Shop Solutions: VMC Sets Gears Up for Precision
Since its founding in 1947, Arrow Gear Co. (Downers Grove, IL) has provided precision gears to industries including aerospace, defense, mining, racing, irrigation, and power tool. The company produces a full range of gears, including spur and helical designs and precision spiral-bevel gears for aerospace and commercial applications in mining equipment, automotive racing, and agricultural technology.
Arrow also produces gears for its own Arrow Stock line of high-precision gears that can be purchased from catalog. "Through our On-Demand ground-tooth spiral-bevel gear program, we are able to produce groundtooth spiral-bevel gears from a variety of our stock gears in less time than it would take to produce a gear from scratch," says Ron Kauzlarich, Arrow Gear facilities manager. The program offers 57 different combinations of ground-tooth spiral bevel gears for low-volume and prototype work.
"The main industry we serve is aircraft," says Kauzlarich. "Aircraft gears are difficult to produce, because they include wingflap gears, jet-engine parts/gears, helicopter gears, missiles, and prototype gears for unmanned drones that are in production today." The highly intricate geometry of bevel gears, for example, requires costly and lengthy development, and a variety of critical manufacturing processes.
"The contact pattern of a spiralbevel gear is the area in which the gear teeth engage and disengage during their rotation. It is a critical design element, and the process for determining the right size, shape, and position is lengthy. For a gear to perform properly under the significant loads placed on most lightweight aerospace gearboxes, the contact pattern must be a very precise shape," Kauzlarich explains.
"Every design requires very high tolerances in tough steels, including 4620, 6265, 8620, 9310, E16N, and Pyroware steels, and numerous operations," says Kauzlarich. "We do a lot of parts that require thin webs, which can weaken the part. Their thinness makes them difficult to hold and prevent chatter, requiring highly complex processes and treatments to achieve superior quality."
Aerospace gears demand tight tolerances, distinct material properties, and unique load-bearing capabilities. This involves going through hundreds of operations during development. Machining alone can require several setups. It is possible for a single workpiece to have four or five consecutive drilling operations, each tilted at completely different angles. It is typical for setup time to exceed cycle time during machining.
When Arrow Gear was ready to purchase a new VMC, machine ergonomics and precision machining capability were of utmost importance. "Our operators spend more time setting up and loading/unloading parts than the machine actually spends in process," explains CNC Programmer Mark Murphy. "Operator accessibility was by far the most important factor in our decision," he recalls. The management team considered machines from several manufacturers, and found similar speed and feed specifications across the board. A visit with local dealer Yamazen to the Toyoda Machinery facility in Arlington Heights, IL, however, made a lasting impression.
"When we saw the machine, there was no question that it had the most accessible design," says Kauzlarich about a Toyoda FV1165 VMC. In his 32 years at Arrow Gear, he has heard operator complaints that included backaches caused by restricted access and messy work areas due to coolant. "Toyoda was the only manufacturer that obviously invested time thinking about the best design for the machine operators," he says.
The deciding factors were found in overall performance factors. "The new machine delivered better part quality, faster setups, less downtime, and better accuracy. Runtimes are faster because of faster axis rapids, and the high-pressure coolantthrough spindle provides deeper hole-drilling capabilities," Kauzlarich says.
Murphy adds, "Also, this is our first boxway machine, and there's a visible difference in part finish and quality." Toyoda's boxway design pairs a large Meehanite cast-iron base with an extra-wide, inverted Y-shaped column for greater tensile strength and maximum vibration dampening. This helps Arrow Gear achieve the surface finishes and intricate geometries the gear industry requires.
"Our lot sizes are approximately 40 pieces; 100 pieces is a big lot," says Kauzlarich. "Prototype work varies, but, in most cases, if we're involved in the prototyping of a project that goes into production, we get the work. "Sometimes, we will lose a job to overseas production, but inevitably it comes back because of our expertise and thorough understanding of the complexity of these parts. One example was a component for a military truck. We briefly lost the job to overseas production. We had designed the prototypes with them, but they said our costs were too high. It turns out the overseas supplier couldn't achieve the same level of quality that we could, and now it's back here."
"In terms of tolerances, we are holding 0.0005" [0.013-mm] total on key slots. We wouldn't even attempt those tolerances on our previous machine," says Kauzlarich. "Surface finishes depend on the requirements of the job, but we've had no problem meeting all required surface finishes."
Between setup and cycle time on a 30–40-piece lot we're reducing total time by about 25%, and the parts have higher accuracy," says Kauzlarich. "Every job is different, but lost time was our biggest problem. The Toyoda made up for it with several benefits that all added up to a significant time savings. Setup time, faster axes movements, faster spindle, coolant-through spindle, and rigidity all had something to do with the improvements we experienced," says Kauzlarich.
According to Murphy, another bonus of the Toyoda is its extended workspace. Compared to other machines with the same table size, theThe FV1165 delivers 4" (102 mm) more of travel in the X, Y, Z axes, when compared with most competitors. This additional reach gives Arrow Gear more flexibility in the work envelope for a wider range of part- size accommodation.
"The Toyoda's larger opening allowed easier operator access, resulted in faster setup time, and overall reduction in production time. We looked at some machines with such tight doors that it was difficult to even maneuver inside the work envelope. Because of the complexity of our gears, setup time was playing a significant role in our overall production time," says Murphy.
"Design/ergonomic features that make setup on the Toyoda easier include height of table and bigger doors that make access easier. Machine axis travels and table dimensions are bigger, so we could leave the rotary table on with the fourth axis on the top when swapping parts in and out. There is no machine device to handle the workpiece, but it is easier for our operator to position workpieces inside the work envelope due to the larger opening and access," Kauzlarich concludes.
For more information on Toyoda Machinery, go to: www.toyoda.com, or telephone 847.253.0340.
Changing CAM Systems on the Fly
Ask a busy shop to change its CAM system, and you are likely to get a comment something like this: "We don't need it. We're doing fine right now."
That was exactly the case for Concept Components (Bohemia, NY), which, according to President Jim McGuigan, was "doing quite well." Founded in 1988, Concept Components is a leading supplier of machined parts to the microwave, medical, commercial, electronics, and aerospace industries. Services range from prototyping to volume production runs.
The company has four Swiss machines from Star CNC Machine Tool Corp. (Elk Grove Village, IL) along with 25 Mazak CNC milling and turning centers from Mazak Corp. (Florence, KY). The Mazak machines were chosen for their precision, productivity, and user-friendly Mazatrol on-machine programming software.
McGuigan, however, was able to take a longer view of the company's potential and wanted to improve the shop's CAM productivity and multiaxis machining capabilities. Because this couldn't be done with its present software, the company researched the marketplace, chose a CAM package, and worked out a plan with the dealer that would make the transition as clean and painless as possible.
"You have to reinvent yourself every year in this business," McGuigan explains. "If you don't modernize or upgrade every year or two, you eventually fall behind. Then it is too big of a step to go forward again. Every year, we try to do something—add another Swiss CNC lathe, a mill, a lathe. We are constantly trying to upgrade to the latest technology in one of those departments in every year. Changing over to more powerful CAM software was one of those upgrades."
Concept Components started using Mazatrol software with its Mazak equipment nearly 20 years ago, and in many respects, he is still pleased with it. Over the years, this simple alternative to writing G-code and M-code kept the company lean by allowing McGuigan and two others to stay out on the shop floor programming and setting up equipment with the help of just two assistants.
"The software wasn't taking us where we wanted to go," McGuigan says. "As we have become involved with more complex, nonstandard parts, particularly for aerospace and microwave components manufacturers, we needed a tool to efficiently program CNC manufacturing of parts with three and four axes, and complex 2-D parts as well. In addition, our customers rarely send us drawings any more. They want to send us STEP, IGES, and other types of CAD models. We were not going to make it to the next level unless we had CAM software that would import a wide variety of CAD files seamlessly."
With this in mind, McGuigan went to the IMTS 2008 machine tool show to scout out his options. Based on what he learned at the booths and during conversations with other manufacturers, he selected Mastercam X3 Mill from CNC Software Inc. (Tolland, CT). What ultimately sealed the deal for him was the willingness of his software reseller, Cimquest Inc. (Bedminster, NJ) to provide a postprocessor that would deliver clean Mazatrol programs as part of a complete package that also included training, technical support, and an annual software maintenance agreement.
The Mazatrol postprocessor allows the Concept Components' programmers/setup people to work in the shop, as they always had, while employing Mastercam to import CAD files and write CNC programs for the most difficult new jobs off-line.
McGuigan worked with Cimquest to develop an implementation plan that would ensure a successful transition to this new way of creating and managing manufacturing programs.
The transition plan addressed the requirements of maintaining the company's ongoing business, while training staff in the capabilities of the new software. The company initially focused on just one Mastercam module, even though there were additional applications that would also fit other types of equipment and manufacturing at the shop. Four members of the staff would be trained during approximately 8-hr sessions on Friday and Saturday, with one week on and one week off. The intervening week off gave students a chance to assimilate what they had learned.
Instead of Concept Components going to the reseller's facility for training, Cimquest went to Concept Components. This allowed the trainees to take breaks and check on some of the work that was in progress. This also allowed everyone to take the training at the same time. If issues came up that could be better explained out in the shop, the trainees could learn on their own equipment.
The reseller would be readily available to answer questions, and even conduct online meetings to go over any problems the new users were having with the assignments. After the first couple of weeks, Concept Components rarely availed themselves of this option. This was partially because one of the trainees was enrolled in the Mechanical Engineering Technology Program at Farmingdale State College. He already had training in Mastercam as part of his studies, and was available to help others at the shop.
Cimquest provided three trainers for various portions of the implementation period. One was a full-time trainer on staff. Another was the individual who actually wrote the Mazatrol postprocessor for Mastercam. The third trainer attended for Cimquest's benefit, because she was looking to become more experienced with the Mastercam applications for Mazak equipment.
During the third week of training, Concept Components identified several difficult parts from their current workflow that they would like to program in Mastercam. During the final session, these were reviewed and problems were corrected.
As part of the agreement, Cimquest continued to provide technical support to Concept Components as needed throughout the year.
Several weeks after the training, McGuigan felt the Mastercam implementation had been a successful one. Though he and his people weren't entirely acclimated to the new software, he says: "We are comfortable with it and we all like it."
McGuigan thought that it might take another year to become fully conversant with all the ways the new CAM capabilities could improve his manufacturing efficiency. He cites toolpath optimization and Mastercam Lathe as a couple of examples of what they might focus on next. He is looking forward to implementing as many of these improvements as possible—but in an orderly fashion.
For more information on Mastercam/CNC Software Inc., go to: www.mastercam.com, or telephone 860.875.5006.
Robot Automates Watch-Case Machining
Titan Industries (Tamil Nadu, India) is the world's fifth largest and India's leading manufacturer of watches. The company has manufactured more than 100 million watches to date, and has a customer base of more than 80 million. Its dominance of the market in India, and growth in southeast Asia, Asia, and the Middle East, have resulted in 18% CAGR for the last three years, with a projection of 20% CAGR this year.
To meet this growing demand, Titan Industries has turned to a four-axis robot with vision system to automate its handling of watch cases and components during machining in the company's watch-case manufacturing plant. Until now, this step in the manufacturing line required the parts to be loaded manually. Loading the cases manually meant that production speed was limited, because an operator could accurately, continuously load and unload the pieces for only about 3 hr. This repetitious step in the machining line was using valuable skilled employee resources that could be better used elsewhere in the production facility.
Automation was recognized as the way to free up human resources. According to Ravi Chandran, senior plant manager, it was determined that a four-axis robot with a vision system would be the way to handle the required horizontal loading of components. "After researching the options available from all the leading automation manufacturers, we determined that an Adept Cobra four-axis robot combined with an AdeptSight vision system would fit the bill," says Chandran.
In terms of cost and return on investment, a lower-cost four-axis robot got the nod over a more dexterous and costly six-axis model. The Cobra i600 from Adept Technology Inc. (Pleasanton, CA) is a self-contained, stand-alone four-axis SCARA robot with no external electronics. The vision guidance and inspection package runs on a PC, and comes complete with all the necessary hardware and accessories.
Titan's internal engineering resources were used to install the robot and vision system. "Once we installed the software and went through the help menu, we found that the programming language was similar to MSDOS's version of C software. This, coupled with the sample program and the help file, made our job much easier. We were up and running in a couple of weeks," says Chandran.
The company's engineers designed the gripper, conveyor, and additional parts of the workcell from materials already on hand, so all the company had to purchase was the robot and the vision system.
The robot was placed in such a way that it could attend a set of three machines. As a result, Titan was able to reduce the number of operators required from three employees per shift to one. Running two shifts a day meant that four operators were freed up each day. Without the need to manually load the machines, the operator's only task is to set the line and do component inspection. Setting of the robot after setting the machines takes 5 min. The Z-axis brake release switch makes it possible to set the robot in short order.
In production, one operator brings a stack of trays holding 25.50 components per tray, depending on the size of the parts being worked on that day. The trays are then automatically fed into the work area as needed. The components are not oriented, so the Adept Vision system is used to orient them. The robot picks up a part and places it on a stage, so that the vision system can capture an image and orient the part. The robot then picks the component from the stage and places it into the first of three machines. As each machining process is completed, the robot moves the machined component to the next machine for the next machining step.
Stages are used between the machines as resting points for parts while the robot unloads a part from one machine to prepare it for the next component. The robot continuously loads and unloads the parts through each of the three machines, and finally unloads the completed piece from the third machine.
With the robot continually loading and unloading parts as each piece moves from one machine to the next, the entire sequence takes about 15 sec. With this process almost fully automated, the company's volume in an 8-hr shift has doubled from the original 750 pieces being processed per shift to 1500 pieces processed per shift.
"With doubling our production and freeing up a total of four employees per shift to work on other projects, I would say that through this project, we anticipate achieving a return on investment in less than 12 months," Chandran concludes.
For more information on Adept Technology Inc., go to: www.adept.com, or telephone 925.245.3400.
This article was first published in the November 2009 edition of Manufacturing Engineering magazine.