Metal additive manufacturing technology is being used to produce new ranges of cutting tools. As well as allowing special cutters to be produced more quickly, the use of additive manufacturing enables more complex shapes to be generated, both for the external shape of the tooling and for the internal cooling channels.
The Komet Group from has supplied precision cutting tools in the fields of drilling, reaming, milling, and threading to the machining industry for almost 100 years. With headquarters in Besigheim, Germany, the company currently employs more than 1,500 people, including its subsidiaries, and is represented in around 50 countries.
In addition to developing, manufacturing and distributing cutting tools, the company analyses customers’ production processes and then develops tailored solutions to help them with efficiency in machining.
Making The Unconventional
With conventional manufacturing methods, some tooling designs that came up were too expensive or even unfeasible to make. As a result, Dr Reinhard Durst, research and development manager for hard metal, Komet, has been investigating the potential of additive manufacturing for tooling production and the equipment available on the market for several years.
Dr Durst has been working with Renishaw for the last year. The company’s network of additive manufacturing solution centres allow for the transfer of knowledge and know-how. Customers are able to lease the equipment at a solutions centre and work independently on their projects before buying outright.
“Parts produced with additive manufacturing can reach up to 99.9 percent consistent structure, just like rolled or cast metal components,” explained Ralph Mayer, additive manufacturing services manager, Renishaw. “However, the correct strategy must be applied for every component.” He added that the company analyses the technical challenges of customers’ components and works with to find an effective solution.
The company’s metal additive manufacturing system uses laser powder bed fusion technology in an inert argon atmosphere. An extremely thin bed of metal powder is laid down and areas that will form the component are melted using a high-performance ytterbium fibre laser and then solidified on cooling. This process is repeated with layers of metal powder, typically between 20 and 60 μm thick, until the part is finished. The thinner the layers, the better the accuracy and surface quality of the finished part.
Previously Unattainable Geometries
The first of the projects handled jointly between Komet and Renishaw was the development of a new range of poly-crystalline diamond (PCD) screw-in milling cutters. The main bodies of the cutters were manufactured on the metal additive manufacturing system, with multiple bodies produced during each cycle of the machine, and then fitted with PCD blades and screwed onto their tool holders.
The use of additive technology to manufacture the tools allows geometries to be produced that would be almost unattainable by conventional means. “Thanks to the additive process we have been able to place many more PCD blades on each tool,” explained Dr Durst.
“We have changed the arrangement of the blades and achieved a substantially greater axis angle. Compared to conventional milled tools, we have greatly shortened the grooves. These changes mean that the tool is a lot more productive for the user.” For example, with a 32 mm screw-in head, the number of grooves and blades has been increased from six to ten, achieving a feed rate that can be up to 50 percent higher.
Freedom To Design
In addition, the ability to optimise the paths of the coolant channels sees each cutting edge supplied with coolant through a separate channel, while the external design of the bodies helps to ensure that chips are removed from the face of the tool.
Dr Durst said that the ability to freely design the internal and external tool geometry was also another advantage. The technology offers the potential to reduce component weight, since material can be used only where it is necessary for the optimum functionality in the component. Delivery time can also be saved when compared to conventional production methods for any special or experimental tools needed by customers.