Research On Cutting-Speed Integrated Preventive Tool Replacement Decision Making Method

In the cutting processes of mechanical parts, the wear of tools has great influenceon the processing precision of machine tools, or even results in equipment damaged orcasualties. Replacing the tools in the right time is a important measure to ensure thequality of parts and avoid equipment damage. However, frequent replacement of toolsleads to a large number of production interruptions and downtime of the machine tools,which affects the production efficiency. On the contrary, postponing the replacement oftools can increase the reworking rate and equipments damaged, more loss is caused.That phenomenon is particularly significant in the production line, especially when thebuffer capacities are small. Frequent tool replacement not only affects the efficiency ofequipments itself, but also brings on production interruption of the production of otherwork stations or even the whole line. This paper focuses on the preventive toolreplacement strategy, aiming to establish a decision method of the multi-factorsintegrated preventive tool replacement decision making method.Firstly, the paper analyzes both the influence between cutting speed and the servicelife of tools and the methods used to describe the undetermined service life of tools. Adescription method for the service life of tools is proposed using the Weibulldistribution and the Taylor tool life formulae. And an example is given to analyze thecharacteristics of the description method.Then, according to the problem of preventive tool replacement decision making,two kinds of multi-factors integrated preventive tool replacement decision models arebuilt separately with the aim of maximizing the production efficiency and the revenue.Optimization algorithm for the decision parameters are separately designed, andcompare is made between the preventive tool replacement decision method and the lifebased tool replacement decision method.Finally, two examples of serial production lines with two and five machine toolsare given separately. The performance of the production lines under the two toolreplacement decision making methods and two objectives is analyzed and contrasted bysome indexes such as output, production efficiency, profit, the average number of WIPand so on.