Polystyrene Injection Molding

Polystyrene (PS) injection molding is a reliable process for producing lightweight and durable plastic parts.

We Provide Polystyrene Injection Molding Service to Match Your Needs!

Polystyrene (PS) injection molding is a common process we use when we need to make lightweight and rigid plastic parts at a lower cost. PS is easy to mold and holds its shape well, which makes it a good fit for parts that need fine details and smooth surfaces. We use this process a lot for things like consumer goods, packaging parts, and some basic industrial components—anywhere a clean, precise result is needed.

Custom PS injection molding for various applications
Able to run small batches or large volume production
Capable of both general-purpose or high-impact PS based on your needs
Can take care of extra steps like assembly or surface finishing
We check every batch to make sure quality stays consistent

Polystyrene Injection Molding Services

Service	Details
Maximum Part Size	2500mm x 2000mm (98 in. x 78 in.)
Recommended Wall Thickness	0.75 mm and 5 mm(0.030 to 0.200 inches)
Color Options	Any color according to RAL or Pantone Code
Standard Finishes	SPI and VDI
Mold Ownership	Customer owned with mold maintenance
Mold Life	Unlimited (If the PS injection mold worn out, Erye will cover the cost of new mold)

Polystyrene Injection Molding Design Guide

To get better results with PS molding, there are a few basic things we usually keep in mind:

Item	Description
Wall Thickness	Keep the wall thickness between 1.5–3.0 mm and try to keep it uniform. That helps prevent warping and stress spots. If you're working with thin-walled parts, PS can still mold down to about 0.8 mm.
Draft Angles for Ejection	Add draft angles to make demolding easier. For polished surfaces, go with at least 1.5°. If the surface has texture, 2–3° works better to avoid drag marks.
Ribs & Reinforcements	Ribs should be about 50–60% of the wall thickness. That gives strength without causing sink marks. We also add a fillet radius at the rib base, around 0.25 times the wall thickness, to cut down on stress buildup.
Shrinkage & Dimensional Stability	PS has pretty low shrinkage, around 0.3–0.6%, which makes it dimensionally stable. If you're using reinforced grades, expect even better performance and slightly lower shrinkage.
Snap-Fits & Living Hinges	When we design snap-fits in PS, we use fillets to avoid stress cracks. PS is on the brittle side, so it's not really suited for living hinges.

Start Polystyrene Injection Molding Project

Get high-quality PS injection molded parts! Contact with Erye to request a quote!

Advantages of Polystyrene Injection Molding

Low Production Cost

Polystyrene parts are very cost-effective, especially for high-volume production. If low unit cost is important, PS injection molding is often a strong option.

Good for Transparent Products

Certain PS grades offer excellent clarity. Customers often choose PS injection molding when they want a lightweight transparent plastic at a lower cost than acrylic or polycarbonate.

Lightweight

Polystyrene injection molding parts are lightweight, which helps reduce shipping cost, handling effort, and overall product weight.

High Dimensional Accuracy

PS injection molded parts can maintain good consistency and precise detail, which is helpful for products requiring repeatable dimensions.

Disadvantages of Polystyrene Injection Molding

Parts Can Crack or Break Easily

Standard PS is relatively brittle compared to materials like: ABS, Polypropylene, or Polycarbonate. If the product may be dropped, bent, or impacted during use or shipping, PS may not be the best choice.

Limited Durability for Long-Term Use

Polystyrene injection molding works well for disposable or short-life products, but it is generally less suitable for products expected to last many years under mechanical stress.

Lower Premium Feel

Although PS can look clean and glossy, it may feel less durable or “premium” compared with engineering plastics used in higher-end products.

Polystyrene Injection Molding Application

Packaging

Rigid food containers
Disposable cups and cutlery
CD and DVD cases
Cosmetic packaging

Consumer Goods

Household appliance casings
Stationery items (rulers, pen bodies)
Toys and figurines

Electronics

Battery housings
Electrical insulation components
TV and computer casings

Industrial & Construction

Light diffusers and panels
Insulating foam inserts
Disposable lab equipment

Additonal Options for Polystyrene Parts

What Exactly is PS Plastic?

Polystyrene (PS) is a cost-effective thermoplastic selected for parts that need good dimensional accuracy, smooth surface finish, rigidity, and easy processing. It is commonly used for injection molded housings, packaging components, display parts, appliance components, prototypes, and CNC machined parts where appearance, consistency, and manufacturing efficiency are important.

MATERIAL

PS

POLYSTYRENE

THERMOPLASTIC

MATERIAL FAMILY AMORPHOUS THERMOPLASTIC

DENSITY 1.04-1.07 g/cm³

SHRINKAGE RATE 0.3%-0.6%

TENSILE STRENGTH 35-60 MPa

WORKING TEMPERATURE Up to 80°C

IMPACT STRENGTH 15-30 J/m

KEY CHARACTERISTICS

Dimensional Accuracy Smooth Surface Low Cost Easy Processing

Case Study

Case Study of Automotive Glove Box Development

Learn how to help a customer move from an early glove box concept to a fully tooled, production-ready part. This case shows how we designed the mold, optimized the tooling, and reached reliable mass production.