PPS+GF vs Aluminum: Which One Survives Heat and Chemicals?
PPS+GF40% withstands 200–220°C continuous service, resists aggressive chemicals without any coating, is inherently flame retardant, and weighs 1.65 g/cm³ versus aluminum's 2.70. Aluminum keeps the advantage in absolute stiffness and thermal conductivity. For corrosion-exposed structural parts below its temperature ceiling, PPS+GF is usually the stronger total-cost answer.
Why is PPS the default resin for harsh environments?
TL;DR: PPS combines 200°C+ long-term heat resistance, near-universal chemical resistance, inherent flame retardancy, and low warpage. No other commonly molded resin matches that combination at its price point.
Polyphenylene sulfide (PPS) is a semi-crystalline high-performance resin. With 40% glass fiber, its heat deflection temperature (HDT at 1.8 MPa) exceeds 260°C, its UL long-term rating (RTI) is 200–220°C, and it tolerates short-term excursions to about 250°C. It resists acids, bases, fuels, and solvents at levels where aluminum would already need protective coating. It burns only with extreme difficulty, with no flame-retardant additives required.
That profile is why PPS+GF is a first-choice material for parts near motors, power electronics, and chemical exposure in demanding industrial applications.
Where does aluminum still win?
TL;DR: Absolute stiffness, thermal conductivity, and very large or thick-walled parts. If the part is a heat sink or spans dimensions beyond molding limits, aluminum stays.
AL 6061 has a Young's modulus roughly 5 times that of PPS+GF40% (about 69 GPa versus 15 GPa). Where geometry cannot accommodate ribs (very thin flat plates, for example), plastic cannot recover the stiffness gap. Aluminum also conducts heat well, which is a feature for heat sinks and a liability for insulating supports. And machining has no tooling cost, so one-off or very low-volume parts stay with CNC.
We state this plainly because a material recommendation that ignores its own limits is not engineering. It is sales copy.
What does molding PPS demand from the manufacturer?
TL;DR: High mold temperatures, disciplined process control, and gate design planned around fiber orientation. Crystallization behavior directly affects final dimensions.
PPS is process-sensitive: mold temperature affects how the material crystallizes, which affects shrinkage and final dimensions. Glass fiber adds anisotropic shrinkage on top. Getting stable dimensions on a warp-prone PPS part requires planning gate locations early, keeping walls uniform, and controlling mold temperature, not tweaking parameters after the fact.
Fiber-filled resins are also abrasive and wear mold steel measurably faster than unfilled plastics, which is why steel selection and hardening strategy are part of our tooling quotes for GF materials.
“Most PPS warpage traces back to decisions made at design and process stage: gate position, wall uniformity, and whether mold temperature allows full crystallization. Incomplete crystallization can still shift dimensions and stiffness once the part enters its real thermal environment. That is the fundamental gap between PPS and forgiving resins like ABS, and it is what we verify first during DFM.”
Frequently Asked Questions
- Does PPS need anodizing or coating like aluminum?
- No. PPS is inherently corrosion-resistant and comes out of the mold in final color. Aluminum typically requires anodizing for corrosion protection and coloring; eliminating that step shortens lead time.
- Is PPS brittle?
- Unfilled PPS is relatively brittle; glass fiber reinforcement raises strength and stiffness substantially. Impact-critical designs are reviewed at DFM stage, and where impact dominates over heat, we may recommend PC or PA-based alternatives instead.
- Can you mold other high-temperature resins?
- PEI (e.g. ULTEM-type) is in regular production for high-heat structural parts. PEEK is not something we mass-produce today; we can evaluate it per project, with dedicated process trials before any production commitment.