The Process of Custom Rubber Moulding
Rubber moulding is a versatile manufacturing process that converts uncured rubber or rubber compounds into a number of parts that are durable and can withstand harsh operating conditions. Rubber is an adaptable material that can be formed into parts with complex shapes and variable dimensions and properties.
Rubber is particularly suited to extensive customisation and so can provide cost-effective and reliable solutions for many applications. Custom rubber mouldings can be produced from a variety of materials and different processes are used to achieve the desired outcome.
Initial Consultation & Design Phase
Since a custom rubber moulding is specifically created for a particular application, the design stage is crucial to the success of the project. This will start with a consultation between the customer and the supplier, where the application will be assessed and the exact requirements will be established.
If the custom mouldings are for a new product, this stage can assist the design of the required equipment to ensure that everything works together. A working conceptual design will be produced and agreed upon before moving to a more detailed design. The main element is the design of the mould, which will determine the final shape and size of the rubber moulding.
Material Selection & Prototyping
Rubber and rubber compounds are well known for their flexibility and durability. However, they all have different properties so selection of the most suitable material will depend on what is required. Before choosing, assess your application and determine:
- The range of temperatures the material has to withstand.
- The amount of tension or pressure that will be applied.
- Environmental stresses such as chemicals, moisture or sunlight.
- Your available budget, since materials vary in cost.
Suitable materials include:
- Natural rubber that has great tensile strength and elasticity, resistance to various liquids and is a sustainable material.
- Neoprene that is durable, flexible and good for outdoor use.
- Nitrile rubber that is particularly suitable for harsh environments.
- Butyl rubber that is weather resistant and has good air and gas retention.
- Styrene-butadiene that is versatile with excellent abrasion resistance and suitable for harsh environments.
- Silicone rubber that is flexible and resists heat, UV rays and ozone.
Various additives can be used with selected rubber compounds to create the desired properties. Before moving to the next stage, a prototype will be created to test the design.
Tooling and Mould Creation
This stage makes custom mouldings more expensive than standard equivalents since the mould and tooling have to be specifically created or adapted. The mould is crucial to the whole process because it will determine the size and shape of the finished moulding.
The mould is made of metal, typically steel or aluminium, and its actual construction will depend on the process that is to be used. It may have ridges and holes, and can be used to produce single or multiple parts.
After creating the basic mould, it will be machined and polished to remove imperfections and will be assembled for use. All required tooling will be created at the same time.
The Manufacturing Stage
Different types of moulding processes are available and the most suitable will depend on factors such as cost, complexity of the moulding and production volumes.
- Compression moulding – Rubber is placed into a heated mould and is compressed to create the required shape. The process allows a variety of materials and is relatively low cost but is not as accurate as other methods and some finishing is necessary.
- Injection moulding – Molten rubber is injected under pressure into a closed mould. Although there are material limitations and a high initial cost, the process can handle complex geometry with great accuracy, is fast with no finishing needed and is good for long production runs.
- Transfer moulding – Pre-heated rubber is forced into an enclosed mould cavity. The process can handle large parts with great accuracy but has high tooling costs, long cycle times and finishing is necessary.
All the processes involve heating and pressure to vulcanise the rubber, which chemically bonds the molecules for stability and durability. A cooling period is also necessary to allow the rubber to set hard.
Post-Moulding Finishing and Trimming
Depending on the process used, a degree of trimming and finishing may be needed. This is limited for injection moulding but necessary for compression and transfer moulding where flashing has to be removed.
Quality Inspection and Testing
Once the moulding is set and finished, testing may be needed to ensure it meets the required specification. Custom rubber mouldings have a crucial role in preventing leaks, ensuring controlled flows, providing insulation and dampening vibration to reduce friction so the quality and reliability of the products are crucial.
The main factor in quality control is ensuring the mould is completely right. If so, this determines the characteristics of the finished mouldings and these should in turn be correct, especially if the process is largely automated so that human error is minimised.
Delivery & Customer Support
Customers requiring custom rubber mouldings want not only to receive products that are manufactured to specification and work reliably and consistently, they also need deliveries that are on time and within budget. It is all part of the complete customer service that suppliers need to provide.
At Gulf Rubber, we value all our customers and treat each one as an individual. The process for each new product starts with an assessment of the customer’s needs and then runs from the design process right through to delivery of the finished components. Every stage is fully explained and agreed, and the customer is always kept fully informed.
We do not believe in shocks and nasty surprises so we are always completely open about what is going on. That extends beyond delivery of the product because we provide an after-sales service that is of the highest quality. We want all our customers to be completely satisfied so we are always available to answer questions and give advice, even long after the product has been supplied.
Get in touch to experience our quality service and to obtain the very best custom rubber mouldings.