Short fill or knit-line weakness
Likely cause: Poor charge placement, low flow or inadequate venting
Evidence: First article, section review and critical-load test
China FRP process guide
SMC/BMC compression molding
Compression molding forms a measured charge of sheet molding compound (SMC) or bulk molding compound (BMC) in a heated matched-metal tool. It supports integrated ribs, bosses, inserts, color and high-volume repeatability, but tooling, charge pattern, compound maturation and the molding window must be controlled together to prevent cosmetic and structural variation.
When this process fits
- Electrical enclosures and covers
- Automotive and transport components
- Meter boxes and infrastructure parts
- Repeat molded parts with integrated features
Process controls a buyer can audit
| Control field | Factory control | Buyer evidence |
|---|---|---|
| Compound | Resin, glass length/content, filler, thickener, inhibitor and maturation | Approved compound specification and batch record |
| Charge pattern | Charge weight, placement and material coverage | Documented setup tied to part revision |
| Molding cycle | Tool temperature, pressure, close speed and cure time | Parameter log and first-off approval |
| Tool and inserts | Cavity condition, venting, release system and insert placement | Tool-maintenance status and insert traceability |
Common failure modes
Blister, porosity or surface waviness
Likely cause: Moisture, trapped gas or unstable cure
Evidence: Appearance limit sample and destructive validation where required
Warpage or dimensional drift
Likely cause: Uneven shrinkage, ejection or tool temperature
Evidence: Fixture/CMM plan and capability study
RFQ inputs before supplier matching
- 013D model and controlled drawing
- 02Annual volume and batch size
- 03Mechanical, electrical and fire requirements
- 04Surface class, color and texture
- 05Insert and assembly requirements
- 06Tool ownership, maintenance and spare strategy
Missing inputs should be recorded as deviations, not silently filled with a factory default.
Related product families
SMC & BMC
Find China SMC and BMC compounders and compression molders for electrical, automotive, rail and industrial parts, from formulation through serial production.
Open product evidenceComposite Resin & Gelcoat
Compare Chinese polyester, vinyl ester, epoxy resin and gelcoat suppliers by chemistry, application, documentation, packaging and export capability.
Open product evidenceComposite Fiber & Glass
Source glass, carbon, basalt and aramid reinforcement from China suppliers by fibre type, sizing, product form, application and traceable evidence.
Open product evidenceMatch the process, then the factory.
Send the product definition and required evidence. GetFRP will return process-fit suppliers and identify open controls.
Submit controlled RFQ