TIPS WITH TONY: High-Temperature Thermoplastics

We offer two high-temperature thermoplastics: PEEK and PEI. Both high-performance materials can be machined and injection molded, and produce parts that can withstand extreme temperatures.

PEEK parts contain excellent mechanical and chemical resistance during high-temperature applications. Its mechanical properties consist of tensile modulus strengths of 90-200 MPa and a melting temperature of 662˚F (343˚C). Some grades of PEEK have operating temperatures around 482˚F (250˚C).

Because of its robustness, PEEK is commonly used in applications for mechanical and medical instruments. PEEK is also used widely in the aerospace, automotive and chemical industries due to the insulating properties and creep resistance of any dimensional changes in high-temperature applications.

Like PEEK, PEI (often called by its trade name Ultem) offers outstanding elevated thermal resistance, high strength, stiffness and chemical resistance. PEI consists of tensile modulus strengths of 96-190 MPa and with a melting temperature above 420˚F.

PEI is available in transparent and opaque colors including glass additives for improved mechanical properties. Unlike other thermoplastics, PEI provides optimal strength and resists stress cracking when the material is exposed to hydrocarbons, alcohols and acids that makes them ideal for automotive and aerospace applications.

Which Manufacturing Process is Best?
If you’re in need of small quantities (up to 200) of PEEK and PEI parts, we can machined them in less than 3 days. For increased quantities in the thousands, rapid injection molding can produce parts in 15 days or less.

The physical properties vary little between processes, so please test out one sample using machining before moving to injection molding if you are unsure if your parts design is complete or not.

Contact us if you have any further questions about high-temp plastics and specific questions regarding PEEK or PEI. We have a full staff of customer service engineers who can be reached at or 877-479-3680.

WATCH: How Draft Makes Your Drink Cold

We’re kicking off an animated series that takes a quirky look at the fundamentals of molding. The first short video is on draft, one of the most important consideration during injection molding part design.

Check it out:

For more information on designing with draft, read our recent tip on 5 ways to improve part moldability with draft.

5 Ways to Improve Part Moldability with Draft

When designing parts for plastic injection molding, applying draft (or a taper) to the faces of the part is critical to improving the moldability of your part. Without it, parts run the risk of poor cosmetic finishes, and may bend, break or warp due to molding stresses caused by the plastic cooling.

Equally important, an absence of draft may prevent parts from ejecting from the mold, damaging not only the parts, but possibly the mold itself — a costly and time-consuming detour.

Chevron arrows indicate surfaces that require draft in Proto Labs’ design for manufacturability (DFM) analysis.

In this month’s design tip, learn how to improve the moldability of your plastic parts by:

  • drafting early and often
  • sticking to the rules of draft
  • factoring in surface finish
  • implementing the core-cavity approach
  • leveraging design for manufacturability analysis


TIPS WITH TONY: Mixing It Up with Plastic Colorants

Proto Labs’ material selection and available color options for thermoplastics can be found online at

You may require colored resin or transparent coloring for your injection-molded parts, but exactly how much colorant is added and what consistency can you achieve?

Salt-and-Pepper Mix
Proto Labs offers colorant at no charge to most natural, white or clear materials. In most cases, we do this by adding a 3 percent salt-and-pepper mixture of colorant based on weight to the base resin, but on occasion, less colorant is added to transparent resins like polycarbonate.

A 3 percent salt-and-pepper colorant mix is typically used.


Since we hand mix the colorant and base resin, you may have a higher or lower concentrate of colorant throughout the order. The injection molding press does a good job of mixing the colorant and base resin when it melts and grinds the resin in the barrel before molding, but it isn’t 100 percent.

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TIPS WITH TONY: Prototyping with Soft Metals

Soft metals — aluminum, magnesium, brass, copper — are available in different grades at Proto Labs depending on the 3D printing, CNC machining and injection molding service chosen. Quantities range from 1 to 5,000+ parts in 1 to 15 business days.

Aluminum engine bracket 3D printed through DMLS.

At Proto Labs, we use the industrial 3D printing process of direct metal laser sintering (DMLS) to build parts from soft (and hard) materials like aluminum.

DMLS-built aluminum provides parts with excellent strength-to-weight ratios, temperature and corrosion resistance, and provides good tensile, fatigue creep and rupture strength. With a tensile strength of 37.7 ksi (260 MPa) and a hardness of 47.2 HRB, for example, you are able to have parts produced in nearly any part geometry with features like internal channels or complex undercuts that can’t be manufactured through any other method. And, final parts are still up to 98% dense.

You can also get aluminum parts using CNC machining in 6061 and 7075 grades. 6061 can provide you with improved corrosion resistance and can be welded while 7075 provides you a part that has a higher tensile strength and is harder than 6061.

Do you need a prototype of an aluminum die-cast part? We can mimic aluminum die casting using our stereolithography (SL) process and SLArmor technology. SLArmor uses our DSM Somos (NanoTool) material, applying a nickel metal coating that gives the look and feel of metal without the added strength or weight.


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