HARD COATING ON TOOLS

HARD COATING ON TOOLS

ABSTRACT:

Present seminar report covers new features of TiN TiA1N, etc. special coating on cutting tools. The initial articles deal with necessity and types of tool coating. The industrial tool coating procedures PVD and CVD have been explained in detail. Preparation of tool surface for coating process is equally important for good adhesion and long life. The performance of coated tools is critically examined in various applications under several parameters. These results are graphically represented for better understanding. Different types of coatings having different properties are discussed. The relative performances of various coatings are graphically represented for milling cutters and drills.

INTRODUCTION:

Wearing of machine tools is a major problem in machining industry. Since more and more processes are automated and interlinked wearing of individual parts hinder the process. The increasing time raises the cost of the products. Hence wear protection is essential from the economic viewpoint. Multilayers coating of mechanical resistant materials (hard coating) have proved successful in increasing the life of machine tools.

It is proved for a long time that nitrates and carbides of certain compounds are
very hard. These materials exhibit good sliding behaviour and extremely high resistance to wear. Though these materials are brittle and fracture susceptible in bulk solid state they exhibit totally different properties when coated in thin film form.

Thin coating of nitrates and carbides on steel and other tools confirm to the toughness of the base material. Due to these coatings extremely hard, abrasion resistant surfaces are produced. The coating increases the toughness of the surface (wear resistance) secondly, certain coatings like titanium nitrate (TIN) gives attractive golden appearance to the surface. This property is used in increasing the appearance of the finished product.

With this data at hand an extensive study of the hard coating processes is under taken in the present seminar. The coating processes (CVD, PVD) are studies in details. The relative merits and demerits of these processes are compared. The increase in tool life as a result of coating is compared from standard data. Attempt is also made to explain the physical significance of increase in strengths. Essential diagrams and industrial data from standard source supplement the present study.


for more info visit.
http://www.enjineer.com/forum