Bonding rubber and metal? How is it done?

reluctant allies

Rubber and metal are not natural allies. Yet, they form an indispensable power duo in the rubber industry. It makes sense – combining flexibility and strength often provides the ideal solution.

Friends or not, at RIS Rubber, we bond rubber and metal every day. Metal provides added reinforcement or support and can sometimes serve as a fastening element. By combining these materials, a product gains the flexibility of rubber and the strength of metal. So it will come as no surprise that this golden combination is widely used.

durable bond

RBONDING RUBBER AND METAL:
A PRECISE STEP-BY-STEP PROCESS

To forge a bond between metal and rubber, they must vulcanise together – a method far stronger and more durable than gluing. Successfully bonding rubber to metal requires the proper pretreatment. Without it, creating a lasting connection between these two materials is impossible. The process begins with preparing the metal: first degreasing, followed by roughening (sanding), applying an adhesive primer and finally bonding the materials during vulcanisation.

precision work

THE PREPARATION FOR RUBBER TO METAL BONDING

When presented like this, bonding rubber to metal might sound straightforward, but it is anything but simple. In practice, the exact approach varies by product. Using specialised software, we determine the precise location(s) where rubber and metal should be bonded to ensure optimal performance of the final product. Factors such as the amount of degreasing, the degree of roughening and the thickness of the adhesion primer layer all play a crucial role and are carefully calculated and determined in advance. Once all the necessary details are gathered, the Metalworking department prepares the metal for the application of rubber. Bonding rubber to metal can be done either chemically or mechanically. The best method depends on the specific type of product.

ingenious process

CHEMICAL BONDING: FROM DEGREASING TO ADHESION PRIMER

Degreasing is the first critical step in chemically bonding metal to rubber. Once complete, the process moves on to the next phase: roughening, or in other words, sanding. This is performed in specialised blasting booths in the Metalworking department. Our largest booth is an impressive 200 m² in size. Blasting is an efficient method for cleaning and roughening metal. During this treatment, steel grit is propelled at the product using compressed air. This process removes contaminants such as rust, oils and paint residues, while increasing the surface area of the metal. This establishes an optimal bonding structure for further treatment.

After the roughening process, the next step is to apply an adhesion layer to the metal product, ensuring the materials bond effectively. The adhesive is applied either manually or by a spraying robot, covering the roughened metal to allow the rubber to vulcanise evenly and adhere securely to the metal. It is crucial that this adhesive layer is neither too thick nor too thin, as it plays a vital role in the heat-induced bonding of the rubber to the metal.

The final step is vulcanisation. The product is placed in a mould within a moulding machine, where the heat and pressure cause the molecules of the metal and rubber to bond. And so, with exacting precision, this unlikely alliance is forged.

down to the smallest details

MECHANICAL BONDING: A SIMPLER PROCESS

Mechanical bonding of rubber and metal is significantly simpler. The method is pre-designed to ensure the rubber remains securely attached to or around the metal. For example, a notch or holes may be made in the metal, allowing the rubber to flow into or through these openings during the vulcanisation process, creating a bond with the metal.

Our technical team carefully plans the optimal bonding approach and prepares a quotation for the customer. Once approved, we produce the mould and initial samples. After the samples have been approved, full-scale production begins.

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