Section 50. TimeTakt Time

50. TimeTakt Time

Overview

Takt (a real word, not an abbreviation) is the German word for rhythm or cadence. A common mistake here is to confuse it with TACT (Total Activity Cycle Time) or similar, which is an entirely different thing.

Takt is defined as "The rate at which the end product or service must be produced and delivered in order to satisfy a defined customer demand within a given period of time." Simply put, it is the drumbeat of the market demand based on our working hours. Takt Time is calculated as

If a process were perfectly balanced with the market demand, then every Takt increment an entity is processed and used by the market. See Figure 7.49.1. For example, if a process runs 24 hours a day and the market demand is 240 entities per day then

If an entity is not processed (on average) each and every six minutes, the process falls behind Customer demand. In Lean Sigma terms, the processing time is known as the Global Process Cycle Time. Thus, if the Global Process Cycle Time is above the Takt Time, the process falls behind Customer demand. Likewise if the Global Process Cycle Time is less than the Takt Time of, for example, five minutes, then the process is cycling faster than Customer demand and building inventory or spending one minute in every six waiting, to avoid creating unused inventory.

Figure 7.49.1. Graphical representation of Replenishment Time (versus Process Lead Time).

Note that there is no mention in Takt of how quickly the process can possibly go or how quickly it is actually going, only how fast it should go to meet demand.

Clearly if the work period (shift time) is less than 24 hours per day, then the process has to go proportionately faster during those times that work is actually done to meet the daily market demand. For example, if the work period is 12 hours per day in the preceding example, then the new Takt Time is now three minutes, because there is only half the available work time and the process has to cycle twice as fast. So, if the Global Process Cycle Time is not three minutes, the process is not balanced with the demand.

Figure 7.50.1. Graphical representation of Takt Time.

Most processes deal with more than one entity type, and if this is the case, then the Takt Time must be adjusted to take this into account. For example, if a process has two main entity types:

• Product "A" currently has demand for 350 a month

• Product "B" currently has demand for 525 a month

Then the total demand is 875/month.

If the business runs a two-shift operation, 5 days/week, 4.2 weeks/month

• 5 days x 4.2 weeks = 21 available days

• 21 days x 16 hours = 336 hours

And so monthly available time is 336 hours x 60 minutes = 20160 minutes

There is a strong caution here that Takt is a metric based on average demand and does not take into account the variation in demand. For this you should also consider a tool such as Demand Segmentation.

Takt is Customer or Market dependent; thus, as the demand changes, then the Takt has to be recalculated. This is usually done on a monthly, or more typically, quarterly basis as a matter of course. Takt, however, should not be used as a reactive measure to tweak daily operations planning; it is a longer term guiding metric for determining how a process should be structured. Based on the Takt, the required Global Process Cycle Time can be determined and from this the number of operators or lines in the process.

Governing a process by Takt only makes sense when demand is reasonably consistent, either for a single entity type or for the total output across multiple entity types.

Logistics

On a quarterly basis, the Process Owners should calculate the Takt Times for all the processes under their control. It is not particularly a team sport to do this and all the data to make the calculation should be readily available historically.

Roadmap

The roadmap typically requires no fresh data capture and is as follows:

Step 1.	Identify the process(es) for which the Takt Time is calculated. Takt is process-specific and should not be aggregated across multiple lines unless they generate the same entity types.
Step 2.	Select the time period for which the Takt is calculatedusually a week or a month. For the time period selected, identify the true time available to produce units within that period. If using Monthly demand, then the time available per month is (#Days/Month x #Shifts/Day x #Hours/Shift x #Min/Hour) If using Weekly demand, then the time available per week is (#Shifts x #Days/Week x #Hours/Shift x #Min/Hour) The available work time should be calculated based on the full-shift time and not a depleted time that might have deducted the following: Wait for information or material time Rework time Equipment breakdown time Regular labor break time Fatigue/rest time It is done this way because the preceding elements are NVA activity in the process. If the Takt is calculated around them, then they tend to be overlooked as opportunities for capacity increase. The process still has to be generating entities every Takt increment and thus the drive should be to discover how to actively manage that.
Step 3.	Identify which entities likely flow through the process during the next time period. Unless absolute booked work is available, then this can be taken from a historical perspective; the assumption being that the pace of the process in the coming period should be close to that of the last period.
Step 4.	Calculate the total demand for this process for all of the entities identified in Step 3. This is a unit count of entities. As in the preceding example, if the demand is for 350 units of Product A and 525 units of Product B, then the total demand is 875 units.
Step 5.	Calculate the Takt Time from the work time calculated in Step 2 and the demand calculated in Step 4 as

Interpreting the Output

Interpreting the Takt Time should not be done in isolation from other elements. The trick is to understand the relationship between the internal times relating to the process:

• Process Lead Time Total time for an entity to progress through the process

• Replenishment Time to Customer Time to fill the Customer's "in-box" when they request it be refilled

• Global Process Cycle Time Rate (expressed in time) at which the process can generate entities

And to understand the relationship with the external Customer or Market related times:

• Requested Delivery Time How quickly the Customer needs delivery of an entity when they request it

• Takt Time The pace of usage of entities by the Customer, expressed in time

If the Global Process Cycle Time is greater than the Takt Time, then the process cannot meet Customer demand and options are

• Shedding the load from the process to speed it up

• Eliminating work content (specifically NVA)

• Providing the correct Work In Process inventory to ensure no steps are starved of entities to work on

• Adding more resource to the process, specifically on the bottleneck steps

• Using multiple lines in parallel