How Injection Molding Products Are Made

How Injection Molding Products Are Made

Injection molding is widely used for manufacturing a wide variety of products, ranging from the smallest machine widgets to entire car body panels.injection molding products It involves injecting hot, liquid polymers into a precision-designed mould to create a component with the precise size, shape and colour needed for the product. The moulds are typically made from a strong, hard tool metal like steel or aluminium and precision-machined to form the part features. Injection-molded parts may be thermoset or thermoplastic.

The injection process starts when the raw plastic is fed into a heated cylinder of the injection machine.injection molding products The injection nozzle then enters the mold, and the injection screw rotates to force the melted plastic into the mould cavity, where it cools and solidifies. The injection process is repeated for each desired part, with the injection cycle time being controlled by the amount of injected material and the speed of the injection screw.

When a part is ready, the injection machine stops rotating the screw and the stationary screw moves forward to a transfer position just below the gate (cavity entrance).injection molding products At this point the packing pressure is applied, which completes mould filling and compensates for thermal shrinkage of the molded product. Often the packing pressure is only applied for about 1 second, as it can be dangerous to the integrity of the finished part.

If the design of a part includes undercuts, then additional steps are needed to ensure that they can be manufactured with the injection process.injection molding products Undercuts are part features that can’t be manufactured with a simple two-part mold, either because the mould cannot be CNC milled to accommodate the feature or because it would be in the way of ejecting the molded product. Examples of undercuts include the teeth on a thread or the hook on a snap-fit joint.

Once the injection is complete and the part has solidified, the mould opens and a robotic arm pushes the molded part out of the mould. The molded part then drops through a chute and into a container to be used in the final product.

The injection molding process is a highly repeatable, consistent and reliable method for manufacturing parts, but there are many factors that influence the quality of the end result. Parts that are designed for injection-molding need to have uniform wall thickness, draft angles, ribs and other structural features that are all well-engineered for best results. Also, it is important to keep in mind that the injection process itself is not very forgiving of flaws or defects in the part designs or the resulting mouldings. Various problems can occur during the injection process, including short shots, knit lines, trapped air and misaligned gates, and ejector pin marks. All of these can be avoided or minimized by good design and careful processing. Despite the many variables involved, injection molding products remain an increasingly popular choice for medical devices and other critical components that require tight tolerances and high levels of performance.

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