Beyond tooling limits

beyond-tooling-limits
beyond-tooling-limits

Kennametal wonders where tooling manufacturers stand regarding economic working methods for machining composite materials and the new tooling concepts currently available.

Cutting tools specialist,
A trend towards lightweight construction materials is gathering pace, and not just in the aerospace sector. As far as lightweight construction is concerned, alongside titanium, aluminium and magnesium, CFRP and its composite materials will dominate the future. For the moment, at least how Kennametal’s senior manager for solid carbide milling equipment, Oliver Sax sees things, the technological impetus still lies with the aircraft industry: “We can see a clear customer trend towards tool-specific inquiries regarding working methods for CFRP and composites.” However, he also sees considerable interest in CFRPs developing in another area: “The internal technology departments of major motor vehicle manufacturers report strong interest in the material.” He’s therefore certain that the automotive industry will be the next technological driving force for fibre reinforced plastics. His assessment is no accident. According to a Roland Berger e-mobility survey, by 2025 about 40% of new motor vehicles registered will feature hybrid or fully electric drive systems. From an economic standpoint, this is only logical if new lightweight construction concepts are implemented. For tool manufacturers, this could be both a blessing and a curse: the resulting work in the engine/motor and drive fields will be reduced, but on the other hand, the new lightweight construction materials constitute an attractive field of activity. A role reversal Kennametal’s manager for the European aerospace market, Werner Penkert foresees a certain reversal in trends over the next ten years: “The switch from aluminium and steel to composite materials is bound to lead to a certain reduction in levels of metal removal work. Nonetheless, there will still be a certain amount of mechanical work on CFRP materials, such as that for the connecting and mating surfaces.” As the automotive industry steps on the gas, tool manufacturers are benefiting, albeit unintentionally, from the tooling service life reducing properties of CFRP materials. Although the aerospace industry has come to terms with this to a certain extent, in part because new developments involve long trial periods and lead-times due to safety considerations, the automotive industry will take a different approach. If series production of vehicles with significant levels of CFRP parts gets the go-ahead, a highly dynamic development and conversion phase can be expected. “If a series production vehicle is available,” says Sax, “the next steps will be very different from those in the aircraft industry. High volume activities will kick in immediately, for the manufacturers and their suppliers alike.” Kennametal says its years of experience in working for the aircraft industry have led it to examine composites processing. Meanwhile, numerous projects have enabled them to build up considerable know-how and find solutions. As well as the usual suspects such as delamination and shorter service lives, Kennametal is also scrutinising more fundamental themes. One important field is classification of CFRP materials. “That's why it’s important,” adds Sax, “to think along the same lines as our customers in our discussions with them, at least to start with.” Up to now, CFRP materials were shown in materials lists under ‘C’ for ‘CFRP’, but all the CFRP materials were lumped together, with the pure carbon fibre matrix rubbing shoulders with the tricky-to-work stacks comprising aluminium, CFRP and titanium. As this nomenclature isn’t very useful for technological discussions with users, Kennametal has created five sub-groups, which should result in clearer material profiles and a consistent basis for discussions: C1 - pure CFRP; C2 - CFRP in combination with non-ferrous metals; C3 - CFRP in combination with high-temperature resistant steels; C4 - CFRP in combination with stainless steels; C5 - CFRP in combination with non-ferrous metals and high-temperature resistant steels. As Sax is aware, the system doesn’t cover the full bandwidth: “We are one of the first companies to approach this complex theme in a structured way. We also set out to show users that each material has its own highly specific requirements, and put forward the solutions we can provide.” Meeting the drilling challenge The problem of drilling CFRP, which is the main function leading to delamination effects has led Kennametal to develop a wide range of tools. For Kennametal’s boring and fine surfacing manager, Thilo Müller, there are two main avenues: diamond coated carbide tools to machine CFRP and PKD tools to machine stacks, i.e. composite metal and CFRP materials: “To machine pure CFRP, our diamond-tipped SPF drill that provides the best value for money in terms of service life and the best results as to delamination and several hundred drilling sequences can be executed.” PKD tools provide service lives that are up to 30-50% longer, but users have to accept certain restrictions as to tool diameter and geometry. For these tools, the diamond crystals grow directly on the carbide supporting shaft. The advantage here is that a different ground section can be provided from what is possible with brazed PKD cutting edges with positive front rake angles. Contoured cutting edges can also be provided. “In short, we can make contours that are similar to those for carbide cores,” adds Penkert. As well as drilling systems, Kennametal claims it is also working on milling systems for CFRP. According to Sax, compression style routers with their V-shaped geometry spiralled to the right at the tip and to the left on the shaft, provide the optimum set-up for cutting grooves and trimming work: “The V-shaped inverted spirals press the matrix layers together. That enables us to execute very fine surfacing work.” The burr style router For machining pure CFRP, Kennametal has developed a universal tool in the shape of a burr style router. The ‘down cut’ style router has been designed for milling recesses and for surfacing work. The main advantage of the left-spiralled tool lies in the higher cutting speeds that can be attained. The return on the development work is not limited to customer acceptance; in fact, rival technologies such as waterjet cutting can also be kept at bay. Penkert is convinced of this, in any case: “Our routers already provide highly attractive machining times and service lives. Water is no longer the only investment solution now that these routers can be used.” www.kennametal.com

Tags
Related Articles

The strength to survive

Hit hard when the A1GP motorsport series collapsed in 2009, URT Group has seen a dramatic turnaround in fortunes after being selected as the lead laminator of Ocelot, the world's
12 years ago Features

The shape of things to come

Mike Richardson talks to a panel of experts to discover how the latest cutting tool innovations are shaping up to meet the manufacturing challenges of ever-evolving composite materials.
13 years ago Features

Experience is everything

The milling and drilling of modern composite products may still be seen as a 'black art' by many, but with the aid of machinery developed specifically for the task, suppliers and OEMs have
13 years ago Features
Most recent Articles

Exel secures deal with Chinese bus builder

Finnish composite manufacturer Exel Composites has secured a new project with Chinese automotive manufacturer Foton Bus and Coach Company to supply pultruded glass fibre composite profiles.
22 hours ago News

Zünd establishes branch in Australia

Zünd Systemtechnik has announced the establishment of its own branch in Australia. Zund Australia will be based in Melbourne serving existing and new customers from all areas of application in which Zünd is active.
2 days ago News

Login / Sign up