FAQs

What are the different types of rubber moulding?

Companies often use injection, transfer, and compression moulding to produce quality rubber parts.

What is rubber transfer moulding?

Transfer moulding begins with placing a specific amount of uncured rubber into a pot that serves as part of the mould. The mould is then closed, and a plunger compresses the material. Heat is then applied, and the pressure forces or “transfers” the uncured rubber through sprues into the mould cavities. The mould remains closed during the curing process. Finally, the rubber part is removed from the transfer mould and trimmed to remove any excess material or flash.

What are the advantages of transfer moulding?

• Precise control of dimensional tolerances.
• Improved uniformity.
• Fast curing and short production cycle.

What are the drawbacks of transfer moulding?

• Longer production cycle than injection moulding.
• Costly tooling due to the complex design.
• Significant material waste.
• Increased repair and cleaning required.

What is transfer moulding used for?

Transfer moulding is excellent for producing composite seals with float-in-the-cavity insert moulding. Because the cavities are not linked, they can move freely instead of being cut straight into the same plate. This absorbs changes in tolerance, allowing the moulding to remain constant.

• Metal-to-rubber face seals connect gas valves in the natural gas industry.
• Wires are placed in cavities to form connector seals around the wires like spark plugs in the electrical industry.
• Transfer moulding provides sharper cut-offs that greatly benefit lip or U-cup designs in the hydraulic industry.

What is rubber compression moulding?

Elastomers and durometers are moulded using compression moulding. Uncured rubber is inserted into the cavity of the mould, the mould is closed, and heat and pressure are applied. Excess material fills the mould’s overflow grooves when it is filled. The flashing is removed when the product is demoulded after curing is complete, and the mould is opened.

What is compression moulding used for?

Compression moulding is ideal for difficult-to-flow materials because it eliminates the need to push the rubber through sprues, gates, or runners.

What are the benefits of compression moulding?

• Great for working with expensive materials.
• Ideal for moulding large parts
• Preferred for running low-volume applications.
• Lower tooling cost than other moulding methods.
• Cost-effective for smaller runs of parts.
• No weight limit on the parts that can be made.

What are the drawbacks of compression moulding?

• Less precise than injection moulding.
• Generates more waste than injection moulding.
• Slower process times.

What products are manufactured through compression moulding?

Some examples of compression moulding products include O-rings, grommets, plugs, and bumpers.

How does rubber injection moulding work?

A ribbon-like strip of uncured rubber is fed into a rotating screw during injection moulding. A portion of the rubber is then drawn into the injection unit, where it is pre-heated and plasticised before being injected into a mould cavity. The rubber is cured here under high pressure and temperatures. When the curing process is finished, the moulded rubber part is ejected from the mould.

What is injection moulding used for?

Injection moulding is ideal for producing large quantities of parts with medium-to-high precision.

What are the advantages of injection moulding?

• Short curing time.
• Reduced material waste.
• High levels of control and consistency.

What are the drawbacks of injection moulding?

• Injection moulding machinery is more expensive than other moulding tools.
• Expensive small part runs.
• Prolonged setup times.
• Part design constraints.

What materials are used by Specialized Moulding?

Some of the materials we work with include EPDM, neoprene, silicone, nitrile, butyl, SBR, Viton®, and natural rubber.

Which industries contracts services from Specialized Moulding?

We service agricultural, chemical and petrochemical, food and beverage, mining, and motoring industries.

What rubber products do you offer?

• Rubber vibration mounts
• Rubber couplings
• Rubber bushes
• Rubber bellows
• Rubber boots
• Rubber diaphragms
• Rubber sheets
• Rubber grommets
• Rubber seals
• Rubber balls
• Rubber O-rings

Contact Specialised Mouldings for details

Please contact a representative from Specialized Mouldings South Africa today to discuss all your rubber moulding needs.