How do you use Lean and Six Sigma tools to identify and address defects in industrial engineering?

1 What are defects?

Defects are any errors, flaws, or deviations from the specifications or expectations of a product, service, or process that result in customer dissatisfaction, rework, scrap, or waste. Defects can occur at any stage of the industrial engineering process, from design and planning to production and delivery. Defects can have negative impacts on the quality, cost, time, and safety of the process and the product.

2 How to measure defects?

To measure defects, you need to define what constitutes a defect and how to quantify it. One way to do this is to use the concept of defects per unit (DPU), which is the number of defects divided by the number of units produced or inspected. Another way is to use the concept of defects per million opportunities (DPMO), which is the number of defects divided by the number of opportunities for defects multiplied by one million. Opportunities for defects are the potential points or steps in the process where defects can occur. You can use these metrics to calculate the defect rate, which is the percentage of units or opportunities that have defects.

3 How to identify defects?

To identify defects, you need to collect and analyze data from the process and the product. Pareto chart is a graphical tool that can show the frequency and impact of different types of defects, helping you prioritize the most significant ones. Fishbone diagram is another graphical tool that can help you categorize potential causes of defects into six main categories. The 5 Whys technique can help you drill down to the root cause of defects by asking why a problem occurred and then why that cause occurred until you reach the underlying factor. Lastly, FMEA is a technique that assists in assessing the severity, occurrence, and detection of potential failures and defects, so that you can prioritize actions to prevent or mitigate them.

4 How to address defects?

To address defects, you need to implement solutions that eliminate or reduce their root causes and prevent them from recurring. Kaizen is a philosophy of continuous improvement that involves small and incremental changes to the process and product. Poka-yoke is a technique that prevents errors or defects from happening or makes them easily detectable and correctable. DMAIC is a structured problem-solving methodology with five phases: define, measure, analyze, improve, and control. It helps define the problem, measure the current state, analyze root causes, improve the process or product, and control results. DFSS is a structured design methodology with six phases: define, measure, analyze, design, verify, and optimize. It helps design or redesign the process or product to meet customer requirements and minimize defects.

5 How to monitor and improve defects?

To monitor and improve defects, you need to establish and track key performance indicators (KPIs) that measure the quality and efficiency of the process and the product. You can use a control chart to detect any abnormal or out-of-control situations that may indicate defects, as well as statistical process control (SPC) to monitor and control the process or product within acceptable limits of variation and defects. Additionally, the plan-do-check-act (PDCA) cycle helps you plan, do, check, and act on feedback to adjust or standardize the actions.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?