Back

Rubber Moulding Expertise

Our rubber moulding facility offers a wide range of processes, to allow us to produce a vast range of products in small to medium volume for a huge range of industries. These processes can be undertaken in a vast range of raw materials, many of which are in stock, backed up by full support from our Technical staff and subcontractors.

Rubber to Metal Bonding

Examples of injection moulded, extruded and compression moulded rubber products we provideMartin’s Rubber offer an extensive rubber to substrate bonding capability, with the skills, knowledge and equipment to produce high quality bonded products with a variety of materials. We have the technical expertise and knowledge to ensure that we consistently produce high quality finished products that you can rely on. Whilst most substrates are metallic, we have increasingly begun to bond to other substrates such as PTFE, Peek, Carbon Fibre etc in order to ally the properties of rubber with an ever increasing range of materials. Rubber to metal bonding is a generic phrase covering a number of interdependent processes. The rubber-bonded units that result from the process are used for the isolation of noise and vibration in many automotive and engineering applications. There are three essential elements that form the bonding process: the rubber, the bonding agents and the substrate. The selection of the polymer base and the associated compound depends mainly on the product specification. A bond can be formed using just about any rubber compound. The choice of substrate rests solely with the component designer, who must consider the necessary strength and durability requirements in its use. The traditional substrate is steel, in all its forms and grades, but increasing use is made of aluminium alloys and polyamides to save weight. Almost any material can be bonded to rubber, provided that it can withstand the heat and pressure of the rubber moulding process.

Rubber Metal bonding can be successfully undertaken with many compounds and substances including:

Rubbers:
  • Natural
  • Neoprene®
  • Nitrile
  • Aflas®
  • FKM (Viton®)
  • Silicone
  • Flurorosilicone
  • HNBR
  • EPDM
  • Polyurethane
Substrates:
  • Brass
  • Stainless Steel
  • Mild Steel
  • Aluminium
  • Titanium
  • PTFE
  • Carbon Fibre
  • Peek®
  • Acetal
  • Acrylic

If you have any requirements for rubber to metal bondings, please speak to our Technical staff who can assist you with selecting the right compound and substrate to meet your design requirements.

Compression Moulding

We have a wide range of compression moulding machines, from 5 tonnes up to a 500 tonne press with a maximum of a 1 square metre press area and daylight. Compression Moulding involves taking a rubber compound and making a pre-form that is in the shape of the end product, but is larger than the final shape. The process continues by loading the shape and closing the mould, which is heated by the press platens. The excess rubber is then vented from the cavity along with any air under the compression force of the press, then held closed by the press whilst the rubber is cured, and then when the press is opened, the tool can be split and the part de-moulded. Compression Moulding was the original method for moulding rubber, developed back in the 1850’s, and is still ideal for manufacturing low to medium volumes of rubber product and remains a useful moulding process for forming bulky parts.

Advantages

  • If the part requires a long cure time
  • If the part cross section is very large
  • If the quantity required is low
  • Creates least amount of waste
  • Has the capacity to process stiff, high durometer materials
  • Short set up time
  • Tooling is generally more cost effective than Transfer or Injection as it is simpler

Disadvantages

  • Parts can be less consistent
  • Cure times can be extended as heat transfer is slow through the rubber
  • Coloured rubber can be easily contaminated

Examples

  • Bearing pads and blocks
  • Large valve seals
  • Coupling bushes
  • Wear strips
  • Large hose/pipe adaptors
  • Special mats

 

Transfer Moulding

This is a valuable process that provides the accuracy and consistency of injection moulding without the requirement for long production runs, or costly full injection tooling. Using a secondary raw material prepared into “pre-forms” these are loaded into a pot internal to the mould tool. When the mould is closed, an integral plunger compresses the rubber in the pot and forces it through holes or sprues into the product cavity to fill it in the same way as an injection moulding would. This is an ideal process for forming parts that require exact positioning inserts to be bonded, intricate parts with lower volume requirements and mould designs that contain multiple cavities or can trap air. The mouldings provided are much less likely to exhibit knit lines or other defects, providing much more consistent production.

Advantages

  • Shorter production cycles for higher weight parts
  • Tighter dimensional tolerance
  • Provides better uniformity
  • Reduced tooling lead times compared to a full Injection tool
  • More accurate and consistent than compression moulding

Disadvantages

  • More expensive tooling than a Compression mould
  • Slower production cycle than an injection tool
  • Manual handling of the piston can be a problem.

Examples

  • High precision rollers
  • Coloured instrument protective boots
  • High impact natural rubber buffers
  • Bonded rubber to metal assemblies

 

Injection Moulding

Defined as “The Process of rapidly forcing an exact amount of rubber from a tube/cylinder into a closed, heated mould”. We have a wide range of dedicated injection moulding machines with up to 1litre capacity and a clamp force of 220 tonnes. Injection Moulding was created as an extension of the plastics industry in the early 1960s. After overcoming initial issues of temperature (plastics is cooled during moulding whereas rubber is heated) and pressure (rubber injection moulding requires significantly more pressure per square inch of cavity surface), the process has become the most efficient way to mould rubber in many cases. It is an ideal process for large shot weights, high volumes of small to medium size parts, incorporating bonded inserts, achieving close dimensional tolerances, and making components that require uniformity or consistency of colour.

Advantages

  • Lower unit costs
  • Faster cycle times
  • High dimensional tolerances
  • Low levels of flash
  • Little scrap/waste
  • Reduced need for secondary trimming work

Disadvantages

  • Higher set up costs
  • More expensive machinery & tooling
  • Small runs of parts can be costly

Examples

  • Coloured Instrument Boots
  • O Rings
  • Drive coupling assemblies
  • Automotive parts
Finishing

We employ dedicated skilled finishers to ensure that your product is not only manufactured, but also trimmed, finished and packed to the excellence that we maintain throughout our manufacturing cells, meaning that there is a level of craftsmanship akin to the quality level you would expect. From this section of our web site you can access details on our general Products, our Industries served and detailed technical information on the specific Rubber Mouldings we produce. Please follow the links for further information.