TIPS WITH TONY: Replace Metal with Plastic to Save Weight, Cost

To decrease weight and potentially cost, you can replace metal with plastic on certain parts through 3D printing and injection molding. At Proto Labs, we use industrial 3D printing process stereolithography (SL) to produce thermoplastic-like parts that have a nickel coating on the surface. This offers the increased strength of aluminum die-cast components, without the weight. With injection molding, the introduction of thermally conductive plastics has broken new ground when looking for heat dissipation of expensive heat sinks.

Stereolithography parts built with SLArmor have a metal coating applied over a thermoplastic-like base.

SLArmor involves a ceramic-filled DSM Somos material, which has a metal coating applied to achieve the look, feel and, most importantly, comparable strength of aluminum without added weight. SL is a cost-effective prototyping method for initial parts that mimic metal before moving to higher volumes of die-casted parts.

The material properties of SLArmor are greatly improved in regards to heat deflection, tensile strength, elongation at break and elasticity. The chart below shows exactly how the material relates to die-cast aluminum in three different thicknesses that can be applied based on geometry of SL parts. Note that the thickness of the nickel plating may vary on each part due to the ability to apply the coatings.

Continue reading

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 or 877-479-3680. For more information on 3D printing, CNC machining or injection molding at Proto Labs, head over to

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: Using Additive Fillers to Improve Durability

There are hundreds of thermoplastic materials available for injection molding, and various grades provide strength, durability, impact resistance and many other beneficial attributes. By adding compounded fillers to the equation, you can further increase the durability of your parts.

A component molded with glass-filled nylon to improve durability.

Glass-Fiber Filler
Glass is the most commonly used additive in plastics. Glass-filled materials provide a higher level of strength and rigidity to a part versus an unfilled base material. You can adjust the level of glass in a material depending on your needs, but be cautious as glass can affect how a part turns out dimensionally and cosmetically. We typically see 13 percent and 33 percent glass-filled materials, but occasionally it pushes upwards to 45 percent.

Other Additives and Fillers
There more additives than just glass fiber, and many of these are easily compounded by material manufacturers for your specific needs (or they may already have a pre-compounded material that meets your needs). Glass bead, mineral, metal, carbon, glass mica, talk and Teflon are just a few that Proto Labs has worked with in the past. These fillers can improve:

Strength Conductivity
Chemical resistance Impact resistance
Hardness Flame retardancy
UV stability Heat resistance
Stiffness Lubricity

Continue reading