The Material Properties of Machined Plastic

Posted On May 25, 2017 By Tony Holtz

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. Protolabs 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 215°F 214°F 138°F
Tensile Strength 6,091 psi 6,100 psi 7,800 psi
Elongation at Break 30% 40% 6 - 20%
  PC Molded PC Machined PC-like SL
Heat Deflection 280°F 280°F 482°F
Tensile Strength 10,442 psi 8,000 psi 11,300 psi
Elongation at Break 100% 50% 1.0-13%
  PP Molded PP Machined PP-like SL
Heat Deflection 203°F 210°F 142°F
Tensile Strength 5,801 psi 4,800 psi 7,250 psi
Elongation at Break 100% 14% 7-25%
  PA Molded PA Machined PA-like SLS
Heat Deflection 410°F 370°F 370°F
Tensile Strength 16,500 psi 10,000 psi 6,946 psi
Elongation at Break 60% 25% 14-51%

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: Plastic 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 [email protected] or 877-479-3680. For more information on 3D printing, CNC machining or injection molding at Protolabs, head over to