Frequently Asked Question

What causes flash in injection molding?

Flash in injection molding is typically caused by molten plastic escaping the mold cavity due to inadequate clamping force, damaged parting line surfaces, or excessive injection pressure. When the clamping force of the machine is insufficient to overcome the internal pressure generated during the injection phase, the mold plates separate slightly, allowing resin to flow into unintended gaps. Other common causes include poor tool alignment, debris trapped on the parting surfaces, or localized deformation of the mold steel due to wear or fatigue. Identifying the specific source of flash requires analyzing the location of the excess material and comparing it against the mold maintenance history and process setup parameters. By monitoring clamping pressure and performing regular inspection of parting faces, operators can effectively isolate and remediate the underlying mechanical issues. For a deeper explanation, see: Flash Troubleshooting.