Glossary of Terms

Glossary of Terms


ABRASION RESISTANCE The ability to resist localized surface damage from contact with other material in use, such as gouging, grinding, scratching or erosion.
ANSI (American National Standards Institute) A privately funded, voluntary membership organization that identifies industrial and public needs for national consensus standards, and coordinates development of such standards. Many ANSI standards relate to the safe design and performance of equipment, such as safety shoes, eyeglasses, smoke detectors, fire pumps and household appliances; and safe practices or procedures, such as noise measurement, testing of fire extinguishers and flame arrestors, industrial lighting practices, and the use of abrasive wheels.
“A” PLATE Part of the stationary section of the mold into which the leader or guide pins are mounted. Also used to hold core, cavity blocks, and sprue bushing.
ASTM (American Society for Testing Materials) A voluntary membership organization with members from a broad spectrum of individuals, agencies, and industries concerned with materials. As the world’s largest source of voluntary consensus standards for materials, products, systems, and services, ASTM is a resource for sampling and testing methods, health and safety aspects of materials, safe performance guidelines, and effects of physical and biological agents and chemicals.
AUTOMATIC MOLD A mold designed and constructed in which the material is loaded into the mold and the finished parts are ejected from the mold without an operator.
BACK TAPER Sometimes called back draft or reverse draft.
BALANCED RUNNER SYSTEM A runner system that is designed to fill each mold cavity equally, continuously, and simultaneously.
BALL END MILL A hardened cutter, capable of machining a half-round slot, or shape into annealed metal using the milling machine.
BENCHING Term used to define the initial steps in polishing to prepare cavity and core blocks for the actual polishing process. 
BERYLLIUM COPPER Beryllium is added to copper to form a hard, strong alloy. It is excellent as a heat sink, or heat absorber, for a component portion of the mold that is hard to reach by typical cooling design. It can also be used to conduct heat.
BOTTOM CLAMPING PLATE Holds the moving portion of the mold to the movable platen of the injection machine.
“B” PLATE Top plate of the movable section of the mold. Forms the parting line of the mold with “A” plate. Used to hold the leader pin bushings as well as core and cavity blocks.
BUSHINGS Hardened and ground steel bushings which are pressed into one of the plates. They serve as bearing surfaces for the leader pins.
CAVITY The depression or female portion of the mold which gives the external surface to the part being produced.
CHILLING UNIT A mechanical refrigerator designed for outgoing water of a specific temperature. Ethylene glycol can be added to the water if a temperature below freezing is required.
COLD SLUG WELL A recess or groove, at the end of a long length that traps the leading cooled plastic. A Cold Slug Well is typically machined in a runner part of a balanced runner system, and can be used to prevent or minimize weld lines.
CONDUCTION Transferring heat from two or more bodies that are in contact with each other, such as heat conducted by mold-base steels.
CONVECTION The ability of a medium to carry heat from one place to another, such as coolant traveling through mold steel channels



COOLING CHANNELS Holes drilled into the various plates or into the various mold components, or channels machined into components, to allow the flow of a cooling medium (water) in order to keep the mold at the proper molding temperature.
COOLING TOWER Heated coolant from a mold is pumped to a cooling tower, inside or outside of the factory, where it falls by gravity past a grid. Some cooling takes place during the fall, but fans are typically used to add extra cooling. The cooled liquid is then collected and returned to pass through the mold again.
COOLING UNIT A mechanical refrigerator designed for outgoing water of a specific temperature. Ethylene glycol could be added to the water if temperatures below freezing were required.
COOLING UNIT A system of cooling channels and components designed to give effective cooling to a molded part or parts.
CORE The male portion of a mold that shapes the interior of a hollow molded part.
CORE PIN A pin for forming a hole or opening in a plastic molded piece.
CUSTOM MOLDS Molds owned by the customer and used by the molder.
CYCLE TIME The total time required to produce a molded part. Cycle time includes the time from the injection of the plastic resin into the mold, to the ejection of the molded part.
DEGATING Separation of the gate and runner system from the molded part. Degating can be done by hand, in a trim fixture, or automatically.
DEOXIDIZERS Elements added during the manufacture of steel to control the residual amount of oxygen that remains in the steel.
DIAMONDING Act of shining molding surfaces with diamond compound and brushes and buffs.
DIMENSIONAL STABILITY The ability of a plastic part to keep the precise shape in which it was molded.
EJECTOR PIN A pin (in a mold) that directly pushes the molded part out of the cavity. Sometimes called a knockout pin. A number of these pins may be used in one mold.
EJECTOR PLATE Bolted together with the ejector retainer plate to form a unit. Contains the plate for the pins in the ejector retainer plate.
EJECTOR RETAINER PLATE Counterbored for the heads of ejector, ejector return pins, and sprue puller pins.
ETHYLENE GLYCOL A colorless, viscous liquid used as antifreeze.
FATIGUE RESISTANCE The ability of a metal to resist fracture from repeated application of stresses. Fatigue failure usually occurs at loads which if applied statically would have little effect, but repeated cycles of the stress or strain lead to eventual failure.
FATIGUE STRENGTH The highest cyclic stress a material can withstand for a given number of cycles before failure occurs.
FLASH A thin piece of plastic material that typically forms along the parting line of a molded part. Flash is a result of a parting line surface or surfaces that is not matched or is shutting off the flow of plastic resin