Poka-Yoke in the Warehouse

Have you ever accidentally plugged a three phase plug into a normal 24 volt socket, no you havn't, because both the plug and socket are not compatible, you physically can’t, and that switch is an excellent everyday example of poka-yoke.

Poka-yoke, a Japanese term that means “mistake-proofing,” refers to any tool or mechanism that keeps a person from being able to perform an action in an incorrect manner. Poka-yoke is used to avoid waste, typically by eliminating or minimizing quality mistakes that lead to rework and scrap as well as eliminating potential safety issues.

Poka-yoke is an especially useful tool when you’re trying to improve upon the cost of quality, which is the concept that the longer it takes to detect an error, the more expensive it is to repair the error.

The reality of being human is that our rate of success at any given task, regardless of simplicity or complexity, is never 100%. Poka-yoke does not change human nature, but it does decrease the opportunities for a failure to occur, which helps drive quality higher and decreases the stress of the working environment.

Think of a warehouse activity that is prone to mistake, order picking? You might think having a double check in place is a Poka-yoke, fool proof way of ensuring the customer’s orders are correct. And on the face of it your almost right. BUT having “administrative” checks in place is not a Poka-yoke fix, this is still prone to error and double checks to achieve 100% DIFOT is a myth.

The best example ive seen of a Poka-yoki picking method has to be the Kardex picking system, very high end but perfect at delivering to the warehouse picker exactly what's required, with a pick by light order consolidation bench where the warehouse picker simply places the goods into the box/bin where the light is illuminated, perfect.

Poka-yoke can be implemented in many different ways. For example, in guide pins, limit switches, counters, alarms, and checklists. They can address the situation by testing the product’s physical attributes, such as shape or colour. They can also address factors such as timings, movements, or process steps through monitoring or verification.

Take for example the warehouse reach truck, these days pre-programmed heights can be entered into the reach truck allowing the warehouse operator to push the switch and the reach truck will automatically stop at the intended pallet/rack height, saves time in the operator having to inch his/her way to the correct height to retrieve the pallet.

Whenever performing a review of a warehouse process, such as a standard work analysis, remember to be on the lookout for poka-yoke opportunities. Standard work is not only about understanding cycle time components — it’s meant to be an exercise that helps you collect many different pieces of information, including points of failure that could benefit the warehouse from mistake-proofing.

Many times, people associate poka-yoke with physical solutions, like guide pins and switches, but remember that it also includes tools like alarms and checklists, which are particularly useful in a warehouse environment. (..and when flying a plane for that matter)

An everyday example is your office calendar software. When set up to do so, the software can send out a meeting reminder to participants when the start time of the meeting is approaching. This is a poka-yoke tool that helps personnel remember to show up for a meeting on time, as every minute participants wait in a meeting for a late attendee to arrive is a loss of both time and money.

Checklists are a widely used tool in the warehouse environment, verifying forklift safety before using the machine, warehouse cleaning schedules, pre-audit checks and sign offs.

Is poka-yoke going to cost a lot of money to implement?

Solutions for poka-yoke can range from fast and cheap to implement to expensive and time-consuming to install. Many solutions will not be expensive, but you might need to perform a cost-benefit analysis to determine how to prioritize the solution.

Consider using the PICK chart when deciding if or when to implement a poka-yoke solution, as this will help you measure both the level of improvement achieved against the cost and difficulty of implementation.

Poka-yoke is an effective method for eliminating certain defects from occurring. When a defect cannot be eliminated, poka-yoke can often assist in identifying the error earlier in the process, decreasing the cost of the rework and the potential of the error reaching the end customer.

Often inexpensive and appreciated by warehouse personnel across the business, poka-yoke can help decrease errors, making quality easier to manage and leading to a less stressful environment.