In order to reduce weight while maintaining high strength in complex components, lightweight materials such as CFRP, GFRP and CFRP-titanium/CFRP-aluminum stacks have become indispensable in the construction of automobiles, aircrafts, wind turbines and sporting equipment. However, machining them is no easy task. Anyone wishing to perform precise countersinking in sandwiched materials with high surface qualities will need special tools such as the CCDia AeroSpeed coated countersink from Dürr Präzisionswerkzeuge GmbH.
“Composites consist of several layers. The individual materials exhibit different properties and are often highly abrasive. Protruding fibers and delamination must be avoided at all costs, as components with these defects end up on the reject pile. With countersinking, the fact that the tool penetrates the material with its angular cutting edges quickly causes tool vibrations that result in chatter marks in the countersink,” says Wilhelm Marx, CEO and Production Manager at Dürr, outlining the challenges of CFRP machining.
Dürr Präzisionswerkzeuge GmbH, founded in Hohenlohe in 1994, is an expert in the manufacture of drilling, countersinking and reaming tools for a wide range of materials, in standard and customized designs. With the innovative ENORM plus countersink for machining wear-resistant and structural steels with tensile strengths of up to 1750 N/mm2, the company has successfully established itself on the market as a problem solver. In order to master the challenges of developing a countersink for machining composite materials, the Hohenlohe-based company first brought the know-how of CemeCon’s coating experts on board.
Perfectly tailored coating and geometry
“Wear-resistant tools with extremely smooth, hard surfaces and special geometries with very sharp cutting edges were required. As part of our Premium Plus Service, we approached the optimum solution with a targeted variation of several factors for both the tool and the coating,” says Marco Furrer, Sales Manager at CemeCon.
During the cooperation, Dürr further developed its tried and tested cutting geometry to meet the special requirements of CFRP machining. ”The customized geometry prevents delamination and cuts the fibers of the laminates very accurately throughout the entire countersink area. This yields countersinks with smooth surfaces – with no objectionable fiber protrusions,” says Wilhelm Marx.
Therefore, it was important to maintain the extremely sharp cutting edges during coating. “The ultra-thin coating specification based on CCDia®AeroSpeed® has no influence on the microgeometry and, therefore, does not affect the sharpness either,” states Marco Furrer. The extremely smooth surface topography of the coating allows the countersinks to operate without vibrations or chatter, and this optimizes the removal of swarf and heat from the machining zone. With a coating hardness of approximately 10,000 HV0.05 – nearly that of natural diamond – the tool also provides outstanding resistance to the very strong, highly abrasive fibers.
An inspiring result
The DIAplus countersink is the result of intensive cooperation – the perfect combination of optimized cutting geometry, a selected grade of carbide and a customized diamond coating. “Countersinking in composites and stacks was previously considered a major challenge. The symbiosis of our countersink and the customized CCDia®AeroSpeed® coating now ensures brilliant performance in the machining of GFRP and CFRP as well as CFRP-titanium and CFRP-aluminum stacks. The service life of the tools is disproportionately long, and DIAplus guarantees almost unrivaled process reliability for machining tasks. Countersinking in installed components can even be done with hand-held machines under difficult operating conditions,” enthuses Wilhelm Marx.
Uwe Späth, CEO and Sales Manager at Dürr, is pleased with the large volume of positive feedback from users: “Satisfied customers are our top priority; firmly convinced users are important to us. With the DIAplus, we have achieved this brilliantly and have been able to prove our status as a solution provider yet again. Last but not least, thanks to our intensive cooperation with CemeCon, we now offer lightweight construction a perfect solution for countersinking in composites.”
