What is Takt Time?
Takt time is the maximum amount of time in which a product needs to be produced in order to satisfy customer demand. The term comes from the German word "takt," which means "pulse." Set by customer demand, takt creates the pulse or rhythm across all processes in a business to ensure continuous flow and utilization of capacities (e.g., man and machine).
Why Do We Need Takt Time?
Takt time is more than a metric of time — it’s a whole different way of thinking for running your operations.
First, takt ensures that all the capacity in a business is planned and utilized and still meets overall customer demand. By and large, takt will help to deliver the right product (RP) at the right time (RT) in the right quantity (RQ) to the customer. You can achieve RP, RT, and RQ without implementing takt; however, this could lead to much waste of man and machine.
Second, takt creates a constant pulse across your processes, which will immediately highlight capacity issues, synchronization issues among processes, quality issues and many others.
How to Calculate Takt Time
The calculation for takt time is as follows:
Production Time Available
Takt time = _______________________
Where production time available = total production time – breaks – maintenance activities – shift changeover – clean down time
Total Time: 8 Hours X 60 Minutes = 480 Minutes
Breaks: 50 Minutes
Time Available : 430 Minutes
Customer Demand in 8 Hours: 100 Pcs
Takt Time: 430 / 100 = 4.3 Minutes = 258 Seconds
This example shows that the customer will need one pcs every 258 seconds. However, you might like to produce a single pcs in little less than 258 seconds in order to accommodate any variation in process steps, breakdowns, quality issues, etc. It’s therefore essential that before you implement takt, you ensure that your processes are dependable and can deliver good quality, and that your machine has a very high uptime.
How to Implement Takt Time
Eliminate the non-value adding time and balance the workload of the operators. (Click on image to enlarge.)
Bring the individual cycle times closer to the takt time. Keep the line balanced. In this case you will need fewer operators. (Click on image to enlarge.)
Consider the process of a water delivery system.
The overall demand of water consumption is set by the homes that consume the water over 24 hours. However, the homes’ occupants do not consume the same amount of water across the 24 hours: There is a huge peak in consumption in the morning, afternoon and late evening, but for the rest of the day consumption is very low.
Based on this data, the plant calculates what the demand is every hour and adds a little buffer to address fluctuations, breakdowns, leakages, etc. The water treatment plant operates based on this demand rate so that each process step must deliver the same amount of water in that period.
If some process is not able to deliver at the same rate, then either the plant needs to add more capacity or run that process for a longer time. The reservoir in between the plant and the homes (shown in the figure below) will smooth the impact of demand on the production process. The reservoir will also help with capacity issues related to the fact that as the water treatment plant is delivering water at a constant rate, consumption remains variable over the course of the day. (Click on image to enlarge.)
Now the trade-off is between the cost advantage to run the power plant at the same run rate across the day and the cost of the reservoir. There is no one answer in the real world. Depending on your cost structure of man, machine and material, you must define how smoothly you can run your processes across the day, week or month, versus the inventory you may need to be able to adjust to customer demand variation. On the other hand, inventory is evil in the Lean world, but you have to look at total cost versus individual costs.