POMCH-15日本宝理----Thelongertheprocesslengthis,thehighertheinjectionpressureisneededtoensurethepartsarefull.Thehighertheholdingpressure,thehigherthedimensionalaccuracyofPOMparts.POMhaslargecrystallinityandnarrowmeltingrange,andthevolumeshrinkagecanreach2.8%whencoolingandhardening.Itisnecessarytohaveenoughpressuretomakeupforthesizedefects.Therefore,intheinjectionmoldingofPOM,properlyincreasingthepackingpressurecanreduceandeliminatethephenomenonofwarpage,shrinkagepitsandinternalholesofPOMproducts造粒温度：POM使用双螺杆挤出造粒时，往往会产生颗粒中心孔洞现象。这是由于POM为结晶型聚合物，其熔体在冷却时往往伴随着较大的体积变化，在挤出过程中，熔融状的料条进入冷却槽后，表面会瞬间固化成表面皮层，而芯层部分还处于熔融状态，随着料条由外向里逐渐硬化的继续，因体积减小所引起的收缩力将作用于芯部尚未硬化的树脂，相当于芯部受到均等的拉力，其结果是在料条的芯部沿长度方向形成连续的缩孔。在挤出过程中，***控制冷却槽中的水温，在可操作的前提下，尽量提高水温。PhysicalperformanceratingunitsystemtestmethodDensity:1.45g/cm?ISO1183Meltflowrate(meltflowrate)(190°C/2.16kg)3.0g/10minISO1133Dissolutionvolumeflowrate(MVR)(190°C/2.16kg)2.40cm3/10minISO1133MechanicalpropertiesratingunitsystemtestmethodTensilemodulus11700MPaISO527-2Tensilestress130MPaISO527-2Tensilestrain(fracture)1.5%ISO527-2Bendingmodulus10000MPaISO178Bendingstress185MPaISO178FrictioncoefficientJISk7218Dynamic10.35JISK7218Andsteel-Dynamic20.27JISk7218WearfactorJISk72180.49MPa,0.30m/sec31010^-8mm³/N·mJISK72180.060MPa,0.15m/sec420010^-8mm³/N·mJISK72180.49MPa,0.30m/sec550010^-8mm³/N·mJISK72180.060MPa,0.15m/sec61000010^-8mm³/N·mJISK7218)