Bernhard Fischbacher, Tobias Telser, and Paul Heilmann were visiting a fair to catch up on laser marking systems when the staff at Rofin-Baasel Lasertech Starnberg made a surprising offer. The managing directors of DHF Precision Mechanics GmbH were invited to take a seat in front of a manual laser welding system and to weld some parts by themselves; an experience that caused the three DHF managers to re-think their investment agenda.
Today, two years later, DHF uses laser material processing to manufacture Brainlab’s Dash, which is an intra-surgical navigation system for knee endoprosthesis that relies on an iPod touch for analysis, planning, and exact positioning of cutting tools.
Headquartered in Ostermünchen, Germany, near Munich, DHF Precision Mechanics counts well-known medical device, electronics, and aerospace engineering companies among its customers. The company specializes in high-precision CNC-milled parts and assemblies. After 15 years of virtually continuous growth, the company now operates 18 CNC machining centers and offers a service portfolio ranging from prototype manufacturing to bulk production of several 10,000 part-per-year lots.
With precision and fast, flexible reaction to customer requirements, DHF has established a good reputation in the market. When needed, DHF pushes the technical limits of CNC milling, such as series production of parts for electrical motors that must be produced on a lathe with tolerances down to microns. These parts feature bearing seats where ball bearings have to be glued into place.
With quick reaction to customer requirements a major objective, DHF established high in-house production depth – from CAD/CAM construction to preparing wrought material (various steel and aluminum alloys and titanium), to CNC-milling, surface finishing, assembly, and quality assurance.
Production processes at DHF are frequently comprised of welding, engraving, and marking. Techniques for marking and joining on high-precision workpieces call for lasers. Welded parts have to feature perfect, pore- and crack-free welded seams. This is especially true of components for medical device manufacturers, who have to provide sterile hardware, so it calls for immaculate surface quality to eliminate any chance of bacterial colonization. The same goes for all deep engravings and markings. Contours have to be free from burrs and ditches. The marking process must not induce any material changes that might promote surface corrosive action.
Until 2012, DHF had been outsourcing laser material processing jobs completely. However, outsourcing significantly reduced production flexibility and speed for certain parts and increased complexity of logistics. Moreover, the annual outsourcing business volume had been reaching the six-digit range – reason enough to think about establishing an in-house laser material processing center. Being laser-rookies, Fischbacher, Telser, and Heilmann initially focused on laser marking because they expected laser welding to be much more difficult to control – at least up to their first personal laser welding experience.
A complete solution
Realizing they had to take a look at bringing this process in-house, the DHF managers decided to incorporate a laser welding system in their investment planning. So, they began by sending samples to various laser manufacturers and asking for a live presentation of the laser welding process – not an easy task, considering the required acuteness and surface quality, namely for medical devices.
Andreas Schöllhorn, sales manager at Rofin, knows about the importance of an optimum presentation in the application lab, but he also knows that’s just the beginning. “Medium-sized companies expect way more from us than just selling suitable laser systems. We take care of the employee training, help set up the first applications, and our application support provides continuous assistance during the first months. If required, we even design the production room according to laser safety standards, just like we did for DHF.”
In-house laser processing center
Within six months of their first hands-on experience during the trade show, Rofin installed a laser-processing center at DHF, comprised of the integrated CNC and manual laser welding system, Intergral, and the marking system, CombiLine Advanced. The laser welding workstation seamlessly integrates manual or joystick-controlled deposition welding with CNC operation. It offers a cross table for workpieces of up to 1,100 lb (500kg) and an additional rotary axis. The Integral was chosen because of its large working chamber, which is spacious enough to freely rotate parts of up to 15.75" (400mm) in diameter.
For Fischbacher, Telser, and Heilmann, the optimum planning of production workflows and precision manufacturing of the required components is an essential part of daily operations. So, the three managers quickly designed a large breadboard, workholding devices, and laser programs for various parts. This modular system, together with systematic documentation, allows setup of any welding or marking application within minutes.
Even today when looking back, Heilmann still expresses his surprise, “We had been planning to slowly ramp up things, and to back-source the laser jobs one by one. In fact, external laser processing was gone within a few weeks. Today, we have ready-to-use setups for some 100 marking and welding applications right at our hands.”
High-tech medical devices
The enduring cooperation with Brainlab, a worldwide market leader for image-guided surgery and radiotherapy, benefitted from laser technology as well.
As Fischbacher explains, “We are already cooperating in early product design stages. It is a big advantage to know not only the possibilities of CNC milling but also of joining technology and marking, not to mention the faster manufacturing of prototypes.”
For Brainlab’s Dash, DHF manufactures and assembles the iPod holder with all fixed or detachable 3D position markers and cutting devices. All pieces have to meet the quality standards for medical devices. The entire parts set is comprised of 14 weld joints of precision milled part, even of different stainless steel alloys. The mostly circular weld seams feature a width of only 100μm and must not show any pores or micro cracks.
DHF deep engraves the plastic iPod holder with the laser to form cavities that will be filled with a special paint. The marking remains visible even when the paint slowly vanishes after numerous sterilizations.
A smart business decision
Fischbacher, Telser, and Heilmann are more than satisfied with their decision for an in-house laser-processing center. After two years, the generated turnover outweighs the investment of about $200,000 and the regular costs of operation. Additionally to its key competencies. Fast and flexible reaction to customer requirements is a critical factor of success, not only for DHF, but also for many medium-sized companies.
DHF Precision Mechanics