Mold Base Terminology - P

Packing

Filling the mold cavity/cavities as full as possible without causing undue stress on the molds or causing flash to appear on the molding.

Pipe Fittings

These are standard pipes that allow for quick disconnects. They are used to connect the hoses to the water manifold to the press. In some case quick disconnects are added to so the mold setting time is reduced. Care must be taken when using the quick disconnects so they do not impede the flow of the water. If the quick disconnect is smaller in diameter than the waterline the water flow is restricted and may result in a laminar flow that will reduce the effectiveness of the water cooling

Pipe Nipples

These extensions to the waterline from the component allow hoses or connectors to be added between the component and the plate. The mold set up department should make sure that the fittings do not restrict the water flow. Sometimes, inadvertently, the flow will be impeded the water flow and will become laminar, reducing the effectiveness of the cooling line

Pipe Plugs

Pipe plugs are used to plug water lines that are drilled into plate components, cores and cavities. Typically the plugs sizes are 1/16 to % N.P.T. standard.

Pinpoint Gate

Gate in an injection mold that is approximately 0.030 inches in diameter. This small gate minimizes the size of the mark left on the molded part.

Projected Area

This consists of the area of the part that faces you when you look inside a mold. One simple way to describe it is that if you were to shine light on the part the projected area would be the shadow. Once you calculate the projected area you can use a general rule of 3-ton/square inch calculation for most crystalline materials to calculate the amount of force the part has generated during the molding process.

Calculating Projected Area: If a projected area of a part is 635 mm (25 in) and you use 3 tons per square inch you will need to generate 75 ton per part. If you have a four-cavity mold this would require a press that has 300 tons of clamping force. By stacking another mold on top the opposing forces would cancel out the force in one direction this allows you to add 4 more cavities in the press that would normally require 600 ton press. By reducing the press size the press rates for a 600-ton would be less than a 300 ton press thus reducing the overall cost to produce the product.

Molder friendly Design Tip - When you need to calculate the projected area of a part that has an irregular shape you can lay the part on a 1"gridpaper and trace the part then count the squares that are filled up. Then count the ones that are half filled divide by two and add it to the amount of full squares. Then you should have a close idea of the projected area.

Prototype

A model suitable for use in complete evaluation of form, design, and performance.

Pry Slots

These are milled slots used to help the toolmaker disassemble the plate. The size of the slots will allow for most standard pry bars to be place between the plates and force the plates a part. Without the pry slots tool disassembly can be very difficult, especially when plates are doweled together.

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