Mold making for racing

For nine years, KME Renntechnik has been supplying several different racing teams. With flexibility, quality and speed in CNC production for mold making, the company helps secure success on the racetrack.

Passion Motorsport

Motorsports have always been an important part of life for Klaus Murnauer, now the owner of KME Renntechnik. As a young boy, the qualified auto mechanic and mechanical engineer watched wide-eyed as fast cars sped around the track. During his studies, training and first few jobs, he learned about the design of motor vehicles and the various areas of mechanical engineering. Today, as owner of KME Renntechnik, Murnauer can draw on this experience when designing and producing molds and parts used in the chassis, engines, gears and other components of race cars. His thriving company currently has six employees and has made a good name for itself among many racing teams. Owner Murnauer says proudly: "Parts that we have produced are used in all DTM brands and can also be found in Formula 1. Just recently we received a big order from a well-known racing team that will be entering its vehicles into the next 24 Hours of Le Mans."


Molds, tools and finished parts offering the highest precision and reliability are KME’s trademark. The company works with metals as well as plastics and carbon. This is one reason other sectors have also become aware of the company based in Rott am Inn, Germany. Racing dominates the company’s business, at just under 70%, but firms from the medical technology and aerospace sectors (certification for airplane parts is already underway) are gaining in importance.

Short throughput times thanks to man and machine

From left to right: Alois Penzkofer, user support and promoter at Siemens; Klaus Murnauer, owner of KME Renntechnik; and Maik Fritsche, sales employee at Böhm Werkzeugmaschinen GmbH, are delighted with the successful collaboration

What is this success based upon? The entrepreneur believes the answer lies in the company’s extensive expertise, as well as flexibility and short throughput times. Customers have long considered compliance with accuracy and quality requirements to be a given. The manufacturing expert explains what he means by short throughput times by using the example of versions of a complicated laminating tool: "To start with, we work with the customer to define the size and form of the component, while we are at the same time acquiring the material. If it’s a complicated component with free-form surfaces, we design and program it on our CAD/CAM system, save the program to SINUMERIK 840D sl via the network and launch our Spinner U5-620 simultaneous five-axis machining center." At the end, all his employees have to do is draw- or mirror-polish the precisely machined laminating tool and install it as required. "Depending on the complexity, we only need three to five days for the entire process," adds the KME boss.

This is made possible by the fact that all his employees are well coordinated and work in 24-hour shift operation if necessary. KME also sees the machine tools, based on Siemens control system technology, as a key factor in the company’s success. Murnauer singles out the two Spinner U5-620 five-axis machining centers with SINUMERIK 840D sl and the user interface SINUMERIK Operate, which were acquired in 2012: "These machining centers equipped with SINUMERIK have the best price/performance ratio on the market for my needs." With component complexity growing, 2+3 axes are extremely helpful, as it means that machining can usually be carried out in one clamping operation. The result is greater precision with shorter through- put times. "We are also getting more and more requests for parts with free-form surfaces. Thanks to the U5-620, that’s no problem for us. This is because we can have the five axes of the milling machine running simultaneously," explains the manufacturing expert.

Five-axis machining and high-end control system for top quality

Various parts are manufactured using different materials and are used in the chassis, bodywork, engines and gears of race cars

On the U5-620, a tool magazine with up to 55 spaces and a dual-arm tool changer minimizes idle time, and axis accelerations of 5 m/s² increase productivity. The digital position measuring system ensures high workpiece accuracy. The machines achieve positioning accuracies of Tp max. = 10 μm in the machining area and repeat accuracies of up to 3 μm in the individual axes. Murnauer cannot make any general statements regarding surface roughness, emphasizing that it depends on the different materials, feeds and feed rates. But he does provide one practical example: "When finishing high-strength aluminum, we often use a 10-mm ball cutter, which turns at 10,000 min–1 and works at a depth and side feed of 0.5 mm, with a feed rate of around 12 m/min. The surface values of Ra = 0.5 μm to 0.8 μm often requested by our customers cannot be achieved directly - however, postprocessing by hand, which takes only a few minutes, is enough to take us safely into the target range."

Alongside stable machine design, the top-quality control system and drive technology from Siemens is a great help here. KME uses the new version of the SINUMERIK MDynamics milling technology package with the Advanced Surface intelligent motion control. The engineers have further optimized the Look Ahead function and integrated an efficient data compressor that aligns the modeled individual points so well during program generation that the machine can mill extremely smooth surfaces. The manufacturing expert also finds the intelligent jerk control helpful. It means that the axes are sped up and slowed down gently, despite extreme dynamic response.

Optimum operability for experts and “lateral entrant” employees

Klaus Murnauer has been won over by his two five-axis machining centers with SINUMERIK 840D sl and SINUMERIK Operate

The head of KME is clearly also delighted with the ease of operation and programming facilitated by SINUMERIK Operate. Cutting machine operator and CNC programmer Alexander Neumaier, for example, was skeptical when he first joined KME and saw that the company used only Siemens CNCs. He had been programming machines using another manufacturer’s CNC for 10 years. And now? His reservations disappeared after two days: "I didn’t believe I would be able to program and set things up more quickly with SINUMERIK Operate than with my old control system after such a short time. I now create complete 3+2-axis programs directly on the machine."

The modern user interface is also advantageous for "lateral entrants" - employees coming in from different sectors - upon whom companies are becoming increasingly dependent due to the acute shortage of skilled workers. The reason? Contract manufacturing companies expect production workers to be able to program simple components directly on the machine tool. The ShopMill graphical work-step programming system helps here, because in this mode the CNC requests each individual command and models it visually. This means the operator is guided swiftly and accurately from the first to the last programming step. Plain text hints provide assistance in the event of uncertainty. Errors are extremely unlikely, as trained screed installer Georg Schartner confirms: "Although I come from an entirely different sector, I managed to program my first few small parts independently and fault-free after just one day."