Choosing the Right Plastic: A Material Guide for Your Next Product

When you’re developing a new product, one of the most important and most overlooked decisions happens long before the first mold is ever cut: choosing the right material. At Wisconsin Plastics, Inc. (WPI), we work with businesses across the medical, aerospace, automotive, and industrial sectors, and we’ve seen firsthand how the right resin choice can make the difference between a product that performs for years and one that fails in the field.

Here’s a practical rundown of common thermoplastics, what they’re good at, and how to think about matching material to application.

Every plastic resin has its own personality — strength, flexibility, heat resistance, chemical resistance, cost, and appearance all vary widely from one material to the next. The “best” plastic isn’t a fixed answer; it depends on how your product will be used, what environment it will live in, what regulations it needs to meet, and what it needs to cost at scale. Getting this decision right early avoids expensive redesigns and tooling changes down the road.

Commodity vs. Engineering Grade: Know the Difference

Before diving into specific resins, it helps to understand the two broad categories WPI works in:

Commodity resins are standard plastics manufactured in high volumes at a low cost for widespread, everyday products. They’re easy to process, highly available, and well suited to applications that don’t demand extreme durability or heat resistance.

Engineering-grade resins are high-performance plastics formulated to withstand harsher environmental and mechanical conditions. Compared to commodity resins, they offer superior strength, heat resistance, impact endurance, and chemical stability, making them the right call for demanding industrial, medical, or automotive components.

Most products end up using a mix: commodity resins where cost and volume drive the decision, engineering grades where performance can’t be compromised.

ABS (Acrylonitrile Butadiene Styrene)
A workhorse commodity resin known for toughness, impact resistance, and ease of molding. ABS is a popular choice for housings, enclosures, and consumer products where durability and a clean finish matter without the cost of an engineering-grade material.

Nylon 6 and Nylon 6/6
These engineering-grade polyamides bring strength, wear resistance, and low friction to mechanical parts like gears, bushings, and fasteners. Nylon 6/6 in particular holds up well under repeated stress and elevated temperatures, making it a strong fit for components that move or bear load over the life of a product.

Acetal (POM)
Acetal is prized for its stiffness, low friction, and excellent dimensional stability, even in parts with tight tolerances. It’s a common choice for precision mechanical components like gears, bearings, and clips that need to hold their shape under repeated use.

Polystyrene (PS)
A cost-effective commodity resin that’s easy to mold and offers good rigidity and a clean appearance. Polystyrene is often used for packaging, disposable components, and parts where light structural demands make it an economical option.

Polycarbonate (PC)
Prized for exceptional strength and clarity, polycarbonate resists impact far better than standard plastics and holds up well to temperature swings. It’s a go-to engineering resin for safety equipment, lenses, and medical device components where a part needs to take a hit without cracking.

Polypropylene (PP)
A lightweight, fatigue-resistant commodity resin that holds up well to repeated flexing — think living hinges — and resists a wide range of chemicals. PP is common in packaging, medical components, and parts that need to bend without breaking.

High Density Polyethylene (HDPE)
Valued for its chemical resistance, moisture resistance, and favorable strength-to-density ratio, HDPE shows up frequently in containers, packaging, and industrial components exposed to liquids or outdoor conditions.

PC/ASA
PC/ASA is a high-performance polymer blend that combines the strength and heat tolerance of polycarbonate with the weather and UV resistance of acrylonitrile styrene acrylate (ASA). The result is a rigid, impact-strong, color-stable material that resists degrading outdoors — a strong choice for parts that live outside or see prolonged sun exposure.

PVC (Polyvinyl Chloride)
A versatile commodity resin known for chemical resistance and flame-retardant properties, PVC is widely used in components where durability against chemicals or weathering is important.

TPE (Thermoplastic Elastomer)
When a product needs a soft-touch feel, a rubber-like grip, or a flexible seal, TPE delivers that without sacrificing the processing advantages of standard injection molding. TPE is often used for overmolded grips, gaskets, and ergonomic components.

TPO (Thermoplastic Polyolefin)
TPO combines flexibility with good weather and UV resistance, along with resistance to impact even in cold temperatures. It’s a common choice for automotive components and outdoor applications where flexibility and durability both matter.

PEEK (Polyether Ether Ketone)
At the top end of engineering-grade performance, PEEK offers outstanding strength, chemical resistance, and heat tolerance, even in demanding environments. It’s used where standard engineering resins fall short — high-temperature, high-load, or chemically aggressive applications, including certain medical and aerospace components.

A few questions can help narrow the field:

What forces will the part experience? Impact, vibration, tension, or repeated flexing all favor different resins.

What environment will it live in? Heat, UV exposure, moisture, or chemical contact can rule certain materials in or out.

What regulatory standards apply? Medical, automotive, and aerospace applications often come with certification requirements that narrow the material options.

What does the part need to look and feel like? Clarity, color, texture, and surface finish all vary by resin.

What’s the production volume and cost target? Some materials cost more upfront but reduce long-term failure rates or secondary processing needs.

Material choice also plays a role in a product’s environmental footprint. At WPI, sustainability is built into how we approach manufacturing — from reincorporating usable regrind back into the molding process to partnering with third-party recyclers for material that can’t be reused in-house. When it makes sense for a project, recycled content and more sustainable resin options are worth discussing early in the design process.

Material selection isn’t just about mechanical performance, for a lot of products, color is part of the spec too. Whether it’s a branded consumer color, a color that has to match across multiple components, or a shade that needs to hold up to UV exposure without fading, getting color right adds another layer of complexity to material selection.

WPI is well versed in color matching across a wide variety of resins, helping ensure the color you specify is the color you get — consistently, run after run, and across different materials used on the same product. That consistency matters most when parts made from different resins need to match visually, or when a product ships in high volumes and even small color drift is noticeable.

Choosing a material isn’t a step to rush, it shapes performance, cost, and manufacturability for the life of your product. Wisconsin Plastics, Inc. works alongside businesses from early concept through full production, helping match the right resin and process to the product you’re trying to build. And getting it right takes more than a resin data sheet; it takes real-world experience knowing how a material actually behaves once it’s molded, assembled, shipped, and put to use.

That’s where Wisconsin Plastics, Inc. comes in. With more than 50 years of manufacturing experience, we’ve helped businesses across the medical, automotive, aerospace, and industrial sectors navigate exactly these decisions — turning material knowledge and process expertise into products that perform.

Ready to put that experience to work on your next product? Partner with WPI and let’s build it together.