Ratio-Delay — a Method for Analyzing Downtime in Sawmills

Ratio-delay is a work sampling method for getting facts about machine operations and human activities in organized production processes. Workers or machines are not timed, but a sample of observations is made and a tally kept of what each man or machine is doing each time they are observed. In a ratio-delay study, a large number of observations are taken at either random or systematic intervals recording whether or not the machine is operating. The percent of operating time is determined by dividing the total number of observations during which the machine was operating by the total number of observations. If the machine or its operator is not working, the reason for the delay should be noted. The ratio-delay method was applied in a case study sawmill to determine the proportion of time spent on 1) the production of lumber, and 2) downtime and the causes of downtime. The machines to be observed were the headsaw and sashgang resaw. A total of 933 observations made over a period of 8 consecutive working days revealed that the headsaw was inoperative about 25 percent of the time and the resaw about 41 percent of the time. This represented production losses of about 6,200 board feet on the headsaw and about 5,500 board feet on the resaw. The reasons for delay time were also determined. The results of a ratio-delay study do not tell the manager what to do, but they will define problem areas and pinpoint specific operations that need attention.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member