An Introduction to Common Plastics Used in Automotive Manufacturing

Originally published on fastradius.com on July 29, 2020

Many parts for automotive applications are mission-critical, and thus need to be constructed of durable, reliable, and often corrosion- and heat-resistant plastics. Automotive manufacturers also must meet a strict set of industry regulations, and the materials they select for manufacturing purposes must undergo what’s known as the material qualification process to ensure they are both durable and compliant.

Selecting the right material is even more important when considering that certain materials can yield significant energy and cost savings. As an example, applying lighter materials can reduce the overall weight of a vehicle, thereby improving its fuel efficiency. On the other hand, the wrong material can greatly increase costs and energy expenditure.

For all of these reasons, it’s vital that product teams make the right choice when selecting materials for automotive parts. Oftentimes, that material is a plastic.

Plastics commonly used in automotive manufacturing

Because plastics are lightweight and affordable, they’re an incredibly attractive option for automotive manufacturers today. As fuel efficiency becomes an increasing concern for consumers, any decrease in weight can translate directly into a boost in sales. What’s more, plastics are corrosion-resistant, long-lasting, malleable, and offer greater design freedom than metals.

The following plastics are among the most likely to be used in car manufacturing, though polypropylene, polyurethane, and polyvinyl chloride are by far the three most commonly-used.

Polypropylene

By far the most common plastic in automobiles, polypropylene is a highly durable polymer produced from propylene. Because of its durability and chemical resistance, polypropylene is used in everything from bumpers to cable insulation to carpet fibers.

Polyurethane

Polyurethane, which can take on both soft and hard forms, is exceptionally resistant to solvents, radiation, and environmental wear. Because of these qualities, polyurethane is well-suited for numerous applications, including tires, suspension brushes, seating, and more.

Polyvinyl chloride

Polyvinyl chloride makes up approximately 16% of all plastic in a typical modern vehicle. Boasting flexibility, heat resistance, and low lead content, polyvinyl chloride is well-suited for a huge range of auto parts, particularly because it can also take on both soft or hard forms.

ABS

Acrylonitrile butadiene styrene (ABS), a polymer of styrene and acrylonitrile, has a shiny, tough exterior but very high durability and heat resistance. ABS is most typically used to produce dashboards and wheel covers.

Nylon 6/6

A general-use nylon, nylon 6/6 promises high wear resistance and can be used to make parts via both molding and extrusion processes. It’s favored for its strength, low cost, and stability, and it’s commonly found in weatherproof coatings.

Polycarbonate

Polycarbonate provides an exceptional combination of rigidity, hardness, and durability. Because of these qualities, as well as its resistance to heat and weathering, polycarbonate is a go-to material in the manufacturing of car bumpers.

Polyethylene

Offering high-impact resilience, low density, and durability, polyethylene is particularly suitable for applications requiring moisture resistance at a relatively low price point. Typically, polyethylene is used for glass-reinforced car bodies and electrical insulation.

Polyoxymethylene

Highly rigid and stable, polyoxymethylene is most often used to fabricate interior and exterior trims, fuel system parts, and small gears. It’s notably resistant to cold, chemicals, and fuel.

The right plastic, the right application

Choosing the right material for an automotive application can make all the difference between building a durable, fuel-efficient vehicle or not.

To ensure you’re always choosing the best possible material for each part, consider partnering with a full-service manufacturing shop like SyBridge. Our team of experienced engineers and designers are prepared to provide comprehensive support and advisory services through every stage of your automotive design and manufacturing process. If you’re ready to get started on your next project, contact us today.

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 small black Delrin pieces Delrin® can also be found in all-purpose industrial equipment like bearings, gears, pumps, and meters. 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 Fast Radius, 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, Fast Radius can bring your vision to life quickly and easily. Contact us today to get started.

An Introduction to Common Plastics Used in Automotive Manufacturing