Availability of Spare Parts

FOE an effective preventive maintenance programme, it is essential that a proper inventory of spare parts be maintained. A judicious  selection of spare parts should be made and adequate quantities obtained in time. Besides, the total inventory cost should be the least. The level of inventory should be determined depending on the number of machines, their stage in life, job conditions, source of supply, delivery period and the efficiency of the purchase department of the organisation. It would be possible to estimate the rate of demand for spare parts with a fair degree of accuracy if a proper record of consumption is kept for each machine on the project. While selecting equipment for a project, an important consideration is inter-changeability of spare parts. 

There are three types of spare parts for a machine. They are : 

1. consumable parts, 
2. fast-moving parts, and 
3.  slow-moving  parts. 

The assessment of consumable spare parts can be made fairly accurately. The actual working conditions of a project determine the working life of an equipment which in turn determines the requirement of fast-moving parts that are vital in spare inventory. Because the requirements of the slow-moving parts are less exacting, their inventory level should be decided depending on their cost versus the loss of production due to non-availability. Usually, the stocking of slow-moving parts is less than that of fast-moving parts in the 

inventory. On any project the inventories of spare parts runs into several hundreds, if not in thousands. Therefore, it is necessary that the individual items should be properly stocked so that they are easily accessible. It is customary, that standard items like bearings, belts, bolts and nuts, seals, etc., are stocked in one place, while non-standard spare parts, like crankshafts, liners, pistons, etc., are stocked separately for each machine. 

Stocks of spare parts may prove to be a loss in value if they are not utilised on the same project or other projects. Hence, over-stocking of spare parts should never be permitted. There are many reasons why there are excess stock of spare parts. Some of them are as follows : 

1. In the case of imported equipment, the fear of scarcity or non-availability when needed, drives the project authorities to buy large quantities of spare parts. 
2. Having several different makes and models of equipment on the same project prompts stocking of spare parts to cater for all the models and makes. 
3. Manufacturers of equipment insist on the projects to purchase large quantities of spare parts to offset the effects of obsolescence. 
4. Large stocks of spare parts get accumulated in the absence of proper equipment planning . 

A solution to such a problem is to sell or transfer surplus equipment and spare parts to other prospective users. For this, an effective coordinating agency is required. For 

disposing off surplus stock, information on the availability of surplus stocks should be well disseminated.