Coatings: “All factors must be perfectly matched”
Coatings are the key to increasing the performance of precision tools and thereby improving the effectiveness of the overall production system. LMT experts have been driving this technology forward for more than 30 years. An interview on this important subject with Philipp Immich, the engineer who is head of R&D on cutting materials and coatings at LMT Fette.
Why does LMT develop its own coatings?
The reasons become obvious once you realize what a significant role they play in tool performance: innovative high-tech coatings enable precision tools to make real quantum leaps in productivity. There is, however, one important precondition: working materials, cutting geometries and the composition of the coatings must be perfectly matched for the application in hand. And who knows more about the interplay between these factors than toolmakers?
But do coatings really need to be specially adapted to an application? Isn’t it simply a matter of ensuring that the surface is very stable?
In principle, that’s right, but the stresses on a tool and its surface vary depending on the application. Let’s look at an example. Last year, at the AMB fair, we presented Protec, the world’s first coating for thread rolling heads. The entire surface is involved in the forming process during rolling. This stress confronts developers of tool coating with new challenges. Instead of concentrating on protecting the blade, as you would in cutting processes, in thread rolling the entire roller needs to be protected.
How was this challenge solved?
First we precisely analyzed the stress that occurs during the rolling process. Then we worked out an appropriate protection strategy. The surface coating produced using thin-film technology is actually only one part of the Protec Power tool concept. The new, tailor-made technology designed by LMT Fette developers enables and guarantees that the entire thread roller is protected against the compressive stress of the forming process and provides significantly longer tool life. Furthermore, the rolling characteristics are positively influenced by an optimized surface topography.
How many people are normally involved in the development of a new coating?
A very large number. When the need arises, we work with external partners from various higher education institutions. Then, of course, there are the firms that manufacture coating equipment as well as the internal experts at LMT and its alliance partners itself.
And you still manage to keep track of everything?
This is where the strengths of the LMT Group become clear. First there is a division of labour between individual LMT companies, which naturally exchange relevant information among themselves. Additionally, we visit one another and exchange samples whenever problems or specific customer requirements make that necessary.
What role does reconditioning play?
For many tools it is very important. Precision tools are high-tech products. Their cost-effective use depends largely on how frequently they can be reconditioned. At the same time, their performance after reconditioning should return completely to the original levels.
Could you give us an example here?
Hob cutters with the Nanosphere coating illustrate this challenge. By applying this coating we have been able to increase tool life by one third – with significantly improved cutting speeds. Another crucial point here for users is the fact that the Nanosphere coating system allows LMT to guarantee these hob cutters will be reconditioned to the standard of new tools throughout their entire life cycle. The consistent performance of these hobs ensures a high level of production reliability.
Is there a kind of holy grail, an ultimate goal, in coating development?
By its very nature, research on tool coatings will never be completed. After all, every new product requires an appropriate coating. New materials and customer applications will therefore always present new challenges for tool coating development.