Key Technology for ±0.02mm Grade Precision Control of High-Precision Injection Molds for Home Appliances

Abstract

This study addresses the critical industrial challenge of achieving stable ±0.02mm-grade dimensional tolerance control in injection molds for high-end home appliances, which is a mandatory requirement for global supply chain access. Current industrial practices and academic research lack a systematic, quantifiable framework that integrates upstream material processing, midstream machining, and downstream forming quality management, leading to unstable batch precision and limited scalability.Taking core structural component molds for washing machines as representative case studies, we first quantitatively decomposed the contribution of six independent error sources via full-factor experiments and analysis of variance (ANOVA). A second-order error propagation model incorporating coupled interaction effects was established to define the tolerance budget for each process link. We then optimized the composite material system of mold steel and matching heat treatment processes, obtained the optimal forming process window via multi-physics coupling simulation and response surface methodology (RSM), proposed a four-step closed-loop reverse pre-compensation strategy for cavity machining, and built a full-process inspection system with standardized measurement uncertainty evaluation. Industrial validation shows that the proposed framework enables stable dimensional tolerance control within ±0.02mm, with a process capability index (CPK) ≥ 1.33, surface roughness Ra ≤ 0.2μm, and precision degradation < 0.005mm after 500,000 injection cycles. Validation across 32 production-grade mold sets shows that the first-shot success rate increased from 72% to 94%, production efficiency improved by 40%, and manufacturing cost reduced by 25%.