Maybe you have had the chance to ride in an old trolley like the ones that are used to travel and tour on the steep, hilly streets of San Francisco or a historical trolley tour in Philadelphia or Savannah. If so, one activity riders enjoy doing is pulling on a rope which sounds an alert like a bell to indicate that the driver should stop to let someone off. Some bus systems also use this system in the form of a push button, color-coded strips which passengers can press to let the driver know that someone wants to get off at the next stop. These are all forms of Andon.

What is Andon?

The word Andon is Japanese, and its origins come from the use of traditional lighting equipment made out of paper and bamboo that was commonly used as a fire burning lamp. It is now a commonly used term in lean manufacturing where it is used as a signal to highlight an anomaly using a visual system of communication that is often relayed with a lit signboard or stacked lights.

In English, Andon means “signal” or “sign.” In manufacturing, it refers to a system to notify maintenance, management, and other workers of a process or quality problem. The focus of this concept is an electronic device that uses some form of signal lights to let workers know which work area has a problem.

Just like the street trolley example, the alert can be worker activated by pulling on a cord or pushing a button. It may also be able to be activated automatically by the Production equipment. It means to stop production may also be included in the system so issues can be corrected immediately. Some advanced alert systems incorporate text, audio alarms, and other forms of visual displays.

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A Principle Element of Jidoka Quality Control Method

To understand Andon, you must understand how it supports the Jidoka quality control method. It originates with the Toyota System Corporation where the company first implemented the process of stopping a system when a defect was suspected. The concept behind Jidoka is that once the system is stopped, you get an immediate opportunity for improvement. Since there is more opportunity to find the root-cause of problems, there is a lesser chance of letting the defect continue further down the line and remaining unresolved.

Jidoka also referred to as “autonomation,” is used in lean manufacturing to highlight a problem as it occurs to immediately introduce countermeasures that will help prevent the problem from reoccurring. Andon is a principal and a typical tool that is applied to the Jidoka principal. It is activated using a pull cord or button so that:

Today, this concept is still used even for consumers. One example is the colored lights that you see in a vehicle’s dashboard. If you have low fuel or oil, these colored lights indicate a problem so that you can pull over at the next gas station or service station to fix the problem as soon as possible.

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How is Andon Used in Manufacturing?

The concept of giving permission to make a line stop to a non-management worker, particularly someone working on the production line, was pioneered by W. Edwards Deming. He is known for being credited with helping Japan witness rapid economic development in the 1940s and 1950s. Known as the Japanese post-war economic miracle, people in Japan give thanks to many processes Deming founded on the ideas he taught. Some of his ideas included:

These systems are incredibly valuable in manufacturing, particularly when used in conjunction with plant-wide supervisory control and data acquisition (SCADA) systems that have the ability to send Andon-related data where it is needed the most such as control rooms or maintenance departments. A fully functioning Andon-powered system eliminates reliance on clipboards, whiteboards, and word-of-mouth for instant and up-to-date status information on plant cycles.

Common reasons for workers to manually activate the Andon alert is:

Once the alert is signaled, work is stopped until a solution has been found. Alerts are then logged into a database by management as part of a continuous improvement program.

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Types of Andon

There are two types of andon: manual and automatic. A manual type is activated manually by the employee or operator on the assembly line by either pulling a cord or pressing a static button. Automatic andon are activated automatically on the conveyor when specific criteria that are assigned on the assembly line is lacking or not met. These were initially in the form of light signals in the manufacturing process to enable the operator to signal the status based on the indicator light color. They also help organizations to not rely on whiteboards, clipboards, word-of-mouth, email, or even the Internet as a communication tool.

Today, boards and visual displays are more technologically advanced to include the introduction of status board mobile apps which is helping to redefine the role of status boards. However, they all serve the same purpose as a highly effective tool to enable the operation to run smoothly without any bottlenecks by communicating efficiency and real-time status of the plant floor.

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Benefits of an Andon Cord

A key benefit of the cord is that it makes a condition of manufacturing processes easy to see and readily visible for operators, plant managers, and maintenance personnel.

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Other benefits include:

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Toyota and the Andon Cord

One of the best examples of the use of the Andon cord was at the Toyota Corporation. As a manifestation of the original Jidoka system, Toyota implemented the cord as a physical rope that follows the assembly line and any operator could pull the cord to stop the manufacturing line at any time. Most Western culture analyses of this type of system would probably assume that this system was implemented to serve as some form of a safety cut off switch. However, Toyota used it differently as a tool to instill autonomic behavior patterns.

To further increase its effectiveness, the cord stopped the line and could be pulled by anyone at any time. There was never any need to ask permission to stop the line, and instead, it will stop automatically once the cord is pulled. Within Toyota Production Systems (TPS), the cord was often pulled. Not only did a line stop, but a light would show up on a signal board to indicate the workstation that is having a problem. This would allow a team leader to immediately respond and see what the issue is about by visiting the workstation.

The method of implementing the Andon cord within this TPS system was unconditional. In a Western culture organization, a team leader may be sitting at a desk when a problem is indicated and just give a call to the workstation to find out the problem. This is in contrast to Toyota which lived by a “Show Me” culture where team leaders had to go and visually see the workstation to remove any potential bias or preconceived notions related to the problem. These direct actions would make each process fact-based which influenced both the mechanics and the culture of the organization.

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Why Have Status Boards?

If you have ever heard of the famous children’s story “The Boy Who Cried Wolf,” there may be a reverse condition when it comes to using status boards. For example, there could be a situation where a worker pulls the cord to signal a need for help, but no one responds. The employee will eventually stop wasting his time pulling on the cord. If the cord is not pulled, the management team will miss out on the opportunity to permanently fix the problem. Also, there will likely be more frequent line stops because of a lack of an early warning system.

These boards are lighted like traffic lights with three colors on top of each level of the production assembly line. When a worker finds that he is unable to keep pace with the line or detects a problem in the production line, he can pull the cord to stop the operation which will also set off an alarm system and eliminate the color-coded electric light board. If problems are not fixed within a specific time., The entire production line would either stop automatically or manually. If there is no problem, the board will illuminate a green signal which means the process can continue with normal operations.

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Color codes usually come with a condition and action:

Green

Condition: Production is normal or smooth. / Action: Proceed to the next level.

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Yellow

Condition: A Problem Appeared / Action: Operator gets help from a team leader/supervisor to fix the problem.

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Red

Condition: Production stopped. / Action: Problem is not identified and needs further investigation.

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Netflix and the Chaos Cord

Netflix is a popular company with millions of subscribers, and they follow some of the same principles as Toyota by considering failures as a good thing. Using their built-in automated form of Jidoka, the Andon cord is used with Netflix in their system known as the Chaos Monkey. This system relies on intentionally breaking systems in production using a process that randomly kills production servers that are running live.

These failures are treated as sort of a science experiment for the company and allow them to learn where dormant defects existed in their process and fixed them. It also helps to identify where injected and intentional failure was corrected automatically. This type of implementation of the Andon cord requires a continuous improvement roadmap, sufficient reported data, as well as behavior reinforcement built into the process.

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A Highly Effective Visual Management Tool

As you can see, an idea that was invented and implemented over 70 years ago is still effective today as companies seek to become leaner organizations. Andon boards are the best solutions for highlighting the status of any operation at a glance and making a signal whenever an abnormality occurs.