Toolmaking and mold-making professionals routinely face many challenges unique to their industry. In order to ensure the stability of the tools produced, very hard grades of steel are required.
Specialists must also be able to precisely shape this material for use in creating demanding components for things such as car-body manufacturing. In other words, quality in the toolmaking process has an enormous impact on quality in automobile manufacturing. It is clear that under these conditions the final surface hardness of the tools is essential, and additional hardening of the cutting edges is usually necessary.
The production planners at Werkzeugbau Laichingen (WBL), a producer of high-performance tools for the automotive and automotive-supply industry and for domestic appliance manufacturers in Ulm, Germany, have been relying on technology from eldec. Their cutting edges are hardened by mobile and robust MICO (mobile induction coolant on board) generators. This flexible technology significantly decreases and simplifies the production process.
Experts often describe toolmaking as a link between development and production with a considerable impact on the industrial value added. This is why the industry is considered a trendsetter for the continued development of production technologies and is always in search of new solutions to improve workflows and quality. Hardening of the cutting edge is no exception. This process hardens the features of the tool that later have to bear the greatest load in the punching or embossing machine. The stability of the cutting edge is decisive in determining the length of the tool life.
Benefits of Induction Hardening
Toolmakers generally use edge-layer hardening where the outermost layer of the cutting edge is heated to about 800 or 900°C (1472-1652°F), depending on the material. The “quenching,” where the real transformation takes place, then happens by natural cooling in the ambient air. As a result, the surface of the edge is harder and more resilient to wear (toolmaking typically requires a hardness of between 54 and 56 HRC), while the core of the material retains its toughness.
Various methods are available to achieve these results. Toolmakers primarily use either flame hardening, the very expensive laser hardening or induction hardening. Why is that?
“For starters, all these methods have flexible applications. Even large, bulky components with complex geometries can be produced manually or automatically when using lasers,” explained Stefan Tzschupke, head of business development, generators at eldec. “However, induction hardening offers significant advantages in terms of processing quality and time, as well as safety and cost. Our technology is becoming increasingly important for a growing number of toolmakers.”
A quick look at the characteristics of the procedure confirms this assessment. The cutting edge is heated by induction. The tool reaches the required temperature much quicker because the heat is delivered directly to the volume underneath the surface. With flame or laser hardening, only the surface itself is heated at first. The energy sources also make it possible to precisely control power, current or temperature, enabling users to respond optimally to special requirements as well as the ambient conditions of the process. As a result, the hardening pattern is very uniform.
“Another benefit is that the process generates no toxic or explosive gases that might contaminate the workplace,” Tzschupke said. “Finally, its good energy efficiency makes our technology much more environmentally friendly than flame hardening.”
Significant Reduction in Cycle Time
WBL is a new eldec customer that relies on the advantages of induction hardening. At its locations in Laichingen and Leipzig, the German company has comprehensive knowledge and experience ranging from tool design to complete production processes and comprehensive services for pressing and shaping tools. The specialists also provide the in-house presses for the start and phase-out of series production.
“We are able to respond to customer needs on extremely short notice, as missing or incomplete tools can cost a lot of money. We are continuously working to improve and further shorten our production processes,” said Gottlieb Schwertfeger, who is in charge of purchasing and quality management at WBL. “In pursuit of this goal, we recently changed the processes for cutting-edge hardening, which had been taking too much time overall.”
In the past, tools were mostly treated on site by flame hardening. The alternative was laser hardening at external contractors – an additional logistical effort that has now become unnecessary thanks to the fast induction hardening process. Since the fall of last year, the company has used a MICO generator as the energy source. This flexible energy container is perfect for toolmakers. A generator, cooling system and hose bundle are packed into a compact housing that is available with casters if required. Users are able to easily move the machine wherever it is needed on the factory floor, and an intuitive user interface with a touchscreen simplifies the configuration.
Processes also ensure that MICO generators have high stability and a long service life because they are developed for challenging manufacturing applications. Before shipping, they undergo comprehensive testing and are held to extremely high quality standards.
Developing In-House Know-How
“We are more than satisfied with the technology,” Schwertfeger said. “We’re already saving a lot of money. While we are improving our processes, we’re also simultaneously developing new know-how around the technology that 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.”
The technology is being used in a wide variety of punching, bending and forming tools. It creates a uniform hardness distribution on many straight and arched surfaces and radii. The flexibility of the applied technology is very important.
The referenced application example has something of a model function since experts are seeing a lot of market potential for their flexible generators, as Tzschupke confirms.
“Our new MICO series is providing a major solution for the energy source and cooling system,” Tzschupke said. “It covers a wide range of services and can be fitted with many different tools, which gives toolmakers a lot of options for implementing perfect and efficient hardening processes. We want to bring these strengths to the market even more than before in the coming years.”
For more information: Contact Markus Isgro, marketing communications specialist, EMAG GmbH & Co.KG, Austrasse 24, D-73084 Salach; tel: +49(0)7162/17-4658; fax: +49(0)7162/17-199; e-mail: email@example.com; web: www.emag.com
Industrial Heating posed some reader-interest questions to the author. We hope our questions and his answers enhance your reading experience.
Q-1: Are there other markets (other than toolmaking) that are utilizing this technology?
A: Induction is being used in a variety of different industries. Starting with automotive, axle shafts, gears and bearing surfaces are induction hardened. The technology is used to heat materials such as copper, aluminum or brass for brazing. Shrink-fitting is another technology where induction works very well. The heat created within the part expands the material and can be used to create an interference fit.
Q-2: Is there a part size range (dimension or weight) for your technology?
A: Size is related to power. The bigger is the size, the higher the power and the bigger the inductor. Generators range from 5 kW to 2 MW in power, so the spectrum is wide.
Q-3: Do you need special tools for specific part geometries?
A: The tools are always somewhat “specific.” For tool hardening, however, a few “standardized” tools have been developed that will work for most of the applications. In most other cases, the inductor is designed and built specifically for its application.
Q-4: What makes MICO more useful/unique than competing processes?
A: Even though the initial investment appears to be high in comparison to a gas-burning torch, the quality (case depth) is much more controllable. This increases the tool life of the die, which is where the real costs can be saved by keeping the tool in production longer. It is also faster than flame processes based on the much higher efficiency of induction. This reduces turnaround time, which saves money. A unique feature is how the inductor coolant lines and power supplies are designed. It pretty much allows the tool to be manually guided.
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