Work Study; Method Study and Activity Timing (Time and Motion Studies)

Work study; activity timing and method study are an important part of any lean manufacturing implementation if you wish to design manufacturing cells or balance and improve existing flow lines and cells.

Traditional work study usually involves the use of an industrial engineer standing over an operator with a stop watch to time the operations involved in producing a product to measure standard times for costing and payment. These times would be used to estimate costs for products and to set production targets that could be used to either reward or penalize the workforce.

Methods used within lean manufacturing try to avoid some of the problems associated with these traditional methods by including the workforce in taking these measurements and using them to help drive continual improvement.

There were many problems with the traditional methods of work study or the dreaded "time and motion" studies;

They used an “expert” who’s opinion of what should be done and how could often be at odds with the people who actually did the work and so often failed to make improvements to the process.

Their appearance with their stop watches caused an immediate change in behavior by the operators (usually slowing down to ensure that targets were not set too high!)

The targets set were average measurements – 50% of operators would be slower and 50% faster – but management would expect everyone to meet the production targets. In practice the slower people would fail to meet targets set and the faster more able operators would slow down to only produce the target causing an actual reduction in output!

Where incentive schemes were introduced for exceeding targets the operators would often take “short cuts” such as failing to do quality checks to try to gain bonus leading to higher levels of rejects at the customer.

With lean we try to simplify the activity timing as much as possible, we also try to identify the individual work elements and identify them as either adding value or as being non-value adding and wasteful steps to be eliminated or reduced.

Lean manufacturing tools are team tools, by this I mean they should not be used by an expert who comes to town to implement their changes on the workplace; they are for the use of the people involved in the workplace to help them create and agree their own improvements through the use of 5S, Kaizen, smed and a host of other lean manufacturing tools.

So rather than have an industrial engineer stood over the workforce using a stop watch or even the team watching other members with stop watches we can use video to record the process during each shift. Each operator should understand that we are trying to make the process easier and more efficient not just for the companies benefit but for the operators benefit also. The method study and activity timing is undertaken by the team as a whole not by an outside expert.

The video should cover each shift and each operator; the team can then use the video to view differences in methods and to time the elements of each operation as well as identify them as being value adding or non-value adding.

Work elements are the individual steps of the process, picking up a component (non-value adding), loading a fixture (non-value adding but maybe unavoidable), operating the press (value adding), and so on.

Each should be timed at least 10 times to the nearest second and the time used should be the lowest repeated time; so if the operation took – 10, 13, 12, 12, 11, 14, 13, 12, 15, 14 we would select 12 seconds as the lowest repeatable time. Comparisons should be made between operators and between shifts to identify differences in methods used. Elements in which something goes wrong should not be included within the study.

As per 5S the best possible method should be documented on a standard operating instruction to ensure that they are maintained across all shifts and employees and as an aid for training.

By identifying each work element as being either value adding or non-value adding we have an opportunity for the teams to either totally eliminate the non-value adding steps or to reduce them making their processes more efficient and also easier and safer for themselves.

They can also create additional improvements by considering the work method study itself and comparing between shifts and individuals to find the most efficient way. These methods can be used within your kaizen teams to ensure continual improvement of processes.

By taking measurements of each work element you are able to review the entire process in line with the customer demand rate or Takt time. By using a tool known as a Yamazumi chart you can balance the work elements of a process between the operators to ensure the optimal number of operators and machine utilization to achieve customer demand.

If one operator has too many work elements and their total time exceeds takt time we can give some of these elements to the operators that either precede or come after them to balance the amount of work between all of the operators in the cell. We aim to achieve around 95% of Takt time for each operator.

This can often mean slowing down some jobs within the process which may seem the wrong way to approach improving efficiency, but the slowing of these processes prevents the buildup of inventory and all of the associated wastes and costs.

If you have any questions regarding Work study, activity timing and method study or about lean manufacturing tools and techniques in general please leave them below.