Learn about Takt time and Cycle time in detail with examples. We will also see what approach can be taken for cycle time reduction.
The word takt is a German word for baton, used by an orchestra conductor. This provides a rhythm to the process similar to a heartbeat. This means that the process is flowing at a certain pace or rhythm. It will be explained here with some simple examples, takt time is not only about calculation but we also need to understand the role of takt time in CFM (Continuous Flow Manufacturing) .
In CFM (Continuous Flow Manufacturing) a certain pace is maintained, the line must be engineered to do so. Takt time is term used (first by Toyota) to define a time element that equals the demand rate. In CFM or one piece flow, the time allowed for each activity/line operation is limited. The line is balanced so that each operator can perform their work in the time allowed.
An example of the calculation of takt time is shown below :
The takt time will be 1.43 min per unit or 86 sec per unit. The ideal pace of each operation is set at 86 sec.
For the plant that does not have the luxury of mass production to establish a single takt time, the solution may be to develop multiple takt time, breaking the requirements into smaller components.
The necessary quality, machine, personnel, materials and supplier resources must be coordinated and made available as needed. The layout of the line or cell is a starting point. The line should be examined as necessary to:
1. Improve cycle time
2. Reduce product defects
3. Correct long changeover times
4. Address equipment reliability (or breakdown) issues
In the next step we observe that station 1, 2 and 5 do not come up to the takt time. There is slack there which needs to be addressed. Only station 3 has a full 60 sec of work. In Lean manufacturing, we need to review the line for a redesign of the process.
The total work time used in the current scenario is 265 sec. With 5 operators, this will be 53 sec on a balanced line. A deeper look indicates that 4 operators will require 66.25 sec. This is a little more than the desired takt time of 60 sec. Now the most important task will be to look at the value add(Vas) and non value add(NVAs) in the process. A thorough study of the tasks may reveal that a significant portion of time can be eliminated leading to a reduction of 1 operator and possibly a reduction of floor space as well.
We will take an example of a line with 5 stations. If the takt time for a station is 60 sec, the first observation is that station 4 exceeds the takt time and will not be able to maintain the pace. An option would be to have some of the time eliminated by moving work to another station.
Fig – 3 shows various options, option 1 is to balance the line at 53 sec. This will provide 7 sec of slack for each operator as the takt time was 60 sec. Option 2 reduces the number of operators and redistributes the work load. This redesign has an initial takt time of 66.25 sec.
The next step is a kaizen event in which the team can identify NVAs and reduce the work time for each station to 60 sec as shown in option 3.
Cycle time is defined as the amount of time needed to complete a single task and to move it forward in the process. The cycle time may differ by task, but to make the line flow, all operations must be completed under the given Takt time.
Cycle time is also known as turnaround time for any given task, in many industries people are familiar with this term and use it rather than cycle time. An example of cycle time from service industry could be installation of internet connection at home. If the provider does it in 24 hrs, then the cycle time here would be 24 hrs.
As you can see cycle time calculation is independent of customer requirement, while takt time calculation is based on customer requirement.
In our business processes, we always try to reduce cycle time because it is directly linked to cost reduction and customer satisfaction. We take up projects to reduce cycle time for following reasons:
- To please a customer: If we can deliver product or service before the customer expectation then obviously customer would be happy in most of the scenarios. It will set us apart from the competition.
- To reduce waste: When we work on to reduce Non Value Adds (NVA), we can reengineer and redesign the process. It helps us to understand the process constraints better. As we start measuring NVAs, we can track and try to reduce it through different measures. It can be a process change or better training of staff. As we reduce NVA, cycle time reduces and benefits all stakeholders.
- To increase capacity and productivity: As we reduce cycle time, we can produce more with less resources being used. It decreases overall cost of operations.
- To simplify the operations: When we study the process, we try to automate activities which can be automated and eliminate steps which are not required. This can be done as a Kaizen event or can be part of Value Stream Mapping.
- To remain competitive: To keep the costs low and customer happy, we have to keep the cycle time at the lowest and very competitive. Firms conduct benchmarking studies to compare their cycle times with competitors. Many top consulting firms provide these kind of benchmarking studies.
Let us reconsider the below example again, it is a line of 5 stations and observed cycle time for each station.
In this case let us assume the Takt time required by the customer is 60 Sec, as you can see station 3 is at 60 Sec. It is good that station 1,2 and 5 are below the Takt time. Station 4 is above Takt time so something should be done to bring station 4 below the Takt time.
This is a very frequent problem faced by process managers and here we will talk about the approach which can be taken in addressing such a scenario.
We can take the approach of a Kaizen Blitz event or the similar thing can be done over a longer period of time. The basic approach is to do Time and Motion and understand current non value adds (NVA) in the process. The next step would be to find solutions to reduce NVAs or automate some of the steps.
Let us understand the Kaizen Blitz approach –
A team of subject matter experts would be formed with a facilitator. The team facilitator would guide the team to a significant cycle time reduction within 5-6 days using Kaizen event.
There is a general format to the Kaizen format:
- Training must be provided, since some members may not be familiar with lean thinking techniques
- Time limit of 5 days to accomplish the change
- 2 days of training provided on lean techniques
- 2 days are allocated for collecting data and making changes
- The last day consists of a presentation on the results to the workforce
While this is the Kaizen format, we can take a similar approach for more complicated processes, but it generally takes more time. Following are the critical steps explained ;
Before we initiate identification of NVAs, the auditors need to be trained and calibrated so that the data collected is correct. Some of the things which need to be covered in training are:
- Identification of value add and non value add activities, explain with examples
- Identification of Muda
- Principles of motion study
- 5S workplace organization
- Next process as customer
- Problem solving techniques like 5 Whys
- Poka yoke techniques
- Work flow patterns
Once the training is done, next step is calibration of the team members. Let trained employees capture time and NVAs, facilitator needs to calibrate each auditor.
It is advisable to use video recording for time and motion. It becomes very easy and accuracy levels increase many folds, in case of any doubt you can always go back and calibrate.
Next step is to capture time and motion, operators and other staff members can all be team members and be involved in this activity.
The work sampling studies will provide a picture of the work content of the station. This will reveal the content and ratio of work, inspection, walking and other factors
As you can check in the table, value add is around 60% only for each station. The activities of inspection, delay, walking and other are considered Muda and are NVAs.
We usually study 30 cycles of the line in order to determine average cycle time, this is statistically valid sample size.
Now that the team knows break up of different NVAs, the team can investigate ways to eliminate these Muda types. We can try different layouts to reduce walking, example of a U shaped layout or L shaped. Change place of tools to reduce motion.
Inspection Muda can be reduced by better calibration or automation of inspection process. Stations might be inspecting something which may not be required. We can check the defect rate out of inspection activity, RCA and solutioning can be proposed to eliminate those defects itself.
There are many opportunities for innovation and creativity in the composition of line work layout.
- Takt time is calculated based on customer demand or requirement, it is not based on actual time that it takes to complete the task. While Cycle time is calculated basis actual time to complete the task.
- We always work on adjusting Cycle time keeping Takt time in mind. We work on Cycle time reduction not Takt time reduction.
- Reducing Cycle time benefits in terms of improving productivity and reducing costs.
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