Principle #5 of Toyota Way says:
“Build a culture of stopping to fix problems, to get quality right the first time.”
In essence, this principle enables creating a culture in which problems are solved as soon as they are detected and prevents them to cause major issues such as:
- Increased levels of scrap.
- Lower quality of the final product.
- Lower machine and workforce productivity. The more time employees work without fixing the problem the more time the machine is producing with defects, which is not effective productive time.
- Lower service to the customers (more scrap implies on more working time for the workforce and machinery to manufacture the same amount of OK product).
- Lower creation of added value as time is wasted on manufacturing NOK pieces.
- Overconsumption of raw material and other resources.
In words from Fujio Cho (President of Toyota Motor Corporation): “Mr. Ohno often said that whatever problem encountered while stopping a manufacturing line should not wait more than 24 h for its resolution. When manufacturing a car, we would know every minute that on the next day we would have the same problem”.
In order to stop and fix a problem, you have first to be able to identify it. We need to recognise the difference between a correct scenario and a problematic scenario.
There are different ways to identify problems while they are occurring. Some of them are by using standardised procedures (SOP, Standardised Operating Procedures), Quality Control Plans, Product and Process Control Checklists or First Piece Checklists, for instance. In general, the aforementioned techniques are an example of perfect scenarios – a perfectly-timed process, a perfect part with zero defects, a photographic example of a standardized layout – and is used for comparison purposes between what is supposed perfect and OK for the customer and what is the current scenario.
As an example, when a manufacturing operator is receiving parts from any manufacturing process, the operator can compare the newly-produced part to the standard part and check if there are any significant differences. There are some products that may require destructive tests to show whether or not they are defective (such as tempered glass). If defects are found, then there is a problem and it has to be rectified in a short period of time.
A very effective way of detecting process problems right away is what Japanese call “Andon”.
Andon refers to a system that notifies about a quality or process problem. It consists on a device incorporating signal lights to indicate which workstation has the problem. The alert can be activated manually by a worker using a pullcord or button, or automatically by the production equipment itself, which has to be previously programmed accordingly. The system may include means to stop production so the issue can be corrected. The Andon is usually part of a PLC-programmed network in which you can report the specific issue so that the receiver of the problem focuses more effectively on its resolution.
It gives the operator the ability and empowerment to stop the production process when a defect is found and immediately call for assistance. The most common causes for manual activation of the Andon are part shortage, defect created or found, tool malfunction or the existence of a safety problem. Work is stopped until a solution has been found. The alerts are usually logged to a database so that they can be studied as part of a continuous-improvement program. It commonly indicates where the alert was generated, and can also provide a description of the issue.
The revolutionary idea (as it was implemented several decades ago, 50’s and 60’s) of giving a non-management (production line) worker the authority to stop the production line because of a supposed quality issue is thought to have been pioneered by W. Edwards Deming (one of the most important influencers within the Quality Control and Process Improvement in the manufacturing industry).
What could be a good example of the andon system in our real life? Our car’s “service engine, the washing machine sound when it finishes, the sound of the microwave oven when it ends the timer and plenty of other Andon-based systems are living together to make our life easier.