Molded Rubber & Plastic Corp. is expanding its resources in medical device manufacturing with the addition of another liquid silicone rubber injection molding press at its Butler, Wis., headquarters plant.
MRPC ordered a 150-ton Engel rotary injection press to be part of in an integrated manufacturing cell in the company's newest Class 8 clean room. The new press, an Engel 200/150 insert V US, will be installed in March. It will join another Engel press, a 40-ton shuttle table machine, in the production cell. MRPC bought that press, a 60/40 insert V US in mid-2016.
MRPC has a long history of liquid silicone molding, originally using silicone rubber in tooling and bonding agents. It has evolved into a LSR specialist that also has expertise in thermoplastic injection molding.
The latest project for an undisclosed customer needs an injection press with impressive credentials.
“This project requires a process with extremely tight tolerances and exceptionally accurate shot control,” explained MRPC Process Engineering Manager Brunson Parish.
“Their [Engel's] machinery provides the level of precision required for our core business, allowing us to meet the quality standards required by our customers. That, along with the flexibility provided by their machine design, made them our supplier of choice.”
MRPC has been in expansion mode for several years. In March 2016 it bought Johnson Precision, a global supplier of plastic injection molded components and assemblies in Hudson, N.H. Johnson Precision was an experienced molder for medical devices and also brought in-house mold building to MRPC. As well, Johnson Precision's Class 8 clean room became MRPC's seventh clean room within the company. Johnson Precision's partnership in Malaysia led to more business opportunities in the Pacific Rim region.
The Johnson Precision acquisition came a year after the delivery of two Engel 750/180V horizontal presses retrofitted to run liquid silicone resins to make a cosmetic part. One of the machines went to Butler, the other to MRPC's Largo, Fla., facility.
MRPC was in a hurry to get the 750/180V up and running in Butler to be ready for the production tool. Sensitive to MRPC's needs, Engel was able to retrofit within four weeks a stock 750/180V thermoplastic machine into one able to run liquid silicone resin. The retrofitted press was in Butler and ready to run a week before the customer could take delivery of parts.
Engel delivered the other LSR-retrofitted press to Largo under similar time constraints.
“Other stateside quotes were for a minimal 12 weeks delivery,” Parish said. “So they beat that by several months.”
MRPC had already completed an expansion at Butler in 2014. The program entailed another Class 8 clean room and several modern injection molding machines needed for growth in sales. Two years prior to that program, MRPC acquired ETI, a medical plastic molder in Largo, giving it a bigger presence in the southeastern United States.
Brunson said the latest press purchase will go into the production cell where thermoplastic is overmolded onto a metal substrate rod. That part in turn will be overmolded with liquid silicone rubber. The thermoplastic provides a structural element while the silicone layer contributes heat resistance and dampening.
Brunson said injection molding is its core competency but MRPC also does a lot of silicone and rubber compression/transfer molding and silicone extrusion. It selects from a variety of silicones with different durometer hardnesses and other properties and does much of its own compounding. In thermoplastics it process numerous engineering grades ranging from thermoplastic elastomers and acetal to high-performance types like PEEK, fluoropolymers and polyphenylene sulfide. Medical applications are key but MRPC molds many industrial parts too.
Brunson said Engel's expertise in liquid silicone molding from tooling through to process set-up made it the machinery supplier of choice.
“Their knowledge in all things LSR helps us tremendously when developing new production systems.”
Engel's range of machine models and sizes include features such as tie-bar-less platens and insertion equipment that save cost and floor space. Engel also retrofits injection units and plasticizing assemblies.
“MRPC is the perfect model of a production company,” noted Engel technical sales engineer Steve Broadbent, because the company looks for cost competitiveness while focusing on the best technology for each project to support its rapid growth in the medical device market.