Flexible and reliable production

Virtual process support: The milling centers at Hummel-Formen frequently perform the majority of the machining before the final form is known. Upon customer request, designers can actually change the data for a planned injection mold during the machining process. The result: Up to 30% shorter throughput times, thanks to a Tebis software solution that supports the entire process.

The front end of a vehicle is formed mostly automatically on this Scharmann horizontal machining center in accordance with the specifications of the Tebis CAD/CAM software.

The integration of Tebis software for electrode manufacture and simulation of the complete milling machining process allowed Hummel-Formen to further optimize its process chain in 2007. This company in Lenningen has now reduced its throughput times by up to 30% and has also partially automated its generation of NC programs for electrode manufacturing. Other benefits include improved quality and reduced stress when dealing with time constraints. We are a very innovative organization, and we like to take new paths. We had already begun acquiring electronic operating data in 1983," explains partner Jochen Hummel. In 2007, we expanded our end-to-end IT manufacturing system with the Tebis Electrode Design and Simulation modules. These have given us a significant edge in flexibility, time and quality."

• Complexity and size

  Right from the start, Hummel specialists relied on innovative milling machines to be faster than the competition in subcontracting work. They have relied on the integrated Tebis solution for their CAD/CAM software for more than ten years. "It’s the best solution for our preferred design and manufacturing process," explains Mr. Hummel. Hummel-Formen primarily manufactures injection molds for the automotive industry. Their complexity and size is evident from the manufacturing times on the one hand and from their weight of up to 112 tons on the other. The steel blocks that the company can have delivered are too small for the large molds. Mold parts therefore need to be milled from several blocks and then put together.

  Three-dimensional representations – in this case, of a mold insert for an injection molding tool – has replaced the drawings formerly used throughout Hummel-Formen.

  Tebis starts by importing design data at Hummel-Formen. They can originate from various programs from external service providers, from customers or from their own CAD department. For the subsequent processes, the interface has to evaluate and implement the information from the different data sources at perfect quality.

• High success rate, even for disparate data

  "One reason for using Tebis was and still is the high success rate even given the wide range of quality of the data provided to us," explains Andy Weirich, head of the Hummel-Formen milling department and also responsible for EDM. "Personal qualifications and the knowledge of the programmer also play a role. And the better the interfaces work, the less time and effort is required on our part." One of the more demanding activities they perform with support from Tebis is product development of aluminum prototype molds. Designers and manufacturers are often heavily dependent on the vehicle designers. The final design – whether it’s for an instrument panel or a front end – is first developed one piece at a time for visual and safety reasons. Multiple test molds can therefore result. Even the final steel mold often goes through another development process.

  Graphite electrodes for eroding the injection molding tool for a cylinder head cover.

• Accumulated practical experience

  The company’s developers and programmers have benefited from their experience with Tebis. In the past two years alone, they’ve created 29,000 machining templates (NCSets) and stored them in the database. They take into account specifications from the customer and from mechanical manufacturing. The rate of new additions is now down to two or three in an average week. This is how the experts accumulate their NC manufacturing expertise. And the virtual library supplied by Tebis systematically manages this expert knowledge so the Hummel specialists can use it for targeted solutions in future projects. The CAD-Feature-Scanner also simplifies and accelerates the process. "Three or four machining strategies might be stored for a single bore or milled pocket," explains Weirich, "because we will machine it differently on a large machine than on a small one." Of course we want to exploit all the potential of our resources. Tebis's organizational principle enables an extremely transparent management of the large library of templates. The efficiency of the Tebis CAD/CAM software also determines personnel resources. Only 3 1/2 NC programmers are needed to program the total of 20 NC machines. This applies to both 2.5D as well as 3D machining, as well as to the corresponding integrated software modules.

  The Viewer realistically images the workpiece for the die makers better than any drawing.

  The software system offers even more benefits for the programmers and manufacturing workers. The interface, logic and operation are identical. "I don't know any other system provider or software that maps the entire process so comprehensively from start to finish," states Weirich. The involved employees work so well together using the CAD/CAM system that milling frequently begins before the designers are finished. "Many employees, mainly the older ones, voiced their concerns during implementation in the shop," explains Weirich. "The move from paper into the digital virtual world required some supportive measures." "We had to remove the drawings, including the means for hanging them up." The end-to-end work plans generated from the program data have now completely replaced the former single-part drawings: "now, everyone wants to have the colored, realistic image of the NC viewer on the display. And when we receive a drawing from an external partner, even those who were once the greatest skeptics now ask for digital data."

   

• Comprehensive overview

  More than 50 employees are now using the Viewer system. When asked his advice from colleagues who are still faced with similar decisions, he responds: "You have to take a comprehensive overview of the entire process – from workpiece design through tools to the machine, simulation of the machining process and documentation. While separate individual solutions bring few benefits, an end-to-end solution with an expert partner yields significant benefits. This solution also makes sense based on expenditure." Tebis installed the Simulator module at Hummel-Formen in mid-2007. This module simulates the entire milling process. However, in contrast to an actual manufacturing process, it only requires a fraction of the time, and it warns of possible collisions or contact with limit switches with no damage. This eliminates the often high cost of the "trial and error" approach previously used. The Electrode Design module also helped the company’s manufacturing process succeed. Electrode design is primarily automated based on the available CAD data.

  The worker can check every step, its boundary conditions and its effects on the monitor.

  The Simulation model eliminates the trial-and-error method and provides reliable information on the process, including any collision risks.

  It also includes revision of the design specifications. Beyond the eroding form itself, the program completes areas like base and shaft extensions that are useful for downstream manufacturing processes. The program also handles all data management. Automated manufacturing of the 26 graphite electrodes was taken over by a Röders RFM 760 with a pallet system for blank setup. The Hummel machines are now essentially running around the clock. "From a technological point of view, this is a milestone. Now that our processes are simulated in advance, machine downtime due to collisions or tripped limit switches is a thing of the past," says Hummel. "The bottom line is that we’re observing a reduction of up to 30% in processing time. The short run times especially benefit our customers."

  The Electrode Design module automatically generated the CAM data for eroding the mold insert for a cylinder head cover.

   

• Profile

  Hummel-Formen

  Manfred Hummel founded the company in 1960 at its headquarters in Lenningen, close to Stuttgart Airport and at the edge of the Swabian Jura. Today his two sons Jochen and Volker run the family business as personally liable partners. With approximately 250 employees, including those in its Romanian subsidiary, the corporate group had revenues of roughly €20 million in 2007.