Shop Solutions: Pressed Form Tools Produce No-Burr Threading
If you believe hand deburring is an unavoidable evil in external thread cutting, recent experience at Warren Screw Machine (WSM; Niles, OH), should come as good news.
By switching from a ground top notch tool to a pressed threading form tool from Ingersoll Cutting Tools (Rockford, IL) on one high-volume job, Warren Screw Machine eliminated 2 min of hand deburring per part. Not incidentally, the company also lopped 20 sec per part off the threading cycle.
WSM runs two shifts a day, five days a week, producing machined and ground parts mainly for the aerospace, hydraulics, and automotive industries. The company is capable of small runs, long runs, and prototyping with its mix of Swiss turning machines, CNC turning machines, VMCs, and CNC screw machines. Production volumes range from 100 to 150,000 parts per year.
One part family, involving several sizes of a threaded plug, represents 250,000 parts per year, and is the biggest piece of business in the shop. "On that job alone, we project a significant saving from all sources with this drop-in retooling," says John Condoleon, WSM president. "The gain includes savings from labor and tooling as well as freed-up machine capacity stemming from reduced threading-cycle times."
Relieving a deburring bottleneck was a focal point of WSM's ongoing lean manufacturing campaign, which at the time was attacking handwork on a plant-wide basis. "That formal process forced us to study—and solve—a problem we had often pecked at in the past but never got rid of entirely," says Condoleon. "We'd try a new threading tool, see that it didn't completely eliminate the handwork, and let it go at that. This time, we resolved not to quit until we got to literally zero manual deburring."
WSM produces the plugs in Ledloy 12L14 free-cutting steel on a Hitachi Hi Cell bar-fed CNC turning center and Okuma bar-fed CNC lathes. Highest-volume member of the family, with an annual volume of 150,000, is the 1.5" (38-mm) size, produced in 5000-piece lots.
The operations sheet for the plug includes turning, center drilling, machining the standard class 2 UN threads, rerunning the turning tool over first and last thread, cutoff, followed by 2 min of hand deburring. "In fact, manual deburring was taking longer than all the machining," says Craig Rossi, lean manufacturing engineer.
The previous threading tool was a ground 60° flat-topped, carbide singlepoint tool (two edges per tool), also called a "top notch tool." Running at 432 fpm [132 m/min] with water-based cutting fluid, the threading operation took 16 passes and 45 sec to complete. Edge life averaged just 50 pieces because the sharp ground edges broke down quickly. And then, inevitably, came the tedious hand deburring that added 25 cents of cost to every part. The same problem arose for every single piece.
"We regard every job we have as one we could lose offshore unless we continuously grow more efficient and competitive," says Condoleon. "Right now, getting rid of low-end manual work is our quickest ticket to improved efficiency."
To eliminate hand deburring, the WSM lean manufacturing team asked their distributor representative, Don Gilanyi of Jergens Inc. (Cleveland) for ideas. He brought in Ingersoll's Jeff Hogya to demonstrate the company's new pressed-carbide form threading tool.
"Frankly, we were surprised to hear that Ingersoll even made threading tools," says Bill Southern, WSM tooling engineer. "We always thought of them as mainly a milling-tool house. Our guys even attended Ingersoll seminars, and found them valuable, but we focused so much on milling, the thread-burr issue never even arose."
Back on the WSM shop floor, Rossi and Southern chose the 1.5" (38-mm) plug for the test part. As the highest-volume part in the shop, it stood to produce the biggest saving if the new tool worked. Initially, Hogya set up the new tool to run at 500 fpm [152 m/min] using the same cutting fluid, and taking the same 16 passes as before.
On the first run, there were zero burrs, even after 500 pieces. "We knew we were onto something," says Rossi. Adding to the new tool's value was its lower unit cost and the additional edge, thereby reducing the cost per edge and tooling-inventory requirements.
After Ingersoll and Jergens left the picture, Southern continued to tweak the settings. "Ingersoll trainers always stressed pushing the tool beyond initial recommended settings at their milling seminars, so we decided to take them at their word," Rossi remarks.
Result: the threading operation now runs at 600 fpm and needs just 13 passes, cutting a full 20 sec from the original 45-sec threading cycle. Still, the parts are 100% burr-free, and there's no loss of edge life.
Several key physical differences between the old tool and the Ingersoll 16ERM 12 UN TT9030 tool account for the improvements, Hogya explains, "First, as a pressed form tool with a full nose and crest radius, the insert is fundamentally stronger than a ground single-point tool. Second, the pressed insert has a slight radius on the cutting edge and chip-breaking geometry on the top face. It's not ground with a flat top and sharp edge. The small edge radius eliminates the weak sharp edge that breaks down so easily on ground inserts and causes the burrs. The chip-breaking top face clears out the chips, and the heat, so the tool runs cooler. Pressing the insert to final shape also eliminates the expense of grinding carbide, which is always considerable. Finally, each insert provides three, not two, cutting edges."
Although WSM is pursuing its lean manufacturing program over all manual jobs, this thread retooling has been the biggest single winner so far. The company started up the new process in February 2007 and has run it on about 20% of the plug family. "Results have been uniformly better on all sizes, so I see no reason why we shouldn't realize that full annual gain by next February," concludes Condoleon.
Toolholding Pushes Machining to High Level
It is no secret that the evolving global marketplace has changed the face of American manufacturing. While many tend to focus on the negative effects of competition from countries with low labor costs, this same trend has often resulted in increased levels of innovation and process refinement.
For Ultra Machining Company (UMC; Monticello, MN), success has been found in viewing higher levels of competition as more of a challenge than a threat. Visitors to UMC's current facilities might have a hard time envisioning the company's humble beginnings, operating out of its founder's garage in 1968. Today, UMC occupies a 73,000 ft2 (6781 m2) state-of-the-art building that is much closer in appearance to a scientific research facility than to a traditional machine shop.
Throughout its history, the company has differentiated itself by specializing in the production of highprecision components. It's currently focused on the medical and aerospace industries. To maintain a competitive advantage, UMC continuously evaluates and implements new technologies that can improve the overall efficiency of its operations.
In early 2006, UMC management realized that it was becoming difficult to keep pace with the rapid rate of evolution in cutting technology. To address this problem, Jeff Larch, a senior multiaxis mill-turn machine operator, was appointed to the newly created position of continuous-improvement applications specialist. By having an employee dedicated solely to process optimization, UMC hoped to maintain its edge over the competition.
This decision has produced tremendous results throughout the company's operations. Among the many changes adopted, the implementation of a new toolholding system stands out as one of the most beneficial to UMC's operations. During the summer of 2006, its local distributor, Productivity Inc., was working with UMC on the use of a 0.250" (6.35-mm) collet for production of a medical component.
A number of issues arose in the areas of setup time, accuracy, and tool life. "The problem wasn't with the quality of the toolholding system," explains Lisa Bailey of Productivity Inc. "The problem was that it was the wrong system for the levels of performance that UMC required. They wanted to place an order for twenty collet-type holders for the job and work through the issues. I told them that before I could take that order, I felt they needed to try a higher level of toolholding system. At that point, we began discussing the capabilities and setup reduction benefits of Rego-Fix's powRgrip system."
Often compared to shrink-fit toolholders, the powRgrip system from Rego-Fix Tool Corp. (Indianapolis) uses a press capable of generating 6 tons (5.4 t) of force to join the tool and toolholder. Instead of relying on heat or hydraulics to expand the material, powRgrip uses the interference between the holder and collet to provide gripping forces, and deliver a runout below 0.0001" (0.003 mm). In addition to high accuracy, the system also achieves extremely short setup times, taking less than 10 sec to press in or remove a tool.
"We had been at the point where we were considering the purchase of a new machine tool," says Randy Hatcher, vice president of UMC. "In working with Productivity Inc., it became very clear to us that our toolholding systems were not allowing us to get maximum performance out of the machines we had on the floor. We decided to hold off on investing in a new machine, and instead do everything we could to get the most out of our current equipment."
After integrating powRgrip, significant productivity gains and cost savings were achieved. On a medical component machined from 17-4 heat-treated stainless, cycle times had previously been a little over 32 min. A 0.250" (6.35-mm) long, 0.125" (3.2-mm) diam end mill was being used on the part, running at 1700 rpm and 1 ipm (25.4 mm/min). The feed rate had to be kept slow to maintain the 16 µm finish needed to meet the cosmetic requirements.
"We have to finish surgical instruments with a bead blast to give them a matte finish that eliminates the potential for glare during surgery," says Larch. "Any kind of feed lines, harmonics, or tool vibration sticks out like a sore thumb after the bead-blast process. With the previous end-mill holder, we had to go extremely slowly, or else we would basically end up cutting with only one side of the tool, failing to meet our surface-finish requirements."
After implementing the powRgrip system, UMC was able to increase speeds and feeds to 5000 rpm and 5 ipm (127 mm/min), respectively. Previously, it took five passes to produce the necessary level of surface finish, but the new toolholding reduced the number of passes required to two. Cycle time decreased to 24 min, and overall part cost was reduced by approximately 20%.
On another difficult job, UMC needed to drill a series of 4" (101.6-mm) deep, 0.178" (4.5-mm) diam holes for the completion of an aerospace component. Initially, that feature on the part had to be outsourced to a vendor with gun-drilling capabilities. To shorten lead times and reduce costs, UMC brought the gundrilling process in-house, but could not achieve the desired levels of performance. Tool life was sporadic and, often, less than 100 holes could be completed with a tool.
"Once we had powRgrip, we were able to take advantage of a special 30x diam drill from Mitsubishi," says Larch. "Our process time had been at 2 min 11 sec. With the toolholding necessary to use the new drill, we were able to reduce that to 12 sec. On top of that, we can now drill over 600 holes per tool. The powRgrip system enabled a process that reduced setup time, boosted productivity, and eliminated costs. We were able to eliminate approximately 30% of the cost from that process."
The implementation of new toolholding also aided in jobs where cycle time was not a primary concern. A low-volume aerospace component produced by UMC is machined from an expensive casting, and requires a series of 0.001" (0.03-mm) tolerance slots. With previous toolholding systems, it was very difficult to machine the slots without introducing taper from runout of the end mill. Maintaining the integrity of the part was a stressful and time-consuming project. With powRgrip, runout was eliminated, and the slots could be manufactured confidently and quickly.
In addition to improving specific jobs, the adoption of powRgrip has increased the reliability of UMC's machining processes. This has allowed the company to boost its competitiveness through more unmanned operation.
"The Rego-Fix system reduced a lot of our cycle times, but even more than that, it has given us much more consistent tool life and stabilized our processes," says Larch. "When you're working with high-precision components, your processes really have to be bullet-proof before you consider integrating significant levels of automation. We are now to the point where we can run jobs at night and over the weekend, and be sure of the results."
UMC is presently experiencing approximately 40% annual growth in sales, with current forecasts of $19 million in 2007. The company has not increased its total number of machines in the past year, and credits the growth to replacing older machines with new multitask machining centers and implementing innovative technologies like powRgrip to allow it to get the most out of its investments.
Swiss Turning Targets Gun Cleaning
After a day of hunting, 15-year-old Doreen Williams returned home without any game, but possessed of a breakthrough idea: a portable gun-cleaning kit that utilized a flexible cable in place of the rigid ramrod that had been in use for centuries.
Following a year of development, a prototype, packaged in a shoe polish tin and marketed as "The Whole Kit & Caboodle," was exhibited at an industry trade show and proved an immediate success.
Now known as Otis Technology Inc., Doreen's company is an industry leader occupying a 43,000 ft2 (3994 m2) facility in Lyons Falls, NY, serving an expanding market including major retailers, law enforcement organizations, and the US Armed Forces. The Otis name is an acronym for Outstanding Technology, Innovation and Service, and the Williams family and over 100 employees never lose sight of the importance of their products to the end users.
The Otis product line has grown extensively. The company offers cleaning products for firearms ranging from antique muzzleloaders to rifles, pistols, and shotguns of virtually every caliber. The company holds more than 30 patents and is continually developing new products and refining existing ones. Sales have increased 25% annually over the last five years.
A singular advantage of the Otis cleaning system is the ability to clean from the breech to the muzzle, thereby expelling carbon, powder grains, and residue rather than forcing them back into the firearm as is the case with conventional cleaning systems. Most of the parts, including brushes and tips, are machined from a specially formulated brass that is strong enough to last a lifetime, but soft enough to avoid damaging delicate rifling inside the barrel.
To meet growing demand for its products, Otis Technology uses several models of CNC Swiss-type automatic lathes manufactured by Star CNC Machine Tool Corp. (Elk Grove Village, IL).
"We bought our first Swiss machine in 1996. Prior to that, we outsourced our parts," explains Nick Williams, vice president and design engineer. "We have always set a high standard of quality and wanted to take responsibility for every aspect of production. Initially, we resisted Swiss turning machines because they had a reputation for being slower than cam machines, but we decided to investigate," Williams says.
Otis contacted a number of builders and asked for a complete set of literature on available machines so that they could familiarize themselves with the technology.
"Star was the only one that provided the material," Williams says.
"The first machine that we bought was a Star SA-12 model. The capacity was right. All of our parts were under 0.50" [12.7-mm] diam, and the gang slide, coupled with a fully independent back spindle, enabled us to complete all of the operations required. The tool capacity was a consideration, because redundancy is necessary when you plan to run constantly," Williams says.
Otis manufacturing personnel liked other features on this model for the same reason. "We were impressed by the machine's heavy-duty construction. Although nonferrous parts might get by with less machine weight, we believed that it would translate into longer machine life, and it has. Of course, being new to the game, user friendliness and ease of programming were especially important factors," Williams says.
The Star SA-12 worked so well that Otis subsequently bought a second machine.
"When we bought our first machine, we were making over 75 parts on it and running 24/7 with the lights out," says Williams. As production grew, another machine was added.
A major manufacturing breakthrough came with the addition of a later model—a Star SR-20 and two ECAS-20 machines.
The ECAS-20 machine offers a new tooling layout integrated with Star's NICS (New Integrated Control System), which provides faster cycle times by keeping nonproductive time to a bare minimum. The motion-control system, equipped with "Program Optimization," optimizes tool selection, and further reduces cycle times.
Split gang slides are equipped with turning tools, live tools, face and back working tools to facilitate pinch turning, simultaneous cross drilling/milling, front/back operation, and independent backworking.
Star's patented integrated control system, incorporated with the Siemens 840DI controller, is able to produce consistently accurate components in the least possible time.
The SR-20 machine provides larger capacity, an increased number of tools, fully independent overlapping operation between main and subspindle, and a larger chip bucket and coolant tank, for extended operating hours. The tooling package includes a plate holder accommodating six turning tools; a sleeve holder for four sleeves for front ID work; and five live tool positions accommodating five single tools for cross drilling/milling.
In combination with these, it is also possible to perform off-center face drilling/milling, polygon turning, slotting, and thread whirling. The back-working subspindle is equipped with a fully independent toolblock which has four positions for fixed or live tools and can share another four tools from the main side for ID work, using double-ended spindles from the main toolpost.
"One of the critical factors to us is machine reliability," Williams says. "At present, we make 1.2 million parts per year per machine. Our average cycle time is 20 seconds, and we perform up to nine operations per part. We manufacture to Six Sigma standards, and inspection is virtually continuous. In fact, any employee can reject a part."
Perhaps most important, the combination of standard machines and the two ECAS units has enabled Otis to adopt a manufacturing philosophy based on logistical analysis.
Nick Williams is sold on the concept: "The ability to run multiple programs, coupled with the machine's ten-axis capability, has helped us to make dramatic production increases. On one part alone, we went from a one-minute cycle time on a standard machine to 20 seconds on the ECAS. That's a three-to-one improvement," he points out.
Doreen (Williams) Garrett, founder and president of Otis, is extremely enthusiastic about the advances in manufacturing capability: "In looking forward, we hope to expand the use of our Star machines into areas beyond gun cleaning. We feel that applications exist to provide services to a wide array of industries.
"By applying logistics to our combination of standard and high-speed ECAS machines, we're able to balance our production in relation to demand and deliver product on time," Garrett says.
This emphasis on meeting customer needs has resulted in continual corporate growth and expansion. Currently, several new patents have been applied for, and an additional 13,000 ft2 (1207 m2) will be added to the plant.
Lee Hinkleman of Otis points out that "along with a willingness to adopt the latest technologies, our growth has derived from our ability to develop an exceptional workforce. We're exceptionally proud of our people, and management takes every opportunity to show appreciation. For instance, we've just completed a $1.3 million daycare facility, and we employ a full-time chef."
Recently, the company was contacted by an Army commander serving in the Middle East who stated that frequent sand storms in the area "caused me to instruct my men to clean their weapons every hour."
This is one of many "thank you's" that Otis has received from those on the front line in the military and law enforcement, as well as from sportsmen and hunters worldwide. They provide a sense of satisfaction in the knowledge that a young girl's idea, coupled with the latest in technology, can touch thousands of lives throughout the world.
This article was first published in the December 2007 edition of Manufacturing Engineering magazine.
Published Date : 12/1/2007