Commodity resins vs. engineering resins
Commodity resins are inexpensive, easy-to-process plastics used across toys, packaging, and consumer products. Engineering resins offer better mechanical and/or thermal properties — strength, heat resistance, wear and chemical resistance — and are the usual choice for metal or wood replacement where cost or weight must come down without losing performance.
Ratings below are general comparisons for injection molding. Grades, fillers, and additives shift every one of them, which is why API samples and validates the specific compound before release.
StrengthHeat strengthImpactFlowShrink / warp resistanceFlash resistanceResin costMold wear
Commodity resins
Acrylonitrile Butadiene Styrene
ABS
Advantages: Chemical resistant, easily processed, good surface finish, RoHS Compliant, flame retardant
Watch for: Limited weathering resistance
Typical uses: Consumer Goods, auto interiors, toys
Trade names: Cycolac, Lustran, Trilac
Acrylic
PMMA
Advantages: Good weatherability, insulation, clear/colorable
Typical uses: Glass replacement, lenses, casings, aquariums
Trade names: Acrylite, Kydex, Plexiglass
High Density Polyethylene
HDPE
Advantages: Food contact acceptable, easily processed
Watch for: High thermal expansion, poor weather resistance
Typical uses: Toys, Buckets
Trade names: Chevron, Dow, Relene
Polypropylene
PP
Advantages: Food contact acceptable, easily processed
Watch for: Degraded by UV
Typical uses: Consumer Goods / Living Hinge Applications
Trade names: Hival, Lupol, ProFax
Polyethylene
PE
Advantages: Corrosion resistant, low weight, high flexibility, food contact acceptable, easily processed
Watch for: Poor weatherability, high thermal expansion
Typical uses: Toys, Bearings, Buckets
Trade names: Bapolene
Polystyrene
PS
Advantages: Food contact acceptable, flame retardant, fast cycle time, expandable
Watch for: Poor solvent and chemical resistance
Typical uses: Toys, packaging, product casings (Crystal PS for clear cases, cups)
Trade names: Starex, Styron
Polyvinyl Chloride
PVC
Advantages: Flame retardant, high Gloss, UV resistant
Watch for: High density, UV sensitive
Typical uses: Soft, flexible parts; fencing; containers, can also be rigid to add strength
Trade names: Mixvil, Vital-line
Styrene Acrylonitrile
SAN
Advantages: Good weatherability, chemical resistant, high Clarity, good processability
Watch for: Higher water absorption and yellowing than PS
Typical uses: Electical and Automotive applications, cosmetic Packaging, containers
Trade names: Absolan
Engineering resins
API specializes in difficult-to-process and high-performance engineering resins — including glass- and carbon-filled grades and metal-loaded alloys of up to 94% metal content — and runs them on tie-bar-less and all-electric presses built for the clamp force, platen parallelism, and shot control they demand.
Acetal
POM
Advantages: Low fatigue, low moisture sensitivity, chemical resistant, good chemical properties
Watch for: Poor resistance to acids, UV Degradation
Typical uses: Springs, bearings, valve parts
Trade names: Ashlene, Celcon, Delrin
Polybutylene Terephthalate
PBT
Advantages: Dispersible, good electrical properties, food contact acceptable
Watch for: Difficult to fill thin parts, poor resistance to acid
Typical uses: Electronic components, housings, automotive connectors
Trade names: Celstran, Celanex, Valox
PBT / PET, glass-filled
GF-PBT/PET
Advantages: Low moisture absorption, high stiffness-to-weight ratio, medical and UV resistant grades
Typical uses: Structural parts, housings, automotive components
Trade names: Crastin, Rynite, Makroblend
Polyethylene Terephthalate
PET
Advantages: Chemical resistant, clarity, easily processed
Typical uses: Infant products, sterilizer lids, dishwasher parts
Trade names: Celanex, Ramapet
Polycarbonate
PC
Advantages: RoHS compliant, dimensionally stable, easily Processed
Watch for: Fair chemical resistance, degrades during extended processing times
Typical uses: Lenses, light covers, single use containers
Trade names: Hopolex, Lexan, Makrolon
Polyether Ether Ketone
PEEK
Advantages: Chemical resistant, abrasive resistant, corrosive and hydrolysis resistant, can be filled with carbon fiber, graphite, molybdenum disulfide, etc. for lubricating properties and enhanced mechanical strength, food contact acceptable, good sterilizability
Typical uses: Engineering applications, medical/healthcare
Trade names: Victrex
Polyether Imide
PEI
Advantages: Flame Retardant, good chemical resistance, good processability
Watch for: Notch sensitive, limited colorability
Typical uses: Medical/healthcare, automotive, aerospace, metal replacement, thin walled parts
Trade names: Duron, Ultem
Polyethersulfone / Polysulfone
PES / PSU
Advantages: Acid resistant, thermal stability, hydrolysis resistant
Watch for: Poor weatherability, difficult to process, cost
Typical uses: Food service, automotive, medical/healthcare, aerospace, engineering applications
Trade names: HiFill, Thermocomp
Polyphenylene Ether
PPE
Advantages: Excellent electrical properties, resistant to acids and bases, can be blended with PS to improve processability and toughness
Watch for: High viscosity, high cost, color degrades with UV
Typical uses: Automotive, electrical and industrial applications
Trade names: Ashlene, Norpex
Polyamide (Nylon)
PA
Advantages: Food contact acceptable, easily processed
Watch for: Degraded by UV
Typical uses: Bearings, medium stress components
Trade names: Akromid, Celanese, Zytel
Nylon, glass-filled
GF-PA
Advantages: High Strength, wear and chemical resistance
Typical uses: Metal replacement, connectors, bushings
Trade names: Capron, Zytel
Polyphenylene Sulfide
PPS
Advantages: Lubricated, electrically conductive, good wear Resistance, flame retardant, high strength
Watch for: Difficult to process, fillers required for impact strength, high cost
Typical uses: Automotive, medical/healthcare, engineering, and electrical applications, metal replacement
Trade names: Celstran, Fortron
Thermoplastic Elastomer
TPE
Advantages: Good weatherability, recyclable, good UV Resistance, good adhesion, good colorability
Typical uses: Rubber replacement, bushings, seals
Trade names: Elastocon, Santoprene
Thermoplastic Polyurethane
TPU
Advantages: Wide durometer range, oil, chemical and hydrolysis resistant, good wear resistance
Watch for: Limited service temperature, processability
Typical uses: Gaskets, surgical instruments, sporting goods
Trade names: Celstran, Elastollan
How API selects a material
- Application first. Load, temperature, chemical exposure, UV, flammability, sterilization, and regulatory requirements (FDA, REACH, NSF, RoHS, UL) define the candidate list.
- Moldability second. Flow length, shrink, warp tendency, and mold wear determine tooling steel, gating, and cycle — and therefore piece price.
- Sample and validate. Scientific molding establishes a documented window; first-article inspection confirms the part before production release.
- Customer approval. API recommends; the customer approves the final material.
See the Plastic Part Design Guide for geometry rules, or call 516-333-7577 to discuss a material with an API engineer.
Have a part in mind?
Send a model or a sketch — an API engineer will review it and tell you how we would build it.