Mold Base Terminology - B

Back Pressures

The resistance of plastic material to flow during processing due to its viscosity.

Balanced Runner

For a molded part in a multi cavity mold to have a remote possibility of being the same the material should arrive at the gate in each cavity at the same time. As designers we were trained to use the geometrically balanced runner concept. This was achieved by making each path to the cavity the same distance from the nozzle to each cavity. This was thought to be the ultimate method for achieving perfect mold filling balance. Because we believed that consistent parts were desirable we forced this concept into our mold-quoting standard in mold making. We also quickly discovered that a balanced geometry could stay balanced if the cavity layout is mirrored. For example if a 2 cavity is balanced then a, 4 cavity is balanced and if a 4 cavity is balanced then an 8 cavity is balanced etc... for16, 32 and 64 and this is also why we quote molds in these cavitations. Then in some cases 3-cavity molds could be semi-balanced so we began quoting, 6,12,24, and 48 cavities.

Band Heater

Electrical heaters that are round and used as the primary source of heat on barrels and nozzles of injection molding machines and extruders.

Boring Mills (Horizontal)

These are used on any shape of work piece, holes, pockets, channels, ribs, slots, bores, counter bores, screws, and simple molding areas.

Bottom Clamp Plate

This is the bottom plate on the mold. This plate has knockout holes that interface with the press platens. It can also have clamp slots milled in to the sides if the rails are not recessed above.

Boss

Small projection from the part's surface designed to add strength, facilitate alignment with another part during assembly, or permit attachment to another part.

Burn

This is a result of having applied too much energy for too long to a polymer chain. Evidence of thermal decomposition is seen by some discoloration, distortion, or destruction of the surface of the plastic. Normally it is either black or brown depending in the plastic material type or additive and length of time the energy has been applied.

 

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