Shop Solutions: Jet Engine Repair Flies High With CNC
Engine components for Air Force One, aircraft parts riddled with bullet holes, jet engine cases ripped open by ice and other projectiles—these are just some of the repair and overhaul jobs that Component Repair Technologies Inc. (Mentor, OH) has handled in its more than 20 years in business.
CRT was founded in 1985 by Tom Wheeler and Chuck Bart as an independent turbine engine overhaul shop. Over the years, the company has expanded its facility and process capabilities to perform all repair work in-house. Messrs. Wheeler and Bart pride themselves on their extensive capabilities that enable them to control costs, minimize turn times, and deliver quality work to a customer list that includes major OEMs, commercial air carriers, and large engine shops.
The company, which occupies a 115,000-ft2 (10,683-m2) facility, is segmented into three business units according to product category: cases (turbine sections of engines), rotating workpieces (shafts, disks, and spools), and small parts for both small and large engines. Each unit is set up in cellular configuration with its own machining, assembly, and inspection capabilities.
CRT initially depended on large manual boring machines and manual lathes for its machining. As the need for more complex machining capability became apparent, the company has moved to adopt the latest in CNC technology to improve productivity, quality, and production flexibility.
In 1999 the company expanded its capability to handle large duct replacements and flange replacements in the cases unit. "We needed the ability to contour using CNC technology," explains General Manager Andrew LaTourette.
"You can contour manually, but it’s very time-consuming if you don’t have the capability to do pick feeds and repetitive back and forth necessary for stock removal." For CRT, this work is especially challenging because the cases are thin-walled and made of high nickel 718 and 625 Inconel. "These are gummy and unforgiving materials," LaTourette points out.
Most of CRT’s jobs don’t lend themselves to pushing off a lot of stock. Instead, the company does a lot of skim-and-trim finesse machining. "When you are doing flange replacements or replacing large duct segments, you have to keep things round and parallel," LaTourette explains. "The problems crop up when you get to the finish size because the parts will have a residual stress, and that’s tricky to machine and keep round—especially when you have ±0.003" [0.08-mm] tolerances on a 43" [1.1-m] diam."
The need for the capabilities that CNC machining could provide was apparent to CRT. "In the aircraft repair business, we have to stay sharp, offer excellent quality, and really keep pushing ourselves on our process capabilities so we can compete and stay in the game," says LaTourette.
"We’re both a job shop and a custom manufacturer. Even though 65% of the parts go through the same work scope, all bets are off because you never know how someone is going to treat an airplane engine. We think of everything as a one-off. Our turnarounds are tight, so the flexibility of our CNC machines is critical," he explains.
Over the last six years, CRT has invested in four CNC machines from Absolute Machine Tools Inc. (Lorain, OH): two You Ji YV-1200ATC vertical turning lathes; a Johnford VMC-1600SHD for its cases unit; and a Johnford DMC-1500H bridge mill, which was recently installed in its small parts unit.
The YV-1200ATCs turn all the angular geometry on duct and flange replacements. "The grooves are whittled out on the You Ji VTLs," says LaTourette. "You plunge the slots, cut to size on the drop, cut the shelves, and once all that cutting is finished, a right-angle head takes over. Then we machine the slots, the scallops with a straight mill, and the hole patterns. We also do the geometry on the other side of the case."
All this work could be done on manual machines with form tools, LaTourette admits, "but not economically or even competitively."
The You Ji machines also helped CRT move certain parts out of the grind room. The company formerly ground a particular hub component to tight tolerances on its ID/OD grinders. Now it single-points the part to size on the You Ji VTLs, reducing grinding time by about 12 hr. The two You Ji VTLs are set up so that only one operator is needed to run both machines.
Grouped next to the two You Ji VTLs is the Johnford VMC-1600SHD. The VMC is equipped with a 31.5" (800-mm) precision turntable that provides a fourth axis. It also includes right-angle heads that supply a manual fifth axis. The additional axes allow CRT to do bolt circles without changing tools, and the VMC also has probing capability.
The flexibility of the Johnford VMC has allowed CRT to pursue additional duct and flange replacement work. One such job calls for the Johnford to drill 102 holes in a flange for rotation pins and tackle all the scallop work on the part.
"You can do a large flange replacement like this manually and drill all the holes, but not competitively," says LaTourette. "You really have to push the envelope today if you want to stay in business."
Within the last two years, CRT has upgraded the VMC with Heidenhain scales. "We have them on our Johnford DMC-1500H bridge mill and they really enhance the accuracy of the machines," he says.
The Johnford bridge mill in the small parts and small engine unit is both accurate and flexible. "We’re actually using it for some grinding operations. The Johnford has a 15,000-rpm grinding head that lets us grind square holes in some of our parts," LaTourette says.
"We do everything on it—single-pointing nickel to size, grinding, deburring, and circular interpolation of threads." The Johnford bridge mill’s flexibility has enabled CRT to reduce lead times, for example by cutting deburring time in half on a part called "a six holer."
"Our guys figured out how to bore it, single-point the nickel plate, and then come in with another boring bar that is offset. The second boring bar faces off the nickel flash and basically deburrs the part," LaTourette explains. The machine is equipped with a subplate, allowing the operator to set up one job while another is running, further reducing lead times.
A key consideration in selecting Absolute Machine was the training and application assistance available to CRT. "Absolute’s support is excellent," says LaTourette. "Investing in the right CNC equipment has yielded a significant amount of new work and has given us a huge competitive advantage," he concludes.
Retooling Improves Aluminum Milling
When Excel Machine and Fabrication (Baltimore) retooled an aluminum milling job to meet an 8-rms surface finish spec, the job shop also got three unexpected cost savings as well.
Surface finishes on the part now fall so well within tolerance that the company can safely eliminate one inspection job. Cycle time for the critical milling operation has been reduced by half, and insert indexing time has dropped from half an hour to minutes. Since the edges last more than ten times longer, indexing time has become a non-issue.
"And we’re not done yet," says Jeff Grueninger, milling foreman, Excel Machine and Fabrication (Baltimore). "With the retooling, the process itself is under control," he says.
The tool that made it all happen is Ingersoll Cutting Tool’s (Rockford, IL) Aluminator face mill. The workpiece in question is a housing for an airborne contaminant detection system, also known as a "sniffer." Consisting of mating halves made of 6061 aluminum, the housings measure about the size of a paperback book. Each half contains eight deep, intricately machined pockets to hold the filter media, more than a dozen variously sized holes in two different planes, and a difficult gasket channel.
The key machining challenge was to consistently achieve the 8-rms finish and 0.0005" (0.013 mm) flatness on surfaces in that gasket channel—as machined—without taking all day. Specs ruled out all handworking. Moreover, the customer needed 125 complete housings each, leaving no time for handwork. The channel goes around three sides of the housing.
Excel first tried a 2" (51-mm) wiper-style face mill with four inserts. Even at 42 ipm (1.1 m/min) feed or less, surface finish ranged from 7 to 35 rms. Every piece needed a profilometer check, and scrap and rework rates were unacceptable. Moreover, insert edges lasted less than 100 pieces. Indexing involved handling three different types of insert, taking more than half an hour each time.
"It took rocket science to index the thing," says Grueninger.
Trying another cutter with triangular inserts failed to show any improvement, and ran cutting loads up to 120% of spindle capacity.
Ingersoll Field Engineer Jim Smith suggested the Aluminator face mill for aluminum and set up a test on Excel’s Kitamura CNC machining center. Both Messrs. Smith and Grueninger knew very well that there’s a big difference between tests and the real world.
"We can take risks in a one-time test that we can’t in day-to-day shop practice, Grueninger explains. "The test gives us a road sign on the way to a more robust process that produces in-spec parts every time."
The new cutter consistently delivered surface finishes in the 4-rms range and at much higher cutting rates. In the test with the Aluminator (vs. previously used cutter), speed increased to 5240 fpm or 1600 m/min (vs. 2096 fpm or 640 m/min); feed rate climbed to 105 ipm (2.7 m/min vs. >42 ipm); index time was reduced to >5 min (vs. <30 min); and edge life reached more than 200 parts and still going (vs. >100 parts).
Excel had never run the previous cutter as hard operationally as in the test, and they’re holding back on the new one as well. Previous feed rates in practice were closer to 25 ipm (635 mm/min) and depth of cut was 0.200" (5.1 mm), not 0.250" (6.4 mm). And for now the feed rate is being held at 80 ipm (2 m/min) rather than 105 ipm as "a judgment call."
"Once we’re sure the retooled process meets finish and flatness specs every single time, we’ll tweak the feed rate," Grueninger explains.
"The test gave us a good basis for setting expectations, but we’ll take it a step at a time. Besides, a consistent 4-rms finish in aluminum with a nonbalanced, three-insert cutter running at 80 ipm is nothing to sneeze at," he points out.
After several months of running with the Aluminator, surface finish has remained so consistently within limits that Excel dispensed with 100% inspection. "The operation runs twice as fast as before, yet surface finish remains steady, and the edges seem as good as new," says Grueninger.
The Aluminator’s ability to improve performance results from a combination of ground and polished inserts and a high-positive, rake-free cutting geometry that delivers better surface finish and lower spindle loads (80% in test vs. 120% with previous cutter).
Excel reports that retooling savings from all sources, including the lower cost of the standard Aluminator cutter and inserts, is more than $10,000 a year on this job alone.
Metrology In The Clutch
For more than 50 years, Formsprag Clutch Inc. (Warren, MI) has been designing, manufacturing, and delivering precision power transmission products, providing one of the broadest lines of overrunning clutches in the world.
For more than 30 of those years, Formsprag has supplied the aerospace industry with products noted for their long life and dependability that are used in a variety of applications including helicopter transmissions, auxiliary power units, gas turbine engine starters, and gearboxes.
In 2004, Formsprag’s Manufacturing Process Control (MPC) group thoroughly analyzed several key manufacturing processes to identify critical needs that when met could reduce inspection time, maintain the highest quality standards, and streamline product flow.
As a result, the company implemented some important process control and gaging techniques for inspecting its sprag clutches that included a new piece of inspection equipment, the multisensor SmartScope ZIP benchtop metrology system made by Optical Gaging Products (OGP; Rochester, NY).
"Sprag clutches are purely mechanical devices designed to transmit torque when driven in one direction while having the ability to freewheel when driven in the opposite direction," explains Formsprag Project Engineer Ben Blondin.
With sprags functioning as load-transmitting members, sprag clutches rotate in excess of 25,000 rpm in some aerospace applications. At these speeds, load-bearing surfaces must meet exacting design criteria to function properly.
The basic sprag inspection technique used at Formsprag had remained unchanged for over 30 years. Highly skilled inspectors fed sprags by hand, one by one, along a flat rail under an amplified needle gage that traversed the load-bearing surface. Part size would be projected onto an analog screen for the inspector to assess.
This method had worked well, but Formsprag decided to investigate noncontact optical measurement equipment in order to reduce costs and product lead time."We have always used amplified needle gages to detect sprag size, but questioned their efficiency," explains Blondin, who was responsible for implementing the OGP SmartScope ZIP benchtop metrology system.
A test demonstration of the effectiveness of the OGP Smartscope system measuring a sprag was conducted by Clark Technical Systems (Grand Rapids, MI). It measured the distortion of the sprag in a fraction of the time that the amplified needle gage required. Most important, the repeatability and reliability of the measuring process exceeded Formsprag’s requirements. Impressed by the demonstration, Formsprag purchased the unit with additional custom features and software.
During processing, a sample of each sprag lot must undergo a battery of inspection procedures. To inspect a sample, 20 sprags are placed on a custom material-handling system on the OGP SmartScope ZIP benchtop system. The software is configured to measure a large number of features at numerous alignment angles for each sprag. It takes just 12 minutes to complete hundreds of measurements. These data are displayed on a separate monitor and stored for instantaneous statistical process control (SPC) feedback.
The software generates a three-page process capability report to summarize the data of the 20-piece sample. "Each report contains distribution curves, specification limits, and Cpk values. It tells us how well we are holding a particular feature within the allowable tolerance," Blondin explains. Not only can the system be used for sampling purposes, it can also be configured for production sorting.
In the past, after using the amplified needle gages to perform a full inspection on a sample of sprags, Formsprag’s inspectors would document the findings in a handwritten report, and submit that report to a Material Review Board made up of aerospace engineers and quality engineers.
Since acquiring the OGP SmartScope ZIP benchtop system, Formsprag has seen dramatic improvements in its reporting methods. Instead of the handwritten reports, feedback is delivered automatically via the software, saving time and resources. Where it once took four hours to process a sample lot, operators with a minimum of training can now do the process in less than 30 minutes.
The improved inspection times have been important in helping Formsprag streamline its production operation. "At times, inspectors were using the amplified needle gages 10 hours a day. Being able to measure faster enables us to get the sprags into the assemblies and to the customer faster," says Jason Greenwood, aerospace production leader.
The OGP SmartScope ZIP benchtop system is much more than just a pass/fail gaging system. The speed and accuracy of the video measuring system also give Formsprag the capability to more effectively explore root causes of manufacturing defects. "With the new OGP technology, we are able to collect a vast amount of physical data in a very short amount of time," explains Blondin. "This will help us contrast pre and post-processing dimensions to help us determine the root causes of out-of-tolerance dimensions."
At first, Formsprag had a few concerns about purchasing a video-based measurement system. The OGP video-based system had to be reliable, repeatable, and, most of all, flexible. Today, with minimal training, operators of the OGP SmartScope ZIP benchtop system at Formsprag are able to configure the master routine rapidly to handle different parts just by changing a few coordinates.
The OGP video measuring system has proven to be a valuable asset, but Blondin believes that the company has only begun to realize the full potential of the system. "The flexibility of the OGP SmartScope system coupled with the software is amazing. We are now able to keep an active history on key characteristics utilizing SPC methodology," he says.
"In addition, we’re just beginning to use the laser on the SmartScope ZIP to perform surface scans. With the laser, we can capture several thousand data points on a contour in a matter of minutes and export this geometry to form-fitting software to compare actual data to a theoretically perfect CAD model. Our intent is to use this system to help evaluate components from our suppliers and help them provide better material."
By implementing the SmartScope ZIP system, inspection time has been reduced and the entire inspection process has been automated with reliable results. Noncontact measurement of sprag surfaces allows Formsprag engineers to improve their processes and ensure the high quality their customers expect.
Indexable Drill Saves Setup And Cycle Time
Rapid growth and a large number of orders are a good thing, but only if the contract manufacturer can meet the demands placed on its machining capability.
Harrison CNC Machine Co. (Sherman, TX) is a company that has experienced rapid growth in diverse industries in addition to projects for its core mining and medical industry customers.
The rapid growth and variety of customers made it difficult to keep up with the large number of orders being received. While welcoming the new business, Harrison CNC needed to improve its machining processes in order to keep up with the demand for its services.
Harrison CNC was founded in 2002 by Sam Harrison, who had 25 years experience in manufacturing. For 20 of those years, Harrison had been involved with CNC machining. With only five employees and four machines, it became imperative for Harrison to become as efficient as possible.
On one particular project, Harrison needed to drill eight holes in a 1" (25.4-mm) thick flange. Each of the holes was 0.625" (15.88 mm) in diam and required being machined holding 0.004" (0.10-mm) tolerance. In addition, chipping the material had to be avoided when breaking through the hole. The goals for this project were to produce these parts in one minute or less per part, and to be able to produce 10,000 pieces per year with one machine.
The first tool tested on this project was an HSS drill. This tool produced one part in 3 min and had a setup time of 10 min to change and recalibrate. The tool operated at 80 fpm (24.4 m/min) while taking a cut of 0.005" (0.13-mm) per revolution. Operating with these parameters, the life of this drill was 30 holes, or five parts. A disadvantage, however, was that the feed rate had to be slowed down as the drill broke through the hole in order to avoid chipping the work piece. Also, the HSS drill was unable to hold the exact tolerance needed on this project.
The second tooling option tested was the Chamdrill Jet from Iscar Metals Inc. (Arlington, TX). This drill offers many advantages over the more traditional HSS drills. The Chamdrill Jet is an evolution of the original Chamdrill replaceable-tip drilling system. This system features a solid steel shank with a replaceable solid carbide drilling head. This makes it possible to quickly and easily replace a worn drilling head without the need to touch off and recalibrate the drill. The time saved in the setup of the Chamdrill leads to savings throughout the machining process.
The Chamdrill Jet system offers many of the same advantages as the Chamdrill, in addition to two internal coolant holes that extend through the drill body and out through the cutting edges. This feature allows coolant to be delivered directly to the cutting zone where it is needed most.
In addition, there are four standard drillhead geometries available, each designed specifically for optimal performance on specific types of material. The four types of drill-head geometries are:
- IDP—Features a honed cutting edge for use on carbon and alloy steel (ISO P).
- IDM—Features a T-land on the cutting edge for use on stainless steel and high temperature alloys (ISO M).
- IDK—Features a honed cutting edge and two peripheral chamfers for use on cast iron (ISO K).
- IDN—Features a sharp cutting edge and polished flutes for use on aluminum (ISO N).
For Harrison’s particular project, the IDK-type drilling head was selected and is used. Its specific design for cast iron makes it well suited to drilling the gray and ductile cast iron flanges on this project.
With this tooling in place, Harrison CNC was able to operate at 450 fpm (137 m/min) taking 0.012" (0.30 mm/rev). Under these machining conditions, the Chamdrill Jet had a cycle time of 30 sec per part and a setup time of approximately 3 min. The quick-change design of the Chamdrill Jet made it possible to reduce the setup time from the HSS drilling system by 7 min. In addition, the specially designed IDK drilling head geometry and internal coolant helped to reduce the cycle time from 3 min down to 30 sec.
Even with the increased speeds and feeds, the Chamdrill Jet had a tool life of 15,000 holes or 2500 parts. This is a 500× increase from the tool life of 30 holes, or 5 parts with the previous tools. Furthermore, the Chamdrill Jet did not need to be slowed as it broke through the hole. It could be operated using the same parameters throughout the entire cut without chipping the material as it broke through, while also achieving the required tolerance.
The Chamdrill Jet enabled Harrison CNC to meet its goals of a cycle time of 1 min or less per part with the ability to produce 10,000 parts per year with one machine.
Granite Meets Precision Machining For Wafer Inspection
The essential components for this inspection story could not be more dissimilar.
One is an ultra-thin wafer sliced from semiconductor material; the other is a 40,000-lb (18,144-kg) block of granite that must be machined to the precision required for inspection of wafers by the semiconductor industry.
Machined granite from Tru-Stone Technologies Inc. (Waite Park, MN) is a critical component of the metrology industry's technology for wafer inspection.
For over 50 years, Tru-Stone Technologies Inc. has been manufacturing precision granite, ceramic, carbon fiber, and other media for use in the precision metrology field and pushing the limits of technology to refine its products and expertise.
Granite is considered a superior choice for machine bases and metrology components for a number of reasons including its machinability, durability, and ultimate flatness. In addition granite doesn’t rust, is easy to clean, is transportable, and is readily customizable to various sizes.
Tru-Stone Technologies works mainly with the foremost manufacturers in the wafer inspection, glass inspection, lithography, and coordinate measuring machine industries. In addition to granite surfaces, it also produces support stands, covers, and cleaners designed to protect and lengthen the life span of granite products for calibration labs and manufacturers.
"Increasingly, we’re establishing ourselves in a niche market," explains President Marc Illies. "As these clients look to develop smaller and faster products that offer more precision, we’re able to respond to those needs and deliver a quality product on time."
The company places a strong emphasis on engineering knowledge and experience in all its employees. Even salespeople are prepared to discuss detailed engineering issues with clients, and staff members get involved with clients much earlier in the development process than those clients may be accustomed. They are prepared to work from initial concept through prototype development to help refine ideas and also integrate assembly components that can enhance the overall performance of the equipment.
In a field where competitors tend to focus solely on granite—and therefore limit themselves to only a granite solution—Tru-Stone has evolved its business by exploring the potential of other materials, including porous or dense ceramic, carbon fiber, and even metals.
The technology boom of the mid-1990s was a watershed moment for Tru-Stone as the company began investing in CNC equipment to handle the complexity of products that the market demanded. In 1999, Tru-Stone purchased its first Quickmill 96-180-36 gantry machine from Quickmill (Peterborough, ON, Canada).
"Tru-Stone had a major breakdown of a machine that was effectively beyond repair," remembers Gord Buchholz, Quickmill’s sales director. The company contacted Quickmill immediately. "As we worked together conducting some key testing over the course of a week, we actually sold them our in-house production machine," says Buchholz. "We may have sacrificed some of our needs at the time, but Tru-Stone got back into production and we established a good working relationship."
Impressed by the performance that the first Quickmill 96-180-36 delivered, Tru-Stone soon ordered its second model, a Quickdrill. Beyond the affordability factor for Tru-Stone, the Quickdrill didn’t require a foundation or extensive installation. It could be dropped on the floor and ramped up to production quickly.
In 2004, for example, with the profile that Tru-Stone was gaining, the increase in the number of orders started to create a milling backlog. As Marc Illies recalls: "We typically carry a six-to-eight week turnaround on our jobs, but once that becomes a 10—12-week turnaround the threat of lost business becomes more of a problem."
That’s when Tru-Stone decided to purchase its third Quickmill— this time an Eliminator model, which quickly erased the bottleneck and actually upped the company’s production by $150,000 a month. "We looked at various options in 2004 and in doing our assessment of what worked for us. It came down to the cost-benefit analysis," Illies explains. "The return on investment and the internal rate of return both ranked very strongly in Quickmill’s favor, especially when compared with the German-made machinery that Tru-Stone also relies upon," Illies says.
The improved precision and performance of the newer generation Quickmill helped the decision process, too. "While the first Quickmill we sold to Tru-Stone could already achieve tight tolerances, our newer machines built today can hold a 50% tighter tolerance than that of the 1999 machine," Quickmill’s Buchholz notes.
Production Manager Dale Shortell points out that "Quickmill machines can hold about 0.0008" (0.02 mm) on locations," adding that "they are used the most for workpieces requiring point-to-point location holes and milled features with required tolerances as low as 0.002" (0.05 mm). This addresses approximately 60% of our workloads."
All the Quickmill machines used by Tru-Stone are loaded with diamond-impregnated tools to handle the demands of cutting granite, along with the many other materials the company offers. As plunge cuts are not possible with granite, the block has to be core-drilled first, which the Quickmill machinery can perform to 18" (457 mm).
This most recent purchase by Tru-Stone also features custom way covers, a more robust hand pendant, plus a notably faster control system and machine that is twice as fast as the previous Quickmill, according to Production Manager Dale Shortell.
"Not only has the machine improved our cycle times, but since most machinists learn on the Fanuc control, it’s much easier to hire the staff that we need," Shortell says.
CNC Manager, Dan Whitney, notes that the right-angle head on the Eliminator, which can machine five sides at one setup, was "a big plus, too."
Another aspect of the machine that Tru-Stone’s engineering team identified as vital to performance was dealing with the harsh conditions. "Machining granite is flat-out nasty on these machines. You’re always dealing with lots of water, dust, and abrasive grit," Whitney points out.To help alleviate this problem and provide additional protection for the operation and longevity of the equipment on the most recent purchase, Quickmill developed an accordion-style Y-axis bridge cover.
With the high-tech field holding explosive potential for the company, Tru-Stone Technologies continues to focus primarily on granite and ceramic solutions for the CMM, semiconductor, and OEM markets.
Live Tooling Helps Eliminate Workflow Issues
For many US manufacturers, the last several years have brought with them an array of difficult choices.
Cheap overseas labor has caused customers to demand lower prices. In these situations, suppliers must often choose to redesign their products to lessen costs, reduce profits by lowering prices without decreasing costs, or keep prices constant and risk losing business.
The Kinetic Company (Greendale, WI), a manufacturer of high-quality industrial knives primarily serving the steel and paper industries, found itself faced with this very dilemma.
C.L. Masters founded the company in 1947 in Greendale, originally operating the business out of his garage. By establishing a firm reputation for providing high-quality industrial knives, the company has experienced steady growth throughout its history.
Kinetic currently occupies a state-of-the-art 60,000-ft2 (5574-m2) facility in which all operations are performed in-house, a level of vertical integration unmatched in its industry. When relatively inexpensive labor and diminished quality began to drive down average market prices, Kinetic refused to turn its back on what had served as the key to its success.
In its quest to minimize costs, Kinetic began looking for equipment that would bring flexibility to the shop and lower machining costs per part by increasing efficiency. The company decided to invest in an SL-403 turning center from Mori Seiki USA Inc. (Irving, TX).
"We knew that Mori Seiki had a reputation for producing durable machines that provided high speed and accuracy," says Paul Lewandowski, project engineer at Kinetic. "We needed something that could stand up to the challenges of hard turning and Mori seemed to be the best fit."
The SL-403 outperformed Kinetic’s initial expectations, increasing the productivity of its turning department. Unfortunately, the unique particulars of its market led to continued challenges.
"Most manufacturers our size are dealing in large lot sizes," says Jared T. Masters, vice president of Kinetic. "We deal in very small runs. We produce circular slitting knives for the steel industry and those run in batches of 48. The bar-shear knives we produce, also for the steel industry, often go through in runs of two or four."
Dealing with relatively small lot sizes, Kinetic often found itself at a disadvantage. Many products would start in the turning area, move across the shop for milling operations, and then return to be finished with turning. Because setup times could take up to an hour, regardless of lot size, it made sense to prioritize larger batches in the milling department. This resulted in a high inventory of work-in-process moving very slowly through the shop.
To combat this long-standing problem, Kinetic began looking for fresh alternatives. Out of this search came the company’s first expedition into turning centers containing live tooling. In late 2004, Kinetic purchased a Mori Seiki NL2500 with the live tooling option. Knowing that a variety of processes carried out by the machine involved a level of complexity beyond what its operators had been exposed to, Kinetic approached integration of the machine with great care."When we first brought the NL2500 in, Mori provided onsite training to those responsible for running the machine," says Masters. "They continue to provide us with technical expertise whenever we need their support. Additionally, we’ve worked with tooling supplier Sandvik Coromant and CAM supplier MasterCAM to ensure that we’re using the machine to its maximum potential.
"The shift paid off. Many of the parts that previously required an inefficient and time-consuming detour through the milling department are now fully completed on the NL2500. Setup times have been reduced as parts can be completed in one setup. More important, possessing a turning center with live tooling eased the backload of the work-in-process flowing to the milling department. From the point when an order was initially received to when it shipped, turnaround time had averaged over 10 weeks. Through the use of the NL2500, this time span has shrunk to eight weeks and Kinetic believes the time will soon be reduced to six weeks.
In addition to diminished turnaround times, the NL2500 has resulted in cost savings for Kinetic. On a knife specifically designed for the steel industry, total machining cost was reduced by 30%.
"The NL2500 has definitely justified its purchase," says Jeff Kulinski, lead machinist in Kinetic’s lathe department. "The overall rigidity of the machine, coupled with strong performance by the live tooling, provides real cost-savings to our operations."
To benefit from further efficiencies, Kinetic ordered another turning center from Mori Seiki, this time an NL2000, again with live tooling. The machine arrived in April of 2004 and has already served to further dilute the bottleneck of unfinished parts waiting on milling operations.
Kinetic selected the optional subspindle for the new NL2000. Coupled with a bar feeder, the company hopes to expand its business by using automation to become cost competitive on parts that have gone to foreign markets over the last several years.
"In addition to our premium products, we used to have a very strong presence in the area of commodity slitting knives for the paper industry," says Masters. "Foreign competition eroded a lot of that business for us. Using the NL2000 with a bar feeder, we’re able to get the price down to a point where we’re once again competitive on that front."
This article was first published in the May 2006 edition of Manufacturing Engineering magazine.
Published Date : 5/1/2006