Hartwell Corporation

Hartwell designed a unique latching mechanism that exceeded post 9/11 regulatory guidelines for security and pressurization of the cabin door controlling access to the flight deck. Wide acceptance of the design left Hartwell with the challenge of implementing a machining solution that would dramatically reduce latch manufacturing costs while simultaneously accelerating throughput to meet aggressive cost and delivery requirements of the FAA.

Assessment
The existing process utilized Fadal Vertical Machining Centers, which were at or near capacity and lacked the rigidity to support process quality and volume requirements. The current cycle time for producing a latch was measured at just over 25 minutes against an FAA delivery schedule requirement of 7 minutes. A team comprised of Ellison and Hartwell engineers was assembled to evaluate the use of leading-edge technologies to optimize the latch manufacturing process.

Solution
The solution utilized Mori Seiki NV5000B Vertical Machining Centers with a 30 tool ATC, and 12,000 RPM 30HP spindle. Each machine was equipped with a 1000PSI 8 Gallons a minute high pressure coolant system, and Renishaw spindle and tool setting probes to allow for continuous process flow. An SMW 4th axis enables a completed set of components to be removed after each cycle, facilitating parallel assembly and eliminating batch and queue delays as well as costly investments in work in process inventory.

End Result
A horse-shoe cell configuration significantly reduced labor requirements. Probing allowed the machine to control and monitor process quality while intelligent fixturing minimized machine load and unload times. Engineers leveraged the advanced machining capability of the Mori Seiki VMC, and the benefits of the high-pressure coolant and probing systems, to take the cycle time first from over 25 minutes to 7 minutes. By a process of continuous improvement, which includes real time production monitoring of the cell using a patented software system RaPiD™, engineers have further reduced the cycle time to 5 minutes.