by Jim Longshore
Have you walked away from a Tier 1 supplier because their quality isn’t up to par?
A Tier 1 supplier was under normal review for potential new business. The supplier in question was reliable, provided a good value proposition and had the capacity to accommodate expanded business. However, one main item affected their supplier rating: Quality. The Tier 1 supplier was under in-house review as their historic quality required internal acceptance sampling, leading to costly inspection and reliability concerns.
Creating a Pareto chart of their product quality issues revealed that they had one main issue that wouldn’t seem to go away. The hardy perennial identified was due to a rubber piece that would pop off of their product presumably in transit.
In the spirit of working together the Tier 1 supplier allowed one of your Black Belts to have access to their production area and their own experts. They created a team to investigate and the team quickly identified a possible cause for the missing rubber piece to be excess variation in the size of the groove where the rubber piece is set. Like all projects of this nature the team started by performing a Measurement System Analysis (MSA) on the groove to assure that they could adequately measure the dimension prior to making any improvements.
The Tier 1 supplier was somewhat frustrated because this dimension was considered critical, and both an MSA and capability are maintained to assure quality.
Trials, Triumphs & Transformations
Since the data was already collected, they shared the raw data and to everyone’s surprise the Tier 1 supplier had a different result. This MSA is also called a Gage Repeatable and Reproducible Study (Gage R&R). Their results showed the Gage R&R was satisfactory, whereas the Black Belt indicated that it needs improving. How could this be? The same data provides two different perspectives.
Enter SBTI, serving as mediator for this situation the results from both parties were reviewed. It turns out that the Tier 1 supplier used an industry standard spreadsheet that calculates Gage R&R and the Black Belt used Minitab 17 to calculate Gage R&R. In reviewing the spreadsheet, it was identified that the Spreadsheet is based on an Xbar and R calculation, which is the historically correct way to assure your measurement system is accurate. The Minitab 17 uses an ANOVA method to calculate Gage R&R. SBTI showed how Minitab 17 could also calculate using the Xbar and R method, which resulted in both parties having the same answer! This gave everyone involved more confidence that both parties knew what they were doing. But why was ANOVA different?
It turns out that the ANOVA method has one additional benefit over the Xbar and R method. The ANOVA method shows reproducibility broken down into both its operator and operator by part components. In this case it showed that different operators measure different parts differently. So even though the measurement system was repeatable by operators and the measurements were reproducible by multiple operators, the combination of operators and parts created inconsistent answers. This significant effect is called an operator-by-part interaction.
Once the Tier 1 supplier witnessed the results of the ANOVA method, they immediately put in place training to standardize the way that all operators measure all parts. They quickly learned that their historic capability of that groove dimension could not be trusted. They began running new capability data and learned that the dimension wasn’t nearly as capable as they once thought. However, with the better measurement system in place it was just a machine setting change away to address this lack of capability.
The Tier 1 supplier learned the value of collaboration. They feared that allowing their customer into their production area would lead to massive costs spikes due to a desire to shift the inspection process to them. What was uncovered was their systematic analysis of quality just needed to be updated with some of the latest Minitab tools and application. The improved capability of the groove did lead to the rubber piece remaining intact. Understanding interactions (both supplier and ANOVA) ultimately allowed this hardy perennial to be eradicated.
SBTI offers Minitab training integrated into the open enrollment GB / BB classes. This course offers both hands-on application of the tool and more than 20-year guidance from leaders that will assure its proper application in your business.
If you would like additional information on these classes or if you would like to request a Listen session for your business where we will help identify a plan to eradicate your hardy perennials, you can contact me, Jim Longshore, at 317-681-4707, or by email at firstname.lastname@example.org.