„Use Bihler’s digital technology“

Schnöring: Earthing brackets and Schuko contacts in particularly high component quality

Schnöring GmbH has recently started using three type-MC 42 and MC 82 Bihler Multicenters to manufacture assemblies for GIRA sockets. This long-standing company uses a virtual animation of the new production solution for targeted demonstrations and training activities. The animation illustrates every detail of the entire, highly-complex process chain, which not only achieves the desired 50 percent increase in throughput but also ensures that Schnöring is able to deliver particularly high-quality ground connectors and Schuko contacts. Close, constructive cooperation with Otto Bihler Maschinenfabrik played a key role in ensuring the overall success of the project.

Since it was founded in 1926, Schnöring GmbH, which is based in Schalksmühle, has grown continuously and now possesses approximately 110 spring winding machines as well as some 50 Bihler stamping-and-bending systems. The family-run company, which has been part of the KERN-LIEBERS Group since 2018, uses this equipment to manufacture springs, wireform parts, stamped-and-bended parts and assemblies on a production area of approximately 16,000 m². Since 2008, the company’s assemblies business has also included the manufacture of components for GIRA sockets. More specifically, it produces ground connectors together with the right and left-hand variants of the associated Schuko contacts. And the company now possesses a new manufacturing solution for precisely these components that not only brings practical advantages but also creates significant virtual value-added.

Digitalized production process

This is because the entire Schuko contact production process has been digitalized and is available as an animation – in a similar way to the digital animation module in the Bihler Digital App, which makes it possible to visualize and animate complete production systems, as well as individual assemblies or tools, without the need for any additional software. “We mainly use the animation for training purposes. It enables us to show even inexperienced employees without any CAD knowledge exactly what happens where and when in the tool. The information and notes on specific tool setting capabilities that are stored in the animation are also useful,” explains Axel Schnöring, who is responsible for the KERN-LIEBERS Lead Center Stamped Bent Parts in Schalksmühle. “The animation helps us give our employees the know-how they need to handle what is, after all, a complex process chain and give them exactly the skills they need to operate it,” adds Jürgen Brielmaier, COO of the KERN-LIEBERS Group. “However, we can also use this type of animation to provide our customers with valuable support, for example when they make a change to a product and need the corresponding solution. Animations therefore perfectly complement conventional sample parts.”

Clear requirements

“In the past, we also manufactured the components for the old GIRA socket on Bihler machines. Starting with a throughput of 80 strokes per minute, we were able to increase output up to approximately 100 per minute over the years, but that was definitively the limit to our capacity,” recounts Schnöring. “However, a few years ago, our customer further developed the sockets. In addition to adapting our production approach, we also had to find a way of increasing throughput in order to be able to manufacture more than 700,000 components per week. And the dimensional precision of the components, which was already very good, had to be improved even further.

Manufacturing at the strip

It was clear that these requirements could not be met using the existing equipment – with the result that Schnöring GmbH worked together with Otto Bihler Maschinenfabrik to develop a completely new production concept. This is designed around two new Multicenter MC 42 machines together with a new Multicenter MC 82. The latter of these is used to manufacture the ground connector, which consists of six individual parts. Of these six parts, the clip and the casing are stamped and bended on the MC 82 and are then assembled with the other four parts (two fingers, a retaining spring and the plastic release toggle), which are fed to the system via a conveyor mechanism. During the production process, the ground connector is transported via conveyor belt from machine face A to machine face B. The components are then separated and enter an automatic measuring cell that uses a cycle-synchronized camera to check that the products are completely free from any defects. By contrast, the two Multicenter MC 42 machines are used to manufacture the right and left-hand variants of the Schuko contacts.

Exceptionally high component quality

The first step in the process is to stamp the housing, followed by the infeed and preassembly of the already manufactured retaining spring. The preassembled contact is then transported on the strip to the machine’s B face where it, too, is equipped with a plastic release toggle. The part is bended to the required shape on the strip and is transported – still on the strip – to the measuring cell before then being separated. “The crucial difference compared to our earlier production process is that practically all the process steps are performed at the strip and not at the individual component. This was the key factor allowing us to achieve the necessary throughput, while also guaranteeing the extremely high component quality that was required,” explains Schnöring. All aspects of tooling and assembly were developed and constructed in the company’s in-house Design and Toolmaking Department, where Schnöring GmbH uses the Bihler bNX software for its CAD activities. The solution has been operational since April 2022 and provides the capacity necessary for more than 35 million components per year.

A partnership crucial for success

“The very close cooperation with Otto Bihler Maschinenfabrik right from the start was crucial for the success of the entire project. This enabled us to meet the customer’s requirements for a 50 percent increase in throughput coupled with particularly high component quality, and we are able to do so reliably and consistently. And in the years to come, we will continue to nurture this partnership, which started with our first Bihler system back in the 1950s and has grown even more intense over the last 20 years,” says Schnöring. And, in its role as partner, Otto Bihler Maschinenfabrik provides particularly wide-ranging support: “We assist our partners and customers in all their developments, irrespective of whether they require a completely new system or need to adapt and optimize existing equipment or tools,” stresses Mathias Bihler. “Together, we can develop outstandingly efficient, forward-looking solutions that open up new prospective avenues of success for all of us.” And this is particularly true of the solution described here, which is now being used by Schnöring GmbH to manufacture socket components which GIRA then assembles itself to produce finished sockets: “The new solution has vastly extended our range of competencies and clearly differentiates us from our competitors,” is how both Axel Schnöring and Jürgen Brielmaier sum up their experience. “For us, it clears the path towards new, pioneering, forward-looking projects. One of these, for example, will be a laser-welded, multi-part assembly that we will produce on a Bihler BM 4500.”