Shop Solutions: Mill-Turns Cut Setup, Cycle Times
Armstrong International Inc. (Three Rivers, MI) is a global supplier to commercial users of steam, air, and hot water for environmental and process control. Its products serve industries worldwide as diverse as food processing, health care, manufacturing, petrochemicals, pharmaceuticals, electronics, and agriculture. Armstrong even owns and/or operates and maintains utility plants for Fortune 500 energy users.
Founded more than 100 years ago, the family-owned company has more than 1000 employees worldwide, 12 manufacturing centers here and abroad, and a commitment to generating and conserving energy while protecting and preserving the environment.
For steam applications, Armstrong manufactures steam traps, humidifiers, strainers, and steam-powered water heaters. Typically, to heat a process, water is heated to steam, circulated, and condensed steam is trapped and returned to the boiler to complete the cycle. Stainless steam traps, for example, are used in demanding petrochemical applications in cold areas where steam heat is pushed through a line wrapped around the pipe to keep oil flowing.
As a global competitor, Armstrong is always looking for ways to improve its manufacturing to reduce cost and lead times. For one type of stainless steam trap, five operations were required to complete workpieces using several multispindles and other machines. Process steps included blanking, broaching, deep-hole drilling the length of the part, and other machining operations.
According to Bill Hartman, manufacturing engineer at Armstrong, total time to set up for the part was 6.75 hr, and total cycle time was more than 4.5 min. Based on that, the economic order quantity for the part was 4000 parts.
"We wanted to be the sole corporate supplier for this product line to our manufacturing plants worldwide," Hartman says. "To do that, we needed to have the lowest cost per piece. To accomplish that we looked for a machine that could drop the part complete," Hartman says. Armstrong had narrowed the choice down to two solutions—one with Traub turn-mill centers from Index Corp. (Noblesville, IN) and another solution, which, although quicker, involved two machines and a robot.
"The three-machine solution meant that if you had a problem, you had no backup, and your operation would be down until it was solved. For the same money, we were able to buy two Traub TNX 65/42 turn-mill centers. The decision was easy to justify, because it replaced the five machines the process used to require, each of which took a day for each operation, including WIP time, and took up a lot of valuable floor space.
"When we first saw the TNX, I could hardly believe how fast it was, but Index proved the cycle time by programming and running our parts," Hartman says.
The Traub TNX takes 15 min to set up and 2.5 min to run the part, dropping it complete. Economic order quantity was reduced to 2500—which fits into what Armstrong customers are asking for: no inventory on their floor and quick delivery.
"Special customer specifications used to cause us real headaches, but now we take them all in stride," Hartman says, "dropping the parts complete with no need for any secondary operation, no matter what the part design."
Tolerances required are "pretty much the same as previously." During the transition to machining parts with the Traubs, welders noticed the machined parts were more consistent, and surfaces held a weld much better.
The TNX not only reduced cycle time, but it has helped reduce tooling cost. "A deep hole is drilled in the workpiece with a carbide drill with tool life going to 2500 parts," Hartman points out. "We used to peck the hole until it was done, using three heads on the former machine. The drills did not last as long, and could not produce at the rate the Traub does."
"We can program on a desktop or on the machine itself, either way. The CAM package really helped us take time out of our process—and we continually find ways to improve our cycle times," Hartman says. All the members of the 100-part family are now programmed, and selection at the machine is simple, so a lot of one is no problem, if needed.
The modular Traub TNX65/42 turn-mill centers machine complex parts from bar to 65 mm in diam and a length of up to 300 mm. The reason is the machine's ability to simultaneously use four tool carriers, putting up to four tools in cut at the same time. Identical main and counterspindles feature 37.5/32.2 hp (28/24 kW) and may be equipped with two, three, or four turrets, each capable of holding ten live tools with 7.4-hp (5.5-kW), 6000-rpm drives or fixed tools. Each turret can travel in X and Z directions 175 mm and 650 mm, and optionally ±40 mm in the Y direction.
Thread milling and deep hole drilling—even at an angle—are processes required of the Traub machines at Armstrong. Both machines are tooled alike and can do all of the work. One of the tools in the turret is a heat code stamp, all done in the machine.
The part feeds through the main spindle where the material is faced, drilled, and threaded. After feeding out more, the flat is milled and the part is drilled and thread-milled. Then the counterspindle grabs the material, pulls it out, and the material is cut off. The part is further drilled and tapped, then the TNX drills, thread-mills, spotfaces, and produces an angled hole.
Hartman has noted that balanced turning of shaft-type workpieces or two dissimilar machining operations performed at the same time are key advantages of twin-turret turning characteristic of the TNX. Off-center drilling, side-face milling and similar operations are performed. Because complex components can be completed in one setup on the TNX, Armstrong sees less work-in-process, shorter lead times, zero fixture costs, and reduced labor.
The control is the Traub TX8i-s running Traub's in-house developed software adapted to the requirements of the customer or application. Index Traub's 3-D Win Flex process simulation shortens setup time and prevents collisions. The real-time simulation on the control allows the operator to see what is happening by looking at the model.
There is a family of about 100 different parts in the steam trap line and most economic order quantities have been reduced 75%, making Armstrong more responsive to market requirements and more profitable doing so. Setup time has been reduced by 94% and cycle time nearly 50%.
The impact of the TNX on the processing of the steam traps at Armstrong also has changed the way the manufacturing floor is organized. "When the Traubs came in, because they need only a fraction of the floor space of the old machines, we were able to reorganize our manufacturing layout to put the machining near the assembly operations, saving time in process," Hartman points out.
Once the bar feeder is loaded, the machines run fast. "I was out on the floor one day and noticed that the machines were not running," Hartman says, "so I approached our manufacturing planner and told him the operator said he doesn't have any work. The planner said the machines are too fast and we did not want too much inventory on our floor. Needless to say, I'm finding more different work for the Traubs to do."
Surfing Uncovers Turning-Tool Match
Next time you spot an employee surfing the net on company time, don't be too quick to shut him down. Think about Jerry Busche of Busche-CNC (Albion, IN), who has surfing to thank for uncovering a solution to a bottleneck. a high-volume rough-turning operation on a difficult-to-machine material. The "debottlenecking" improved Busche's quick-delivery capabilities to its first-tier automotive customers, and helped the company contain costs in this highly competitive business.
Busche Enterprises has seven manufacturing facilities that have been acquired over the last decade or so, located on 16 acres (6.5 hectares) in Albion, IN, and various ancillary buildings, totaling 303,600 ft2 (28,200 m2). Its customer list reads like a Who's Who of manufacturing, and has included John Deere, Caterpillar, American Showa, Navistar, and Honeywell, among others. Additional facilities include a cold-storage warehouse, climate-controlled warehouse, education center, distribution center, and central stores building.
Jerry Busche's surfing uncovered a new tool that turned around a real bottleneck operation on a "bear of a metal." He is vice president for the diversified contract machining company. By coincidence, just days before Jerry went surfing, Ingersoll Cutting Tools (Rockford, IL) had posted its recently released Hex-Turn tool on its Web site.
The story began far earlier, when Busche was still working out the wrinkles on a new job, machining a family of automotive ring gears with an aggregate annual volume of 2.75-million pieces. Materials were steel forgings, mainly 5130 and some hardened 4140. The bottleneck was the rough turning and facing operation, which ran too slow and demolished the tooling.
The 400-person shop machines the ring gears in seven, two-lathe machining cells that run 24/5. The original inserts for the application were rhombic, with opposing 80° and 100° edges on each side. Plans were to rough the ODs with the 80° edges, then do the faces with the 100° edges, and to use all eight edges per insert.
As it turned out, however, the 5130 steel was so gummy that the inserts cratered after less than 20 cuts. Toolbars snapped every other day on average. Type 5130 steel is known to be a bear on rough-turning tools for several reasons. The material is so gummy that it generates severe cutting friction, built-up edge, and heat. In continuous cuts, moreover, the hot chips are stringy, and tend to hang up on the insert, worsening the heat problem.
As an interim measure to minimize downtime until a permanent solution could be found, Busche manufacturing engineer Mike Pearson incorporated four backup toolbars into each tool package, and programmed the machine to automatically index every 17 cuts. That way, the operators had to shut down only once every 68 cuts to index all four toolbars, not every 17. Because the cratering often wrecked the insert's opposite face, moreover, Busche rarely got more than two useable edges from any insert.
Cratering also quashed the original plan to rough both the OD and face with different edges of the same insert. Experience indicated they would need separate tools for each operation. "We were looking at buying an awful lot of toolbars and inserts to keep the operations going this way," Busche says.
That's when he turned to the internet to find a better match. This was just about the time Raymon Avery, Ingersoll turning product manager, had introduced their new Taeguline Hex-Turn hexagonal turning inserts and holder on Ingersoll's Web site.
Sure enough, Jerry spotted it.
Ingersoll had developed the tool specifically for turning and facing in tough applications where strength was important to success. The insert's hexagonal shape comes closer to a true round, the strongest possible insert geometry, than the previous rhombic inserts. And being double-sided, the Hex-Turn offered 12 edges, all equally able to turn and face.
Busche talked it over with Avery, and the two agreed they had a likely fit with real upside potential. Busche stood to eliminate a problem that had eaten up their tooling on a very big job, while Ingersoll would get realworld validation for their newcomer in a formidable application.
For the trial, Mike Pearson and Ingersoll's field rep Tony Lovatto chose one of the cells running a 6" (152-mm) diam ring-gear blank. This is the highest-volume size in the part family. Actually, Busche makes two ring gears out of each forged blank. After completing all machining on the ODs, IDs, and faces, the blank is split in two with a cutoff operation.
Messrs. Pearson and Lovatto, together with Ingersoll engineer Mitch Bair and Busche's Levi Krider, began the test early one morning just a couple of weeks after Jerry's surfing foray. The tooling was installed and the CNC program was changed to accommodate the change in insert geometry. To be conservative, the test was set up to use separate Hex-Turn tools for the OD turning and the facing, just like before.
About one hour later, they started running parts at the same machine settings as previously. The new tool outlasted the old one by more than 8:1—140 cuts vs. 17. Moreover, edges wore out gradually rather than breaking off catastrophically.
Once the dramatic gain in edge life—Busche's No.1 priority—was established, the two men gradually ramped up the feed rate, from 0.017 to over 0.020 ipr (0.43–0.51 mm/rev). Yet edge life remained at 140 cuts or better. Next, the program was altered to enable a single Hex-Turn insert to handle both the OD and the face, as originally planned. When that proved successful, they again raised the feed rate to 0.025 ipr (0.64 mm/rev), a 50% jump. Still, the edges lasted through 140 cuts.
"It was essentially a drop-in replacement," says Pearson. "The only reprogramming was to accommodate the new insert geometry to realize the original plan for a single insert to handle both cuts, and to get rid of those interim tools. That's the kind of reprogramming I'd gladly do any day."
Today, with all seven machining cells up and running with the new Hex-Turn tools, Busche has seen the bottleneck disappear, with resulting improvements in delivery and cost containment. Standard practice on the 5130 forgings is to turn the ODs at 900 fpm (274 m/min), at 0.150" (3.8-mm) depth of cut and 0.0250 ipr (0.64 mm/rev).
For the runs in hardened 4140 steel. Busche simply eases back slightly on the feed. Still, the harder parts run about 40% faster than before, with the same improvement in edge life.
What accounts for Busche's performance gain?
"Other things being equal, the hexagonal geometry is intrinsically stronger than the previous rhombus," explains Ingersoll's Tony Lovatto. "There's also a pressed-in positive rake and chipbreakers on the top face, leading to freer cutting, cooler running, and better chip control. Improved coatings also reduce friction at the cutting face and resist built-up edge, which can be a real nuisance machining gummy materials. In addition, the wiper geometry on the cutting edge allowed us to get very aggressive on the feed rate."
Tooling Focus Grows Shop's Business
Morton Welding (Morton, IL) is a production machine shop that produces over 15,000 parts for the agriculture, construction, and transmission industries. Operating around the clock with three shifts and about 500 employees, the company often faces new tooling challenges.
Typical component runs consist of pumps, manifold valve bodies, or flanges in quantities from about 150 to 200 pieces. In addition to metalcutting, Morton also performs welding and brazing operations that produce about 5000 various subassembly types that are delivered to end-users.
The company must meet a variety of tight-tolerance situations, and be versatile enough to handle a wide range of materials. Success and profitability rely on the timely and efficient production of parts, and the company understands the importance of careful planning, reliable tooling, precision programming, and cutting-edge machining techniques.
Reducing the number of vendors seemed like one way to help simplify and streamline its manufacturing processes. Morton Welding was using four brands of tooling and had relationships with six distributors. "We have a lot of machine changeover," explains Ron McIntosh, Morton Welding tooling supervisor. "We thought that tool standardization and inventory reduction could save us a lot of time."
After meeting with distributors and analyzing tooling capabilities, Morton Welding considered Seco Tools (Warren, MI), which had a history for more than ten years as a major supplier. Then a project came in that helped Seco establish itself as a premier supplier of tooling and services to Morton Welding.
The operation involved tight-tolerance pump housings. The initial machining step in the current operation relied upon solid-carbide end mills that were wearing out at an inefficient and costly rate. In addition, McIntosh says that Morton was having trouble stocking the tool.
Through Seco distributor Sanders Tools & Supplies (STS; Peoria, IL), McIntosh contacted Seco's technical specialist Scott Johnson and application engineer Ken Burch to see if they could do better. Together, Messrs. Johnson and Burch re-engineered this step in the process using Seco's TurboMill indexable end mills with the MD15 geometry in grade T200M. This resulted in a cycle time reduction from 17 to 1.2 min, and increased tool life on the roughing application from 12 to 60 parts to result in a significant part savings per year.
The success of this application led McIntosh to invite Seco to analyze the entire process and make further recommendations. It was decided that the operation could benefit from a Seco Productivity and Cost Analysis (PCA). Burch explains, "PCA lets us take a wider view of the manufacturing methodology, focusing not just on the cost of tooling, but the total cost of production." PCA software provides a comprehensive report with both process information such as tooling and cutting data, and cost information such as cost per part, output per hour, tool consumption, and investment cost.
The pump housing being produced is made of graphitic cast iron about 12 x 5" x 2.5–4" (63.5–101.6-mm) thick. Morton manufactures about 6400 of this style pump per year. Run on Mori Seiki MC-linear HMCs, the pump requires 12 different milling or drilling operations. "We started the process by analyzing which part of the operation was taking up the bulk of the time," says Burch. "PCA identifies bottlenecks and let's us work on those."
After examining the process, the team agreed to reconfigure certain steps, using Seco tooling for the operations where appropriate. This allowed for an increase in some feeds and speeds as well as the elimination of a rough-drilling operation, a semi-finish boring process, and a secondary lapping process. This resulted in two less tools required for the process, simplifying inventory, and more than doubling the part output per hour from the original method.
"We were very pleased with the initial Turbo Mill results," says Chuck Rinkenberger, Morton Welding vice president. "Total cost savings for the entire process represented a 63% savings in both tooling and machining costs." An ancillary benefit is that this particular part of the pump house machining process is no longer a bottleneck that affects the efficiency of the other operations.
As a sign of appreciation for Seco's success in the pump house application, Morton agreed to work with Seco on its product development efforts for the new Duratomic MK1500 and MP1500 milling grades, introduced in 2008. Seco was eager to find production environments in which to prove the new grades' efficiency. "Not only did the grades prove to be successful, but we were able to capture significant annual savings in reduced cycle time on the rough-milling operation shown in the PCAs we conducted on the pump housings," says Johnson.
These experiences have strengthened the relationship between the two companies, with Morton Welding choosing Seco as a major supplier of its tooling. "Milling, turning, grooving, rotary adaptors, Seco is pretty much supplying us everything at this point except for CBN, PCD, and reaming," McIntosh says.
Tooling System Is A Winner
Being a primary vendor to some of the world's largest companies certainly has its benefits, but it also means operating in the era of costcutting strategies and constantly seeking productivity gains.
Woodward Governor Company is an independent designer, manufacturer, and service provider of energy control and optimization solutions for electrical power system equipment, engines, aircraft, and industrial turbines. Woodward's Aircraft Engine Systems division (Rockford, IL) develops and manufactures integrated turbine engine control and combustion systems, including fuel, combustion, and electrical systems, as well as heat-management components.
Their systems are used in high-thrust military engines such as the F135 and F136 that power the Joint Strike Fighter, and in the GE turbine engines for the Black Hawk and Apache military helicopters. Among their commercial applications, Woodward systems are found in the GEnx engines that power the Boeing 787 Dreamliner and the 747-8, and in the Pratt & Whitney Canada PW600 family of engines for the revolutionary Eclipse 500 and Cessna Mustang VLJs (Very Light Jets) that recently entered the marketplace.
Engine manufacturers expect Woodward and all its suppliers to deliver annual cost reductions while maintaining exacting standards of quality. To help achieve these goals, a Woodward engineering and manufacturing team, led by Woodward tooling application engineer Jim Hedlund, meets every two months with its authorized suppliers to discuss ways to reduce costs throughout its manufacturing operations.
Focusing on quality and productivity improvement is a constant theme for the Woodward staff. In evaluating every step of their processes, they concentrate on changes that will lead to significant savings or increases in throughput, rather than accepting small performance increases.
A Six Sigma Black Belt, Hedlund regularly invites Kennametal's senior application engineer Terry Cesar to the bimonthly meetings. Kennametal offers a comprehensive portfolio of metalworking tooling systems and services to Woodward, including turning, milling, holemaking, end-milling, and tooling systems. Cesar shares his expertise in maximizing tooling performance and tooling life, as well as how to manage inventory for cost reduction and productivity enhancements.
During one such bimonthly meeting, Cesar, along with Woodward engineers and machinists, discussed the need for better tooling usage and auditing data on the shop floor. The uncontrolled use of metalworking tooling systems can quickly lead to lost tools. Some tooling simply disappears because it's misplaced, causing unnecessary purchases. Other tooling is replaced before its useful life has ended because of a lack of accountability by the users. Another problem is that machinists lose valuable time searching for tooling that isn't consistently placed in an established location.
Woodward had been relying on vending machines supplied by a tool distributor to retrieve and store their tooling. Unfortunately, the machines provided no usage or auditing data, causing Woodward to retrieve its own usage data from the distributor, who would manually count the tooling on hand monthly or quarterly and produce a report.
Cesar recommended that Woodward consider converting from the vending machines to Kennametal's ToolBOSS Management System. The ToolBOSS system integrates with a company's supply-chain service to cut tooling inventory, reduce spending on tooling and administrative costs, and gain continuous improvements by gathering and analyzing tool usage data.
Working with Woodward manufacturing teams to plan the ToolBOSS application, Cesar recommended 14 bays, or storage columns, stationed in three strategic work cells on the manufacturing floor at Woodward's Rockford facility. The ToolBOSS system is a locked, drawer-based system for secure and controlled dispensing and replenishment of metalcutting tools and supplies. In addition, the system provides a full audit trail of usage and consumption.
Interfacing with a computer touch screen using a stylus allows machinists to select the tooling needed. The built-in user-access feature requires each employee to swipe a magnetic identification card that tracks the tools he or she removes or returns. The system automatically unlocks the correct drawer, and can dispense reconditioned tools before issuing new ones. The system can also prevent the dispensing of a tool until the user returns a previously issued tool. When the machinist clicks on a particular tool, a color photo displays to show exactly what is being retrieved, ensuring that the correct drawer is opened. The system is also set to automatically reorder tools and supplies from authorized vendors.
The ToolBOSS bays are configured with an array of drawer sizes, cupboards, and lockers to accommodate various tools and dimensions. Kennametal's Knowledge Center provides both onsite and online turning-processes training. More than 20 Woodward engineers and machinists participated in the two-day program.
Even though the ToolBOSS system contains an inventory of new tools, Woodward does not pay for any tool until it is actually dispensed, a Lean Manufacturing concept that holds down costs on inventory. Hedlund says Woodward now has full inventory control and audit information of all its tooling, and it has complete ownership of the information. Woodward supply-chain managers no longer have to contact their distributor to obtain monthly or quarterly tool reports containing limited information.
Plant and work cell managers have accurate, up-to-date details about who is using which tools, and how often they use them. The managers also have a better understanding of the life-cycle management of the tools, because they can determine which tools are being consumed at what rate, how often tools need reconditioning, and the rate at which tools reach their end of life. Such information also enables Woodward managers to compare different grades of tooling to determine the most cost-effective solutions over the full life cycle.
This article was first published in the October 2008 edition of Manufacturing Engineering magazine.