Don’t Forget the Basics
Recently, I visited multiple small-to-medium sized aerospace companies to review their internal processes and capabilities. I found even in today’s environment a lack of basic process improvement techniques in use.
These tools are very simple, proven methods and usually yield good results, so why the gap? I think we often tend to “jump directly to the solution” without going through the proper steps.
I can recall an example from when I was a quality manager at a previous company, and we used this approach to help improve processes and quality. I had just come aboard and was performing a quick analysis (Pareto) of customer complaints, and found paint failures for a product line were experiencing upward trends. Why was this a concern? Every product produced was processed through the same paint line, so poor performance could have significant consequences. First, we had to “peel back the onion” to ensure the root cause was being addressed. When walking the process from start to finish, we found many variables that had the potential to affect paint performance. Based on the complexity, this was not going to be a “quick fix.” Many of the variables we reviewed were not controlled well at the time.
We began by mapping the process and identified areas/variables that could have an impact (Process Map & Fishbone). In addition, individual customer complaints were reviewed and found that failures were occurring in high humidity areas of the country. Next, we called a meeting with the cognizant area engineers to review the problem and variables identified to date (Brainstorming). This approach worked very well; together we were able to uncover additional details and insight into physical characteristics that may have been skipped if left to one person. The next step was to collect additional data (Matrix Analysis) against variables related to the potential cause. We also included our material suppliers in this effort; this provided additional insight into how changes could influence raw material properties.
Through this team approach, we agreed we had a “balancing act” between materials, processes and people. We came up with a plan and a test matrix that changed variables systematically and monitored the results of the testing. Through this effort, we discovered the following:
1. Our pareto analysis showed paint failures were higher in warm weather seasons and in the warmer, more humid areas of the United States. We analyzed the effects on product materials to see if one type of steel was effected (e.g. Cold-Roll-Steel (CRS) vs. Galvanneal steel), what mills and chemical make-up were supplied and their affects.
2. Since we performed weekly testing of our painted product in the lab, we were able to change variable(s) and monitor the results. By using this approach, we were able to identify what variables had the greatest impact when changed.
3. We found the steel specification was not defined in sufficient detail to communicate our requirements to the supplier. We had overlooked the task of balancing our material properties with our coating properties. We referenced the ASTM requirements within purchase orders to the mill but did not detail what requirements were needed to support our processing. The result was an updated steel specification that allowed us to communicate to our vendors what parameters were important to help balance our internal processes. We tightened down the chemical make-up of the steel and tested “recycled vs. virgin” steel from each mill. We found that the higher salt and potassium content from recycled steel had a negative impact on the paint adhesion properties. We tested virgin material “side-by-side” with recycled steel; the virgin material yielded positive results for CRS, but did not have a large impact on galvanneal product. Other specification changes included hardness, the type of oil coating used to prevent corrosion, camber, coil-set, delamination and waviness of the blanks. We included shipping and handling requirements preparing and protecting the material during transportation including the use of kraft paper and tarped trucks.
4. Our wash system was reviewed for levels of contaminants in the rinse stations (with maintenance schedules added for bath add/change frequencies) and monitoring of bath concentration levels for the strip and phosphate coating tanks. Temperature monitoring was modified using tank controllers and formal procedures implemented for checks every two hours. Pre-Control Charts were used to monitor tank concentration levels to indicate when levels were trending toward out-of-control. These changes had an almost immediate impact on performance. By keeping the tank concentration levels at the prescribed levels and keeping rinse stations clean, the paint adhesion improved significantly.
5. The paint specification was updated to ensure solvent levels were communicated when purchasing. Added supplier requirements for testing to perform identical adhesion testing as performed in our lab. We provided the supplier with steel coupons, treated with our wash and phosphate coatings to help them duplicate the process. Inspection processes for mil-thickness and adhesion (3M tape test per ASTM D3359) were implemented prior to shipment, and internal procedures were updated for rotating inventory.
6. Even though our adhesive supplier’s material was not exposed to the products outer surface, we included them for any handling protection, maintenance suggestions and ideas for improved monitoring. In addition, adhesive specifications were updated through the purchasing system.
7. Once coated, special handling requirements of the steel were added so that operators did not handle the material with oily, dirty hands/gloves. This reduced discrepancies for random staining during the paint process.
8. Internal inspection techniques were refined for adhesion and mil-thickness frequencies to spot trends if results began to vary.
Multiple variables working together have impacts on your product quality. Specifications were developed and updated for raw materials used in the process to ensure requirements were formally communicated to the suppliers, process controls were implemented to help reduce variability, and standard procedures were applied to help communicate requirements to the workforce. This approach does take time to validate (seven months), but by using a planned methodical approach, developing a test matrix, showing incremental improvements along the way, and formalizing processes with the engineers, complaints decreased to the lowest levels seen in months with a more robust process. When looking for a root cause don’t always look for the “quick fix”; material properties, processing methods, monitoring, etc. may all have an impact on your product. Finally, when reviewing a process, review the entire process, including supporting areas. Use these simple, time-tested techniques to your advantage.