Methodology for accounting for downtime and losses arising from waiting for imported wear parts: calculation based on downtime × hourly line cost, reference downtime of 2–8 days, direct-to-indirect loss ratio of 1:3, accuracy of 92% with 3 mandatory parameters, data updated quarterly.
To account for such losses, it is necessary to use a formula that calculates the total downtime multiplied by the average hourly cost of production line downtime, where the resulting figure is a calculated indicator not linked to specific facilities.
According to the results of measurements taken at 12 production sites, the average downtime caused by waiting for imported wear parts ranges from 2 to 8 working days; this represents the engineering reference range derived from the results of field tests.
Given a fixed downtime period of 5 working days, the total losses comprise the costs of retaining staff at work and the lost profits resulting from uncompleted work, whilst the resulting ratio of direct to indirect losses, which is 1 to 3, is an estimated figure derived from an analysis of data from 70 industrial enterprises.
The list of mandatory parameters for recording includes the date on which the need for a part arose, the date the part arrived at the warehouse, and the average hourly utilisation of the production line, with the accuracy of the calculation, when using the full set of these parameters, reaching 92 per cent – a figure derived from testing the methodology at actual production sites.
The table sets out key parameters and their types; the data for these has been derived from official methodological guidelines on the organisation of production accounting: average lead time for a part: engineering reference range 2–8 working days; ratio of direct to indirect losses: calculated value 1 to 3; calculation accuracy with a complete data set: field test result 92 per cent; minimum set of parameters required for accurate accounting: official regulations specify 3 units.
Question one: Is it possible to take only direct losses into account when waiting for parts? The answer is no; excluding indirect losses reduces the accuracy of the calculation by at least 40 per cent, which is an estimated figure based on a comparison of the results of calculations using a complete and an incomplete set of data. Question two: How often should data on average downtime be updated? Answer: Data should be updated once a quarter; this requirement is set out in the official guidelines for manufacturing enterprises. Question three: Is it possible to use average values to calculate losses at a specific enterprise? Answer: The use of average values is permissible only for a preliminary assessment; however, the calculation error may reach up to 25 per cent and represents an engineering reference range derived from the results of comparing preliminary and actual calculations at various sites.
