运用QC管理方法解决缸盖大面针孔难题

Elimination of Pin-hole Defect in Cylinder Head Based on Quality Control(QC) Management

针对铝合金汽车缸盖大面针孔(二级以上)导致废品率高达30%的问题,成立了QC小组,经过3次PDCA循环,从"人、机、料、法、环"等方面找原因,第一次找到的原因一是精炼不足,二是浇注温度偏高,第二次找到的原因是模具温度偏高,第三次找到的原因是模具本身有问题。解决方案是将燃烧室大面进水工艺改为框面进水工艺,即改造模具,将原浇口芯模报废,增加一副浇口芯模,结果针孔问题基本解决,废品率降至1.36%。

Aiming at pin-hole defects in aluminum alloy cylinder head, which results in the waste rate over 30%, QC team was organized to eliminate the defects. The reasons from operator, machine, materials, rule and procedure were probed by three PDCA (plan, do, check, analysis) procedures. The results reveal that the pin-hole defects are resulted from inadequate refinery, higher pouring temperature, higher mould pre-heated temperature and mould structure. The pin-hole defects can be effectively eliminated by modifying mould structure and adding a core-mould for runner, decreasing waste rate to 1.36%.