More than 20,000 holes drilled in the master class of stainless steel
Dieter Prinz | OSG Germany
Lower cutting force, lower cutting temperature and lower feed rate achieved by switching to a new tool – these ideals sound great on paper. However, whether or not ideals can be achieved often is not based on cutting data alone, but also by the various components surrounding the actual cutting environment. That is why Heinz Edelstahl in the German town of Salach, gave little attention to cutting data achieved under controlled laboratory environment. What Heinz Edelstahl cares about is process reliability, especially in difficult-to-machine materials such as stainless steel.
Heinz Edelstahl was founded in 1990 and has established itself as a supplier of small batches and custom stainless steel parts. In Salach, up to 1,200 tons of stainless steel are processed each year, 95 percent of which are machined by milling, turning, grinding and drilling. The company also offers plasma cutting with three cutters. Together with efficient cutting optimizations by using state-of-the-art CAM software, very little waste is created. Customers today come from the medical and food industry, architecture and construction, as well as pipe manufacturing and the petrochemical sector.
Although Heinz Edelstahl was not encountering any machining difficulties, it is a company that continuously strive for improvement and decided to give one of OSG’s latest drilling innovations – the WDO-SUS drill – a try on a new order that involves drilling sieve segments for a renowned manufacturer of paper machines. In total, the processing requires more than 10,000 through-holes at 12 mm diameter in stainless steel 1.4462.
This particular stainless steel is very difficult to machine, and the processing of this steel belongs in the master class. This cryogenic stainless steel is highly weather resistant and is therefore mainly used in architecture and sometimes in the petrochemical industry. For drilling one of these sieve segments, the standard was three days and two and a half drills. The up to then exceptional cutting conditions were achieved with a top shelf carbide drill.
By implementing the WDO-SUS drill from OSG, cutting parameters have been increased by 3.5 times, while tool life has more than doubled. The WDO-SUS series has adopted a tool geometry that emphasizes sharpness to reduce work hardening, thereby prolonging tool life for post-processing including reaming and tapping. Its new flute form encourages the creation of small cutting chips, which is essential for trouble-free chip evacuation. Furthermore, the WDO-SUS has employed a unique oil hole design for diameter sizes above 6 mm to suppress heat generation and to facilitate smooth chip evacuation. With the addition of OSG’s patented WXL coating, stronger adhesion strength and resistance against welding can be achieved.
By switching to the WDO-SUS, cutting force and friction as with that cutting temperature are reduced. In addition, because of the new chamfer design, less feed is needed. The performance of the WDO-SUS has far exceeded the expectation of Peter Heinz, head of sales and engineering at Heinz Edelstahl.
“We have been machining stainless steels for 25 years and have tested a lot. Based on our experience, the performance of a tool usually is maximized under ideal conditions like temperature controlled environment and with the utilization of state-of-the-art machinery,” said Heinz.
“Our machines aren’t the latest models, radial deviation isn’t the best either. That’s why I was surprised by the WDO-SUS. It’s completely reliable, evacuates chips really well and tool life is also great.”
OSG had set up testing for cycle time and tool life. First, cutting parameters were set to the maximum to shorten cycle time. As a result, cycle time was reduced from three days to one and a half. The next step was unsupervised production. The result was a tool life of two sieve segments with one drill, but even after that, it didn’t need to be replaced and could be used further without problems. These results were able to build enough trust to start considering unsupervised manufacturing overnight. It’s just that the optimizations OSG did with the WDO-SUS were meant to relieve the machine and to reduce power intake. But that’s not what it is about in Salach. There is no mass production, no permanent load. Process reliability is far more important. Higher speed and longer tool life are just an additional bonus according to Peter Heinz.
“Less stress on machines and warehouse is nice, but for us that’s not really the point. With our lot sizes, there is not much need for maximized cutting speed. It’s more about reliability, with noticeably less machine idle time because of the reduction in tool replacement or breakage.”
Cost efficiency itself is a big concern for small and mid-sized companies. OSG eliminates the need for a stockpile of tools because the WDO-SUS can demonstrate its strength even in carbide and tool steel. With cheaper products, one has to stock multiple tools with the risk of causing damage to an important part. In addition to the 1.4462 stainless, a variety of other stainless steels are also processed in Salach, Germany. However, according to Peter Heinz, other stainless steels are no match in terms of problematic machining in comparison with the 1.4462 stainless master class.