OVERVIEW

Ford Motor Company’s Livonia Plant produces transmissions for the Ford and Lincoln-Mercury product lines, including the popular 4X4 vehicles. The tracer lathe is a roughing operation for the output shaft on rear wheel drive transmissions. The auto maker requested a CNC solution for their PTI (Programmable Tracing Incorporated) lathe. The existing process consisted of a tracing operation wherein hydraulic cylinders moved the cutting tool along the part in accordance with a stylus that was held against a fixed template. A 50 HP hydraulic spindle motor was used to spin the work piece. The total hydraulic package required in excess of 60 HP to run both the servo/tracer system and the spindle, and was nearly as big as the machine itself. The part was cut without coolant, adversely affecting finish.

SOLUTION

The PTI tracer lathe needed a complete system overhaul to fulfill the customer’s specifications. The new system would have to be fully programmable eliminating hydraulics, and performing the operation within tolerances at a rate of 85 parts per hour (not including load/unload time). The entire electrical system would be replaced and the hydraulic cylinders and tracer system would be replaced with electric servos and ball screws. A smaller hydraulic package would operate the spindle chuck and tail stock.

The new control package included GE Fanuc’s 18I-TA control with three (optionally four) fully programmable AC servo axes and a 50 HP AC spindle system. In addition, the customer’s post-process gage was connected to the system allowing the operator to compensate the axes for tool wear with the push of a button.

The retrofitted mechanical package included new ball screws along with a spindle rebuild. Dry floor guarding was added to the machine allowing coolant to be used while still meeting the customer’s environmental requirements. The main slides were rebuilt and the gibs were refit.

The complete rebuild was done according to Ford Motor Company’s Plant mechanical and electrical specifications. Galco accepted turnkey responsibility on this project, controlling and verifying all aspects of the project prior to shipping the completed machine to the Livonia Transmission Plant.

OPERATION

Once the rebuild was complete, Galco’s engineers performed a 24 hour endurance run and then assisted plant personnel during their machine data capability study on Galco’s premises. Ford’s specified accuracy requirement for the machine was a cpk of 1.66. The completed machine was capable in excess of 3 cpk. A second capability study was then performed after shipment to the customer’s location.

The machine is capable of cutting different output shafts, and changeover is done quickly. All axes are fully programmable and the new process cuts the part with coolant, improving part finish.