DMG MORI: Fully Automatic, Safe and Precise
As a first-tier supplier to the automotive and commercial vehicle industry, Grede manufactures safety-critical components for the powertrain or chassis, among others. For this purpose, the team has more than 40 machining centers and lathes from DMG MORI at its disposal.Production line with 18 NHX 5500s and 10 robots. One robot feeds 2 NHX 5500s. The tenth robot feeds the blanks and transfers the finished parts into a separate washing & measuring cell.
Grede Holdings LLC has its origins in a foundry established in 1920 in Wauwatosa, Wisconsin. Today, with 3,000 employees at ten locations in North America, the company is one of the leading experts in the field of metal casting.
At its machining and assembly facility in Menomonee Falls, Wisconsin, the machine tool manufacturer optimized the production of steering knuckles in 2019. The result is impressive: Over 650,000 steering knuckles are produced per year in a fully automated production line comprising 18 NHX 5500s.
„Thanks to the combination of machining speed, stability and accuracy, the NHX 5500 is the ideal machine for fully automated processes. The entire system of 18 machines manufactures reliably and safely to an accuracy of ± 0.01 mm.“
Holistic manufacturing from casting to ready-to-install component
“As a full-service provider, we cover the entire process chain from design and casting to final machining and quality control,” explains Mike Latwesen, General Manager at Grede in Menomonee Falls. He says the focus is primarily on safety-critical components for customers in demanding industries. “To remain competitive, we have to manufacture high-quality products and deliver them on time.” The fact that Grede has been one of the leading suppliers in the industry for decades is a direct result of continuous process optimization. Particularly in machining – which accounts for up to 50 percent of the value chain – there is a lot of potential for savings, says Mike Latwesen: “Today's machining centers are more versatile, faster and more precise.” Grede has been using machine tools from DMG MORI since 1980, so he knows the technology very well.
Feeding of the blanks; Tornover station; Discharge of finished parts.
Turnkey project for complete machining of 650,000 steering knuckles per year
Recent installations at Grede include a production line for steering knuckles, which was installed in Menomonee Falls in 2019. “In DMG MORI, we found a partner for this turnkey project that, offers leading manufacturing technologies. Additionally, their engineers have the necessary competence to implement such an extensive project in the allotted time,” says Mike Latwesen. In view of the order situation, the capacity expansion had already been planned. The project took six months to complete. Since then, the plant has been producing over 650,000 steering knuckles for passenger cars per year in a fully automated and highly flexible process – a complete set for one vehicle per process operation.
18 NHX 5500s for reliable one-hit machining
The production line in Menomonee Falls consists of 18 NHX 5500s that perform a total of four milling operations. Ten robots load and unload the machines with heavy knuckle parts. This removes the risk of injury to the operators, while ensuring the machines are always supplied with raw parts. The operator loads the raw parts at one location and the intelligent parts conveyor transports them to all 18 machines. The DMG MORI Messenger monitoring software allows status monitoring of the machines, which enables the operators to address issues such as tool change in a timely manner. “After the steering knuckles have passed through the production line, only final quality control follows,” adds Mike Latwesen.
The fully automated process naturally requires absolute reliability – one reason for acquisition of horizontal machining centers: “Efficient chip evacuation makes the NHX 5500 an ideal machine tool for such automated processes.” The integrated tool breakage sensing and the high-pressure coolant system are also crucial for the reliable operation of the production line, he adds. The same applies to the powerMASTER spindles, on which DMG MORI offers a 36-month warranty with no hourly limit, thanks to their robust design.
According to Mike Latwesen, reliable horizontal machining was just one of several arguments in favor of the NHX 5500: “The combination of machining speed, stability and accuracy made the decision easy.” The system machines to an accuracy of +/- 0.01 mm. Another advantage was the small footprint in relation to the large work area. “It offers sufficient space for the required fixtures.”
The finished steering knuckles are then washed andautomatically measured.
In addition, CELOS played a role, adds Mike Latwesen: “We've been using the intuitive control interface since 2014 on NLX 2500s installed at the time, so in the case of the NHX 5500, our team was already familiar with its operation.”
Turnkey project perfectly implemented
With the turnkey solution, DMG MORI met all Grede's productivity and machining quality requirements, and Mike Latwesen looks back positively at the entire project implementation: “In a project of this size, there are always hurdles to overcome. DMG MORI mastered the installation professionally and on schedule at all times.”