Measure Phase

Measure Phase

The measure phase of the project, as agreed by the team, included the following.

Process mapping:

We conducted a map of the process that was causing us the most issues on the line, the plasma station and the hub attach station. This tool proved to be a very important tool for us when dealing with the kink issue on the line. While monitoring the plasma station we found that a piece of balloon tubing which was put on at the previous station to help prevent kinks on the end of the unit was actually causing the units to kink. The Product Builder at the plasma station puts the units into a hoop to carry the units to the plasma station. While putting the units into the hoop the balloon tubing was getting pushed and logged into the hoop by the Product Builder. When the next unit was pushed into the hoop it was getting caught on the tubing and kinking the unit.  The product builder told us that they see this from time to time, but this was never reported to us before this. We were able to inform the product builder at that stage to ensure that they check the hoops before putting units into them and to discard the hoops that had tubing stuck in them. We found 25 out of 50 with balloon tubing in the hoops at the time of the observation. 

When we looked at the hub attach station we found  that after Hub attach the units are removed from the hoops and placed on a rack to hang. Unless the units are removed carefully there is a potential to kink the unit. A unit was kinked during our observation of this step in the process. We also found that there is also the potential for kinking units when the balloon tubing, which is inserted on to the units at mandrel removal, needs to be replaced back on the unit before removing the full lot to the next station. Below is a Map of the Hub Attach process. This tool is very visual but can be time consuming when mapping out on Mini tab.

We then looked at the biggest issue with that station which was the glue issues with the 2 different types of mandrels. Neither of the mandrels we were using was going to improve our gluing process so we decided that we would look at alternative mandrels and trial these mandrels on what we call shorties. This trial is in process at this time.



Data Collection

For data collection we opted for a p Chart. The reason we opted for this tool was we felt that it had the best visual indicator. These charts enables the user to pull out each scrap reason code and it allows the user to see if the process is out of control with that particular scrap issue See below p chart for 8 lots of IDE units showing the kink issue on the line

Rolled throughput Yield

We now knew what issues were causing the biggest issues on the line but we also wanted to see how the overall line was performing and to do this we took a snap shot of both IDE units and CE units to see how the yield was performing on both types of products. Below is a snap shot of the CE units and the rolled throughput yield for that product.

CE Snap shot of 240 units (RTY)

Station                            Yield   

Station 1                            100%          

Station 2                            99.2%         

Station 3                           99.12%       

Station 4                           100%          

Station 5                           94.5%         

Station 6                           23.7%         

RTY =                              22%

Six Sigma Yield Improvement Project

                                            Six Sigma Yield Improvement Project 


Define Phase 

My name is Ann Coughlan. I am working in a Multi National medical device company and I am the Team Leader for a new product introduced in January of this year. The project is still in the development phase but we have deadlines for various builds and one of our biggest challenges is yield.

 The overall project objective was to achieve a 20% improvement . A team was assembled by me to look at the best way to complete this goal and the first meeting took place on Tuesday 12th Nov 2013 to discuss the plan.

In the Define phase the team agreed to  complete a Project Charter. The team agreed on a Project Charter (see figure1 below 2nd page of project charter)  as a visual reminder of what needs to happen in each stage of the DMAIC process. This,we felt,would guide us through each stage and it would also allow us to add or subtract if necessary as the project progressed.  

Figure 1 Project Charter

From there it was decided to map the process (see figure 2 below "process flow chart") and highlight the area's of concern so that we could focus our energy in those area's. A process map is a visual aid used by the company as part a "work content graph"  which is continuously up dated when a line is asked to produce more units or if for some reason it introduced a step on one of the stations. The high lighted area's on the chart are the stations we looked at from a yield  perspective. We needed to know which stations were causing the poor yield on the line. The chart shows where the issues originated from. 

Figure 2 Process flow chart

Yield

We also decided on a pareto chart (see below figure 3&4) to see what the biggest issues were on the line. It became very evident where the issues were on the line. We were using a gluing method to glue our hubs to the units. The first chart shows a straight mandrel being used and the second one shows a tapered mandrel being used. As you can see from the charts both gave very different  outcomes. There were other issues on the line, but from a pareto stand point our main focus was the  hub gluing station. Th pareto was a very useful tool because it enabled us to focus on the problem area. 

Figure 3 Straight Mandrel

Figure 4 Tapered Mandrel