dedicate themselves to helping you create the best part possible, guiding you through each step of the process. With SyBridge, gain insight into choosing the right material and optimizing product design at every turn. Contact us today to get started.

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