Lean and waiting

Waiting is one of the important wastes identified in lean manufacturing. What is actually waiting in the context of lean? If the customer has to wait to receive what they want it is known as waiting in the context of lean. The customer can be internal or external. So lean manufacturing proposes not to make any of your customers wait when they have a requirement. But how to stop waiting?

When it comes to manufacturing, lean works according to the pull concept. That is products are manufactured when there is a requirement for them. If this process is interrupted the flow of value will stop hence will create wastes. Creating a manufacturing environment which is smooth and will not have any stops and waiting is the challenge faced by many manufacturers. In lean manufacturing context waiting is the second largest contributor to the work in progress.

Lean doesn’t propose to have a higher inventory levels to eliminate waiting time. But the system should be fine-tuned and quipped to supply products when there is s a demand without making the requester waiting. This is where the system is really challenged. In lean manufacturing there will be frequent changes to the models manufactured, quantities are smaller and there is no inventory to level out the production. This requires robust systems. SMED techniques, careful layout planning, training and work cells are some of the techniques used to stop the interruptions to the flow of value hence the waiting time.

In lean office and lean service contexts waiting can be people who are waiting to get their documents done, people waiting for the information, people waiting for the reply for their email or a document waiting to be processed. Although this is not very much visible, offices and services have very high degree of waiting and higher cycle times.

Carefully mapping and identifying the value stream will make it possible to identify wastes in the office (or in your service). When these are identified we can remove these wastes from the system.

In lean software development waiting is mainly due to the development model. If the projects are planned to develop larger pieces of software then the customers have to wait till the full thing is done. Internal customers like testing people will have to wait till the full piece of software to come out to complete testing. When it comes to testing it will take lots of time to complete the testing these large software pieces. If errors are identified it will take more time to correct them and retest them. The result is end customer will have wait for longer without seeing anything. Once the software is delivered he might have a different set of requirements and expectations which are evolved with time.

This can be avoided by developing software in small pieces putting them together subsequently. It takes lesser time to develop small pieces of software and it is less complicated to test them individually. Once the minimum requirements are met product can be delivered to the end customer after an integration testing. This will make customer happy since he has to wait only for a short while.

In lean manufacturing there is one very important theory. If we waste time in the process we can not catch up to that time again. No matter how hard we work, no matter how fast we work if we have already lost one minute of time it will be lost for ever. Waiting is the main contributor to longer cycle times. Waiting means longer lead times.