Injection molding materials

Injection Molding Plastic material

Pictures	Materials	Details	Service
	ABS	The opaque thermoplastic, it is an amorphous polymer comprised of three monome	Injection Molding
	Polycarbonate (PC)	Strong, tough materials, and some grades are optically transparent.	Injection Molding
	Polypropylene (PP)	Slightly harder than polyethylene, a commodity plastic with low density and high heat resistance. application in packaging, automotive, consumer goods, medical, cast films, etc.	Injection Molding
	Nylon	Excellent abrasion resistance, high impact strength and good mechanical properties.	Injection Molding
	POM	High mechanical strength and rigidity. POM material has very good sliding properties, excellent wear resistance and low moisture absorption.	Injection Molding
	PVC	Being hydrophobic, non-wetting, high density and resistant to high temperatures, PTFE is an incredibly versatile material with non-stick properties.	Injection Molding
	Polyethylen (PE)	It is available in different crystalline structures, referred to as HDPE, LDPE, and LLDPE.	Injection Molding
	Polystyrene (PS)	The thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde	Injection Molding
	TPU	Strong, lightweight, and stiff material that is made from thin, strong crystalline filaments of carbon.	Injection Molding

How to Select a Plastic for Injection Moulding

In moulding, the material choice is locked in for the life of the tool. Changing resin later means a new shrink rate, new tooling adjustments and a new validation cycle — so it pays to decide properly the first time.

Service temperature. The working temperature, not the peak, sets the shortlist. Continuous heat above a resin's limit causes creep and warpage.
Mechanical duty. Static housings tolerate cheap resins; snap fits, living hinges and load-bearing parts need tougher grades and careful gate design.
Chemical environment. Fuels, oils, cleaners and UV all eliminate certain resins immediately.
Appearance requirement. Some resins take a high-gloss Class A finish easily; others show flow marks and require more tool polish.
Cost at volume. Resin price is only part of it — cycle time, scrap rate and mould cooling all depend on the material.
Regulatory needs. Food contact, flame retardancy and medical grades are specific product families, not generic resins.

Shrinkage and Mould Design

Every resin shrinks as it cools from melt to solid, and the tool must be cut oversize to compensate. The problem is that shrinkage is not one number — it varies with wall thickness, flow direction and gate location.

Resin	Typical shrinkage	Design note
ABS	0.4–0.7 %	Predictable, forgiving, the default for enclosures
PC	0.5–0.7 %	Needs thorough drying; high melt viscosity
PP	1.0–2.5 %	High and direction-dependent; living hinges work well
PA (Nylon)	0.7–2.0 %	Moisture-sensitive; dimensions drift after moulding
POM	1.8–2.2 %	Low friction, excellent for precision moving parts

Uniform wall thickness is the single best defence against sink marks, warpage and internal stress. Where a thick section is unavoidable, core it out rather than accept a solid mass of plastic.

Common Moulding Resins at a Glance

ABS — tough, easy to mould, easy to paint and glue. The safe general-purpose choice.
PC — strong and transparent, but costly and demanding on the tool.
PP — chemically resistant and cheap; ideal for containers and living hinges.
PA (Nylon) — tough and wear-resistant for functional mechanical parts.
POM — stiff, low-friction and dimensionally stable for gears and slides.
TPE / TPU — soft-touch, flexible grips and seals moulded over a rigid core.

Fillers and Additives

Most production resins are not the base polymer alone. Glass fibre raises stiffness and cuts shrinkage; mineral fillers improve dimensional stability; UV stabilisers extend outdoor life; colour masterbatch sets the shade; flame retardants meet safety codes. Each addition changes the flow behaviour, so tell us the grade, not just the polymer name.

Frequently Asked Questions

How do I know which resin my part needs?

Start from the environment (temperature, chemicals, UV) and the mechanical duty, then let cost and appearance narrow the rest. Send the application details and we will shortlist grades for you.

Can I start with one resin and switch later?

Sometimes, but only within a family with similar shrinkage. A change from ABS to PP, for example, can require a different cavity size and new tooling work.

Do you make the mould as well as the parts?

Yes — tooling and moulding are handled together, which is why we can tune gate and cooling design to the resin you select rather than working around a fixed tool.

What is a reasonable order quantity?

Moulding becomes economical once tooling cost is spread over volume; below that, CNC machining or 3D printing is usually the cheaper route for the first parts.