About Tony Holtz

Tony is a technical specialist at Proto Labs with more than 10 years of experience ranging from CNC mill operator to mold designer to customer service engineer. While his formal education is in industrial machinery operations, he has extensive knowledge and experience in both traditional and advanced manufacturing processes and materials. Throughout his tenure at Proto Labs, Tony has worked with countless designers, engineers and product developers to improve the manufacturability of their parts.

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 customerservice@protolabs.com or 877-479-3680.

DESIGN TIP: Thermoplastic-like vs. Thermoplastic

Many factors come into play when comparing the material properties of thermoplastics found in injection molding versus “thermoplastic-like” materials used in a 3D printing technology like stereolithlography (SL). At Proto Labs, a thorough selection of thermoplastic-like materials are offered through SL, but what may surprise you is the versatility and range of potential applications for SL parts.

This month’s tip discusses:

  • heat deflection, tensile strength and other important properties of thermoplastic-like materials
  • how SL materials compare to similar injection-molded thermoplastics
  • the benefits and range of suitable applications for each SL material
  • the impact of light and moisture exposure on 3D-printed parts


TIPS WITH TONY: The Material Properties of Machined Plastic

If your ultimate product development plan involves a move to injection molding, CNC machining offers a material selection conducive to a transition into increased molded quantities. Proto Labs has more than 30 engineering-grade thermoplastic materials with various benefits.

To illustrate the material properties better (Figure 1), we took four frequently used thermoplastics — ABS, polycarbonate (PC), polypropylene (PP) and nylon polyamide (PA) — and compared the maximum heat deflection, tensile strength and elongation at break that occurs within injection molding, machining and 3D printing.

ABS Molded

ABS Machined

ABS-like SL

Heat Deflection




Tensile Strength

6,091 psi

6,100 psi

7,800 psi

Elongation at Break




PC Molded

PC Machined

PC-like SL

Heat Deflection




Tensile Strength


8,000 psi

11,300 psi

Elongation at Break




PP Molded

PP Machined

PP-like SL

Heat Deflection




Tensile Strength

5,801 psi

4,800 psi

7,250 psi

Elongation at Break




PA Molded

PA Machined


Heat Deflection




Tensile Strength

16,500 psi

10,000 psi

6,946 psi

Elongation at Break




Figure 1: Thermoplastic material properties compared between different manufacturing processes. Properties are dependent on actual material selected, part thickness and geometry. Please review each material data sheet individually as these are estimates.

Translation: CNC machining is ideal for functional prototyping and end-use production parts, and readies your design for an eventual move to injection molding. We have a full staff of technical experts that can answer any machining questions you have at customerservice@protolabs.com or 877-479-3680. For more information on 3D printing, CNC machining or injection molding at Proto Labs, head over to protolabs.com.

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 protolabs.com.

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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