Moulding is a common manufacturing process, where the liquid material is inserted into a mould cavity in order to create a product or part. There are a number of different types of mouding, including injection moulding.
Widely used to create custom and standard parts, injection moulding is one of the most common rubber moulding methods with many advantages and benefits.
What is injection moulding?
Injection moulding is a rubber moulding process that uses injection technology to inject the raw material into the mould cavity.
A hot liquid compound such as rubber is injected into a closed cavity and vulcanised. This produces a stable, perfectly-cured rubber requiring little to no post-production trimming.
Injection moulding technology can be used to create complex, intricate parts and large production runs.
What is injection moulding used for?
Injection moulding can be used to create a wide variety of parts for applications in a number of different industries, including:
Construction industry - seals, gaskets, grommets, tubing, vibration control
Automotive industry - engine parts, valves, extrusions
Agricultural industry - seals, noise control, bushings, suspension, vibration control
Medical industry - seals, medical equipment, tubing.
How does injection moulding work?
The injection rubber moulding process typically follows the process below:
Step 1 - A mould is created to meet the manufacturing requirements
Step 2 - Uncured rubber is fed into the screw of the injection moulding machine
Step 3 - The rubber is then pulled into the injector
Step 4 - The rubber is liquidised at a high temperature
Step 5 - The polymer is then moved into the injection mould cavity via a runner and gate
Step 6 - The rubber is cured and vulcanised at high pressure and temperature
Step 7 - The finished part is removed from the mould cavity
Advantages of injection moulding
Injection moulding offers a number of advantages, it is cost-effective, especially when making custom rubber components to order, it is precise, and can be used to produce a large number of parts per hour. Industrial Rubber Ltd offers custom made, to order a minimum of 500 pieces.
Advantages include:
Faster production cycle time
Injection moulding has a cycle time of approximately 15-30 seconds; this means the technique can be used to produce a significant number of parts per hour.
Lower cost
Injection moulding often involves a lower production cost per unit. This is due to higher levels of automation leading to faster cycle times.
High dimensional tolerance
The injection moulding process can achieve tight tolerances on small, intricate parts.
High consistency
Because injection moulding involves a greater level of automation, it is possible to achieve a much higher level of consistency.
Low flash levels
The force of the injection press clamp ensures that the mould remains tightly sealed during the cycle. This results in higher levels of tolerance and lower levels of flash.
Minimal secondary trimming
Parts that have been injection moulded usually look finished upon completion, meaning that very little, if any, post-production work is required.
Reduced waste
If thermoplastic material is used in the injection moulding process, any excess material or scrap can be recycled and reused.
High quality
The final parts are usually high quality, solid and durable.
Compression moulding vs Injection Moulding
Is compression moulding or injection moulding the most effective process? Both types of moulding offer their own advantages and limitations.
Like injection moulding, compression moulding is a moulding process. However, rather than using injection technology, compression moulding is defined by its use of pressure and heat. During the moulding process, the material is placed into the mould cavity and heated. Plugs are then inserted into the top of the mould cavity and pressurised. The application of both heat and pressure cures the raw material, creating a new part or product.
The main differences between the two technologies are:
Smaller rubber parts - based on size
Injection moulding is ideal for smaller rubber parts requiring tight tolerances. Compression moulding, on the other hand, is suited to creating larger rubber products.
Rubber moulded - based on shape
Compression moulding is suited to producing simpler shapes, while injection moulding allows far more complex rubber parts to be produced.
Cycle time
Compression moulding has a significantly longer cycle time than injection moulding. Not only this, but compression moulding also often requires manual rubber finishing and post-production trimming, slowing down the process further still. Injection moulding is more efficient as the process can be fully automated.
Volume
Compression moulding is best used for low and medium volumes of large rubber products. Injection moulding is automated and offers short cycle times, meaning it is possible to produce a high quantity of parts or components quickly.
Quality in injection moulding
Injection moulding typically delivers stronger parts than compression moulding.
At Industrial Rubber, we manufacture a wide variety of rubber parts and components only made to order, not off the shelf, we use injection moulding technology. Get in touch to discuss your needs or to find out more about our rubber moulding services.
