Silicone Rubber Compression Molding for Grommet
Rubber Compression Molding, also known as Rubber Compression Moulding Process and Silicone Compression Molding, is one of the most common and oldest manufacturing technique for molding rubber parts, such as bellows, grommet, washer, O Ring and gasket & Seals, etc. During rubber compression molding, rubber material is placed in heated mould cavity, then mold is closed while heat and pressure are maintained until the material has cured and final product is finished.
Rubber Compression Molding is a widely used for low production volumes and higher cost materials due to effective and economical advantages, compared with transfer molding or traditional injection molding.
1. For most of projects during developing stage, you usually need to make prototypes for verifying your design in actual working condition, which will give you some feedback on your design and then you can make continuous improvement until your design is perfect and can be moved on mass production. During this process, you only need to pay small development cost for sample mold and modification cost if needed.
2. For some projects, the manufacturability analysis is OK for making molds and producing some samples. But moldability is not available and there exist some potential difficulties during mass production. For avoiding much modification work and cost on production mold, we can make a small mold for trial production to verify moldability, which can save much cost and time on modification processing work.
3. Some projects only have low production volumes. You can choose to make a sample mold or small mold with few cavities, which can save much mold cost.
4. For some silicone rubber parts required high precision or some other parts with complicated design structure, you also can choose rubber compression molding. We will choose good steel material for mold-making, such as P20 Steel, 718H,etc. (Notes: for most compression mold, we tend to choose 45# steel or 50# steel).
Besides, we will choose good mold-making machines for manufacturing mold tool. Also we will choose good location pins for fitting molds. Then we can control the burrs & flashing up to +/-0.05mm, some even up to +/-0.02mm or +/-0.03mm.
Rubber Compression Molding also has some defects as the oldest manufacturing technique.
1. Limited by Mold design structure, compression molding type and rubber compression molding machine, the precision and parting line are not superior to transfer molding or traditional injection molding and LSR Injection Molding.
2. Product’s burrs & flashing manufactured by compression molding is bigger.
3. Longer process & curing time
4. Low automation: from placing raw material, demoulding, and removing burrs&flash, all work is finished by manual, which require high labor cost.
