Process
Injection moulding (IM)
Injection moulding (IM) is a high-precision manufacturing process that is particularly suitable for producing complex rubber moulded parts in large quantities.
Also known as
Injection moulding
Precision
very high
Cavities per mould
16, 32, 64 or 128
Series
high quantities
Overview
What is injection moulding?
Injection moulding (IM) is a high-precision manufacturing process that is particularly suitable for producing complex rubber moulded parts in large quantities.
In the IM process, the raw material is injected under high pressure and with precise temperature control through runners into a closed mould, where it is vulcanised in so-called cavities. The usual mould design mostly has 16, 32, 64 or 128 cavities. Each heating cycle produces the corresponding number of parts.
We also injection-mould moulded parts and moulded sealing rings for drinking water applications, for example from EPDM blue or from EPDM compounds with KTW-BWGL certificate or conformity. More under drinking water.
Process sequence
The injection moulding process sequence
- 01
Material feed
The unvulcanised rubber compound is drawn in by a screw and usually fed into the machine through a kind of hopper.
- 02
Plasticisation
A screw or piston brings the material up to processing temperature.
- 03
Injection
The prepared material is injected through runners into the closed mould.
- 04
Vulcanisation
The material is vulcanised in the mould at a temperature designed for the respective elastomer.
- 05
Demoulding
After curing, the mould opens and the component is removed from the cavities by air pressure or automatically by pickers (grippers).
Advantages
Advantages of injection moulding
- High-precision production of rubber parts with tight tolerances
- Process can be automated for high quantities
- Less material waste thanks to optimised runner systems
- Excellent reproducibility and consistency
- Very good process control for uniform vulcanisation
Runners
Their importance in the injection moulding process
Runners are an essential part of the injection moulding process, as they control how the material is distributed in the mould.
Cold runner system
Minimises material losses, as the unvulcanised material can be reused.
Hot runner system
Enables precise control of the material feed and reduces rework.
Pin-point gate
Used for small, precise components.
Film gate
Ensures uniform material distribution over a large area.
Materials
Suitable materials
EPDM
High resistance to weathering and ozone, ideal for seals.
FKM (Viton)
Chemical resistance and high temperature stability.
NBR
Resistance to oil and fuel.
Silicone (VMQ)
Very high temperature resistance, suitable for food contact.
TPE
Very flexible, good resistance to weathering and chemicals, easily recyclable and free from plasticisers.
Applications
Typical areas of application
- Automotive industry
- High-precision seals, engine mounts, buffers, bellows and rubber-to-metal bonded parts.
- Electrical engineering
- Connectors, insulators, multiple sealing inserts and cable bushings.
- Medical technology
- Medical seals and biocompatible moulded parts.
- Mechanical engineering
- Vibration dampers, moulded parts for hydraulic and pneumatic systems.
Process comparison
Injection, compression and transfer moulding
| Criterion | Injection moulding (IM) | Compression moulding (CM) | Transfer moulding (TM) |
|---|---|---|---|
| Precision | Very high | Medium | High |
| Complex geometries | Yes | Limited | Yes |
| Production speed | Fast | Slower | Medium |
| Material loss | Low (with cold runner) | Higher | Medium |
| Post-processing | Minimal | Usually required | Less than with compression moulding |
Optimisation
Optimisation options in injection moulding
Process simulation
Computer-aided simulations help to avoid air pockets and develop optimal filling patterns.
Automation
Robotics and sensors improve efficiency and quality assurance.
Reducing material consumption
Cold runner systems and optimised injection points minimise material waste.
Injection moulding offers maximum precision and efficiency for the mass production of rubber moulded parts. Intelligent injection technologies and automated processes allow quality and cost-effectiveness to be optimised even further.
Working together
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