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HARTWELL CORPORATION developed a quick access latching sys-tem for flight deck cabin doors that ex-ceeded post 9/11 security and pressur-ization guidelines. The overwhelming success of the design made it essential that the company quickly implement improvements to its existing machining processes in order to meet customer cost requirements. Hartwell engineers worked with a consultant to develop a new process utilizing multifunction machines that help achieve their manu-facturing cost targets, by reducing cycle time from 25 minutes to five minutes. A critical aspect of this improvement was developing new computer nu-merical control (CNC) programming methods to take full advantage of the multifunction machines. “ESPRIT CNC software helped us quickly generate programs for 300 parts and optimize them to achieve an even greater cycle time reduction than our target,” said Jon Finn, manufacturing engineering manager for Hartwell.

Hartwell Corporation is a subsidiary of McKechnie Aerospace Group, a rapidly growing international company providing solutions for a wide range of aerospace applications. Hartwell is a leader in the design and manufacturing of quick access latches, latching systems, and complex door and other assemblies for aircraft.

Hartwell latches can be found on virtu-ally every commercial aircraft flying in the western world today. A few years ago, the company won a large contract that involved providing latches to secure the cockpit doors of the majority of the existing Boeing fleet to meet tough new requirements.

DECISION TO UPGRADE MACHINING CAPABILITIES“At this time, we were doing basic machining on 3- and 4- axis machining centers and lathes,” Finn said. “We

were using commercial software to program the machining centers and programming the lathes by hand.” The existing machines were at or near capacity and lacked the rigidity to support process quality and volume requirements. Hartwell made the decision to substantially upgrade its machining capabilities by replacing most of its existing machines with the latest multifunction machines such as Mori Seiki NL and NT series multifunction machines. NL series machines have two live spindles,

By Jerry Fireman

Hartwell Corporation pairs the sophistication of ESPRIT CAM with multitasking machinery to dramatically reduce cycle times

A 3/8-inch ball endmill and toolholder roughing out the inside of a camera housing

Mill Setup 1 – sample programming images from Hartwell’s use of ESPRIT

Multifunction Machine advanced CNC SOFTWARE save TIME AND MONEY

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live tooling and a Y-axis for milling off center. The company also uses Mori Seiki NT series multifunction machines that consist of a multiaxis, 2-spindle machining center with full 5-axis milling, as well as a lower turret. Both machines provide the capability to perform what previously took three or four operations in a single operation, reducing setup and cycle time and improving quality. Hartwell also purchased Mori Seiki NV5000 vertical machining centers with 30-tool automatic tool changers and 12,000 rpm, 30-horsepower spindles. The machines were equipped with a 1,000 psi, 8-gallons-per-minute high-pressure coolant system, and Renishaw spindle and tool setting probes to improve process flow. The company also purchased a linear pallet pool line that connects four NH5000 horizontal machining centers.

MULTIFUNCTION MACHINE PROGRAMMING CHALLENGES“Multitasking machines can substan-tially increase productivity, but they also substantially increase the complex-ity of the programming task,” Finn said. “The operations are the same but performing several of them simultane-ously is much harder to choreograph. Since this was our first foray into multi-function machines and these machines are notoriously difficult to program, we decided to seek assistance from a company with expertise in this area. We decided to work with Ellison Technolo-gies, a Mori Seiki dealer that also pro-vides application engineering services.” There were about 300 components that needed to be programmed for the con-tract. Hartwell and Ellison agreed that Ellison would program 150 of these parts and Ellison would train Hartwell engineers to deliver the other 150 parts. Ellison recommended that Hartwell upgrade to ESPRIT software because of its exceptional capabilities for program-ming multifunction machines. “We readily agreed to utilize ESPRIT, espe-cially after we learned that ESPRIT has

partnered with our two top machine tool builders, Mori Seiki and Citizen, to support their most advanced machine features,” Finn said.

Hartwell and Ellison Technologies engineers worked together to utilize ESPRIT’s advanced capabilities for optimizing programs for multifunc-tion machines. The company utilized a machine definitions library pro-

vided by DP Technology that includes a template that accurately reflects every component in the machine, including the spindle, chuck and tooling. The machine definitions library elimi-nates the need to manually define the machine geometry and also makes it possible to identify potential crashes when the program is simulated on the computer in order to avoid crashes on the shop floor. Hartwell engineers

Mill setup 2

Mill setup 3

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imported solid model geometry from the computer aided design (CAD) soft-ware used to design the parts. Hartwell engineers interactively defined the fea-tures for most parts. In the future, they are planning to make use of ESPRIT’s automatic feature recognition to catalog the features in the solid model.

SPECIAL FEATURES TO OPTIMIZE MULTIFUNCTION CNC PROGRAMSThe next step is applying machining operations to each feature. Hartwell began by developing a library of the company’s most common machining operations, including rough and finish profiling, facing and cutoff operations on a lathe. The use of standardized operations optimizes productivity while reducing machining time. ESPRIT provides a wide range of options for the purpose of taking advantage of the special capabilities of multifunction machines. For example, there are eight different options for clearance planes used for entering or exiting the cut. The tool rapid advances to the clearance plane to avoid wasting time cutting air. The tool can also enter in the Z-axis by automatically recognizing the X-axis

position of the cut and feeding in from a perpendicular direction to again avoid wasting time cutting air. ESPRIT saves additional time by automatically recog-nizing where holes start and stop even if they are on an angle or counter-bored. The tool is automatically rapid traversed to the beginning of the cut without cutting air.

“The real strength of ESPRIT lies in the tools that it provides to optimize the operation of a multifunction machine,” Finn said. “After we have created the operations, ESPRIT makes it easy to assign them to different turrets, change their sequence, and synchro-nize operations in different turrets. Then we view a simulation that shows the machine, turrets, spindles, tools and workpiece in real-time operation. The realistic graphical depiction of the machining operation often helps our engineers think of ways to improve the CNC program. They might go back and change the order of a few opera-tions or change the sync points and run the simulation again. The comparison function in ESPRIT also highlights any variation between the part machined by the program and the design intent, such

Mill Setup 1 – sample programming images from Hartwell’s use of ESPRIT

“ESPRIT CNC software helped us quickly generate programs for 300 parts and optimize them to achieve an even greater cycle time reduction than our target.”

– Jon Finn, manufacturing engineering manager for Hartwell

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as excess or over-removed material.” By a process of continuous improvement, Hartwell engineers have been able to reduce cycle times for some common components by as much as 80% from the previous single function machines by utilizing multifunction machines.

EDIT-LESS POSTING SAVES MACHINE TIMEHartwell engineers also perform interference checking to fine-tune the program during the simulation. Multitasking machines have more turrets and spindles that are all moving at once so avoiding crashes can be very challenging. “The ability to visualize the machine, spindle, tooling, fixture and workpiece makes it possible to do all of the prove-out and debugging at the CAM station and then post directly to

the machine tool without any editing,” Finn said. “We consider this to be a remarkable achievement that we were never able to accomplish with either of the two previous CNC programming tools that we used in the past, nor with hand coding. We have found the ESPRIT posts for multifunction machines to be very reliable. We almost never need to make any edits to the posted G-code.”

“The software that we used in the past was designed around the requirements of single-function machines, so it would have been a very difficult task to write working programs for our multifunc-tion machines and much, much more difficult to truly achieve their full potential,” Finn concluded. “ESPRIT,

on the other hand, through its devel-oper’s partnerships with the leading multifunction tool builders, provides a wide range of tools that have helped us achieve the full productive potential from our multifunction machines. The simulation and post-processing capa-bilities of ESPRIT have made it pos-sible to achieve edit-less posting, which saves large amounts of editing time that would otherwise have had to be per-formed on these expensive machines. Finally, I have been very impressed with the responsiveness of the technical support team at DP Technology. When I send them an e-mail, I get a response within a couple of hours from their engineers, often with videos showing us exactly how to perform the task.” g

This article appeared in the April 2009 issue of Aerospace Engineering and Manufacturing.

DP Technology Corp. Phone: 1 800 627-84791150 Avenida Acaso Outside the US: + 1 805 388-6000Camarillo, CA 93012 USA Email: esprit@dptechnology.com

ESPRIT is a registered trademark of DP Technology Corp. ©2009 DP Technology Corp. All rights reserved.

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