What are cycle time and takt time in lean manufacturing?
Cycle Time vs Takt Time:
Cycle time in manufacturing is the time taken to produce a final part using different processes. Actually it is a maximum time taking process time. We can get cycle time by observing the process for a defined time period & counting the number of parts produced in that time period. We should do observations at different times & do an average of all observations. We can measure productivity of the manufacturing process with this quality objective (KPI).
Takt time is defined as the required time to produce one unit as per customer demand. It sets the rate of production to match the rate of customer demand. Takt time is an element of lean manufacturing.
Takt Time = Available Production Time / Rate of customer demand
How to calculate Takt time? | Takt time example :
What is the takt time if 1000 units are needed per day the company has one 10 hour shifts per day? Also consider lunch 30 minutes, 2 tea breaks of 10 minutes, 30 minutes other personal breaks and 2 breaks for machine cleaning of 10 minutes each.
Total shift hours = 10 hrs (10 x 60=600 min)
Lunch = 30 min
Tea Break = 20 min ( 2 x 10 min)
Other Break = 30 min ( 3 x 10 min)
Machine Cleaning = 20 min (2 x10 min)
Total breaks = 30+20+30+20 = 100 minutes
Net Available Time = 600 – 100 = 500 minutes
Customer demand = 1000 Units
Takt Time = Available Time / Customer demand
= 500 /1000 = 0.5 min = 30 second
So to meet customer demand we have to make two parts per minute. Cycle time should be less than takt time to meet customer demand.
But in actual operators can never achieve 100 % efficiency, So need to provide some allowances by considering some other stoppages.
What are the benefits of takt time ?
Below are the benefits of balancing takt time and cycle time:
- Control of production: Takt time stabilize the system & control to over-production.
- Performance increase: Feedback of performance works as a motivating factor. When operators work as per takt time, their output increases. They try to achieve takt time & make required planning & solutions.
- Line Balancing: Takt time helps the process designers to make line balancing.
What happen if Takt time is more than cycle time?
In this case, a sheet metal part is produced through these processes. Cycle Time ( highest is 19 sec sec) is just below the Takt Time (20), So customer demand will meet. There is no need to take action immediately. Further we can improve by balancing the cycle times of processes to complete the product of that part.
What happens if Cycle time is more than Takt time?
In this case operation Draw operation (25 sec) exceeds Takt time (20 sec), So customer demand can not meet. So there is need of over time to fulfill the customer demand. Also there will other losses like loss of sale, customer will dissatisfy, increase in freight charges. There will be need to take action ( Kaizen) to the process having cycle time more than takt time.
What are the limitations of takt time?
Takt time is used for simple processes. It is applicable to the processes where is
- Minimum setups
- Single routing
- Similar cycle time for all products
It is difficult to apply on low volume & high variety operations.
Check the story about Cycle Time & Takt Time.