PPS-GF vs PPS-CF: Industrial Fixture Approval

1. Define the fixture before comparing materials

Write down the locating surfaces, fasteners, allowable movement and failure criteria. For chemical contact, record the actual medium or mixture, concentration, temperature, duration, cleaning cycle and whether the part remains loaded. For electrical use, define the insulation or dissipation function separately. A hot inspection nest and an immersed process fixture need different approval plans.

2. Use WJ reference data with their limits

The WJ PPS-GF and PPS-CF documents are V1.0, issued August 1, 2026. The values below are typical references, not minimum specifications, batch measurements or allowable design stresses. ISO 178 flexural modulus describes a different property from flexural strength. Compare matching orientation and conditioning; the document states ISO 291 conditioning and printed specimen settings. Keep the full method and specimen record with any engineering comparison.

• WJ PPS-GF
• WJ PPS-CF
• WJ PPS

3. Keep missing evidence visible

Both published grade tables leave HDT, melting and Vicat values as N/A; N/A does not mean zero or a confirmed limit. These references do not provide a grade-specific chemical immersion dataset or dielectric-strength result. Do not fill those gaps with another supplier’s PPS data. A higher listed modulus can support a stiffness screening decision, but it does not establish better chemical endurance, electrical isolation or long-term hot-load performance.

4. Chemical contact needs a defined exposure

Ask a qualified test provider to agree specimens, controls, exposure and acceptance criteria for the actual medium. ISO 175 describes immersion testing of plastics without external restraint; it does not by itself validate an assembled, loaded fixture. Record mass, dimensions, appearance and the selected retained property before and after exposure. A general PPS compatibility chart is a screening aid, not approval for every acid, mixture, cleaning agent or temperature.

5. Electrical function needs its own evidence

GF and CF identify reinforcement families, not finished-part electrical ratings. Do not approve either WJ grade as an insulator or an ESD material from its name alone. Specify the required property and applicable method: short-time electric strength, surface or volume resistance and other project requirements are separate measurements. IEC 60243-1 addresses short-time electric strength; its result is not a complete assembly approval. Evaluate representative thickness, print direction, conditioning and contamination through qualified testing.

6. Heat and load must be evaluated together

Record measured part temperature, peaks, exposure time, clamp force and allowable deflection. ISO 75 deflection-under-load results depend on the prescribed method; they are not a prediction of long-term service performance. No nozzle setting or annealing temperature is a service rating. Confirm the exact grade’s equipment, conditioning and post-treatment instructions. Record dimensions before and after post-treatment, then evaluate a representative fixture with the agreed load and exposure cycle.

7. Build a traceable approval record

Print matched screening coupons and a representative fixture from identified material. Keep an unexposed control where relevant. Change one factor at a time when comparing grades, and record linked changes when that is impossible. Use the worksheet below to identify required evidence, acceptance criteria, results and approval status. Leave an item pending when no valid measurement exists; a good-looking print does not close the missing checks.

8. Release one defined configuration

Send WJ the exact grade/SKU, color, lot reference, drawing revision, printer/nozzle, profile, conditioning, post-treatment and test requirements, together with the agreed sample reference. Confirm available documentation and the sample plan before production approval. Reassess affected checks after a material, process, geometry or exposure change. No universal chemical-resistance guarantee, electrical certification or finished-part temperature limit is claimed here.