Plastics Blow Molding 240

additives

A substance that is added to a material during manufacturing in order to improve its properties. Additives perform a range of functions, from changing the color of plastic to improving its strength.

biodegradable

Capable of being broken down and naturally absorbed into the ecosystem. Biodegradable materials degrade into simple stable compounds that are not harmful to the environment.

bioplastics

A plastic that is derived from a living source, such as plants. Bioplastics are often biodegradable.

blade

A cutting device that cuts a parison free from an extruder. Blades are commonly heated to prevent plastic from sticking to them.

blow molding

A plastic shaping process in which a heated tube of resin is clamped in a mold while positive air pressure blows the resin into the desired shape. Blow molding creates hollow products such as soft drink bottles and chemical drums.

chemical resistance

The ability of a material to resist chemical changes. Chemical resistance prevents gradual degradation caused by the atmosphere, moisture, or other substances.

compostable

Capable of being broken down and naturally absorbed into the ecosystem. Compostable materials degrade into natural chemicals that are not harmful to the environment and leave no residues.

continuous blow molding

An extrusion process in which the extruder continues to produce a parison while a product is being made in a mold. Continuous blow molding is best for products with short cooling times.

corrosion resistant

A material's ability to resist deterioration and chemical breakdown due to surface exposure in a particular environment. Corrosion resistant materials can extend the lifecycle of components that must be used in harsh operating environments.

cryogenic flash removal tumbler

A machine that freezes plastic parts and tumbles them to remove unwanted tags of material. Cryogenic flash removal tumblers resemble clothes dryers.

durability

The ability of materials to withstand extended exposure to environmental wear and mechanical forces. Durability is an advantage of plastics such as high-density polyethylene and polypropylene.

extruder

A machine that uses a screw to push melted plastic through a shaping die. Extruders create parisons in extrusion blow molding.

extrusion blow molding

A blow molding process in which a cylindrical soft plastic parison is formed using an extrusion machine and then inflated into a mold. Extrusion blow molding can create hollow plastic products such as soft drink bottles and chemical drums.

fatigue

The structural weakening of a material due to stress from repeated loads. Fatigue levels of a material can vary depending on exposure to temperatures and chemicals.

feed barrel

The holding chamber of an extrusion molding machine in which material is melted and mixed. The feed barrel is typically heated and contains a screw to move material through the barrel.

finishing processes

The treatment of a surface to remove roughness and irregularities and improve its appearance. Finishing processes include sanding, filing, and painting.

flashing

An undesired tag of material created when material gets pinched at the seam of a mold. Flashing can be removed by cutting it or by putting the part in a cryogenic flash removal tumbler.

granules

Small pieces of resin that can be melted and combined to form plastic parts. Granules are used in many extrusion processes.

high-density polyethylene

HDPE. A common thermoplastic known for its high strength-to-density ratio. High-density polyethylene is often used to make corrosion-resistant pipes, as well as bleach and detergent containers.

injection blow molding

A blow molding process in which a preform is heated and inflated into a mold. Injection blow molding can produce hollow plastic products such as soft drink bottles and chemical drums.

intermittent blow molding

An extrusion process in which the extruder screw stops pushing the melt through the feed barrel while a parison is in the mold. Intermittent blow molding is best for products with a slow cooling time.

low-density polyethylene

LDPE. A flexible and translucent polyethylene. Low-density polyethylene is often used to make transparent plastic wrap used in food manufacturing.

mechanical arms

An automated device that can manipulate objects. Mechanical arms move and transfer molds to collect parisons in some multi-mold systems.

melt

Liquified plastic material. Melt is produced when an extruder heats resin granules and pushes the material down the barrel.

mold

A hollow cavity used to shape material. Molds are used to shape parisons and preforms into products in blow molding, as well as to create preforms in injection blow molding.

multi-head transfer system

A type of extrusion machine that features multiple extruders. Multi-head transfer systems allow multiple parts to be produced simultaneously.

multi-mold systems

A type of parison transfer system in which a product can be formed in a mold while another product is being loaded into a mold. Multi-mold systems can use a number of molds depending on the required speed of the operation.

parison

A cylindrical tube of molten resin that is placed between mold halves in a blow molding process. Parisons expand to fill mold cavities.

parison transfer systems

A means of moving a parison to a mold. Parison transfer systems use a blade that cuts the parison away from the extruder and clings to the parison until it reaches the mold.

plastics

A lightweight polymer material that has high corrosion resistance, a high strength-to-weight ratio, and a low melting point. Most plastics are easily shaped and formed.

polyethylene terephthalate

PET. A common thermoplastic that is highly resistant to electricity and heat. Polyethylene is used in many products, including durable plastic bags and water bottles.

polyhydroxalkanoate

PHA. A naturally occurring bioplastic that is created through bacterial fermentation. Polyhydroxalkonate can be used to create plastic products that are compostable or biodegradable.

polylactic acid

PLA. A compostable thermoplastic in the polyester family. Polyactic acid is a natural polymer derived from corn starch and other renewable resources.

polypropylene

PP. A thermoplastic that is resistant to fatigue. Polypropylene is used in a wide range of products, from laboratory equipment to microwavable soup cans.

polyvinyl chloride

PVC. A thermoplastic that can be manufactured to produce both rigid and flexible materials. Polyvinyl chloride is used to manufacture many common products, such as corrosion-resistant pipes.

preform

A test-tube shaped plastic part that can be heated and inflated in a mold in injection blow molding. Preforms are created by injection molding and are then later used in blow molding.

rising mold system

A machine or component that brings molds to the parison in blow molding. Rising mold systems move the parison from the machine to an air nozzle, then dispense the completed part before returning for the next parison.

rotary wheel

A circular device with molds along its circumference. Rotary wheels are used in some multi-mold systems in blow molding.

round die

A component of an extruder with a circular opening used to shape plastic that is forced through or against it. Round dies are used in extrusion blow molding.

runners

Unwanted material caused by a channel in a die or mold that provides the path and delivers the molten material to the mold cavities. Runners often connect multiple parts in a mold.

screw

A component of an extrusion molding machine that melts the resin and builds up pressure. Screws push melted resin down the barrel and through a shaping die.

self-extinguishing

A property of a material in which it does not fuel a flame. Self-extinguishing plastics may break down with heat, but do not burn.

spider

A part of a round extrusion die featuring spokes that meet in the center on which an inner ring is attached. A spider allows melt to flow over it and around the inner ring, creating a tube.

sprues

Unwanted material caused by a channel where molten material enters a mold. Sprues must be removed during finishing.

strength-to-density ratio

A material’s strength divided by its mass. A material with a high strength-to-density ratio, like high-density polyethylene, is very strong relative to its light weight.

thermoplastics

A grouping of plastics that can be repeatedly reheated and re-shaped. Thermoplastics are the most commonly used plastics.

threaded

Having a long spiraling groove. Threaded objects can be securely connected to other compatible threaded objects.

threads

A long, spiraling ridge around the exterior or interior of a cylindrically shaped object. Threads are used to fasten or provide motion.

ultrasonic sensor

A type of sensor that detects a workpiece’s thickness by sending out a series of high-frequency sound waves and interpreting the sound that is returned to it. Ultrasonic sensors are extremely precise and can be used with almost any type of material.

ultraviolet degradation

UV degradation. The deterioration of a material due to overexposure to the ultraviolet radiation in sunlight. Ultraviolet degradation in plastic can be reduced by using additives during the manufacturing process.

ultraviolet inhibitor

UV inhibitor. A chemical additive that helps to prevent ultraviolet degradation in plastics. Ultraviolet inhibitors include iron oxide and carbon black.

Vickers hardness test

A hardness test that forces a pyramid-shaped diamond against a material for a standard dwell time to create an indentation. The Vickers hardness test is also known as the diamond pyramid hardness test.