(A)
Age Hardening(precipitation hardening)
A process of aging which increases strength and hardness and ordinarily decreases the ductility. An Age hardening process usually follows speedy cooling from solution heat treatment temperatures.
Alloy
Material that displays metallic properties and is composed typically of two or more chemical elements, one being always metal. The properties of alloy are usually different from those of its components. (B)
Bar
Bar is a solid section that is relatively long in comparison to its cross-sectional dimensions. It has a symmetrical cross-section which can be square or rectangular (excluding flattened wire) with corners that are sharp round corners.
Billet
Billet is a cast bar that can be solid semi-finished round, square or rectangular. Billets are produced in different diameters, lengths and sizes for use in extrusion process.


(C)
Cable Sheathing
Cable sheathing is the technique of extruding tube around another product, like an insulated cable; the cable acting as a moving mandrel.
Core
Core is a mandrel that is fixed in relation to the die which manufactures hollow or semi-hollow sections. For example in a typical bridge die, the mandrel is integral with the bridge.

(D)
Die
Die is a unit of press tooling that has one or more machined openings to produce the desired extruded parts or sections.
Drawing
Drawing can reduce both wall thickness as well as outside diameter of tubing. It is basically a cold working process where an extruded tube bloom is elongated by pulled it through a tapered die or series of tapered dies. A mandrel ascertains the inside diameter.

(E)
Extrusion
Extrusion process is the conversion of billets into lengths of uniform cross-section by the method of forcing plastic metal via a die orifice of the required cross-sectional outline.
Electrical Conductivity
Electrical conductivity is the capacity of a material for conducting or permitting the flow of an electric current.

(F)
Finishing
Finishing is basically a secondary operation that is applied to extrusions for improving the product dimensionally or inducing a change in the surface condition (etching) or color (powder coating, anodizing, etc).

(G)
Grain
Grains are individual crystals that make up the crystalline structure of metal.

(H)
Heat Treatment
Heat treatment is the sequence of steps comprising heating and subsequent fast or slow cooling of aluminum. This helps to change its physical or mechanical properties or to stabilize its dimensions.
Hollow dies
Hollow dies can take variety of forms such as bridge, porthole, and spider dies. A popular variety is the pancake form, which costs less and is easy to make. Extruded sections manufactured on such type of die have more than one seam or longitudinal weld lines, this is due to the metal flow around the supports for holding the stub mandrel.

(I)
Inclusions
Inclusions are impurities like, flux, oxides, refractories, etc. They get trapped in the metal in an ongoing solidification process.
Ingot
Ingots are melted for making cast logs; these are then cut to pieces for the production of extrusion billets.

(L)
Lubricant
Lubricant is the liquids or semi-solids like oil, kerosene, grease, lard, fat, soap, tallow and wax that is used on metal for reducing friction and binding during the extruding operations.

(M)
Mandrel
Mandrel is the projection, that is fixed or floating, placed in the die opening. It forces the metal to flow around it. An extrusion's wall thickness is ascertained by the difference in the diameters of the mandrel and die aperture.
Maximum Speed
Maximum speed is the fastest practical rate for extruding.
Metal Flow
Metal flow is the fashion in which the metal moves in the container as well as through the extrusion die.

(N)
Natural Aging
It is spontaneous aging at room temperature of a supersaturated solid solution

(O)
Orientation (laying out)
It is the positioning of die openings for the best shape and consequent flow distribution.

(P)
Plastic
Plastic is the property of a metal that permits it to deform non-elastically wit hout having any rupture.

(Q)
Quench
Quench is the quick cooling of metal from above the critical range in a quenching medium. It is generally oil or water, but often air.

(R)
Ram
Ram and stem are generally interchangeable terms that describes extensions of the main cylinder in the extrusion press. It is basically the component that applies force against a dummy block.
Reduction Ratio (extrusion ratio)
Reduction ratio is ascertained by the cross-sectional area of the billet or container divided by cross-sectional area of the combined die openings.

(S)
Solid Dies
Solid die is a steel disk that has more than one orifice or aperture of similar cross-sectional area and contour as of the desired product. It is via this the metal is forced. These dies are generally used where non hollow shapes are needed.
Stepped Extrusion
Stepped extrusion is a process that is similar to a conventional extrusion process. However here the extrusion press is stopped as soon as the billet is partially extruded. The split dies are subsequently removed and replaced with dies having a larger opening or orifice. Extrusion is then again resumed.

(T)
Tensile Strength
Tensile strength is the maximum tensile stress which a material can withstand without breaking when load is gradually and uniformly applied.
Tongue
Tongue is that component of a die base metal which is surrounded by the aperture except at one end.

(W)
Water Stain
Water stain is a superficial etching of the surface that happens from prolonged contact with moisture in limited air space. These stains are generally white or gray in appearance.


Plastic and Rubber Extrusion Glossary

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

(A)
Abrasion Resistance
Abrasion resistance refers to the exceptional ability for withstanding repeated scraping, wearing and rubbing which could remove material from its surface.
Additives
Additives refer to extremely diverse group of specialty chemicals which are generally mixed or incorporated into plastic formulations both during processing, or applied to the outside surfaces of finished products after the end of processing operation. The basic aim is to alter the behaviour of plastics during processing for imparting properties that would be useful to the end products.
Adiabatic
Adiabatic refers to the process in which there is no addition or removal of heat.
Anneal
Anneal is the process to remove or prevent stress from plastic by applying a controlled cooling process.

(B)
Blow Moulding
Blow moulding is the process that is used for producing hollow thermoplastic shapes. It is divided into two categories extrusion and injection blow moulding. It is typically used for making items like plastic bottles.
Barrier screws
Barrier screw is the place where a second flight (barrier), that has a larger radial clearance as compared to a normal flight, separates the solid bed from melt in a compression section. Barrier screws comes with a higher melting capacity than any conventional screw. Bond strength: Bond strength is the measure of force needed to separate objects or materials that are bonded together.

(C)
Coefficient of Thermal Expansion
Coefficient of thermal expansion refers to the quantum of change in dimension of a material relative to its temperature change.
Cord
Cord is an extruded section that has a circular profile, they are joined for making O Rings or seals.
Co-extrusion
Coextrusion is the process where parts are typically blow-moulded using a layer of more than two different materials. This process is perfectly suited for recycled materials. High quality plastic can be used outside and recycled plastic are used inside.

(D)
Dissipation
Unused or lost energy

(E)
Elastomer
A material that at normal temperature temperature stretches under low stress condition to at least double its length and then goes back to the original length as soon as the stress is released.

(F)
Flexural Strength
The ability of the plastic to resist bending stresses.
Formulation
The mixture of two or more raw ingredients before a final product is made.
FEP
FEP is the shorter version of Fluorinated ethylene propylene.

(G)
Granulating
The process of size-reduction using a machine for cutting or chopping plastic into smaller parts in order to prepare them for recycling.
Gasket
Gasket is a flexible sealing device that is applied for providing a seal between two or more surface. Gaskets can be punched out of sheet or even a strip material for providing a simple seal or they can be extruded into a complicated shape for more challenging applications. Gaskets can be made out of many materials but rubber or softer plastic (e.g. PVC ) is preferred.

(H)
Hose
Hose is the generic term used for tubular profile that comes with a reinforcement for providing extra flexibility and pressure resistance.

(N)
Natural Rubber
Natural rubber offers a wide range of hardnesses. They are strong (naturally self-reinforcing) and offers very good resistance. They have a comparatively low maximum temperatures (75°C - continuous, 100°C- intermittent). Disadvantage is in the form of poor ozone resistance, and a propensity for perishing in open air.
NBR(Nitrile Based Rubber)
NBR is a copolymer formed by butadiene and acrylonitrile (ACN). It is of low cost: Temperature Range: -40° to +225° F. They offer high tensile strength. Other properties include excellent tear, abrasion, and compression set resistance. Additionally they offer excellent aging properties when put under severe operating conditions.

(P)
Purging
Purging is the process of cleaning of one type of material or color from an extruder. This done by forcing it out with a new material or color. Sometimes special purging substances can also be used. Purging is generally more efficient in case the purging material is more viscous than the material which is being replaced.

(R)
Reactive extrusion
Reactive extrusion is a technique that uses twin screw extruder as a continuous reactor for completing chemical reactions.

(S)
Strain
Strain is the technical term that is synonymous with deformation.

(T)
Thermal mechanical analysis (TMA)
In this process a sample is allowed to deform under a static load when the temperature is being changed. Along with glass transition and softening points the amount of orientation is also measurable by TMA.

(V)
Vulcanization
Vulcanization is an irreversible process. In this process a rubber or polymeric compound undergoes a change in its chemical structure (i.e. Crosslinking), to become thermoset (with improved chemical resistance, extending elastic properties over a more broad range of temperature).