12 guides organized around practical questions, comparisons, process controls and industry use cases.
Injection molding is a system, not a single setting Injection molding works because of a controlled sequence: plastic pellets are melted, injected into a cavity, packed, cooled and eje…
Diagnose the system, not only the visible mark Injection-molding defects are symptoms of interaction among the resin, mold, machine and process. A quick setting change may hide one def…
Polymer resin is only part of the formulation used in many plastic products. Additives can change processing, color, weathering, flame behavior, slip, antistatic performance, stiffness…
What shrinkage means in a molded part Shrinkage is the dimensional change that occurs as a plastic part cools from the mold temperature to room temperature. Some shrinkage is expected …
Why a flat part becomes distorted Warpage occurs when different areas of a molded part contract by different amounts. The part may bend toward a thick section, twist around a gate or s…
Recognizing a sink mark A sink mark is a shallow depression on the visible surface of a molded part. It commonly appears above a thick rib, mounting boss or intersection where the inte…
How a weld line forms A weld line appears where two flow fronts meet after travelling around a hole, insert, rib or split runner. The fronts may bond, but the interface can remain visi…
What a short shot tells you A short shot is an incomplete part caused by the cavity failing to fill before the melt freezes or the machine reaches its limits. The missing area is often…
Why a mold needs vents When plastic enters a cavity, it displaces the air already inside. If that air cannot escape, pressure rises at the flow front. The result may be a gas burn, a s…
Cycle time is more than cooling time Injection molding cycle time includes mold closing, filling, packing, cooling, screw recovery, mold opening, ejection and any robot or operator han…
What the screw has to accomplish An injection molding screw must convey solid pellets, melt them consistently, mix the melt enough for the application and meter a repeatable shot. Its …
Why moisture control matters Some plastic resins absorb water from the air. During melting, that moisture can create hydrolysis, bubbles, splay, silver streaks, reduced strength and un…