The cutting edges of the majority of this German toolmaker’s tools and dies are now hardened with an inductive heating process.
Werkzeugbau Laichingen GmbH is a centre of competence for the design, programming and fabrication of press and forming dies, punching and stage tools, and progressive dies. Founded in 1891 and currently employing 100 people, the company manufactures large-scale tools for automotive structural and body shell parts according to the highest standards with regard to process reliability. Its emphasis on quality has led to Werkzeugbau Laichingen becoming a recognised partner of the automotive industry and receiving the Daimler Supplier Award in 2017 for outstanding performance and partnership in the category “quality”.
Looking for the most efficient hardening process
Tools and dies for forming and cutting need to be hardened, especially along their edges, to cope with the high mechanical stresses to which they are subjected. The stability of the cutting edge is decisive in determining the length of the tool’s life.
Werkzeugbau Laichingen used to harden most of their tools on site by the time-consuming process of flame hardening. An alternative was laser hardening at external contractors. However, this involved an additional logistical step which also was not time-efficient.
“We are continuously working to improve and further shorten our production processes,” says Gottlieb Schwertfeger, who is in charge of purchasing and quality management at Werkzeugbau Laichingen. “In pursuit of this goal, we recently changed the processes for cutting-edge hardening, which had been taking too much time overall.”
EMAG eldec provides an induction heating solution
In 2015, Werkzeugbau Laichingen turned to EMAG eldec Induction GmbH, a company based in Dornstetten, Germany that specializes in developing, manufacturing and marketing highly efficient induction heating technology for a wide variety of industrial applications.
An induction heating/hardening system primarily comprises the inductor, the energy source (frequency converter) and the cooling system. Energy source devices have under proper maintenance a very long lifetime (up to decades). Inductors need to be replaced periodically, but this can vary heavily depending on the processes and applications – after several thousand to several hundred-thousand heating cycles.
Specifically, Werkzeugbau Laichingen started working with the eldec MICO system, an all-in-one mobile energy source with an integrated active cooler and intuitive touchscreen operation. The MICO generator is thus used as the energy source for induction cutting-edge hardening of tools.
“We are more than satisfied with the technology. We are already saving a lot of time and money. While we are improving our processes, we are also simultaneously developing new know-how around the technology which will later directly benefit our customers. For example, we are optimizing the hardening and subsequent annealing processes to improve the fit and configuration of the device for the relevant active part of the tool. The quality and efficiency of the process are continuously being perfected.”
purchasing and quality management at Werkzeugbau Laichingen
The multiple benefits of induction hardening
With induction heating, the tool reaches the required temperature much quicker, because the heat is delivered directly to the volume underneath the surface. With flame or laser heating, only the surface itself is heated at first. The energy and the application of heat can be perfectly controlled, ensuring fast heating times, optimum control of the heating process, and minimal energy consumption.
Soot and other potentially dangerous emissions (e.g. toxic gases) formed by flame hardening are entirely eliminated with induction heating. Induction heating, which is to say induction hardening, thus offers greater process stability than flame hardening and can considerably boost productivity in surface hardening.
“Induction hardening offers significant advantages in terms of processing quality and time, as well as safety and cost. Moreover, its good energy efficiency makes our technology much more environmentally friendly than flame hardening.”
Stefan Tzschupke, Head of Business Development Generators at eldec
Specific results at Werkzeugbau Laichingen
In general, the energy flow density per square metre is much higher with induction heating at 5 kW/cm2 (in some special applications even up to 8-10 kW/cm2) than with flame heating which is only about 1 kW/cm2. Hence in theory a factor 4-5x efficiency gain could be achieved. However, the actual process efficiency depends on the interaction of various parameters: material and geometry of the piece to be heated, frequency of the induction system, inductor current, distance, hardening penetration depth, etc.
Process time savings
Estimated by Werkzeugbau Laichingen at up to 70%-80% (which is also due to the flexibility of the induction system compared to previous processes and logistics).
Improved working conditions through the absence of gases, soot and flames leads to better health and safety for employees. Replicability and automation of processes can be more easily achieved.
Improved image of Werkzeugbau Laichingen as a sustainable company in the region. This is an important topic for the company, which recently introduced an environmental management system and achieved certification after auditing.