Injection molding is often the go-to solution in the industry. It’s a versatile process compatible with many types of complex products and different rubber materials, including silicone. However, for many projects, we find it more effective to employ transfer molding, which is a specific (essentially simplified) injection molding process. We also commonly employ compression molding for simpler shapes and low to medium volume products, or for projects that need to keep tooling costs to a minimum.
Below, we compare conventional rubber injection molding with the transfer and compression molding processes, including the advantages and applications of each.
Conventional Rubber Injection Molding Compared with Transfer Molding
Essentially, the major difference between conventional injection molding services and transfer molding is the way in which the rubber material is forced into the mold.
The raw material we use for injection molding typically comes in a continuous strip form of uncured thermoset rubber. That material is fed into a hydraulic, reciprocating screw-ram, that heats and prepares the material to be injected out of a nozzle and into the mold.
Comparatively, our transfer molding services use a measured amount of thermoset rubber. That material is fed into a “pot” atop the mold and carefully heated. Hydraulic pressure then forces the softened rubber material into the mold.
How Rubber Compression Molding Fits In
Compression molding is another unique process for producing specific types of custom rubber parts. The compression molding process typically uses preformed rubber materials within a heated open mold cavity. The mold is closed, and the compressive closing force causes the softened preform material to take on the shape of the mold.
The Advantages of Conventional Rubber Injection Molding:
- High Efficiency for High-Volume Runs – Injection molding is typically more suitable for high-volume production than transfer molding, offering faster cycle times and streamlined setup.
- Automated for Efficiency – As a result of the streamlined process, injection molding is easier to automate, reducing your labor costs per part.
- Accuracy and Repeatability – Our injection molding process is capable of producing precision parts with tight tolerances and extremely consistent quality.
- Minimal Waste – The injection molding process facilitates a more efficient use of material through the elimination of flash and excessive overflow grooves. That means less material costs and reduced waste for your project, along with better sustainability.
The Advantages of Rubber Transfer Molding:
- Lower Setup Costs – While conventional injection molding is quicker per cycle, the initial setup is more complex and costly. Transfer molding may save your project money through reduced setup costs, especially for low- to mid-volume runs.
- Easier Compatibility with Insert Molding – Transfer molding allows us to more easily integrate inserts and substrates into rubber products, such as self-sealing washers and other complex rubber/bonded components.
The Advantages of Rubber Compression Molding:
- Lower Tooling Costs – Compression molds don’t have to withstand the same high pressures or temperatures that injection and transfer molds. That typically means compression molds don’t have to be as robustly built, reducing your upfront tooling costs.
- Ideal for Hard or Difficult-to-Flow Materials – Obviously, not all rubber materials flow the same when heated. For exceptionally hard rubbers and other materials that don’t flow effectively, compression molding is often the most viable manufacturing solution.
- Ideal for Parts with Varying Wall Thicknesses – Using softened preform materials, compression molding is ideal for parts with multiple wall thicknesses.. These designs can be more challenging for the injection and transfer molding processes to produce consistently.
Quality Custom Rubber Molding Services Since 1977
Panova provides complete manufacturing solutions for custom molded rubber parts – from conventional injection molding to transfer, compression, and liquid injection molding. The versatility of our services facilitates higher quality, more cost-effective production for a wide range of industrial rubber products.
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