manager. “What we found was that very small differences in the tolerance and fit made a profound difference in the overall performance and efficiency.” To solve this problem, Eaton switched to a patented abradable powder coating in 2002. Tis abradable coating is applied electrostatically, and then “worked
process require a high level of operator skill. Tis is especially true when precisely machining and milling the rotors. Aſter precision milling, the abradable coating is electro-
statically applied and then heat-treated and bonded onto each rotor. “Te coating is an inexpensive way to make a high-
“What we found was that very small differences in the tolerance and fit made a profound difference in the overall performance and efficiency.”
in” or “broken in” during operation. What this essentially does is provide a zero-gap fit between the rotors. “It creates a custom fit for each pair of rotors in each supercharger,” said Brouillard. While ingenious, there is more to the design than creating
a custom tight fit with a gap of about 0.0001" (0.0025 mm). “Te essential part of the Eaton intellectual property is the profile of the rotor itself. It is the profile that provides the du- rability, NVH, and other performance,” explained Brouillard. Designing it is one thing, making it is another.
Concentration Is the Key to Success According to Jackson, the Athens plant has established a
number of competencies they believe are necessary in order to produce a finished product that maintains a competitive advantage. Starting around 2004, Eaton chose to concentrate on just three core competencies: rotor machining, assembly, and end-of-line testing. To this end, other on-site functions needed to manufacture the devices—operations such as metrology, maintenance, and MRO—are outsourced: Teir partner company, Advanced Technology Services (ATS), is reponsible for maintenance, while Bruckner handles MRO- related indirect materials replenishment, and Gage performs metrology functions within the plants. Another factor is empowerment. “Tis is an ‘Eaton Phi-
losophy’ plant, where every employee is a salaried worker,” Jackson explained, with the same benefits as professionals and engineers. It is a philosophy that allows a relatively small team to produce hundreds of thousands of precision-built super- chargers each year at the facility. Certainly a unique design is critical to Eaton’s competitive
advantage. So is the design of the tooling and programming of milling machines and assembly automation—especially for milling the critical rotors—according to Brouillard. In fact, profile designs are a joint effort between the design engineer- ing staff in Eaton’s Marshall (MI) facility and the Athens plant. Why? Because manufacturability is just as essential as an ef- ficient design to give Eaton a competitive advantage.
Precision, Automation, Skill and Advantage It was also obvious during an exclusive visit to Eaton’s man- ufacturing facility, that certain aspects of the manufacturing
tolerance device. Tis is in the never-ending fight to balance tolerance against cost,” explained Brouillard. In line with concentrating competency in assembly,
Eaton outsources other parts of the final product (such as housings, gears, and shaſts) that are assembled by Eaton in purpose-designed automation cells. Each cell uses advanced levels of machine vision, servo-processes, and load-mea- suring cells right in the assembly process itself. Each part is marked with a unique bar-code identifier and as the part is assembled, all of the key process information data is measured. Tis is stored and tagged to that unique bar-code identifier. “Tat provides part traceability for individual parts and allows us to perform trending analysis for manu- facturing,” said Brouillard. For such precision equipment, they target a process capability index (Cpk
) in excess of typi-
cal automotive requirements. Te last element of the assembly process is setting the tim-
ing of the rotors—the relationship of how they are geared to turn relative to one another. Again, this is another process that requires operator expertise. “Te difference in rotor fit can make the difference between a good rotor and a ‘do-over’, even scrap,” explained Brouillard. An automatic machine sets the timing, but loading the machine and post-process checking is done manually. Te fit between rotors for each pair is checked to ensure the critical gap is within tolerance. Te final assembly into each sealed end-item is followed by
a final test inside a sound-isolated cabinet. Each supercharger is acoustically and NVH tested before shipping. “We are essentially a build-to-order facility, with low inven-
tories. We build them and ship them basically the same day,” said Brouillard. For manufacturers attempting to sustain competitive
advantages over time, attention to detail is just as important as big decisions like concentrating on key core competen- cies. “We are looking to continue developing technologies for real-time process control and monitoring,” said Steve Poulter, engineering manager for the Athens plant. Con- tinued application of machine vision, RFID tagging, laser marking, and data management are all such details that he thinks will find their way into making the superchargers of the future.
Motorized Vehicle Manufacturing 73
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