A culprit in shrinkage and warpage problems

Residual stress is process-induced stress, frozen in molded plastic parts. It can be either flow-induced or thermal-induced. Residual stresses affect a part similarly to externally applied stresses. If they are strong enough to overcome the structural integrity of the part, the part will warp upon ejection, or later crack, when external service load is applied. Residual stresses are the main cause of part shrinkage and warpage. The process conditions and design elements that reduce shear stress during cavity filling will help to reduce flow-induced residual stress. Likewise, those that promote sufficient packing and uniform mold cooling will reduce thermal-induced residual stress. For fibre-filled materials, those process conditions that […]