Takt time
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Takt time can be defined as the maximum time allowed to produce a product in order to meet demand. It is derived from the German word taktzeit which translates to clock cycle. The pace of production flow would then be set based on this takt time. Product flow is expected to fall within a pace that is less than or equal to the takt time. In a lean manufacturing environment, the pace time is set equal to the takt time.
Takt time has direct implications concerning the allowable time for completing individual steps in a production process. This is the case for both steps that modify (form, assemble, finish…) the product and also the steps that observe and control (test, measure, adjust…) the process. Steps which require a part or assembly of the product to have been put into an accurately fixtured position must be completed in less than the total takt time so that time is allowed for loading and unloading or positioning the part in addition to the time for actually performing the production step. The quicker that a measurement or test step can be completed, the less constraint is placed upon product motion between steps. For example, a metrology process that captures the entire information about a part at once will permit shorter total takt time and a higher pace of production flow.
Takt Time is defined as:
TAKT Time = Net Available Time to Work ÷ Customer Demand
Net available time is the amount of time available for work to be done. This excludes break times and any expected stoppage time (for example scheduled maintenance, Team Briefings etc).
As an example, if you have a total of 8 hours in a shift (gross time) less 30 minutes lunch, 30 minutes breaks (2 x 15 mins), 10 minutes Team Brief and 10 minutes for basic Operator Maintenance checks, then;
Net Available Time to Work = (8 hours x 60 minutes) - 30 - 30 - 10 - 10 = 400 minutes.
If Customer Demand was, say, 400 units a day and you were running one shift, then your line would need to make one part per minute to be able to keep up with Customer Demand. In reality, people can never maintain 100% efficiency and there may also be stoppages for other reasons, so allowances will need to be made for these instances and thus you will set up your line to run at a proportionally faster rate to account for this.
