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An Introduction To Injection Molding | Resin Types | Terminology

Knowledge: About Injection Molding

Injection Molding Material Selection Expertise

Selecting the correct material for each application requires in-depth knowledge of injection molding resins, as well as a thorough understanding of the product’s application.

At Ayanna Plastics & Engineering, we offer our customers a variety of injection molding resins and injection molding materials, from commodity grades to engineering grades. We also make it our business to understand our customers’ needs to make the best recommendations regarding material choices.

As an engineering and plastic injection molding company, we do not limit the types of materials we process. There more than 8,000 injection molding resins on the market today, and we partner with our resin suppliers to find the best solution for our customers. We bring you access to some of the most knowledgeable distributors in the industry.

The resins listed below are merely a sampling of the most common injection molding materials.

ABS (Acrylanitrile Butadiene Styrene)
ABS + PC (ABS + Polycarbonate)
Acetal (POM)
PA-Nylon 6 (Polyamide)
PA-Nylon 6/6 (Polyamide)
PA-Nylon 11 (Polyamide)
PBT (Polybutylene Terepthalate)
PC (Polycarbonate)
PEI (Polyetherimid)
PE (Polyethylene)
LDPE (Low Density Polyethylene)
HDPE (High Density Polyethylene)
PET (Polyethylene Terepthalate)
PP (Polypropylene)
PPA (Polyphthalamide)
PPS (Polyphenylene Sulfide)
PS (Polystyrene)
HIPS (High Impact Polystyrene)
PSU (Polysulfone)
PU (Polyurethane)
SAN (Styrene Acrylonitrile)
TPE (Thermoplastic Elastomer)
TPU (Thermoplastic Polyurethane)

If you would like to research any of these materials in more detail, follow these links to industry sources:
www.ides.com
www.matweb.com
www.entecpolymers.com
www.ptsllc.com

ABS (Acrylanitrile Butadiene Styrene)

ABS plastics provide a balanced combination of mechanical toughness, wide temperature range, good dimensional stability, chemical resistance, electrical insulating properties, and ease of processing. ABS plastic is available in a wide range of grades including medium and high-impact, heat-resistant, plateable fire-retardant, and both low- and high-gloss varieties.

Computer housings, small appliances, automotive interior trim, medical components and thin-walled parts

Good impact resistance with toughness and rigidity
Metal coatings have excellent adhesion to ABS
Ease of processing and appearance
Wide range of additives available

Not weather resistant
Low dielectric strength (not a good insulator)
Low continuous service temperature (melts easily)
Price varies greatly depending on grade

ABS + PC (ABS + Polycarbonate)

PC + ABS plastics offers the properties of both PC and ABS including the strength and heat resistance of PC and the flexibility of ABS with exceptional low temperature impact strength. The material can be modified by additives such as glass fiber, mineral fillers and flame retardants.

Medical hardware, electrical housings, computers, monitors, business equipment housings and enclosures

Good impact resistance with toughness and rigidity
even at cold temperatures
Metal coatings have excellent adhesion to ABS
Very good indoor UV light color stability
Ease of processing and appearance
Wide range of additives available

Not weather resistant
Low dielectric strength (not a good insulator)
Low continuous service temperature (melts easily)

Acetal (POM) (Polyoxymethylene)

Acetal polymers are high crystalline. POM is a high strength and stiff polymer with electrical properties, inherent lubricity, fatigue resistance, and chemical resistance. Acetals are brittle at low temperatures. Glass-filled and added-lubrication grades are available.

Gears, bearings, automotive, industrial, machines and appliances

High tensile strength with rigidity and toughness
Good impact and solvent resistance
Glossy molded surface
Low static and dynamic coefficients of friction (slippery)
Many grades have FDA and NSF approvals on food and water contact

Difficult to bond
Poor resistance to acid and bases
Not flame retardant
Subject to UV degradation

Nylon 6-PA (Polyamide)
Nylons are semi-crystalline polymers with a good range of properties. Nylons are widely used because they have a good cost-to-performance ratio. Lower numbered nylons, 6, 6-6, 4-6, absorb moisture and change their properties as a result. Nylons have been compounded with reinforcements, fillers and additives to produce a very wide variety of properties. Nylon 6 has the lowest modulus of all nylon grades.

Zip fasteners, gears, gun frames, instrument strings, surgical sutures, bearing, electronic components,

Temperature capability 600°-700° for short term
Excellent chemical resistance
High resistance to abrasion
Tough and withstands repeated impact

Absorbs moisture (can affect the electrical and mechanical properties)
Requires UV stability
Attacked by strong acids/bases
High notch sensitivity

Nylon 66-PA (Polyamide)
Nylons are semi-crystalline polymers with a good range of properties. Nylons are widely used because they have a good cost-to-performance ratio. Lower numbered nylons, 6, 6-6, 4-6, absorb moisture and change their properties as a result. Nylons have been compounded with reinforcements, fillers and additives to produce a very wide variety of properties. Nylon 6-6 offers better properties than nylon 6 without being as costly as nylon 4-6. It has the best abrasion resistance of all nylons. Verton, long glass fiber filled materials, by LNP, are excellent metal replacement materials.

Automotive components, electronic connectors, gears, cable ties and power tool housings

Temperature capability 600°-700° for short term
Excellent chemical resistance
High resistance to abrasion
Tough and withstands repeated impact

Absorbs moisture (can affect the electrical and mechanical properties)
Requires UV stability
Attacked by strong acids/bases
High notch sensitivity

Nylon 11-PA (Polyamide)
Nylons are semi-crystalline polymers with a good range of properties. Nylons are widely used because they have a good cost-to-performance ratio. Lower numbered nylons, 6 ,6-6, 4-6, absorb moisture and change their properties as a result. Nylons have been compounded with reinforcements, fillers and additives to produce a very wide variety of properties. Nylon 11 offers better impact strength and dimensional stability than lower numbered nylons. It is also more flexible.

Automotive components, electronic connectors, gears, cable ties and power tool housings

Temperature capability 600°-700° for short term
Excellent chemical resistance
High resistance to abrasion
Tough and withstands repeated impact

Absorbs moisture (can affect the electrical and mechanical properties)
Requires UV stability
Attacked by strong acids/bases
High notch sensitivity

PBT Polyester (Polybutylene Terepthalate)
PBT polyesters are semi-crystalline. They are versatile materials with a good range of properties. They have excellent electrical properties and are abrasion resistant. PBT has been extensively compounded giving a very wide range of properties. PBT performs much like Nylon but can handle higher temperatures and does not absorb moisture. PBT has excellent impact strength but is very notch sensitive. PBT is very anisotropic in shrinkage, so it is difficult to mold to extremely tight tolerances.

Industrial equipment applications, business equipment, automotive housings-under the hood, power tool housings

Good flow
Tough
Hydrollysis resistant
High impact
Easily processed

Low maximum-use temperature
Lower stiffness than similar PET
Lower strength than similar PET
Attacked by strong bases

PC (Polycarbonate)
Polycarbonate is an amorphous material with excellent impact strength, clarity, and optical properties. It is very widely used and a wide variety of compounds are available. Polycarbonate has excellent mechanical properties, and can be molded to tight tolerances. It is not very resistant to solvents and petrochemicals, and its weather resistance is only adequate.

Automotive headlights, business machines, consumer products, telecommunications, medical products and mechanical goods

High impact resistance
Clarity
Good flammability performance
Dimensional stability
Chemical resistance (PC blends)

Only fair solvent resistance
Subject to stress cracking
Degrades if not processed correctly
High processing temperature
Yellowing after long-term exposure to UV light

PEI (Polyetherimid)
PEI is an amorphous, high temperature material with relatively low cost compared to other high temperature materials. It has excellent elongation and impact strength, and can be molded to tight tolerances. Its chemical resistance is not as good as crystalline materials but is excellent for an amorphous material. PEI behaves similar to polycarbonate, but can perform at higher temperatures.

Commercial aircraft interiors, healthcare products, cooking utensils, fiber optics, electrical and electronic applications

High heat resistance
Exceptional strength and impact modulus
High dielectric strength
Broad chemical resistance
Biocompatible
Excellent machinability and finishing characteristics
Very easy to process on conventional molding equipment
Flame resistance with low smoke evolution

Translucent and opaque-clear is not available
High cost
Notch sensitive
High processing temps required

PE (Polyethylene)
Polyethylene is a widely used, inexpensive, thermoplastic. It has good inherent lubricity, and is easy to process. Polyethylene has good to excellent chemical resistance. It is also soft and cannot be used in temperatures much above 150. As a family, they are light in weight and possess toughness, chemical resistance, impermeability as well as excellent electrical insulating properties.

Consumer products, houseware items, electronic wire/cable insulators and medical products

Low cost
Impact resistance from -40° to 194° F
Moisture resistance
Food grades available

Poor weather resistance
High thermal expansion
Subject to stress cracking
Difficult to bond
Flammable
Poor temperature capability

LDPE (Low Density Polyethylene)
Polyethylene is a widely used, inexpensive, thermoplastic. It has good inherent lubricity, and is easy to process. Polyethylene has good to excellent chemical resistance. It is also soft and cannot be used in temperatures much above 150. As a family, they are light in weight and possess toughness, chemical resistance, impermeability as well as excellent electrical insulating properties. Low density polyethylene is the softest and most flexible version of this material. It has high elongation giving it excellent impact strength. This is offset by its permanent deformation upon impact.

Consumer products, houseware items, electronic wire/cable insulators and medical products

Low cost
Impact resistance from -40° to 194° F
Moisture resistance

Food grades available

Poor weather resistance
High thermal expansion
Subject to stress cracking
Difficult to bond
Flammable
Poor temperature capability

HDPE (High Density Polyethylene)
Polyethylene is a widely used, inexpensive, thermoplastic. It has good inherent lubricity, and is easy to process. Polyethylene has good to excellent chemical resistance. It is also soft and cannot be used in temperatures much above 150. As a family, they are light in weight and possess toughness, chemical resistance, impermeability as well as excellent electrical insulating properties. High density polyethylene is the hardest and stiffest version of this material. It does not have the impact strength of low density, but is more resilient.

Consumer products, houseware items, electronic wire/cable insulators and medical products

Low cost
Impact resistance from -40° to 194° F
Moisture resistance
Food grades available

Poor weather resistance
High thermal expansion
Subject to stress cracking
Difficult to bond

PET Polyester (Polyethylene Terepthalate)
PET polyesters are semi-crystalline. They are versatile materials with a good range of properties. They have excellent electrical properties and are abrasion resistant. PET has not been as extensively compounded as PBT because it is more difficult to process. PET has a higher modulus than PBT. Like PBT, PET is very anisotropic in shrink; therefore, it is difficult to mold to extremely close tolerances.

Reusable bottles, pacifiers, sippy cups, medical devices, housewares

High temperature resistance
Some grades FDA approved
Excellent toughness
Excellent clarity
Easy processing

Highly susceptible to degradation when heated above 150°C in the presence of moisture
Cannot be exposed to elevated temperatures
Must be thoroughly dried prior to processing

PP (Polypropylene)
Polypropylene is a widely used, semi-crystalline material. It has been extensively compounded to provide a wide range of properties at a wide range of costs. In general, polypropylene is a low temperature material with excellent chemical resistance. It has no known solvent at 73 F. Polypropylene is difficult to mold to extremely close tolerances.

Packaging, industrial components for fluid processing, household goods, automotive and electrical hardware

Excellent moisture resistance
Food grades available
Mold-in hinge possible
Good impact strength

Degraded by UV
Flammable (retardant grades available)
Attacked by chlorinated solvents

PPA (Polyphthalamide)
PPA is a relatively new, semi-crystalline material, with an excellent cost-to-performance ratio. PPA bridges the performance gap between nylons/polyesters, and higher priced, high temperature materials such as PEI and PEEK. PPA has excellent impact strength and is not notch sensitive. PPA does absorb moisture, and its properties change as a result. This change is not nearly as great as 6-6 nylon. Despite its relatively recent introduction, good design data is available for PPA.

Automotive applications, housing for high temperature electrical connectors, multiple other uses as a replacement to metals

Heat resistance
Chemical resistance
Can resist infrared soldering environments
Relatively low moisture absorption
Strength or physical properties

Not inherently flame retardant
Requires good drying equipment
High processing temperatures

PPS (Polyphenylene Sulfide)
PPS is a high temperature semi-crystalline material. It has good mechanical properties and excellent chemical resistance at elevated temperatures. PPS has been compounded extensively and many different types of properties are available. PTFE filled PPS is one of the best bearing materials available. Unfilled grades of PPS have poor properties, so components are usually made from glass filled or glass/mineral filled grades. PPS is very sensitive to molding conditions and must be processed properly to achieve its maximum potential.

Hydraulic components, bearings, cams, valves and electronic parts

Capable of extended usage at 450° F
Good radiation resistance
Good solvent and chemical resistance
Excellent dimensional stability
Flame retardant
Low water absorption

Difficult to process (high melt temps)
High cost
Fillers required to obtain good impact strength
Attacked by chlorinated hydrocarbons

PS (Polystyrene Crystal)
Crystal polystyrene is the cheapest thermoplastic available. It has properties to match its price. It is transparent and has good optical properties. It has very low impact strength.

Household goods, containers, furniture, housings and packaging.

Optical clarity
High gloss
FDA grades available
Low cost
Good dimensional stability

Flammable, but flame retardant grades available
Poor solvent resistance
Homopolymers are brittle

HIPS (High Impact Polystyrene)
High Impact Polystyrene is what its name implies. A few cents more than crystal styrene, to pay for the rubber modifier. HIPS is opaque and very widely used. It has a lower modulus, better elongation, and is a lot less brittle than crystal styrene.

Household goods, containers, furniture, housings and packaging

Optical clarity
High gloss
FDA grades available
Low cost
Good dimensional stability
Good rigidity

Flammable, but flame retardant grades available
Poor solvent resistance
Homopolymers are brittle
Subject to stress and environmental cracking

PSU (Polysulfone)
Polysulfone is a high temperature amorphous material with relatively low cost. It is transparent and can be used at temperatures of up to 300 F. Polysulfone has been compounded, with glass- and mineral-filled grades available.

Appliance parts, electronic parts, automotive parts, medical components, business equipment, aerospace and insulators

Good thermal stability
Transparent
Tough and rigid
Chemical resistance

Attacked by many solvents
Poor weatherability
Subject to stress cracks
High processing temperature

PU (Polyurethane)
Polyurethane is a resilient, extremely tough abrasion and tear resistant elastomeric material that is available in ether and ester based formulations. These diverse formulations cover an extremely wide range of stiffness, hardness, and densities. These materials offer good chemical resistance, and are transparent in unfilled grades.

Appliance parts, electronic parts, automotive parts, medical components, business equipment, aerospace and insulators

High tensile strength
Chemical and heat resistant
Low temperature flexibility
Abrasion resistant

Can be adversely affected by direct sunlight
Attacked by organic solvents

SAN (Styrene Acrylonitrile)
SAN is ABS without the Butadiene. It does not have the Impact Strength of ABS, but can be crystal clear. Styrene Acrylonitrile has better general chemical resistance than polystyrene and is cheaper than acrylic. It has a good combination of rigidity, strength, toughness and transparency.

Battery cases, dials, knobs, switches, lenses, trays, containers, covers, dental & medical light diffusers

Heat resistant
High clarity
High flow and rigidity
Dimensionally stable

Low impact strength
High processing temps
Flammable – smoke generation

TPE (Thermoplastic Elastomer)
Thermoplastic elastomers (TPE) are a combination of polymers (usually a plastic and a rubber) which consist of both thermoplastic and elastomeric properties, resulting in a product that is extremely easy to use in manufacturing a variety of products. TPEs require little or no compounding and no need to add reinforcing agents, stabilizers or cure systems.

Automotive fluid delivery systems, household appliances, sporting goods, electrical and medical components

Low compression and tension set
Easily processed
Fatigue resistance
Good tear strength

Flammable but flame retardant grades available
Extensive heat aging causes severe change in mechanical properties
High cost

TPU (Thermoplastic Polyurethane Elastomer)
Thermoplastic polyurethane elastomers exhibit excellent abrasion and wear resistance and high tensile and tear strengths. TPUs are tough, durable, easy to clean and well-suited to applications that demand the elasticity of rubber combined with high stability. In addition, the inherent translucency of these products makes it easy to color and that is an added benefit in many applications.

Automotive and aerospace applications, medical and optical purposes, electrical wire and cable coverings

Chemical resistant
Low temperature flexibility
Abrasion and wear resistant

Shorter shelf life
Lower stiffness than similar PET
Drying required pre-processing
Narrow hardness range

Knowledge: About Injection Molding

Injection Molding Material Selection Expertise

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