Brno University of Technology Faculty of Mechanical Engineering The Institute of Manufacturing Technology LESSON 19 Modern PVD Coatings for Metal Cutting Authors: Ing. Miroslav PÍŠKA, PhD., Associate Professor piska@fme.vutbr.cz Ing. Petra CIHLÁŘOVÁ cihlarova@fme.vutbr.cz Bc. Michael Lars George HILL µ Contents Page 1 of 6 Go Back
µ Contents Page 2 of 6 Go Back Contents 1 Modern PVD Coatings for Metal Cutting 3 2 References 5
µ Contents Page 3 of 6 Go Back 1. Modern PVD Coatings for Metal Cutting Video Just as the infinite reaches of the universe with their unfathomable and unillucidated mysteries evoke our curiosity and desire to discover, so microscopic sizes of modern materials with their unique properties based on their complicated atomic structure have the same effect on us. In the area of hard and superhard abrasive layers based on nano-crystaline structures, researchers are managing to push human knowledge ever forward. New layer structures intended for cutting, forming and tribologic applications are prepaired by the company SHM using modern PVD technology to a standard compatible with the most demanding requirements of mechanical engineering. Since the beginning of the 90s, world mechanical engineering has been putting increasing pressure on high productivity, automation and ecology of machining. Developments of machining or cutting centres and modern tools suitable for demanding applications bear out this situation. These tools, which are intended for high rates of machining, machining with minimum cooling fluids, or dry machining as well as so-called high-speed machining, could hardly exist without hard, wear resistant coatings. The long standing determination of the firm s specialists in cooperation with research organizations has led to the company becoming a world leader in industrial preparation of nano-composite layers. These state-of-theart products are newly invented layers made under the trademark MARWIN. Considerable expansion in the production of PVD wear resitant layers at SHM has, in recent times, been based on excellent close cooperation with Pramet Tools, a Czech producer of indexable cutting inserts made of cemented carbides. Development has also focused on increasing the capacity of coating devices, extending the application of MARWIN layers to a wide range of axial tools made of high-speed cutting steel and cemented carbides. This is also based on a considerably accellerated exploitation of the companies own research and development from production results. We can offer you preparation of hard and superhard wear resistant layers as a service. Just send us a new one
µ Contents Page 4 of 6 Go Back coated or renovated reground tool and we will provide it with a coating. According to your own specifications or our reccommendations you can choose a specific kind of coating. The coating process is very complicated. It starts with two-phase tool cleaning and drying which is followed by insertion into suitable planetary holders. These are placed into the coating device where other cleaning grades and the application of hard, super-hard and multi-component layers are carried out. The whole coating process takes about six hours and the last phase is cooling. All coated tools undergo very strict exit checks - based on a visual check of each tool s surfaces and measuring of important physical properties of the layers on the reference samples. This mainly concerns layers of micro-hardeness - of which MARWIN layers can reach 3,500 kg per square mm, layer thickness ranging from 2 to 5 micrometres, layer surface which is assessed according to an optical image analysis, layer roughness ranging from 0.1 to 0.3 micrometres and layer adhesion to the tool surface, which is measured using a scratch test (an indentation method using the Rockwell indentor). After the testing, the tools are carefully wrapped in plastic covers and sent back to the customers using normal postal or courier services. Pressure on continuously increasing work productivity, its effectiveness, speed and ecology leads researchers to search for new methods of cutting using coated tools. Low friction coefficient, high hardness and consequently high resistance to abbrasion and chemical stability are the main assets of MARWIN layers. Their very high heat resistance is a basic condition for dry turning. Development of new layers with low surface roughness also increases their usability for taps, various forming tools and sliding bearings. What advantages do MARWIN layers bring? Increased lifetime of tools, improved quality of workpiece surface, increased machining productivity, increased cutting speeds and feeds, the possiblity of increasing or eliminating cooling, reduced cutting forces, which leads to reduced energy demand during machining, smoother operation of cutting machines and reduced frequency of tool grinding.
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