Robertshaw

The process for manufacturing gas cocks, an integral component of the thermostat, was extremely labors intensive, relying on manual lathes generations behind the latest technology and unable to consistently meet cycle time and tolerance requirements. Robertshaw believed that failure to take significant time and money out of the manufacturing process would limit their ability to compete and putt at risk long standing relationships with a loyal customer base.

Assessment
The gas cock has a metal-to-metal gas seal that requires an accurate machine taper to 16 finish repeatable to 1.67 CPK over a 4 hour run period. Achieving throughput requirements would require doing so without adjustment within a 19 second cycle time. During certain times of the year demand for climate control devises diminishes. As a result, machines would need to be configured for quick setup to allow for the manufacture of other parts within the plant.

Solution
Ellison engineers configured and integrated a solution using 4 Shimada twin spindle automatic CNC lathes, each supported by a Fanuc LR100i Robot. The robot would load and unload the spindle stationed outside of the machine. Raw castings would be offered, oriented to the robot by a bowl feeder, while finished components would be placed on an outbound conveyor for presentation of the finished part to a part washing station.

End Result
Pre-installation run off in Japan confirmed cell capacity to run 4 hours of unattended machining with 2 operators per shift. This reduced the number of required operators by 10. To date, each machine has produced over 2 million parts with repeatable quality and cycle times. The 16 finish specification has been exceeded and the dimensional CPK of 1.67 is consistently achieved. The bowl feed units were fitted with quick disconnects to allow for a quick set up to alternative part production during seasonal lows.