Made in Germany

Jürgen Sielaff, U.I. Lapp GmbH

Highly specialized production with the best levels of quality assurance - this continues to be a unique feature of German industry. The new metal processing center for industrial connectors operated by the Stuttgart-based Lapp Group shows that the industrial production of components can be performed at the highest level, even in the age of globalization and internal competition.

Fully automated, reliable and made in Germany.

 

The Stuttgart-based Lapp Group boasts one of the most modern plants in Europe for the mechanical processing of rectangular industrial connectors, having operated its new metal processing center since mid-2013. Four handling robots, two independent metal processing centers, a washing center and a fully automatic riveting station with a loading and unloading station work around the clock to produce around 580 industrial variants of the EPIC ^® rectangular and circular connectors from 54 unfurnished housings. The new production facility not only achieves greater throughput, it can also manufacture all variants in the product range in a flexible manner with short lead times. The state-of-the-art plant was supplied and manufactured by German-based CHIRON Werke GmbH.

The contact inserts of the rectangular connectors have been manufactured in Germany for some time. This process was previously performed manually, but was now automated and integrated into production so as to reduce delivery times. This has resulted in highly automated production with a very high and consistent level of quality. The process data is subject to continuous digital monitoring – without any added costs. One of the additional aims of this process integration was to enable new product variants to flow flexibly into the processes and to engage in continuous adaptation of the product range in line with the new requirements.

Highest levels of repeat accuracy

Although quality control of the EPIC ^® connectors was previously performed manually, the entire process will now be performed fully automatically. The robots use a measuring button to measure each individual part and calculate any deviation and tolerance. They then immediately offset the deviation and search for the zero point of the hole or identify parts in which the tolerance deviation is too high, enabling the production facility to achieve a very high level of repeat accuracy.

The focus then moves to the riveting station, another area featuring fully automated processes. The bolt is individually moved, positioned and riveted in accordance with the type and position. The riveting point is corrected automatically as required. The riveting pressure is also monitored, with the values being documented and stored. This provides assurance for the operators that each part has been riveted. Conversely, in the case of manual production, this can only be observed by the operators once production is output by the machine. The advantages are obvious: the plant does not output any parts that have been processed incorrectly and traceability is assured at all times.

Milling instead of cutting

A unique feature of the Lapp metal processing center is thread manufacturing with the help of thread milling cutters – a system that was developed in-house. As special aluminum coatings with outstanding hardness are used for the EPIC ^® housing in order to make it suitable for application in all kinds of environments, this results in a fivefold to tenfold reduction in the service life of standard drilling and threading tools. However, thread milling cutters sustain virtually no measurable wear and provide a range of additional advantages.

The thread milling cutters enable spindle rotation speeds of up to 20,000 rpm to be achieved. After processing, it is as though the thread has been polished – no cleaning is required. The dimensional accuracy of the CHIRON precision processing centers is in the m range. In addition, various core hole and thread diameters with an identical gradient can be manufactured using only one tool. A further advantage of PCD cutting, in which polycrystalline diamond is used as a cutting material, is the low level of component heating. Due to the quick processing, there is less of an increase in the work piece temperature. This is more cost-effective as it enables operation with minimum quantities of cooling lubricant. In this case, however, the components are virtually warm to the touch upon exiting the device.

With the help of the circular bore thread milling cutters and the

undercuts that can be generated with them following the thread output, thread depths are achieved in virtually the same way as with through-hole threads. As a result, the rectangular connectors are compatible with conventional cable glands. The fact that there are no longer any burrs in the thread outlet means that deburring does not need to be performed. By implementing the thread milling cutter in the new metal processing center, we were able to further increase the service life of the tool.

New machinery concept

The aim of the new machinery concept was to not leave anything to chance and to turn weaknesses into strengths. "The combination of full automation and digitised quality control enables the machine to attain a high level of repeat accuracy and quality," enthuses Jürgen Sielaff, Production Manager for mechanical processing at Lapp.

The biggest challenge was to ensure that all the different variants of the EPIC ^® rectangular and circular connectors could be produced using a single machinery unit. The adjustment of the various product variants using the zero point calculator was a very complex procedure, but CHIRON was ultimately able to create a basic device with the ability to accommodate all 54 connector variants. "In succeeding in accommodating dozens of product variants across a very broad range at a principal tension, we have created an incredibly flexible production facility," explains Kristoffer Siegmann, Project Manager at CHIRON.

This means that the CHIRON production facility is also equipped for future demands, not least thanks to the integrated cleaning device that exceeds current requirements.

Control is now performed by a central computer with an SAP connection that enables it to immediately convert each customer order into a workshop order. In the event of a complaint, every employee can instantly access all quality assurance data.

Staying competitive through innovation

The example described here is a highly modern production plant that, thanks to the combination of numerous innovations, an elaborate machinery concept, fully automated production and highly qualified and highly trained personnel, achieves the highest level of quality without generating costs any higher than those involved in production in low-wage countries. This means that the "made in Germany" manufacturing process remains competitive whilst guaranteeing the highest levels of quality and dimensional accuracy.