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What is a Tube And Fitting Fabricator

Automated SPC Solves Startup Problems

A Midwestern tube and fittings manufacturer has focused on the concept of continuous improvement to become a major supplier for the furniture and automotive industries. Statistical process control is not a new idea, and manual data collection and charting began in 1986. The program was initiated by upper management, with the goal of significantly reducing the scrap rate. As an example, with one product line there was a 20% rejection rate when SPC began. Two years later that rate was down to 1⁄2 of 1%.


The company planned to start up a new assembly line of fuel sending units for a new customer. This customer, a major supplier for Chrysler Corporation, required tracking 6 critical dimensions and 8 other data points. In addition, the fittings manufacturer had 5 additional points to track for its own records. At full capacity, 3,200 parts per day would be run. The volume and the amount of data to be collected required that the company go beyond manual data collection.


The company worked with a DataMyte specialist to come up with a solution, and as a result, purchased the first DataMyte 953 data collector.

The 953 data collector and a 912 digital multiplexer were installed on the tube machining line. Five Mitutoyo indicators connected to the multiplexer and the data collector allow operators to collect length and diameter dimensions after each critical step in the machining process. In addition, DataMyte software was installed on the computer in the quality engineering office. Data from the 953 is uploaded into TurboSPC for additional analysis and archival storage. See Figure 12.4.1.

 An operator uses a 953 data collector to enter tube length measurements

Using the 953 data collector, operators now spend about 30 seconds collecting data and displaying an x chart. Histograms can be displayed in less than 5 seconds. The total time spent on data collection and charting is now about 15 minutes per shift, or an 89% reduction in time compared with the typical manual data collection and charting process used in other parts of the plant.

Operators and quality engineers like the red screen alert feature of the 953 that lets them know immediately when a process is out of control. The data collection system does all math calculations and provides immediate readouts. Control charts are used on a regular basis, and the company plans to add a surface tester to the system in the future, something it hasn’t had the capability to do before.

Operators are pleased that the system is so easy to use. One operator, who never liked doing the paperwork required with manual charting, was doing both histograms and x charts in less than 3 weeks.

The company found that other systems were limited in what they could do and didn’t survive as well in a shop environment. Now the company has found that hourly workers are coming off the floor with new applications for the 953 data collector.

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