Rubber moulding processes uses heat and pressure to mould raw rubber into the specific shape and size of a desired part. Examples of moulded rubber products include seals, gaskets, O-rings, tubing, and bellows – just to name a few. Today, there are three main types of rubber moulding processes: compression moulding, transfer moulding, and injection moulding. Each has its own advantages and applications.
This article from MACH Rubber explains the differences between all three rubber moulding methods. Keep reading to find out which process you need, or request a quote if you’re ready to order standard or custom moulded rubber products. MACH Rubber offers all three processes at our Barnsley, South Yorkshire location and we’re ISO 9001:2015 certified.
#1 Compression Moulding
Compression moulding is the oldest, most basic, and most cost-effective rubber moulding process. It begins by placing a pre-measured amount of raw rubber into a mould cavity. This pre-measured amount, the pre-form, is compressed under high pressure and heat until the rubber fills the entire cavity. The pressure and heat cause the rubber to flow and take on the shape of the mould while it cures.
Compression moulding is best suited for producing simple shapes and low to medium volumes of rubber products such as seals, gaskets, and simple O-rings. The process is relatively simple, and it requires less machinery than either transfer or injection moulding. All of this makes compression moulding a popular choice for prototyping and small-scale production.
#2 Transfer Moulding
Transfer moulding is more complex than compression moulding but less complex than injection moulding. With transfer moulding, raw rubber material is heated in a chamber. As the press closes, the material is transferred to a mould cavity through a sprue or channel. The mould is then closed and compressed, and the rubber cures in the cavity.
Transfer moulding is best suited for producing complex shapes and higher volumes of rubber products. Often, it’s used to produce electrical connectors, diaphragms, and O-rings with intricate designs. Because it allows for precise control over the amount of material in the mould, transfer moulding creates a higher-quality product. It also minimizes material waste and reduces the need for post-production trimming.
#3 Injection Moulding
Injection moulding is the most advanced and the most precise rubber moulding process. It’s also highly automated, which allows for faster production times and lower costs. Injection moulding involves melting the raw rubber material in a heated barrel and then injecting it into a closed mould cavity under high pressure. The pressure and heat cause the rubber to flow and take on the shape of the mould.
Rubber injection moulding is best suited for producing high volumes of parts that have complex shapes and tight tolerances. Often, it’s used with seals, O-rings, and gaskets for automotive and aerospace applications. The injection moulding process allows for precise control over the amount of material injected into the mould, resulting in high-quality finished products with minimal post-production trimming required.
MACH Rubber v Transfer Moulding
As you’ve learned, each rubber moulding process has its own advantages and applications. Compression moulding is ideal for producing simple shapes and low to medium volumes of rubber products, while injection moulding is recommended for producing complex shapes with tight tolerances and in high volumes. MACH Rubber does not provide transfer moulding services as we consider this to be less efficient.
