The process efficiency is something always in demand and every organization aspires to seek strategies for improving efficiency. The cycle time optimization strategies is one of factors that the management needs to focus on to improve the efficiency of business operation. The strategies for cycle time optimization is applicable to variety of situations such as R&D, project management and operations management. The concept is deeply related with the Kanban method. The idea of Kanban is based on “pull” instead of “push”. More specifically, it means that the main goal is to develop process with zero waist and zero intermediate inventory.
Cycle Time vs Flow Time
In this particular article, we focus on flow and cycle of work across people by measuring and analyzing the flow time and cycle time for WIP (Work in Progress) unit.
The definitions are as follows
Flow Time: The sum of time spent to produce one unit
Cycle Time: The interval between producing successive units
WIP: Work in Progress
An Example – Cycle Time Optimization Strategies
Let’s see the following example. Suppose, we have 3 consecutive tasks to complete the unit, task A to task C. The task A is the first work to be completed in order to continue the rest of process. Task A can start any time, Task B needs a completed Task A WIP (work-in-progress) piece. Lastly, the Task C needs completed Task B WIP piece to start and complete the task. Task B and Task C need preceding WIP to start their work therefore, they can’t start on their own.
The minute per unit and unit per minute are as follows.
Task A = 3 min / unit Task B = 7 min / unit Task C = 4 min / unit
Task A = 1/3 unit / min Task B = 1/7 unit / min Task C = 1/4 unit / min
The process sequence chart is going to look like this
In this case, in order to assess the process efficiency, we need to figure out the flow time and cycle time of entire sequence. As shown in the above chart, the flow time is 15 minutes and cycle time is 7 minutes. This means that it takes 15 minutes to complete one sequence to build one unit. Also, this system produces one unit every 7 minutes after completion of 1st unit.
Hence, the sequence involves 4 minutes of idling time with Task A and 2 minutes of idling time for Task C. This is where inefficiency takes place.
Eliminating The Slowest Task In The System is The Key For Cycle Time Optimization
The overall cycle time is determined by the slowest process in the entire sequence. In this example, there are 3 different tasks to produce 1 unit. Task A takes 3 minutes, Task B takes 7 minutes, Task C takes 4 minutes. The slowest task (process) in this sequence is Task B which takes 7 minutes. This becomes the cycle time of entire sequence.
Thus, Task B is the bottleneck in this system. There are several things that you can do to improve this situation. What about eliminating the idle time by cramming tasks for Task A and C?
If There is No Idle Time for Task A
You might have noticed that Task A does not start until having 4 minutes of idling time so the Task B can start their work immediately after Task A. Let’s consider the scenario that performing task A without having an idling time, the process flow looks like this
Process Flow (No Idling Time for Task A)
In this process, the WIP inventory of Task A is going to shoot through the roof. Task A produces 10 units at 30 minute-mark while Task B produces only 5 units at 31 minute-mark. This setting is worse than the original setting.
Task A WIP Backlog Accumulation
Is Changing Task Order Affect the Cycle Time?
The short answer is no. Although it sounds like it makes a difference, it does not affect the cycle time. The following is an example of switching Task A and Task B order. The flow time still remains 15 minutes and the cycle time remains 7 minutes. Regardless of task order, the system punches out the same cycle time and flow time. Even if the task orders are changed in different ways, the results will end up with the same.
Changing Task Order
Solutions for Cycle Time Optimization
Although there might be a sequential restrictions for the task execution, there are few things you can do to improve the process. The root cause of this inefficiency is originated by the imbalance of processing time for each task. Minimizing the disparity of processing time is what the management needs to focus on. The ideal solution is to take 2 minutes away from Task B and add that 2 minutes to Task A. Therefore, the processing time for every task in this sequence becomes 5 minutes without having idling time. The management may want to consider following review and improvement plans.
- Task execution process
- Adjusting number of personnel working at each task.
- Tools and equipment being utilized
- Ergonomics
Task Execution Process
How the work is performed affect the task execution time. The key is to make process as least complicated as possible. Why? because if the process becomes less complicated, the chance of making mistake becomes less. Thus it helps to speed up the task execution. The workers are less concerned about the difficulty of task and focus more on wellness of output.
Number of Personnel for Each Task
The task assignment is often exerted by the organizational partition. For example, the particular team is dedicated for specific category of task. Then the whole team members work on given task regardless of imbalance of workload.
Tools and Equipment
There are 2 ways to look into the efficiency of tools and equipment. The qualitative and quantitative measure. The qualitative measure is to improve the efficiency of tool itself. The quantitative is increasing the quantity processed per action by modifying or adding more tool/equipment. If the particular given task requires to use caliper, use the digital caliper rather than dial caliper (qualitative). Furthermore, the electronically actuated caliper even reduces strain on the hands, wrists, and arms. Less stress, less likely to make a mistake and motivates faster outcome. Increasing the number of cavity for injection mold (quantitative) will double the production rate if it won’t affect the quality of product.
Ergonomics
This improvement sometimes overlaps with Tools and Equipment improvement. The items require the most frequent access should be at the closest and most reachable. This can be physical or electronic resources. For instance, creating shortcuts for the most frequent files and folders on the desktop PC. Creating bookmarks for websites accessed frequently. This allows single-click-access with minimal time with no typing mistake. For physical environment, for instance, the most frequently used allen wrench set shall be at easily reachable place without deviating the body. For warehouse or production environment, the ergonomics assessment may reveal the high stress motion or posture, which ultimately causes an inefficiency.
Cycle Time Optimization Strategies
These sound like small things but they add up and make a noticeable difference. The management should continuously and curiously explore more efficient ways to manage the cycle time optimization strategies.