arower cost. Wear and obsolescence are the two main causes for replacement of machinery in every aspect of life. The reduction of wear is therefore a primary concern while designing appliances. Wear and tear due to passage of time and/or normal usage of plant and machinery is an accepted fact. Technological obsolescence is a major danger which business firms face in modern era, With the development of new and better techniques or equipment of performing a particular function, existing equipment and machines become uneconomical. Whenever a firm decides to switch over to new machines or improved product designs, existing machine designs are said to be obsolete. Hence, obsolescence is and equipment. A machine is technically obsolete oor issue in the procurement and installation of machinery when another machine can do can do the same job more efficiently. with reduced time and also at a Technological obsolescence arises due to continuous improvements in the methods and and sometime rate of improvement is so fast that it becomes economical to replace the machinery before its expected life. A A machine e may be replaced to reduce the running costs of the concerned machine and the new machines productivity will be more. In replacement decisions, the basic problem is to decide whether to replace a machine or equipment at present or at a future date. It is, therefore, necessary to determine whether obsolescence or deterioration has reached the point where the reduction in operating costs expected from replacement justifies the net capital expenditure involved in installing the new machine and disposing of the old one. Any function aimed at bringing back or restoring an item to its original or acceptable condition or to keep it and retain its health as well as workability is known as Maintenance. Objectives of Maintenance: The objectives of maintenance are: (0) To keep all the production facilities and other allied facilities such as building and premises, power supply system, etc in an optimum working condition. To ensure specified accuracy to products and time schedule of delivery to customers, (m) To keep the down time of the machine at minimum so that the production program is not disturbed, fiv) To keep the production cycle with in the stipulated range. I to modify the machine tools to meet the augmented need for production. (vi) To improve productivity of existing machine tools and to avoid sinking of additional capital. (vii) To keep the maintenance cost at a minimum as far as possible, there by keeping the factory Overheads at minimum, (vi) To extend the useful life of plant and machinery, without sacrificing the level of performance. x26 Illustration 1. A workshop has 20 nos. of identical machines. The failure pattern of the machine is given below:- Elapsed time after Probability of failure Maintenance attention (in month) 1 0.20 2 0.15 3 0.15 4 0.15 5 0.15 6 0.20 It costs * 150 to attend a failed machine and rectify the same. Compute the yearly cost of servicing the broken down machines