Originally published on fastradius.com on June 30, 2021
In manufacturing, we classify some plastics as “tough.” Toughness measures a material’s ability to resist high-impact forces without breaking, fracturing, or deforming. A tough material is strong and can bear loads of force, but it’s also ductile and able to stretch under pressure.
Tough materials are naturally more impact-resistant than other materials, but various factors can affect a material’s impact resistance. For example, plastics tend to be more brittle at cooler temperatures and tougher at warmer temperatures. Prolonged exposure to elevated temperatures and UV light tends to decrease a plastic’s toughness. Part geometry can also affect impact resistance — sharp internal corners can create stress concentrations that cause breakage, whereas round corners tend to make parts more durable.
Choosing the right material from the beginning can extend the service life of a part and prevent part failure down the line. Here’s what you need to know about some of the best impact-resistant plastics.
Best Impact-Resistant Plastics
At SyBridge, we determine a material’s toughness by looking at the results from its Notched IZOD impact test. This test measures the energy absorbed by a plastic, which helps determine how much energy it can stand before deformation. Here are some of the best impact resistant plastic options for creating tough parts.
Acrylonitrile Butadiene Styrene (ABS)
ABS is known for its high impact resistance and mid-range cost, making it a popular choice in many different manufacturing industries. ABS is also easy to machine and bonds well with adhesives, paint, and coatings. The temperature at which ABS is manufactured affects its final properties — low temperatures yield more impact resistance, while high temperatures increase heat resistance.
ABS can be found in many components like instrument panels, luggage, automotive parts like car bumpers, housings for power tools and other appliances, and even children’s toys. Even though ABS is very versatile, product teams should know that this impact-resistant material is not suitable for use in food and beverage applications.
ABS Notched IZOD metrics — min value 200.0 j/m², max value 215.0 j/m²
High-Density Polyethylene (HDPE)
HDPE is a durable, versatile thermoplastic that offers fantastic impact resistance and tensile strength. Since its molecules are packed together so tightly, HDPE boasts incredible toughness and rigidity. HDPE is also resistant to chemicals, corrosion, absorption, and abrasion. However, HDPE can only support low-to-moderate heat resistance.
HDPE is a relatively low-cost material and easy to fabricate. It can be found in chemical tanks and marine construction, outdoor equipment such as playgrounds, and even prosthetics. Despite its toughness, HDPE is susceptible to stress cracking under extreme pressures. Also, there is a risk of mold shrinkage when manufacturing HDPE via injection molding.
HDPE Notched IZOD metrics — min value 20.0 j/m², max value 220.0 j/m²
Polycarbonate is an incredibly tough plastic that can be made transparent, like glass. For this reason, as well as its manufacturability, PC is a common glass alternative when high impact resistance is necessary. Many consumer goods are made from polycarbonate, including indoor and outdoor signs, helmets, protective goggles and face shields, windows, and more. PC is also used in architectural glazing designed to protect buildings from damage. This glazing is often used in medical facilities, government buildings, and transportation centers.
Unfortunately, polycarbonate can be prohibitively expensive for some product teams. Also, even though PC is very impact-resistant, it’s not very scratch-resistant. Teams must keep this in mind when determining whether or not PC is the best overall choice for their use case.
PC Notched IZOD metrics — min value 90.0 j/m², max value 200.0 j/m²
PAI is an extremely tough, strong, and stiff plastic that is also incredibly durable. PAI has good chemical resistance, electrical grade insulation, and low thermal expansion — this means PAI remains dimensionally stable when exposed to elevated temperatures. Polyamide-imide boasts tensile as well as compressive strength, meaning it can stretch and compress to adjust for high impacts.
Along with its toughness and integrity, PAI can also hold tight tolerances. It’s resistant to many regular solvents, fuels, and acids, which further expands its utility. Some common parts made with PAI include bearings and bushings, pump and valve parts, semiconductor machinery, and other electrical connectors.
PAI is versatile when it comes to manufacturing, but it’s expensive, difficult to process, and can only be used in the presence of high temperatures. PAI also has limited hydrolysis resistance, meaning that even though it will remain dimensionally stable in high-impact situations, PAI easily expands when it comes into contact with water.
PAI Notched IZOD metrics — min value 100.0 j/m², max value 150.0 j/m²
High Impact Polystyrene (HIPS)
HIPS boasts high impact resistance and fatigue resistance. HIPS is stiff enough to resist bending but lightweight enough for easy fabrication. Parts built with this sturdy and reliable material will be able to resist fractures caused by repetitive loads.
HIPS can be found in consumer goods, electronics, gas tanks, machinery, and many other industrial applications. HIPS is also commonly found in additive manufacturing technology. Since HIPS is food-safe and durable, you can produce many different kinds of food storage components with this material, like the inside lining of hot coffee cups and refrigerators.
Unfortunately, HIPS is not very eco-friendly — it takes a long time to degrade and is uneconomical to recycle. HIPS is also very flammable and has poor resistance to organic solvents.
HIPS Notched IZOD metrics — min value 50.0 j/m², max value 350.0 j/m²
Choose the Right Impact-Resistant Plastics for Your Next Project
Choosing the best impact resistant plastic can increase the performance and longevity of your upcoming production run. Tough materials help your components withstand the test of time, even while undergoing large amounts of physical stress.
The aforementioned materials offer toughness and high impact resistance alongside other features — chemical resistance, manufacturability, dimensional stability, and compatibility with natural and man-made compounds — to optimize your component. An experienced manufacturing partner can help product teams feel confident in their material choices for impact-resistant plastic parts.
At SyBridge, our team of trusted manufacturers brings years of experience to your product design and processes. When your parts need to stay tough under extreme conditions, we can help optimize your designs and material choices from the very beginning. Contact us to get started!