Silicone molding for medical components leverages the biocompatibility, chemical resistance, and thermal stability of silicone rubber. From seals and valves to catheters, medical grade silicones support design flexibility and healthcare innovations. However, selecting the right molding process is as important as material selection.
Engineers who work in the medical industry often face a decision between compression molding, transfer molding, and injection molding. Each of these processes offers advantages and tradeoffs depending on part geometry, production volume, regulatory requirements, and costs. Keep reading to learn more and contact The Rubber Group to discuss your application.
Silicone Compression Molding
Compression molding is the simplest molding process. It places a pre-measured amount of rubber into a mold, closes the tool, and applies heat and pressure. Typically, the mold is pre-heated so that the material flows more readily and fills the tool as it’s compressed. When molding is complete, the part is cooled, ejected, and trimmed or de-flashed.
Silicone compression molding combines low tooling costs with cost-effective production at low volumes. Large gaskets and relatively thick components are achievable. Despite these advantages, silicone compression molding has longer cycle times and offers less precision. It’s not ideal for complex geometries, and undercuts and other intricate features can be difficult to achieve.
Silicone Transfer Molding
Transfer molding places a preheated molding material in a “pot” or chamber. This rubber material is then forced by a plunger into a preheated mold cavity. The heat and pressure in the mold cause the material to cure, solidifying into the desired shape. Once curing is complete, the mold is opened and the part is removed.
Silicone transfer molding for medical components combines better dimensional control and repeatability with support for moderate design complexity. It has faster cycle times than compression molding but comes with higher tooling costs. Medical applications for silicone transfer molding included molded seals for pumps, valves, and respirators.
Injection Molding
Injection molding feeds a ribbon-like strip of uncured rubber into a rotating screw. A controlled amount is pulled into the injection unit, and this material is injected into a mold cavity through a gate and runner system. The rubber is held under high pressure and at an elevated temperature to achieve vulcanization. When curing is complete, molded rubber parts are removed or ejected.
Silicone injection molding for medical components supports high volumes of parts that require medium-to-high levels of precision. Additional advantages include shorter cycle times, flash-less tooling, and reduced material waste. Depending on the size and complexity of the part, larger volumes may be required to justify the costs of the tool.
Ask Us About Silicone Molding for Medical Components
Along with silicone selection, the success of your next medical molding project depends on choosing the right partner. For custom molded medical products that are backed by application experience and technical expertise, contact The Rubber Group.