A unique combination of machining centers are con-vincing in terms of flexibility and precision
WESKO GmbH - A machine should be replaced due to its age and, in a further step, capacities increased with a larger machine. Also, the product range should be improved upwards. WESKO in Stollberg/Germany opted in favor of the Fehlmann VERSA 645 linear 5-axis machining center and, 12 months later, the Fehlmann VERSA 825. The list of requirements for these investments was long. The decisive factor for increased flexibility was the combination of a small and a large machine, together with an automation solution.
Today, when comparing machine tool manufacturers within the same category, the differences are usually minor. At least, that is how Roland Sandmeier, of Export Sales NW Europe at Fehlmann, sees it. When investing in two machining centers, WESKO saw these details in terms of a high degree of flexibility, compactness and ease of operation of the entire machine cell. However, for Heiko Lehm, Head of Toolmaking at WESKO, these details are of enormous importance: "First of all, the second machine was not installed until one year later. The current machine cell configuration, however, was planned from the beginning and everything was prepared accordingly. As a result, one year later, the VERSA 825 could be commissioned in only four days. And so to the seemingly small details: it was important to us for the machine operators to have a clear view of both machining centers, including the Robot Compact 80, from the front. Another criterion for the decision, however, was the linear drives. These not only allow for faster traverse movements, but also provide more precise imaging in corner areas, thanks to the uniform speeds. This means that we can achieve our tolerances of 1/100 mm reliably and permanently. Even in the unmanned night shifts.”
In Stollberg, manned machining is now happening in two shifts, while the night shift is used for electrode production. This machine cell is excellent in terms of compactness and ease of operation - comparable machines with integrated automation are usually set up offset by 180°. Fehlmann, on the other hand, has succeeded in positioning the machines with the Robot Compact 80 so that the operator always has a good overview of both machines. Roland Sandmeier explains: "It may sound strange, but we take the details of how a machine can be automated and operated into consideration beginning with the first drawing done by our design engineers. This is also the reason for our unique selling point regarding the compactness of the machining cell concept."
Just one try, then the quality must be right
Currently, since spring 2018 and October 2019, respectively, 70% of the highly complex mold inserts (soft and hard up to 60 HRC in some cases) for injection molding tools, small series and copper electrodes are being produced on the two machining centers in WESKO's toolmaking division. Copper electrodes are used because they allow you to see very precisely where erosion is taking place; for example, when making dimensional corrections. Eroding machines also sometimes produce better results - finer textures can be produced and wear is also kept within limits. The proportion of copper electrodes on the machining centers, however, is only around 30 percent.
In order to cover the entire product range with the two machines, the company in Stollberg opted for one large and one small machine. While the 20,000 rpm VERSA 825 is also used for roughing and larger components, the 30,000 rpm VERSA 645 linear is also used for HSC machining. This necessary variety of machining options was a slight challenge for Fehlmann, as 320 x 320 UPC pallets, ITS 85 and 148, as well as electrode holders, are used at WESKO. All this equipment, therefore, had to be integrated into the Robot Compact 80 - with a floor space of only two m2.
In Stollberg, in spite of the VERSA 825 machining center's powerful HSK-A63 motor spindle with a torque of 120 Nm, the focus is not on metal removal rates. It is primarily on highly complex workpieces, where precision is the main focus. This is a fact that Heiko Lehm regards pragmatically: "In contrast to series production, in toolmaking we only get one try and then the quality of the workpiece must be right. That's why we wish to achieve our required tolerances reliably. Clamping devices and milling tools must, however, also be taken into account here. Fehlmann, though, is known for precision anyway. It makes little sense then to push the machine to its limits. We regard a 10-minute longer running time to be irrelevant, because we achieve the necessary efficiency through automation.”
80 percent of WESKO’s business is now focused on the design and manufacture of injection molding tools and 20 percent on the manufacture of parts. This parts manufacturing is mostly concerned with pilot series of connectors. Manufacturing is also carried out here using Fehlmann machining centers, a PICOMAX 60 and 90, also with automation. Machines that have been in operation for more than 10 years continue to mill with the required precision and are also used for automation courses for trainees.
WESKO in the spotlight
The company was founded in 2001 and, with over 100 employees, is a full-range supplier of innovative precision solutions, from prototypes to series production-ready parts, in the divisions of tool- and mold-making, plastics processing and testing technology. In tool- and mold-making, WESKO focuses on the design and manufacture of parameter-monitored injection molding tools, molds for vertical or horizontal overmolding, multi-component injection molding tools as well as micro-injection molding. The customer base includes the optical industry, automotive, medical technology and the automation industry.
Interesting side notes
With the pilot series, WESKO produces prototypes of the series part right at the beginning of the design process, which allows the required functional properties to be checked at an early stage.
By the way
Heiko Lehm: “That's how the machining cell was envisaged from the start. Fehlmann has already commissioned and tested this configuration at the factory. That’s why the VERSA 825 was ready for operation after four days.
Mr. Andreas Hildebrandt
09366 Stollberg / Deutschland
Tel. +49 3 72 96 92 28 0