Machining For Highly Accurate Mold Design

Plastic injection molding has actually changed the manufacturing world. Not only things have become easy, but also automated for accurate part production without serious defects. In order to obtain these highly accurate outcomes, manufacturers have to pay attention to the very beginning of mold shaping parts machining. The more accurate is the machining and tooling, the better the part outcome.

Mold design

Plastic injection mold has two basic components from the design aspect. The first is the cavity half of the mold, called A half; and the second is the ejector half of the mold, called B half.  These two halves have to work in conjunction to ensure better outcomes and hence machining has to be done accordingly.

This is how the two halves work after machining:

• Molten plastic enters the molding machine through a sprue or gate, present on the A half.

• Once the molten resin enters, sprue bushing seals tightly against the nozzle of the injection barrel of the machine. This is a critical step to allow the molten resin flow from the barrel into the cavity or mold.

• Sprue bushing also directs the resin through runners, machined into the faces of A and B halves.

• After flowing through runner, the molten plastic enters one or more specialized gates to enter the cavity for the formation of desired parts.

• A mold is designed in a way that the molded parts remain on the B half when the machine opens. Consequently, runners and sprue are drawn out of the H half so that the molded part falls out of the B part when ejection takes place.

Depending upon the manufacturing requirements, a single plastic injection molding can have one cavity to product one part at a time, or multiple cavities for high-production needs. Based on the needs, mold shaping parts machining takes place.