Behind the picturesque town of Stein am Rhein in Switzerland is the Trelleborg Sealing Solutions manufacturing facility that is helping spearhead a global revolution in Liquid Silicone Rubber (LSR) molding. With its holistic approach to component design, it works concurrently with its customers to supply products in an optimized automated process that begins with black box concepts and ends with delivery to customers’ production lines.
“Our tooling expertise is the secret ingredient that is the hallmark of Trelleborg’s LSR production,” says Jarno Burkhardt, Acting General Manager of the Stein am Rhein manufacturing facility.
For centuries, Switzerland has been renowned for the intricate precision tooling required to produce the high quality watches and clocks the country is famous for. In the 21st century, that expertise is proving a boon in complex, often safety critical, industrial applications.
“Our automated approach to LSR processing is unique in its holistic design,” says Ursula Nollenberger, Product Line Director for Liquid Silicone Rubber (LSR) Components at Trelleborg Sealing Solutions. “The tooling design, from stage one, is developed not just to optimize the function of a component in the application, but also to maximize the effectiveness of our automated operations.”
The polished white floors of the main manufacturing hall at Stein am Rhein show not a speck of dirt and neat rows of automated machines click and whir away as an array of robotic arms dutifully perform their programmed tasks. Clear inspection screens allow sight of intricate multi-cavity tools opening and closing, mechanical arms gripping and delivering product to belts that take parts through computerized quality inspection and then finally deliver the parts to bins ready for dispatch.
“In our holistic design approach we consider, as always, part-function and maximizing performance in application. In addition, right from the earliest point possible, we take into account design for automation, creation of flash-less parts, waste-free production, in-process quality checks, batch by cavity and packaging,” says Burkhardt.
The tool room at Stein am Rhein combines the latest high-tech tooling equipment with traditional age-old tooling benches, their orderly rows of precision hand tools placed ready for use.
“The quality of our tooling determines how effective our automation can be. Not just of the mold tools but in particular our unique robotic grippers that guarantee removal of parts from molds without damage,” continues Burkhardt.
Automation is taken to the ultimate level and there is consistency throughout the manufacturing facility. Most parts produced are untouched by human hand until packaged and some are even boxed or packed robotically. A single operator supervises the whole hall of identical Arburg machines linked to a central computer system that monitors operations 24-7. Allowing the supervisor to move freely, the central computer sends SMS messages to the supervisor’s tablet if there are issues with any machine.
Process systems are also designed to minimize disruption in the case of a quality concern. Quality checks are electronically recorded for each individual component allowing full traceability and products are delivered to the customer separated by cavity. Any issue can therefore be isolated to just a small number of components and delivered quality from the production line can be checked for that batch in detail.
Burkhardt adds: “The holy grail of quality is to ensure quality in process rather than have post production quality checks. At Stein am Rhein we achieve this!”
“We’re often thought of as just a facility for production of LSR moldings for life sciences,” says Nollenberger. “Yes, this does make up a substantial amount of our business, but we are also a key supplier to the automotive industry, especially for electronics for car safety and driver comfort, where our high volume, full traceability and lack of manual handling are key benefits. Complex components for food and beverage equipment are in our portfolio and we are expanding production of parts for high-end sanitary equipment, such as luxury rain and steam shower systems.”
Originally serving Stein am Rhein’s life sciences customers, mirroring the main open production hall in terms of machine type and automation equipment, the facility has a number of large class 100,000, ISO 8 and class 10,000, ISO 7 cleanrooms. The capacity of these has recently doubled in size. Windows allow a view of robotic arms picking, placing and packing while cameras complete inspection processes. The shift supervisor is gowned from head to toe, checking all is running to order in the controlled, super clean environment.
Elevators take product from these cleanrooms up to a class 10,000 ISO 7 cleanroom for product finishing and packing. Parts produced in the main hall can also be washed, finished and packed here.
“The cleanroom is not just for life sciences,” Ursula points out. “Many of our customers from other industries also need parts produced or finished and packed in a clean environment. Automotive electronics, for instance, need to be free of any contamination to work effectively. Food and beverage products sometimes have similar regulations to life sciences, also being subject to FDA, 3A and other standards.”
LSR molding is ideal for production of complex geometries and to consolidate assemblies combining numerous components into a single part.
“Customers often ask us to value engineer their assemblies,” says Burkhardt. “This is where we can offer tangible benefits to our customers in terms of improved performance, prevention of contamination, the opportunity for automating their production lines, elimination of risk of miss-assembly, lower inventories and ultimately lower overall costs.
“We aim for flash-less and waste-less production. We use a cold runner system that means that the injection material is not cured as we mold the parts in the tool. Virtually no runner is produced, there is little overflow and due to the accuracy of our tooling there is literally no flash.”
Perfect flash-free molding is essential in some of the parts produced at Stein am Rhein. Nollenberger gives an example of a nipple protector for nursing mothers.
“The nipple protector is produced in a cleanroom to prevent its high gloss finish being blemished by airborne particles such as dust. The part cannot be manually handled, as the slightest fingerprint would spoil its crystal clear finish. Therefore the nipple protector is removed robotically from the tool and placed on a belt feeder that takes the product through post-cure and straight into the box it is shipped in.
“Timings between all process steps are perfectly aligned to have a continuous process flow. The part must be flash-less, as any flash at the nipple shield hole would prevent effective milk delivery from a nursing mother.”