Stop the line authority

Stop the line authority describes the ability or permission of operators to stop the process when a deviation or problem occurs. By doing so it is prevented that defective parts are passed on the downstream process steps.

A typical example are so called “Andon cords“ that can be pulled to immediately stop the process and inform the supervisor. To read more about Andon itself go here.

When you are in the lean world you might have come across the famous Toyota quality control mechanism “Andon Cord”. The cord is a simple tool to alert others of deviations or problems in the production line, at Toyota everyone has the authority to pull the cord. By pulling the cord almost instantly production will stop and give the alert to responsible supervisors that there is a crucial issue that needs immediate action. Following the lean principles and shop floor structure, a supervisor would step up and help the operator reviewing the deviation of product or process and define counter measures. When doing so and working with an A3 Problem Solving approach, the supervisor is coaching through the problem solving process and shares with others the outcome or lessons learned on how to prevent this failure of happening again.

In Lean Manufacturing - pulling the Andon Cord is emphasized to all operators. The target is simply to block all defective parts from leaving the company and reaching the customer. At the same time it creates the opportunity to improve your processes to prevent future defects.

NEXT STEP: GO GEMBA

Instead of explaining you the complete principle of Gemba Walks here the short version. But if you want to learn more about Gemba Walks go here.

You can discuss problems as much as you want but when you don’t get yourself to see it, it is worthless. This is where the Gemba Walk comes in the game. Gemba is a Japanese term and stands for “the place where it actually happens”. This can be everywhere and everything in the process chain, but by pulling the Andon Cord the place is defined.

Key of Gemba is not to talk in wild theories or totally abstract about problems, but to have a look where it occurs and discuss them on site (looking at the process in the real world, get rid of unnecessary power points and excel sheets! Nobody cares anyway!) Too often we want to believe the statement of an “expert” and forget about it instead of going there and have a look ourselves in oder to gain a better understanding of the problem and make up our own opinion.

VISUALIZATION

When you are at the place of action, make sure to bring an A3 with you. Make sure that you describe the process properly and the failure that occurred.

In the lean manufacturing world the best known use case of the A3 report is the problem solving report. In this case the responsible person from the quality department takes the A3 report, starts the problem solving actions and follows a systematic structure that makes it possible to describe the effects that are currently leading to a deviation from the standard. Using the A3 only makes sense when you don’t know the root cause yet. If you already know the root cause don’t waste your time. Fix it and go back to normal.

Key Questions are with Gemba Walks and A3:

1. What should happen?

2. What is happening?

3. Explain why!

The A3 Report is foldable and can be then placed at the line or the work station. This is a great and a standardized tool to visualize that a problem is known and on the watch list.

LAST BUT NOT LEAST - STOP THE LINE (JIDOKA)

Now it is time to tackle the hardest part for all players in your organization: STOP THE LINE. In Lean Management, the original term is the Japanese word JIDOKA. This concept is driven by the maxim to have the best quality of goods and to bring the potentials out of the processes or products through continuous improvement. You have to stop all production when a deviation occurs and implement effective counter measures before restarting the line.

On the first view stopping the line might sound hard and insane, as you will stop all value adding activities and actually stop shipping goods. But think about it again. Failing to solve problems when they occur will force you to pile up your inventory with non-conforming parts that will need rework before shipping. You will bind additional resources in space and workers and by that you will burn money. Finally it will keep your organization away to improve and move forward with the developments of the market and with your competitors.

This is exactly the point where the principle of continuous improvement comes in the game, where you see all deviation as an opportunity of improvement.

To practice and learn more about continuous improvement and the CIP methodology, go ahead and read the CIP article here.

If you can’t measure you can’t control

Make sure that you have an organization wide monitoring in place which provides you with all KPIs necessary to run your business. Line stops and counter measures will be part of the tracking process in order to understand if the counter measures are effective, gain a better understanding of the processes and documentation of the improvement process itself.

1. What is the deviation?

2. What are the measures implement?

3. Are the counter measures effective?

You see there is again the logic of PDCA in the continuous improvement process.

All this information will be than part of the Shop Floor Mgmt. to get the information throughout the complete organization and to make sure that all players have the same understanding in what direction your organization is heading.

Andon

Andon is a crucial part for the visual management on the shop floor that gives a signal that indicates if and where there is a problem. Typically indicated with a traffic light signal red = failure mode, yellow = non-conforming performance and green = normal operation mode.

The methodology of Andon as part of the shop floor management, is to show the current operating status of a machine or a production line in a way that everyone can see and understand it immediately. As typically in Lean Terms Andon comes from the Japanese language and means paper lamp or just lamp.

Going along the Andon-Systematic there is to mention the Andon-Cords. The cords are used by operators to activate the lamps by either tear the cord or more likely nowadays pressing the corresponding buttons, which are attached above the production line and are easily accessible for the operators hanging downwards or as button attached at the work station.

If a non-conforming condition occurs, the yellow Andon signal initiates the support so that the problem that has occurred can be remedied immediately with additional supportive functions, such as maintenance. In worst case it is also possible to stop the complete production (red signal) until the problem has been solved or at least suitable countermeasures are in place.

An Andon has three main functions:

1. Visualization of the operating status of a machine/assembly line

2. Possibility for the operator to report an non-conforming condition and escalate it using a defined escalation process

3. Production or belt stop, so that no non-conforming products or components are passed on to the next process step

Old fashion Andon Board

The clear display of the operating states of several workstations was used quite early in the development of the Andon systems. The godfather of the TPS, Taiichi Ohno once described it as followed: "When one looks up, the andon (the line stop indication board) comes into view, showing the location and nature of trouble situations at a glance."

In the course of time, the Andon board has increasingly developed into an information board for all employees involved in the process. They display status information regarding the current situation in production, such as the number of units produced per day or per hour, the degree of delivery reliability to the customer or the cumulated amount of backlog. In this way, all process participants are aware of the current situation and can act accordingly.

Andon Boards nowadays