Cause Analysis and Solutions for Appearance Quality Defects

Causes and Solutions for Pore Generation
(1) Complex product shapes and unreasonable mold‑structure design cause exhaust dead zones or narrow exhaust passages. Air inside molds cannot be fully exhausted before or during casting, generating pores. Therefore, mold design shall be reasonable, especially for smooth and short exhaust passages. Air bags shall be designed on molds to collect bubbles trapped in dead zones. Excess resin inside air‑bag cavities shall be removed in post‑processing.
(2) Inadequate drying of moisture in raw materials and incomplete evacuation of small‑molecule substances inside epoxy resin and curing agents also cause pores. Full pre‑treatment of materials shall be completed before production. Moisture in fillers and low‑molecular substances in epoxy resin and curing agents shall be processed via vacuum systems.
(3) Excessive curing‑agent dosage causes anhydride volatilization under vacuum. Avoid over‑dosage of curing agents in formulations; ensure accurate calculation and reliable metering systems.
(4) Failure to adjust flow rate for different molds during casting; full‑speed casting throughout or poor flow‑rate control during mold switching. Excessively fast initial casting‑compound flow inside molds prevents complete bubble evacuation. Casting relies on practical experience; flow velocity and volume vary with molds and casting‑compound viscosity. No automated operation is available so far; experienced casting technicians are required.
(5) Excessively high casting temperature or too‑fast material‑system reaction shortens pot life and increases viscosity; gas cannot escape promptly and slowly migrates to surfaces in subsequent procedures. Therefore, lower system temperature appropriately after adding curing agents, monitor viscosity variation, perform casting at proper viscosity and keep viscosity of fed‑in material relatively stable to reduce pore formation.
(6) Insufficient vacuum degree or inadequate vacuum‑pumping duration during mixing or casting. Replace vacuum‑pump oil and filter elements periodically to guarantee good vacuum‑pump operation. Inspect vacuum‑system for leaks and vacuum level. Extend pumping duration when vacuum drops until target value is achieved.