Since 2014, the Uwe Krumm Burbach GmbH (UKB) uses the first CNC 5-axis milling centre DMF 600 linear from DMG Mori delivered to Europe in the production of complex edging tools and in contract manufacturing. The innovation, presented at the EMO 2013 as a world first, with a six-meter machine bed and a rotary table is designed for a workpiece weight of up to ten tonnes. Clamping of workpieses at UKB for all processings and on all 14 milling machines is made with only two types of vices, regardless of the material, the size and the geometry of the component.
"We do not only want to satisfy our customers, but inspire them. Therefore we always offer the best products and the most efficient solutions. It is our intention to facilitate the daily production routine of our customers. With the new milling centre we cannot only produce complex components in an economical way, but we are now also in the position to machine workpieces with six instead of five meters in length", explains Dominik Enners, Head of Production Planning. An option that has been used immediately after the installation of the new CNC milling machine for a correspondingly long tool.
The new machining centre extends the machinery of the milling shop to currently 14 CNC milling centres. Due to its large size, the new acquisition is particularly suitable for long and heavy workpieces, but because of the integrated NC rotary table and its dynamic performance, UKB uses this milling centre especially for 5-axis complete machining of complex edging tools and in heavy-duty machining. "In view of our rapid company growth, we were looking in 2013 for an efficient machine particularly for this purpose", explained the production engineer.
"Depending on the geometry and size, there are up to seventy percent swarf when producing an edging tool," says Dominik Enners. The blank for a 5 meter long top tool for a producer of facade sheets weighed six tonnes, the weight of the delivered part was just 1.5 tonnes. Enners: "A powerful cutting performance is very important. Because many workpieces we machine are made from hard and tough Hardox steel."
Edging tools with a total weight of about twelve tonnes leave every week the company in Burbach, in Siegerland, Germany. With standard edging tools of UKB sheets up to 20 mm can be edged. For thicker and more complex 3D contours, an in-house engineering department develops customised special edging tools. As an example, Enners mentions a tool with which the complex rotor for a dishwasher can be produced: "These are solutions where the customer benefits from comprehensive engineering services." In the segment edging tools, UKB sees themselves as a leading supplier in Europe. The young business - contract manufacturing and sales of accessories and cutting blades -completes the range of services offered by UKB.
The customers come from all over the world and are active in a variety of industries, the most important ones are automotive, aerospace, mechanical engineering and white goods. According to their outstanding market position, UKB offers a very wide selection of tools: from edging tools weighing only a few hundred grams with a side length of just 60 mm up to large parts with a length of 6,000 mm and a weight of several tonnes. As different as the sizes are the geometries of the tools. Only in the hall for standard tools about a thousand different articles are stored.
The range of services offered does not only include the wide selection and the claim to be in the position to quickly deliver for each request the correct edging tool at affordable prices. Furthermore, UKB promises to modify, regrind and harden standard edging tools at the customer's request within 24 hours. The customer can relax during this time in a modern guest flat.
Besides the CNC milling shop, there is a CNC grinding shop for finishing of the edging tools and customised grinding operations. Moreover, UKB has their own laser-hardening system, which allows to increase the wear resistance of the edging tools. Thanks to the internal quality control with 3D measurement and their own press brake to test the tools, UKB is in the position to guarantee for the functioning of their products. Dominik Enners says: "We always use the optimum material and control the entire manufacturing process from the raw material to the finished workpiece. This is the best way to ensure the high quality of all processing steps and thus the high precision and repeatability of our edging tools."
In order to be fast, flexible and accurate, the company uses on all of the 14 milling machines only HILMA machine vices of the NC160 and VL160 series of ROEMHELD. The configuration varies from five vices on the smaller milling machines up to 14 vices on the new machine. Peter Diehl, Head of Production says: "On all machining centres we have only made the best experiences - no matter what kind of materials, geometry, sizes, processing modes. We can use the vices for simple punching as well as in 5-axis machining and complex machining applications, in which the component must be moved several times. They are highly precise, always reliable and easy to use."
In view of the high workpiece precisions, UKB also makes high demands on the precision of clamping means which are met by the vices with a tolerance of + 0.01 mm. Peter Diehl also attaches special importance to the process reliability: "Clamping with minimum deformation is of mayor importance to us: With the HILMA machine vices we can clamp the workpiece for rough machining at full force, for finish machining clamping can also be made within the mechanical range."
The HILMA machine vices are manufactured in Germany at the ROEMHELD site in Hilchenbach in the Siegerland, only a half hour away from Burbach. The clamping systems can be mounted in horizontal and vertical position and thanks to numerous variants they can be individually configured in many different ways. Thus they can be used very flexibly. Optionally, the clamping force can be introduced mechanically-hydraulically by a crank handle or in case of the hydraulically operated variant via hand or foot switch. On the machine, they can quickly and easily be adapted to very different workpieces. The handling is very simple. And the clamping means are quick and easy to clean.
The maintenance is also undemanding, says production manager Diehl: "Recently, a mechanic has checked all ninety vices on our site. The result: The clamping force of all vices was in order, only at one clamping system a defective socket pin was replaced. Since 1999, when I have started here, we are working with the HILMA machine vices and never have had problems." By the on-site service, expensive and time-consuming transport routes and costly machine downtimes are reduced to a minimum. On request, the mechanic instructs free of charge and in a competent way the operators and service personnel in the company on this occasion.
Enners reported that, in spite of the many different applications at UKB it is rarely necessary to replace clamping jaws. Thanks to the standard base length of 750 mm, the clamping range of machine vices with 508 mm is usually sufficient for large workpieces. Various top jaws are available to enlarge the clamping range, thus the clamping range can be increased to up to max. 772 mm. Like all articles from the extensive range of clamping jaws, they can be quickly and easily installed with only a few steps. The operators of the milling centres like to use the top jaws, if needed, says Enners. Due to the more and more complex tasks, he now considers to use in future the optionally available clamping force display for the precise ACTUAL VALUE display, the reproducibility and the control of the clamping force. This also enables the safe use of clamping jaws and top jaws for slides and fixed jaws with grip and hard-metal jaw inserts.
UKB GmbH is growing steadily since their foundation in 1991. The business unit for special tools (existing since 1999) is considered as a growth driver, which together with the contract manufacturing now contributes almost a quarter to the total sales.
The owner-managed family business currently has 55 qualified employees. But it continues its expansion course: In October, a second shift was introduced in production. Shortly before an extension building was finished, so that besides the new DMG manufacturing centre there is still enough space for further expansion of the production. "UKB is constantly evolving," says production manager Diehl, "because we develop solutions that always meet the latest requirements of the technology. That is the reason why we focus on innovation and optimum production processes."
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