In machining, there are several factors affecting the cycle time of an operation. Size and geometry of the part, material, and the efficiency of the toolpath program have an impact, but at the end of the day, material removal rate is one of the most significant factors. How fast can you make chips?
Recently, a pair of German companies—Machine builder CHIRON and cutting tool manufacturer Gühring—have collaborated, developing a new roughing cutter which blasts through 1000 cc (61 cu. in.) of 16MnCr5 steel in 60 seconds, removing eight kilograms (17.6 lbs.) of steel per minute. Check out this video to see it in action:
Oliver Staiger, Application Engineer at CHIRON and Rolf Ehler, Product Manager Milling Tools at Guhring, discuss the milling strategy.
The record rate was set using two new products from the companies: CHIRON with the new FZ 16 five axis and Gühring with a tool called the RF 100 Speed P. The two companies have a close relationship, and this is not the first collaboration between them. "Due to the ever increasing performance requirements of our customers, we have jointly developed the idea for a record attempt. And the result was an incredible 1,000 cc of steel per minute," says milling specialist Rolf Ehrler from Gühring. The interplay of machine dynamics and milling stability makes such time-saving volumes possible in mold making, the aerospace industry and the automotive industry.
The Guhring tool, the RF 100 Speed P, is a roughing cutter specially adapted for machining steel, high-strength steel and cast iron. According to the company, it has a 48° spiral angle with unequal blade pitch. This reduces the machine load and increases the volume performance. The recessed flute in the front cutting area creates an optimized chip space, improving performance when ramping and helical immersion. Chip breaker and extreme cutting edge length on the cutter ensure a smooth cut and smooth running.
Milling Strategy: HPC Roughing
Guhring's specialists applied a high performance cutting (HPC) strategy. Control of the cutter path with low radial feed allows a comparatively gentle seaming of the workpiece. HPC roughing is particularly suitable for machining large cutting depths, with the roughing cutter machining the workpiece at its entire depth with the entire length of the cutting edge. This way, cutting forces are reduced and evenly distributed over the entire length of the cutting edge. This enables high processing speeds and long service life. The service life of this cutter during testing was 60-250 minutes.
High performance cutting is the first choice for applications with enormous chip removal rates. The components to be machined are usually made of high-strength steels, which place increased demands on the machining. Under HPC conditions, the entire length of the cutting edge is used with a small cutting width (5-15 percent). Thus, enormously high feeds can be achieved. The feed per tooth was 0.5 millimeters. This means four teeth, two millimeters feed per revolution.
High material removal rate in tool steel is valued in many industries including the classic tool and mold making industry, where mainly high-strength steels are found, but above all aviation, where lightweight components made of solid material with a chip removal rate of up to 96 percent are produced.
Check out Toolholding 101: Top Tips for High Productivity Machining.