A clear part that curls, changes dimension or loses flatness is not a diagnosis. Compare timing, direction, location and a controlled baseline before changing the compound.
Record whether the change appears at ejection, after cooling, after a defined storage interval, or only after assembly. Mark the direction of curl, measure the same datum on good and affected parts, and keep photos with a scale. A local sink, uniform dimensional offset, twist and loss of clarity are different observations.
Check whether the pattern follows a cavity, gate direction, wall-thickness transition, insert, cooling side, restart, colour or material lot. A cavity-specific result first points to the mold/process branch; a repeatable lot pattern across equivalent cavities makes a controlled material comparison useful. Neither proves a formulation cause on its own.
Freeze one documented baseline: identified lot and packaging condition, mold/cavity, drawing, machine record, cooling and handling interval. Change one factor at a time and retain the good reference. Do not change compound, mold settings and cooling together; the result cannot identify what changed the outcome.
Use the buyer's specified datum, method, conditioning and acceptance criterion. ASTM D955 is a method for comparing molding shrinkage; a result has meaning only with its specimen and condition. Where a wire/cable component is involved, ASTM D2633 distinguishes material-property tests from completed-cable performance.
Provide the part or drawing, wall sections, gate and cavity identity, material form needed (powder, pellet or other), intended process, clarity reference, quantity with unit, destination, sample timing, feature to measure, method and acceptance criterion. Keep a good and affected retained sample when possible.
| Observation / decision | Evidence to keep | First low-risk check | Escalate when |
|---|---|---|---|
| Curl at ejection or one fixed cavity | Cavity, gate direction, part location, good reference | Compare cavity/gate, thickness transition, cooling and ejection record | It repeats in a controlled run: mold review |
| Dimension moves after cooling or storage | Datum, time, environment, good/affected retained parts | Re-measure the same feature at the agreed time and condition | It follows a lot after other branches are excluded: supplier/lab comparison |
| Transparency changes with deformation | Clarity reference, lot, packaging, flow photos | Confirm identity, contamination and lot record | A composition or compliance question needs actual samples and method |
Send the part drawing or retained samples, material form, molding route, cavity/gate details, measurement method, good/bad photos, requested quantity and destination. We will align a controlled sample brief before quotation.
Start RFQ