Cycle Time

The cycle time is the time it takes to complete a task from start to finish or an average of the completion times of a repetitive productive process or task. Cycle times are commonly used to gauge the time it takes to complete tasks along the productive process, although commonly it is measured as the time it takes to manufacture or produce one unit of output at the end of the production line. Depending on the productive process, it may or may not have idle waiting times in between tasks, the sum of the value-adding tasks and idle times is known as the throughput time which in practical situations is used interchangeably with cycle time.

The cycle time for an item or product together with the resources available to produce the item will determine the total capacity of the productive process, and if there is a demand forecast then the capacity utilization of the process can be predicted. In manual labour intensive processes an average is usually used to derive the cycle time for a task, due to the difference in skills and experience of different operators.

The standard deviation of the average cycle time can be used as an indicator of variability among operators, and if too big it can be difficult to accurately predict total lead times and can produced bottlenecks . One way to eliminate the variability of a task or process cycle time is to introduce automation into the process. Automation reduces variability, improves accuracy and quality.

Calculating Cycle Times

Cycle times are generally easy to measure or calculate but can sometimes involve some calculations in certain applications, a few examples are listed below.

Cycle time for a batch process

The cycle times for items produced in a batch process are usually given in time per a set number of units, usually the batch size. For example in a baking process which can bake 200 units of bread at one time in an hour the cycle time is 200units/hour. If another identical oven is added to the process functioning in parallel the cycle time will still be one hour per 200units, but can also be expressed as 200units/0.5 hours.

When analysing a process it is more convenient to state the cycle time in the correct units as in the example above per 200units, as this will make it easier to spot process bottlenecks.

Cycle time for a service industry process

In a service industry such as fast food or restaurants it is possible to analyse cycle times for tables to optimize restaurant layouts, service times and labour utilization rates.

For example if there is a restaurant which has 25 tables and on average we know that each party at a table takes 45mins to dine then we can calculate the cycle time as 45min per table / 25 tables = 1.8mins, therefore in this example the restaurant turns over a table every 1.8mins on average or a table should be free every 1.8mins. By dividing 60 mins by the cycle time we can calculate the maximum amount of parties the restaurant can serve per hour, in this example 33table-parties (rounded down from 33.3).

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