Various Features Of Reaction Injection Molding

Reaction injection molding?, also known as RIM utilizes very low viscosity liquids, low processing temperatures, low mold temperatures and low internal molding pressures. The need for low temperature insulation combined with structural needs along with cosmetic appeal is considered as a combination of materials, tooling approaches and specific processing opportunities that their RIM (Reaction Injection Molded) Process can offer. It can be used with the low viscosity liquids ranging from 500 to 1500 mPa, low processing temperatures of 30 to 40 °C, low mold temperatures of 30 to 40 °C and low internal molding pressures between 3 and 10 bar.

Highlighted Features Of RIM:

• This is 70% less expensive with think molds and lightweight structural parts without any sink
• Varying wall thicknesses on some parts, it has similar tolerances to injection molding
• It molds over metal, glass, wood, wiring, circuit boards, hardware, etc.
• It is economic for lower volume parts as it features lower high-volume per-part cost
• It is made of colored plastic parts, thus it does not require any paint

Reaction injection molding creates parts by using impingement mixing to combine reactive liquid intermediates as they enter a mold. It differs from the traditional injection molding as it comes in the form of solid parts by cross-linking or polymerization in the mold rather than by cooling. This is great for it financial value as it provides lower volume when compared to traditional injection molding.

Advantages Of Using RIM:

• The flowability of the liquid polyurethane components enables to fill molds for very large parts. The size of the part that can be molded depends on the speed of the reactivity profile of the polyurethane formulation.
• Many types of inserts can be placed into a mold prior to injection of the RIM material. Steel, aluminum shapes and frames, window glass, glass preforms, electronic sensors, PC boards and wiring harnesses are some examples of materials that can be encapsulated using the RIM process.
• The Reaction injection molding process provides the flexibility to design parts with significant wall thickness variations. The wall thickness of RIM ranges from 6 mm and 30 mm, it is possible to have cross-sections in the same molded part though.
• RIM processing also is more automated than other thermoset molding alternatives.
• The surface finishing of parts molded with the RIM process allows manufacturers to produce perfect painted parts. It can greatly reduce secondary finishing costs.
• The extension of this technique is under development allows the molder to use pre-decorated films, vinyl or fabric performs as the decorating material during molding.

The process of Reaction injection molding does not use hot mold cavities to activate the reaction but it must be cooled because an exotherm forms when the intermediates are mixed in the presence of heat. Completed parts can often be demolded in less than 20 seconds.

Honkia Prototype is a Rapid Prototyping and Low Volume Production factory that specializes in Sla/Sls, Cnc Machining, Vacuum Casting, Reaction Injection Molding and Sheet Metal Fabrication.