Engineering Plastic Selection Guide: How to Choose the Right Material for Your Application

The Material Selection Problem

With over 85,000 commercially available plastic grades, material selection paralysis is real. Engineers default to familiar materials (PA66, ABS, POM) not because they are optimal, but because they are known. A systematic comparison framework surfaces better alternatives that might reduce cost by 30% or improve performance by 50% — changes that translate directly to product competitiveness.

The Decision Framework

Step 1: Define the continuous operating temperature. This single parameter eliminates 80% of options. Below 80°C: ABS, PC/ABS, PA6, PA66, POM, PMMA, PET, PBT. 80-120°C: PA66 GF, PBT GF, PET GF, PPO/PPE, PC. 120-180°C: PPS, PPA, PA46, Ultem PEI, PSU, PES. 180-260°C: PEEK, PAI Torlon, LCP. Above 260°C: PI Vespel only.

Step 2: Chemical exposure. Will the part contact fuels, oils, solvents, acids, or bases? If yes, eliminate PA (dissolves in acids), PC (stress cracks in solvents), POM (degrades in acids). Upgrade to PPS, PEEK, or fluoropolymers.

Step 3: Mechanical load. Calculate the required tensile strength with a safety factor of 2. Align with material capability: unfilled (40-100 MPa), glass-reinforced (130-220 MPa), carbon-fiber (200-250 MPa).

Step 4: Cost. Rank remaining candidates by $/kg and check if a lower-tier material can meet the requirements. The most common cost mistake: specifying PEEK when PPS would perform identically at 40% of the cost.

References & Industry Standards

• ASTM International. Standard Specifications for Engineering Plastics & Thermoplastics. astm.org
• ISO. ISO 1043 — Plastics — Symbols and Abbreviated Terms. iso.org
• National Institute of Standards and Technology (NIST). Polymer Properties Database. nist.gov
• UL Prospector. Plastics & Elastomers Material Database. ulprospector.com
• MatWeb — Material Property Data. matweb.com