Glossary

A-Side
The stationary side of the injection mold, mounted on the side of the molding press where the resin is fed into the mold. Also known as the cavity side of the injection mold.

ABS (Acrylonitrile Butadiene Styrene)
ABS is among the most versatile resins in the styrene family and is used widely in plastic products because of its strength, limited shrinkage and availability. It is a terpolymer consisting of three distinct monomers (molecular units) produced from acrylonitrile and styrene liquids and butadiene gas.

Additive
Material added to a resin (raw plastic) to change or improve certain characteristics such as color, flexibility, strength, chemical resistance and flame retardance.

Alloy
In plastics, this term is used to describe blends of polymers or copolymers with other polymers or elastomers. The properties of the alloy usually exceed those of the individual components.

Anisotropy
The tendency of a material to react to stresses differently depending on the direction from which the force or stress is applied.

Annealing
The process of heating and gradually cooling a molded plastic part to prevent or remove stresses without distorting the shape of the part.

ANSI
Acronym for American National Standards Institute.

B-Side
The moving side of the injection mold that is mounted to the moving side of the molding press. Also called the core side of the mold, it is composed of the B-plate, the rails, the eject and return plates, the base plate and support pillars. The ejector pins in the B-side push the finished part out of the open mold.

Back Pressure
The resistance to forward flow of molten plastic. In injection molding, back pressure raises the temperature of the plastic and improves the mixing of additives such as colorant.

Balanced Runner
An injection molding runner system which allows all cavities in the mold to fill evenly and simultaneously. With an unbalanced runner, one cavity will completely fill before the other cavities, which often results in quality problems.

Band Heater
Electrical heating units attached to barrels and nozzles of injection-molding machines and extruders and used to heat a polymer to the desired temperature.

Barrel
The part of an injection-molding machine which contains the feeding screw and where the resin is made molten.

Bead Blast
A bead blast refers to one of the many finishes that can be put on a tool in order to change the appearance of the plastic parts. A bead blast can be light, moderate or heavy.

Bead Blasting
Using abrasives in a pressurized air blast to create a surface texture on a part.

Blister
A raised area, or a defect, on an injection-molded part caused by the pressure of gases inside on its incompletely hardened surface.

Blush
In injection molding, a blemish at the point of injection in the finished part.

Blushing
The tendency of plastic to turn white or lighter in places that are stressed, bent or deformed beyond the elasticity of the material.

Boss
A small projection from the surface of a molded part designed to add strength, to facilitate alignment with another part during assembly or to accept fasteners.

Bridge Tool
A temporary mold made to create production parts until a high-volume production mold can be made.

Burn
Black or brown burned areas on the surface of a plastic part due to too much energy applied for too long, a lack of venting, or an injection speed that is too high.

CAD (Computer-Aided Design)
The use of a computer program such as Solidworks^® or Pro/ENGINEER to create a scale computer model of a part or assembly of parts to be used for testing and making molds.

CAM (Computer-Assisted Machining or Computer-Aided Manufacturing)
Using computers and computer technology to control, manage, operate, and monitor tools and machinery in manufacturing processes. Computer-Aided Manufacturing refers to the use of computers and computer technology to assist in all operations of a manufacturing plant, including planning, management, transportation and storage.

Cast
Forming a plastic part or object by depositing a fluid monomer-polymer solution into an open mold where it finishes polymerization.

Cavity
The space in a mold into which resin is injected to form a plastic part. Molds are either single-cavity or multi-cavity molds.

Center-gated mold
An injection mold in which each cavity is fed through an opening (gate) at the center of the cavity area. This type of gating is used when forming items such as cups, bowls, and lids.

Clamp tonnage
The rated clamping capacity of an injection molding or transfer molding machine.

Clamping force or pressure
The force required to hold a mold shut so resin cannot escape during injection molding. This force is measured in tons, e.g., an 1100-ton press.

Cold Runner
Pathways, which carry the resin to the cavities within an injection mold, solidify during the molding process and are ejected with the plastic parts. Cold runners are considered engineered scrap.

Colorant
An additive to resin which results in a colored plastic part. A colorant can affect the base color and the hue and properties—such as fluorescence—without changing the strength or elasticity of the material.

Core
The eject side of a mold cavity (the B-side) that forms the inside of the part.

Cycle
One full sequence in a molding operation from the closing of the mold, injection of the resin, hardening of the part, opening of the mold and the ejection of the part.

Cycle Time
The amount of time required to complete one cycle. A shorter cycle time will allow a tool to produce more parts in an hour. Parts with thicker cross-sections typically require longer cycle times.

Double-shot molding
Producing plastic parts using two different types or colors of resins sequentially injected into the mold. Double-shot molding is often used to mold a softer rubber cover over part of a hard plastic part.

Drooling
The leakage of resin from the nozzle or nozzle area during injection in the injection-molding process.

Dryer
It is necessary to dry some plastics which have absorbed water before injection molding in order to reduce or prevent defects such as blistering and splay (a surface defect in a plastic part caused by escaping gas and water). A dryer is used to dry plastic resin.

Durometer hardness
A measure of the hardness of a resin as measured by a durometer which has a numeric scale where lower numbers indicate softer material and higher numbers harder material.

Dwell
A pause in the application of pressure to a mold, which is made just before closing the mold, to allow gas to escape from the molding material.

EDM (Electrical Discharge Machining)

A process to electrically remove material from the cavities of a mold and to create very small details and complex shapes.
Ejector pin
A rod or thin plate incorporated into the B-side of a mold which pushes the completed part out of the mold cavity. The ejector pin often leaves a small mark on the part, so designers normally try to avoid having ejector pins on cosmetic surfaces.

ERP (Enterprise Resource Planning)
Computer software used to assist with manufacturing plant operation from planning and management to transportation and storage.

Family mold
A multi-cavity mold where each of the cavities forms one of the component parts of an assembled finished object.

Flash
Plastic material which escapes from the mold during the injection process, solidifies and remains attached to the molded article as a thin protrusion. It can be removed by buffing, grinding, tumbling, or blasting after which the molded part is considered finished.

Flow
During the process of injection molding, the flow of a plastic is a measurement of its fluidity.

Flow Marks
Wavy surface appearances on a molded part which are indications of the flow of plastic within the mold prior to solidification, usually considered imperfections caused by improper flow of the melt into the mold.

Gate
Point within the injection mold where the resin enters the part cavity from the runner system. The gate often leaves a small mark on the plastic part.

Hot-runner mold
A mold in which the runners are insulated from the chilled cavities and are kept hot. Hot-runner molds make parts that leave no scrap.

In-mold labeling
A process for labeling or decorating a plastic object while the object is being formed in the mold.

Injection molding
A manufacturing process in which plastic is melted and injected into a mold containing a cavity in the shape of the desired plastic part. After cooling, the mold opens and the part is ejected.

Insert molding
An injection molding process in which molten plastic is injected into a mold cavity and around an insert piece or pieces placed into the same cavity prior to molding. This process is compatible with both thermoplastic and thermoset materials.

Mold
A hollow form or cavity into which plastic resin is injected to form a part. The term usually refers to the assembly of all the parts that function collectively in the molding process. It is also used to describe the action of forming the part.

Parting Line
The line where the two halves of an injection mold come together. The parting line is sometimes visible on the finished plastic part.

Prototype mold
A simplified mold often made from a light metal casting alloy or from an epoxy resin in order to evaluate design, form, and performance before the final manufacturing of a part or product.

Reinforced Plastic
A plastic material in which fibers or other reinforcements have been imbedded to give it greater strength and stiffness than the original base material.

Resin
The raw plastic as made by the manufacturer. It usually comes in the form of pellets that are about the size of small pebbles.

Runner
The channels in an injection mold that allow molten plastic to flow from the machine nozzle to the cavity.

Runner System
In injection molding, the entire system which directs resin into the molds. It includes sprues, runners and gates.

Sprue
The main feed channel that connects the mold-filling opening with the runners leading to each cavity gate.

Contact Bright Plastics

We hope you’ll contact Bright Plastics to learn more about our products and services. Call us at 336-668-3636, or email sales@brightplastics.com.