Engineer's Toolbox:
Seating innovations with silicone have patient health covered
Molding large shapes is now possible with Simrit’s new liquid silicone injection-molding machine. The new technology allows for a much more complex part to be produced, and a much higher-quality end-product. With Simrit’s help, the Sittris Siliform line of silicone-covered chairs has been a great success.
Every year more than two million North Americans will get a secondary infection during a hospital stay, and about 90,000 will die. This is a problem that healthcare institutions will face more and more and one that puts enormous burdens on financial and human resources.
Canadian seating manufacturer Keilhauer, under their healthcare product line Sittris, partnered with Simrit and developed a new, innovative silicone surface for healthcare seating that addresses the distinct needs of the healthcare industry.
Searching for the right material
Sittris designs and manufactures seating such as stools, chairs, and armrests for patient rooms, waiting rooms, lobbies, nursing stations, public seating areas, and specialty purposes, such as bariatrics. For these products, the company was looking for a material that would be right for seating and contact surfaces in the healthcare environment, as it is Sittris’ objective to provide “clean” seating for this market.
Sittris approached Simrit with the concept of incorporating a silicone surface for healthcare seating. Healthcare furniture has to address several issues, and silicone is an ideal material choice. It is inorganic, so it does not support microbial or fungal growth. It is compatible with humans — as it can even be implanted. It is UV and ozone resistant, flame retardant, and can be color matched to any color of the rainbow. Its unique properties limit anything sticking to it or staining its surface. Finally, it can be cleaned simply with soap and water.
Overcoming the hurdles
The liquid silicone rubber (LSR) press can produce very large, complex components without flash. No human contact with the raw rubber material means greatly reduced chance of contamination.
The problem that the companies had to overcome was: How to design and mold such large, complex silicone components (an entire chair!)? Simrit proposed a solution that met all criteria. A unique liquid silicone rubber (LSR) designated LO 538 was chosen for its high tear strength, abrasion resistance, and compatibility with healthcare environments. The design was jointly developed with the customer, and in the end incorporated a “shower cap” concept that could be assembled on the chairs similar to furniture upholstery. Simrit used its sealing expertise to ensure that when the seat was fully assembled, all joints were sealed. In order to produce such large, complex moldings, Simrit acquired a custom-built liquid silicone injection-molding machine, believed at the time to be the largest in the Americas.
Other unique sealing solutions from Simrit
- Seals for nuclear reactors, some in excess of 600 ft long, to help provide safe, long-term power for millions.
- Vibration isolators (grommets) for automotive are produced in the tens of millions to reduce engine NVH, which provides a quieter and more comfortable driving experience.
- Fire-proof aircraft seals that provide protection to sensitive areas of the aircraft and help ensure passenger safety.
- High-temperature seals for appliance and food and beverage machines.
A unique tool design for the surface finish was combined with a proprietary silicone surface treatment that gives the silicone a “skin-like” feel and also dramatically reduces the surface friction and static and aids in cleaning of the seating. The LSR press is capable of producing very large and complex silicone components without flash, allowing for an end-product of much higher quality and versatility. This would not have been possible with high-consistency rubber (HCR) compression molding, which was the only option until now. Additional benefits of using the new LSR press include greatly reduced chances of contamination or cosmetic defects due to the closed material handling system and no human contact with the raw material.
Using creative problem solving and a unique material, Simrit was able to help Sittris produce a truly clean and healthy line of seating. The Siliform line has now found many healthcare customers, and where other manufacturers’ products look utilitarian and generic, Sittris’ appears cool and hip with its bright, cheery colors and innovative design and material properties. The combination of cleanliness, comfort, and durability makes Sittris the highest-quality healthcare seating available today, and Simrit is proud to have been a partner in that success.
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