At CLAAS Industrietechnik in Paderborn, Germany, a shift in clamping methods has revolutionized production efficiency. Today, the adoption of versatile standard workholding towers, equipped with component-specific clamping mechanisms, has boosted output by 20%, while simultaneously enhancing process reliability. Collaborating with ROEMHELD, CLAAS Industrietechnik has seamlessly integrated these clamping solutions into their flexible pallet-based production system.

In 2002, Stefan Picht, then a production planner at CLAAS Industrietechnik, was tasked with optimizing the hydraulics prefabrication department's operations. Central to his mission was ensuring reliable clamping for cubic components. After thorough evaluation of various options from leading suppliers, the HILMA TS 125 L tower workholding systems emerged as the preferred choice. Despite their initial higher cost, Picht emphasizes their long-term value, “The one-time higher investment I get out every day again.”

Picht highlights the importance of clamping security offered by the Hilma TS 125 systems.

Building on this success, CLAAS Industrietechnik has since expanded its inventory of tower workholding systems. Today, the facility employs eight TS 125 and three TS 125 Vectors for heavy workpieces, alongside a TS 125 Tristar for three-sided clamping. Additionally, CLAAS utilizes six MSH multiple workholding systems and a range of HILMA machine vices.

Streamlining Manufacturing Efficiency with Tower Workholding Systems at CLAAS

Tower workholding systems play an integral role within CLAAS's dynamic manufacturing environment, known internally as the "flexible manufacturing system." These systems are deployed within the "Prefabrication Hydraulics" department, seamlessly integrated into a comprehensive production solution. This system is orchestrated around two horizontal 4-axis machining centers, namely the Heckert CWK 400 D and HEC 400, each intricately linked to pallet stations provided by the Finnish automation company, Fastems.

Located within a two-story station, these pallet stations house forty storage slots, specifically designed to accommodate pallets equipped with the tower workholding systems. Given that ninety percent of components undergo machining in two distinct phases, each workholding tower serves a dual purpose: housing raw parts awaiting initial machining and completed workpieces awaiting final processing. Robotics facilitate the movement of pallets from their storage locations to the designated machining centers, ensuring seamless and efficient production flow.

Achieving Versatile Clamping Solutions with Standard Components

The workholding towers are loaded at two setup stations, facilitating the clamping of 240 different workpieces utilizing standard components. The four machining centers primarily process intricate hydraulic components such as valve housings and pump components, totaling approximately 92,000 pieces annually. These components consist of a combination of grey iron, nodular iron, or wrought aluminum alloys.

The diversity among the 240 workpieces is striking, ranging widely in weight, dimensions, and geometry. Weights vary from less than 1lb to 35lbs, with dimensions spanning from 100 x 80 x 53 mm to 125 x 100 x 242 mm, encompassing both cubic and free-form mold castings. Lot sizes fluctuate from ten in spare parts production to 500 pieces.

Ninety percent of the fixtures utilized are flexible standard configurations employing specialized jaws. Previously, the complexity, cost, and rigidity of clamping components using bespoke fixtures were significant challenges. However, the current approach represents a stark departure, with only the clamping jaws tailored to the specific workpieces. Stefan Picht highlights this shift: “Now we have standard clamping elements with specific jaws. Ninety percent of our jaws are designed specifically for our requirements.” 

ROEMHELD offers an extensive array of interchangeable jaws for standard applications, further supplemented by customer-specific variants. These include swiftly interchangeable jaw inserts, featuring hard-metal grip inserts capable of accommodating non-parallel clamping surfaces or firmly gripping workpieces with narrow edges. Additionally, TUC-coated semi-standard jaws enhance retention forces without altering clamping force, ensuring secure clamping of thin-walled parts during robust machining processes.

The Demanding Design of Workpiece-Specific Clamping

“When there are new components to be machined, CLAAS sends us inquiries for special jaws. This usually happens several times a year,” explains Karl-Heinz Stötzel, product manager for workholding systems at the ROEMHELD Hilchenbach site. “Stefan Picht then sends the component data to the experienced designers in Hilchenbach. They develop suitable clamping solutions, and CLAAS receives the proposals as a drawing or 3D graphic. In the struggle for the best solution, we always have a lively exchange between our work preparation, component design and ROEMHELD's design department,” reports Picht.

Product manager Stötzel points out that the tasks are quite demanding. “For our design department, it is sometimes a challenge to design the clamping jaws so that they guarantee optimum accessibility of the workpiece for machining.”

Enhancing Workstation Ergonomics and Clamping Safety

All utilized workholding systems are entirely mechanical in operation. CLAAS employs two variations of the Hilma TS 125 workholding towers. Those equipped with a 3rd-hand function are operated via a spindle, ensuring uniform clamping force distribution at the central jaw. Conversely, the TS 125 Vector systems utilize two spindles, enabling independent operation of both clamping points with variable clamping forces.

To facilitate operation, all TS tower workholding systems are integrated with a handling system located at the loading station. An ergonomic pneumatic motor, suspended and guided by balancers, is affixed to the spindle by the operator. Operation is initiated via a foot switch, allowing the operator to maintain hands-free operation for workpiece handling while ensuring reproducible clamping force. This setup significantly enhances workstation ergonomics and clamping safety.

As a safety measure, the operator must first secure the torque motor to the setup station before the induction sensor authorizes the robot to retrieve the pallet with the clamping devices.

Production planner Picht expresses high satisfaction with the long-standing collaboration. “Consulting, communication, project execution and service are very good, the quality of the clamping devices is extremely high, their operation simple and reliable. And the improvements in productivity and safety are greater than we originally expected.”

To bolster throughput, CLAAS Industrietechnik intends to expand its practice of clamping additional workpieces on standard workholding towers fitted with specialized jaws in the future.

“Tools have become increasingly powerful, especially for machining aluminum components. As a result, running times have become shorter and shorter, and set-up is becoming increasingly important,” says Picht.