Schmidt Case History - Hamilton Sundstrand Division
MicroLase® Laser Marking System Boosts Consistency and Productivity
The Hamilton Sundstrand manufacturing operation in York, Nebraska, is a leading supplier of precision-machined components used in commercial and corporate aircraft, military aviation and aerospace. Based in Windsor Locks, Connecticut, Hamilton Sundstrand is a subsidiary of United Technologies Corp., one of the largest global suppliers of technologically advanced aerospace and industrial products.
The York plant produces parts that go into integrated-drive generators, ram-air turbines, pumps and torpedo propulsion systems. They go into three Hamilton Sundstrand business enterprises—Electric Systems, Engine Systems and Flight Systems and Services. Ultimate customers include manufacturers of just about anything that flies including long-haul and regional passenger aircraft and corporate aircraft.
Traceability is a critical aspect of manufacturing
Traceability is a critical aspect of manufacturing in the aircraft and aerospace businesses where demand for accountability has always been high. No matter how the marking is done, it must accommodate strict standards for surface finishes, dimensional control and marking accuracy.
Like any aerospace plant, York marks everything it produces. At York, the majority of marking is now done with a MicroLase™ diode pumped laser marker from Geo. T. Schmidt, Inc. (GTS), Niles, Illinois. York evaluated other laser marking systems and settled on Schmidt’s laser because of the excellent performance of their MicroLase laser as reported by other Hamilton Sundstrand plants and because of extensive systems-development work done by GTS engineers at the plant in Denver, Colorado.
Design included a rotary table, indexing fixtures and a tilting head for parts
That development work included the design of a rotary table, indexing fixtures and a tilting head for parts that need to be marked at unusual angles. Working with Hamilton Sundstrand’s Denver engineers, GTS also developed an enclosure for the entire system with lockouts to protect the operator’s fingers, hands and eyes.
Previously the York plant relied almost entirely on manual marking methods—air pencil engraving, electrochemical marking and stamping with permanent inks. “All of these over time can cause repetitive-motion stress injuries such as carpal tunnel syndrome,” noted Jim Liermann, York’s quality control engineer. “We are continuously working very hard to from any such ergonomic issues.” And since penmanship varies widely, these manual methods also led to an undesirable amount of variability and range of legibility in the markings. “As a bonus, we get rid of the chemical etching, which in the past had given us chemical contamination problems,” Liermann added.
At York, Hamilton Sundstrand requires up to 25 letters and numbers to be laser marked on their parts. This information is downloaded from the plant’s production-control system. Marking operations are simplified because nearly all parts are round and their diameters—a quarter inch to six inches—are easily handled. To protect critical surface finishes, nearly all fixturing is plastic. The idea for plastic fixturing came from GTS. The Schmidt engineer built fixtures from Lego™ building blocks when the system was demonstrated at York.
“Cycle times for marking these parts is at least twice as fast as with the previous methods,” Liermann reported, “and it is far less costly than sending the work to an outside shop, as we did for three years with one set of torpedo parts.” Doing these parts in house with the MicroLase laser takes 30 minutes of set up time and yields a run rate of 30 pieces an hour. “The vendor required 14 days,” Liermann said, “and at last count, we had saved 70 days of cycle time. Our average savings is over $2,200 per order.”
A standard MicroLase station is used to mark their parts.
Along with laser focus, mark location, and information accuracy, a critical control variable at York is the depth of the laser penetration. In the online set-up data for each job, laser power settings are spelled out for each part number marked. “Too deep a penetration,” Liermann explained, “means a laser heat-affected zone that is too deep, one that can distort the part’s surface and is rejectable per the part number’s requirements.”
Liermann praised the GTS software for its effectiveness in terms of quickly and accurately setting up new jobs and for simplifying the training and familiarization of new operators. “The MicroLase laser is simple enough to be operated by anyone who has a high-school education and a little computer knowledge. Even part-to-part changeovers are easy to program with the software’s canned cycles. A degree in engineering isn’t needed.”
Part marking data includes the part and revision numbers, the shop order it was run on, the manufacturing plant site, and the type of nondestructive inspection used. “The controls for the MicroLase laser help us monitor this closely,” Liermann pointed out. At York, virtually all marking is done after final inspection, and just before the parts are packaged for shipment to customers.
MicroLase laser benefits at York go far beyond a two-fold boost in marking productivity and the resulting speedier shipments. “Neatness counts,” Liermann noted, “and that wasn’t always something our customers could rely on when we used the manual methods. Now almost all parts that come out of York are marked in a consistent manner.”
Accuracy counts, too. “We always make sure that at least two pairs of eyes verify our marking operations,” he added. “If there is a mistake, the laser marking can be polished away so that the part is placed back in the MicroLase laser and correctly marked.” Laser markings are just a few ten-thousandths of an inch deep.
“There are just two exceptions at York to the MicroLase,” he summarized “and we are working on both of them.” One is nitrided parts. They are now marked with a routing method but we want to laser mark them in the future. The Denver plant marks nitrided parts with the same MicroLase system that we have installed. We will use their settings to speed up our development time.”
The other exception is a group of machined parts that are scribed or engraved in a one-stop metal cutting operation. Ensuring that the right data gets to the machine tool requires a special link between York’s production-control systems and the computer-aided manufacturing (CAM) software with which those machine tools are programmed. “It works,” Liermann said, “but we would like most of our marking done with a laser. Maybe someday lasers for marking will be mounted on the machine tools.”
“The MicroLase laser system has lived up to all our expectations and gone beyond some of them,” Liermann concluded.