Compression Molding

The most cost-effective and widely-used rubber molding method is compression molding. It is best used for low to medium production volumes for larger parts where tightest tolerances and flawless finishes are not required. This process involves compressing pre-heated material into a mold using a press, completely filling the mold cavity and holding it until cured.

Transfer Molding

Like compression molding, transfer molding also utilizes a press and mold. The main difference is that in transfer molding, a piston forces the material through a passage into the mold cavity. While transfer molding can be more costly and take more time than compression molding, this method produces more complex products with a tighter tolerance control while still maintaining a higher production rate.

Rubber Injection Molding

Considered the most cost-effective molding process, rubber injection molding is the best choice for high-volume production runs of small size products that require tight tolerances and little to no finishing. Rubber injection molding involves feeding material into a press, which is then warmed and injected into a mold. The rubber injection molding process is the most precise compared to compression and transfer molding, because the injection process controls the pressure, temperature, and speed at which the material enters the mold. While injection molding costs more than compression and transfer molding due to higher tooling costs and longer initial setup times, it is still considered a cost-effective molding process.

Cryogenic Deflashing and Finishing

Melon Rubber. offers the most versatile and effective way to remove flash from rubber products by means of Cryogenic Deflashing. Flash is typically found in areas where the mold comes together. This is when excess liquid mold material escapes from the cavity during production. In this process rubber parts are placed inside a barrel and liquid nitrogen is used to chill the parts so that the flash becomes brittle. The temperature of the flashing on the rubber is reduced to below its glass transition temperature, a point at which rubber behaves like glass and becomes easy to remove but does not crack the part. Once chilled, the machine tumbles the parts around on themselves allowing all the flash to break off. Cryogenic deflashing does not degrade the parts or harm their finish in any way. Edges stay sharp and recessed areas are completely cleaned of flash.

Rubber Molding Materials (Compounds)

Melon Rubber. has an extensive selection of rubber compounds to choose from. The most common molded rubber compounds we use include: