Hi People. In relation with screw manufactured with planar flat die thread rolling, what do you think? Is better to use dies with coating like TiN or uncoated dies? Why one of this solutions are better?
In case that use coated tool, is necessary to modify the lubrication?
I attach three images of the tool / process to better undestanding?
Providing a TiN coating certainly helps in improving the roll life. But it also need to be based on the material characteristics of the work material. Here I am providing a few references that might help you throw some more information on thread rolling.
http://www.reed-machinery.com/pdf/thread-rolling-with-flat-dies-tech-data-master.pdf
http://www.google.com/patents/US3889516
I check the first information (the document is really excelent), but dont talk about coated dies. I know one screw factory with this type of process and any die of the diferents machines have coating. I dont understand which is the reason? May be the friction is low and the process need friction?
"Ceramic coatings used are hard materials and therefore provide a good abrasion resistance. They also have excellent high temperature properties such as high resistance to diffusion wear, superior oxidation wear resistance, and high hot hardness. Further the good lubricating properties of the coatings minimise friction at the tool–chip and tool–workpiece interfaces, thereby lowering the cutting temperature. All these translate into lower forces generated during machining compared to uncoated tools." This will help in increasing the tool life.
Fox, V., Jones, A., Renevier, N. M., & Teer, D. G. (2000). Hard lubricating coatings for cutting and forming tools and mechanical components. Surface and Coatings Technology, 125(1), 347-353.
Hedenqvist, P., Olsson, M., Wallén, P., Kassman, Å., Hogmark, S., & Jacobson, S. (1990). How TiN coatings improve the performance of high speed steel cutting tools. Surface and Coatings Technology, 41(2), 243-256.
Book Manufacturing Technology, Vol. 2 Metal Cutting and Machine Tools
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