There are more than 85,000 commercial options for plastic materials listed in materials databases, and within those, there are 45 polymer families which can be broadly classified into two categories: thermosets and thermoplastics. Proto Labs primarily focuses on the latter category, offering hundreds of stocked engineering-grade thermoplastic resins through its Protomold Injection Molding service. In addition to its stocked supply of resins, it has the capabilities to support many more customer-supplied resins as well.
Narrowing down that extensive list of materials can sometimes seem like a formidable task, so a quick reference guide (and comprehensive guide online) outlines the benefits and applications of some of the most commonly molded materials. By choosing the right material, you can improve the form, fit and function of your parts — a resolution we can all strive for in the new year.
ABS (Acrylonitrile Butadiene Styrene)
ABS is a tough, impact-resistant plastic that is widely used across many different industries. It has low shrink and high dimensional stability, and it has good resistance to acids and bases. It’s also relatively inexpensive. Applications include cosmetic parts, handheld devices, housings and moldings for electrical tools, and remote controls.
PC is strong and extremely impact resistant with low shrink and good dimensional stability. It’s a transparent plastic that is available in optically clear grades. PC has good heat resistance and accepts high cosmetic finishes well. Applications include lenses, indoor and outdoor lighting, cell phone housings, electrical components and medical devices.
PPA (Aliphatic Polyamides)
There are many types of PPAs, or Nylons, each with its own advantages. Generally, Nylon parts provide high strength and high-temperature strength, especially when reinforced, and are chemically resistant, except to strong acids and bases. Applications include thin-walled features, combs, spools, gears and bearings, screws, structural parts (with glass) and pump parts.
Commonly called Acetal, it is characterized by high toughness, stiffness, hardness and strength. Acetal has good lubricity and resistance to hydrocarbons and organic solvents. It also has good elasticity and is slippery, so it works well for bearing surfaces and gears. Applications include pumps and pump impellers, conveyor links, soap dispensers, fan and blower blades, and automotive switches.
PMMA (Polymethyl Methacrylate)
PMMA, aka Acrylic, has good optical properties, high gloss and is scratch resistant. Acrylic also has low shrink, and has less sink in geometries with thin and think sections. Applications include light pipes, lenses, light shades, optical fibers and signs.
PP is an inexpensive resin option with higher impact resistance in some grades; propylene homopolymer can be brittle in cold temperatures, with copolymers more resistant to impact. PP is wear-resistant, flexible and can have very high elongation. It’s also resistant to acids and bases. Applications include integral hinges or living hinges, fans, snap-over lids (i.e. shampoo bottle tops) and medical pipette tubing.
Protomold has many additional stocked resin options including PBT, PPS, TPE, TPU, LCP, HDPE, LDPE, PPSU and PSU as well as newly added high-performance materials PEEK and Ultem®. A detailed Materials Matter white paper provides a highly technical overview of the materials selection process.