C & M Rubber Co.

United States

C & M Rubber Co. produced this silicone rubber encapsulated ultrasonic sensor assembly for a customer in the manufacturingpackaging industry. This project presented two unique challenges. First, the face thickness of the rubber sensor body needed to be held to a tight .003" tolerance to minimize distortion of the ultrasonic frequencies. Secondly, to maintain the high sheen required on the face of the rubber part, no mold release agent could be used. Working with customer specifications, our engineers developed precision tooling that would keep the part within the tight dimensional tolerances and have the lubricity to release it with no sticking. Utilizing a 25 ton hydraulic press and silicon rubber with a 302 Duro Shore A hardness, we executed a multi-cavity compression molding process to encapsulate the heater and sensor assembly. A manual deflash and inspection process verified that desired high gloss finish was achieved and the tolerances were within specification.

C & M Rubber Co., founded in 1964, was primarily a distributor of rubber goods and related lines for a host of manufacturers including Uniroyal and Goodyear. The primary focus was stocking and reselling a large selection of standard o-rings, gaskets, hose, v-belts and conveyer belt to commercial and military installations. C & M was also heavily involved in military contracts, preparing skin-pak service kits for a variety of repair applications. During the late 1960's and early 70's, C & M entered a new venture; custom silicone molding. Applying the knowledge and experience in successfully bidding military contracts, C & M Rubber Co. landed a significant contract to mold silicone seals for the Zuni rocket. As the military business grew efforts to branch out and serve other industries led to our current concentration in the medical, food service, aerospace and high tech fields. Molding silicone and other elastomers is primarily a function of balancing three variables: time, temperature and pressure. Of equal importance is the quality and workmanship in creating a mold (tool) that will provide a dimensionally accurate part with the desired finish. It is for this reason that we often recommend cutting a single cavity prototype tool to confirm material suitability, shrink calculations and dimensional precision. Once satisfied that the prototype is correct, the construction of production tool follows as the next step. Since our principal market niche is production runs of one to thousands of parts, we employ the use of either a transfer or compression mold (tool) as opposed to liquid injection molding (LIM). The overriding factor in this choice of tooling format is cost. With prototyping or "limited" production runs, customers are rarely willing to commit to a high initial capital cost for tooling. Thus, transfer or compression molds (tools) offer one of the most cost effective ways to produce "limited" numbers of parts.

C & M Rubber Co. was contracted by a manufacturer of medical equipment to mold a silicone foot shown here. The foot is installed on the supporting legs of their examination tables, and is designed to prevent scuffing of tile or linoleum floors, or skidding on commercial carpeting. Originally this job was tooled as a transfer mold consisting of 49 cavities; however after years of service, the tool was scheduled to be reworked to correct a registration issue that had developed over time. It was decided that retooling for liquid injection molding (LIM) was more cost effective, and would avoid price increase to the customer. The LIM parts eliminated a direct labor cost and the expense of cryogenic de-flashing of the silicone foot. Composed of LR 300360 Shore A Durometer silicone rubber, the foot was manufactured on our Boy 22 liquid injection molding unit, which features a fluid automation pump set. This advanced manufacturing process allowed us to meet tolerances of .015".In addition, we were also able to exactly match the customers Pantone color specification.Produced in blanket orders, we currently manufacture over 100, 000 pieces annually.