The Time Observation Sheet is used to, not surprisingly, observe the cycle times of the steps of Standard Work.
Unfortunately, many people dislike filling out this sheet for the simple reason that is it monotonous and fatiguing. To accurately determine cycle times, many observations are required. This means standing in a work area with a clipboard, concentrating deeply on watching an operator so no times are missed.
Despite being a very routine part of Lean, filling out a Time Observation Sheet is a bedrock step of forming Standard Work.
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You may see many different opinions on how to designate times for Standard Work. Feel free to adjust the later steps in the Time Observation Sheet process to suit your needs and Standard Work philosophy.
Draw a map of the work area on a Standard Work Sheet. (This will not be the final version of the Standard Work Sheet—it is just a working document). I often recommend that observers photocopy the map without any additional markings on it to create a template. This speeds things along if there is a mistake.
Watch the operator perform his or her work once without writing anything, just to get a feel for the process. The operator should be an average operator (not the superstar or the slowpoke) operating at a sustainable pace.
Watch the operator a second time, drawing the operator’s path, and jotting down process steps on the Standard Work Sheet. Include ‘observation points’ in the notes. These are specific transition points that act as boundaries between steps. They must be easily observable, discrete points.
Fill out the header information on a Time Observation Sheet.
Write out the steps and observation points in the Time Observation Sheet.
Place a blank sheet of paper under the observation sheet on your clipboard.
Start the stopwatch at the beginning of the process. (Note: The observation point to start a cycle is the same as the observation point that ends the previous cycle.)
Log times down each column above the dashed lines. Don’t reset the stopwatch! Leave the stopwatch running. You’ll be subtracting out the interval times later. It just takes too long and introduces errors to start and stop the watch while you are timing.
When you get to the last step, just leave the clock running and start on the next column.
Record between 6 and 10 cycles to be able to make accurate estimates of cycle times for each step.
NOTE: If you see a special cause problem that changes the time (adds or subtracts), log the problem on the blank page using this convention: “Step-cycle” So, a problem with the 4th step on the 3rd cycle would be 4-3. Be brief—you probably won’t have much time, but make sure the note will refresh your memory. Then circle the time you wrote into the Time Observation Sheet.
After the last time, go back and make sure you understand what you wrote on the log sheet.
Calculate the total cycle time for each column.
Calculate each of the step times. Log that time below the dashed lines in each column. (It will be the time for the end of that step minus the observation time for the previous step.)
Calculate the average times for each row, leaving out the circled steps.
Write in the low time for each step, again disregarding the outliers.
Using the average as a guideline, use your knowledge of the process to add an adjustment to the low time to come up with a step time.
Add up all the step times to get a total cycle time for the Standard Work.
The last step is to compare the full cycle-times and see if the time you derived makes sense. If your company is risk averse, it should be higher than the majority of the times you took. If it is not, it will be on the lower end of the scale. After all, those times were actually done, so it is reasonable to expect similar times regularly.
In either case, if you identify any special causes that occurred more than once, highlight it as a problem that needs resolution.