In the ideal world, yes, batch and queue mentalities are very non-Lean. However, in the real world they can be a necessary and valuable step in approaching a stable and standardized environment.
In a typical laboratory environment, equipment is designed to allow for a number of samples to run at the same time with the same setup. In this situation it makes sense to allow for a reasonable number of samples to run at the same time. While individual samples should not necessarily wait for the machine to be completely full, a repeatable schedule of operations can be identified to enable capitalization of similar setups without jeopardizing lead times.
This approach is generally facilitated through the use of Rhythm Wheels. A Rhythm Wheel functions much like the cam shaft on an automobile. It turns at a set rate, and certain actions occur at predetermined intervals within a single rotation of the wheel. Some of these actions may occur once, and others twice or more.
From a laboratory perspective, this is similar to having many different types of tests that can be run in the lab. Because of volatility in the volume and mix of required tests within the lab, these tests may be required to run at any time. The most significant change will be that the tests now are completed at set intervals. The appropriate interval should be set that will allow for the fullest test batch, without negatively impacting the overall lead time. Common intervals are daily, weekly, every other day, etc.
This method of standard intervals forces a certain amount of batching and drives the mentality of “every test, every interval”. In general, labs implementing an appropriate rhythm wheel enjoy the benefits of: reduced lead times, increased capacity, consistent lead times, full but not overly busy workdays and a more stable work environment. Once the lab has transitioned to a standard and stable work environment, effort can then be effectively spent on more traditional Lean endeavors such as waste elimination, jidoka, and one piece flow.
This blog was written by Preston Chandler, Consultant at BSM-USA Inc. For further information on implementing Lean in Laboratories please send an e-mail to Preston Chandler.