The short answer
Commodity plastics (PE, PP, PS, PVC) are low-cost and high-volume, used for packaging and everyday products. Engineering plastics (nylon, PC, acetal, PBT, ABS) add strength, stiffness, heat and wear resistance for mechanical parts. High-performance plastics (PEEK, PEI, PPS) handle continuous high heat and harsh chemicals at a much higher cost.
The tiers are a useful shorthand when choosing a resin or looking for a cost-down: each step up buys performance and costs more.
The three tiers
| Tier | Common resins | Relative cost | Typical uses |
|---|---|---|---|
| Commodity | PE, PP, PS, PVC, EVA | Low | Packaging, film, containers, pipe, household goods |
| Engineering | Nylon, PC, acetal, PBT, PET (glass-filled molding grades), ABS, PC/ABS, PPE | Moderate | Gears, housings, connectors, automotive and appliance parts |
| High-performance | PEEK, PEI, PPS, PPA, PSU/PPSU, fluoropolymers | High to very high | Hot, chemical, aerospace, medical and electrical parts |
How to pick a tier
- Start with the service temperature and the load at that temperature.
- List the chemicals the part touches.
- Note special needs: clarity, flame rating, wear, food contact.
- Pick the lowest tier that meets all of them, then consider fillers to close small gaps.
- Compare grades, not just families; a filled commodity resin can outperform an unfilled engineering resin in stiffness.
Moving down a tier
Cost-downs often move a part one tier lower, for example nylon to coupled glass-filled PP, or PEEK to PPS. They work when the part was over-specified. See glass-filled PP vs. nylon, PEEK alternatives, the resin selection guide and the resin comparison tool.
What we supply
We source commodity, engineering and high-performance resins, from one gaylord to a railcar, with a COA on every lot, tested to ASTM or ISO methods. See all materials.
Common questions
What are commodity plastics?
High-volume, lower-cost plastics used in packaging and everyday products: polyethylene, polypropylene, polystyrene and PVC. They make up most of the plastic produced.
What are engineering plastics?
Plastics with higher strength, stiffness, heat resistance or wear resistance, used for mechanical and structural parts: nylon, polycarbonate, acetal, PBT, glass-filled PET and ABS are common examples.
What are high-performance plastics?
A step above engineering plastics, for continuous high temperatures or harsh chemicals: PEEK, PEI, PPS, PPA, sulfones and fluoropolymers.
Is ABS an engineering plastic?
It is usually grouped with engineering plastics because of its toughness and finish, though it sits at the low end of the group in heat and chemical resistance.
Can a filled commodity plastic replace an engineering plastic?
Sometimes. Glass-filled or mineral-filled polypropylene replaces nylon or ABS in some parts at lower cost (and lower weight than nylon), when heat and load are moderate.
Tell us what the part needs
A polymer chemist reviews every request, then matches your grade or finds a qualified equivalent and prices it.
What to send for an accurate quote
- The grade name, from any supplier, or a data sheet
- Color (natural, black or a custom match)
- Fill type and percentage, if any
- Melt flow, if you know it
- Quantity for this order and what you use in a year
- Ship-to city and state or province