What does mistake-proofing and error-proofing mean in manufacturing?

Mistake-proofing refers to analyzing a manufacturing process to eliminate the possibility of product defects. It is often referred to as "poka-yoke", a lean manufacturing tool which translates to “avoid” (“yokeru”) “mistakes” (“poka”) in Japanese. The goal of performing the poka-yoke process is to prevent product defects from reaching customers by catching, correcting, and eliminating mistakes at the source.

The importance of error-proofing production processes

Oftentimes when manufacturers look to improve the efficiency of their production, error-proofing processes across their operations is one of the first places they start.

With an increasingly competitive business environment and higher customer expectations, it is now more important than ever to ensure that the product quality is kept at the forefront of digitization efforts.

Tulip’s Frontline Operations Platform with IIoT device and sensor integrations can help you mistake-proof your operations, resulting in a higher quality of output, reduction in waste, and overall increase in efficiency and productivity.

How to Mistake-Proof Operations

1. Where in your process is human error likely to occur?

Product defects are often viewed as a fault of human error. However, human error isn't just a human problem, but a result of systemic operational issues. Understanding when and why humans make mistakes is the key to mistake-proofing your operations.

Relationship between human and equipment failure and organizational performance
The vast majority of human errors are attributable to organizational weaknesses (DOE, “Human Performance Handbook)

Create or obtain a flowchart of your process and identify areas where human error may occur. Examples of human errors that can be prevented with poka-yoke include:

  • Processing errors: missing a process operation or not performing it according to the standard operating procedure
  • Setup errors: setting machine adjustments incorrectly or using the wrong tooling
  • Missing parts: Not all parts included in the assembly, welding, or other processes
  • Improper parts/items: using the wrong parts in a process
  • Operations errors: carrying out an operation incorrectly or having the incorrect version of the standard operating procedure
  • Measurement errors: making an error in measurement in a process, machine adjustment, or the dimensions of a part coming from a supplier

Here are some situations where it would be particularly important to mistake-proof a process:

  • At a hand-off step in a process, when output is transferred to another worker
  • When a minor error early in the process will cause major problems later in the process
  • When the consequences of an error are expensive or dangerous

Digitizing your processes with Tulip allows you to collect production data from your users, such as which steps defects occur and where bottlenecks are occurring. These insights can help identify areas where it may be appropriate to intervene and mistake-proof your process.

2. What is the source of each potential error?

Once you’ve determined areas that need to be error-proofed, you can identify the root cause of each potential error. Tulip’s analytics can help you gain visibility into exactly when errors are occurring in your processes.

Now is also a good time to run a root cause analysis exercise. Use tools such as the 5 Whys or the Fishbone (Ishikawa) diagram to help your team identify the source of the error.

3. How can you reduce the potential for error?

Augmented worker technologies can be implemented to assist operators and error-proof workflows. Tulip’s digital work instructions apps can be configured so that an operator cannot advance to the next step unless the correct conditions have been satisfied.

Pick to Light Station
Using a pick-to-light system to guide the operator to the right bins

For example, you can use a pick-to-light system (such as Tulip Light Kit) to light up the correct bin or part needed during a process step. You can also use break beams to detect whether the operator has reached into the correct bin and prevent the process from advancing to the next step until the correct part has been obtained.

Operator using torque driver integrated with Tulip
Integrate smart devices such as torque drivers to perform to exact specifications.

Tulip also allows you to integrate smart devices such as torque drivers, calipers, scales, and cameras into your processes. You can program tools such as torque drivers to perform to your exact specifications during a particular step, making it impossible for the operation to be performed incorrectly. You can also integrate a caliper to ensure that a part is the right size before continuing.

4. If you cannot make it impossible for the error to occur, how can you detect the error and minimize its effects?

Integrate sensors into your processes to detect errors, alert the user when an error occurs, and prevent them from moving onto the next step until the error has been corrected.

Tulip app with weighing scale
Connecting a digital scale ensures that the product weight is correct before proceeding to the next

For example, for a shipping application, you can connect a digital scale to the process to detect product weight and halt the process if the weight does not meet the requirements.

You can also connect cameras and require products to pass machine vision inspections before allowing them to proceed down the line.

Quality inspection application running in Tulip
Require products to pass machine vision inspections before moving downstream.

5. How can you measure the success of your poka-yoke methods?

With Tulip, it’s easy to test your poka-yoke methods, measure their success, and quickly iterate on your strategies. Tulip’s drag-and-drop App Editor doesn’t require any coding, so you can digitize your processes and integrate mistake-proofing measures easily.

Operations apps collect production data as your employees use them, providing valuable visibility into the KPIs that will help you measure improvement and the success of your poka-yoke efforts. Over time, you’ll gain data-driven insights into whether the measures you’ve implemented are working. Some indicators to look out for include a reduction in defect and scrap rates and higher production count. You may also see a decrease in the amount of time your employees spend on the process.

6. How can you improve your mistake-proofing methods?

You can easily edit your apps based on the data you’ve collected on which methods are working and which aren’t. If you don’t see any improvements from a particular strategy, you can make adjustments and test them again–just rinse and repeat.

Because Tulip is cloud-based, any changes you make to your apps will automatically be reflected across your factory to ensure that your processes are always up-to-date.

Watch Our On-Demand Webinar: 5 Steps to Optimize Your Assembly Line With Digital Workflows →

Benefits of Mistake-Proofing in Manufacturing

Mistake-proofing following the poka-yoke method provides many benefits to manufacturing processes, the foremost being an improvement in overall quality control. By integrating poka-yoke inline, mistakes are either prevented or caught shortly after they happen. This prevents products with quality defects from making it to the end of the process. As a result, a higher quality of output naturally follows.

Further, these solutions get to the root cause of problems and prevent them from becoming bigger problems. Solving problems immediately takes significantly less time than trying to rework products when they’ve made it to the end of the line.

Applying poka-yoke to mistake-proof your factory can lead to a variety of other benefits, such as:

Reducing time spent on training
Since workers won’t need to look out for as many problems, you won’t need to spend as much time training them on these issues.

Promoting a culture of continuous improvement
Poka-yoke fosters an improvement-oriented approach by encouraging employees to solve problems immediately and address the root cause of problems to prevent them from becoming bigger problems. It’s a great tool to implement within a larger lean manufacturing framework.

Improving safety
You can improve the safety of your factory by putting measures in place to prevent workers from entering unsafe situations.

Reducing waste
It may go without saying, but producing fewer defective products means you’re also wasting fewer materials. You also save time by spending less time reworking defective products: in addition to cutting down on the number of defects that need fixing, it’s faster to fix a defect earlier rather than later.

Higher productivity
Your processes will run more smoothly when errors are prevented, and defects are detected and solved immediately. As a result, faster, more efficient processes and less waste result in higher overall productivity.

Tulip’s Frontline Operations Platform can not only help you achieve these immediate improvements to the quality, efficiency, productivity, and safety of your operations, but it can also help you sustain a culture of continuous improvement for years to come.

Mistake-Proof Your Operations With Tulip's Frontline Operations Platform

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