QI Embraces Poka-Yoke Techniques


Like other leading-edge manufacturers seeking to adopt automotive-style programs in quality management and continuous improvement, Quality Industries (QI) is on the cutting edge by investing in poka-yoke solutions. These solutions, which include mistake-proofing devices as originally conceived in the Toyota Production System of the 1960s, help to drive defects out of products and processes and substantially improve efficiency, quality and reliability. Throughout our enterprise, QI now strives to discover ways to implement these solutions. Using our customer defect history, along with Process Failure Mode Effect Analysis (PFMEA) rating scores, we have been able to determine a list of our highest risk assembly parts to improve through poka-yoke solutions.

For example, our “sleeper baggage door” stood out as an issue from a customer defect and cycle time perspective. When we began designing poka-yoke solutions for this area, we observed that operators were relying on a mirror to align the door with the jamb, which was very dependent on the judgments of individual operators. We also noted reports of misaligned jambs causing uneven gapping around the door. And finally, we noticed an intermittent problem of operators accidentally pairing left-hand jambs with right-hand doors (or vice versa), which led to drain holes oriented upward, instead of down.

Our team saw all these issues as opportunities to develop poka-yoke solutions and mistake-proofing devices. After identifying the processes in question, a cross-functional team was formed to outline all possible defects and to create a plan to prevent those potential failure modes from happening.


The Poka-Yoke Solution

The “sleeper baggage door” poka-yoke solution that was ultimately designed included: (1) a sensor to detect the width of a particular jamb, and (2) a smart cylinder to align jambs with the standard door placement. Once the jamb was aligned (with even gaps on all four sides), the door would be brought forward for the next step. Once in place, the door and the jamb were screwed together. Then a wireless screwdriver counted the screws and ensured the correct torque and angle for each. Next, three cameras captured photos of the door and compared it against a master image, verifying that all components were correctly installed.

Only if every single component passed the required tests would the door-and-jamb be finished and released. In the end, the mistake-proofing devices removed the guesswork from the process, thereby guarding against natural human error. Further, the automated machinery performed all the alignment and inspections, guaranteeing that a part would not be released until it was 100% free of defects.


Benefits of Poka-Yokes

One of the primary goals at QI is the continuous improvement of processes to increase efficiency and reduce waste. To that end, here are some of the positive results we have seen at QI since implementing these poka-yoke solutions for the “sleeper baggage door”:

  • Increased efficiency. Processes which allow mistakes to easily or occasionally happen can slow production to a crawl, leading to unsatisfied customers. Since we’ve implemented poka-yoke, our production efficiency has almost doubled.
  • Increased quality. We have not seen the recurrence of a rejected door for any of the reasons our poka-yoke was designed to address. Poka-yoke has basically eliminated this cause of quality complaints from our plant. This reliability has led to improved customer relations.
  • Reduced cost. Defective parts cost time and money to correct and replace. Internal costs have been reduced when a poka-yoke solution has been implemented—through the elimination or reduction in downtime and rework. Customer costs have also been reduced because they no longer face delays.
  • Increased morale. Every time we put a poka-yoke solution on the floor, we have seen an increased boost of morale among our technicians. It has shown them that QI is investing in their work areas to make their live easier and more productive.

At QI, identifying issues and creating solutions is becoming a way of life, with poka-yoke solutions becoming a valuable part of our culture. QI professionals are now constantly looking for ways to eliminate the possibilities of mistakes. And we do this in an organized effort to bring enhanced quality to our external customers and improved efficiency to our internal processes. All of this is part of our ongoing efforts to become a world-class metal fabrication company.