Throughout history, materials and advances in material technology have influenced humankind. Every shift, from the stone age to the age of plastic, has brought fundamental change: new possibilities, but sometimes new environmental challenges as well.
New demands from industry are pushing the boundaries of applied materials science. The aircraft and car industries, for instance, are requiring that materials be lighter and tougher. These new materials pose new challenges to the manufacturers of drills and cutting tools. Sandvik Coromant is one of the companies that develops new and improved tools able to handle tougher materials.
Increased usage of composites
Recyclability and emission efficiency are becoming increasingly important material properties. The aerospace industry is looking for materials that are able to lessen emissions, cut fuel costs and enable higher speeds. The composites have been the go-to material. Thirty years ago, five percent of an aircraft was made up of composites; now, a commercial plane can be made up of about 50 percent composite material. The Dreamliner, for example, has carbon fibre composites in its wings, tail, doors, fuselage and interiors, which makes it a lighter plane. Experts estimate that reducing the weight of a commercial aircraft by one kilogram (2.2 pounds) can lower the cost of operating it by around 2,000 to 3,000 euros per year.
Composite materials are also increasingly being used in cars, where the combination of strenght and lighter weight can help reduce the fuel consumption. Composites are now cheap to produce, but the production still requires high temperatures, extremely clean environments and a labour-intensive process. And machining these fine-grade composites is even more of a challenge.
“Cutting, and especially drilling, in composites is a major challenge,” says Eleanor Merson, who researches composites for Sandvik Coromant. “An aircraft has tens of thousands holes in it, and the material is very abrasive; carbon fibres quickly wear out the drills.”
Coatings harder than steel
Physical vapour deposition (PVD) and chemical vapour deposition (CVD) are processes for coating objects with an extremely thin but hard and heat-resistant film. The techniques started to be widely used in the 1980s and are still being used for mechanical, optical and electronic devices.
Sandvik Coromant uses these methods to harden the surface of its insert tools. The core of the insert is made of cemented carbide consisting mainly of tungsten carbide and cobalt.
“Add a two- to 10-micrometer layer of PVD and the insert’s life span increases by a factor of 100,” says Dr. Mats Ahlgren, an expert on material physics and head of the PVD Department at Sandvik Coromant. “Not only can customers use the inserts for a much longer time, they can also increase their productivity by working with the inserts at much higher speeds and feeds.”
Current research focuses on making the coating even tougher to meet the demand for durable materials. In 2013, Sandvik Coromant patented its CVD coating Inveio™. With crystals made to point in a uniform direction, Inveio was a leap forward in durability and hardness.
“In recent years, we have developed our ability to control the process of making new coatings,” says Ahlgren. “We can see the structure in microscopes, virtually down to an atomic level, which helps us analyse new solutions before going live.”
Recyclability: increasingly important
Composites contribute to less use of energy, less exhaust and less impact on the climate. But many composites are made with adhesive binders that are difficult to separate and reuse.
“Finding alternative materials is an important path, as is the need to create cost-efficient substitution and recycling processes,” says Dr. Anna Hultin Stigenberg, who is the principal R&D expert at Sandvik Coromant. Until recently, Stigenberg chaired the international steering committee Knowledge and Innovation Community for raw materials, an initiative that brings together more than 100 companies and research facilities to promote the development of sustainable material development.
Recyclability is an issue not only for auto makers and other manufacturers of consumer products. Worn-out tools can also be recycled. Sandvik Coromant has introduced a recycling system to keep worn-out tools out of landfills and junkyards. Actually, most of the company’s solid carbide tools come from recycled carbides.
Making new tools from recycled solid carbide requires 70 percent less energy than making them from virgin raw materials. Production from recycled materials means 40 percent less carbon dioxide emissions. Furthermore, recycling is necessary because in the long run the raw materials, such as tungsten, are scarce and finite.
Customers order special containers from Sandvik Coromant. The cans are filled with used solid carbide tools and inserts. Sandvik Coromant then handles the transport and recycling, and pays market price for the material.
The article was published in April 2016.