Shop Solutions: VMCs Part of Competitive Strategy
"Our key to survival has been to change as we need to," says Robert Shaffer, president of Phoenix, AZ, precision job shop Campro Mfg. Inc. "Right now, we're doing a lot of Tier-2 defense work and starting on some Tier-1 defense work. In the '90s, we were big in semiconductor work, and in the late '90s we were big in medical."Our niche has changed five times in eight years, so we're not a specialist in any one industry. Our job is to make money," he concludes.
According to Shaffer, the usual parts contract today is short-term, one to a maximum of two years, while the customer's contract may be for five years or more. Because the market is under pressure, customers want to maintain the freedom to re-bid contracts. The effect of a short-term contract is a shorter backlog, which makes it difficult to make long-term plans.
"With a shorter backlog, buying high-end machines is risky," Shaffer says. He points out that a high-end machine from an offshore builder costs $270,000, while a VMC from Fadal Machining Centers (Chatsworth, CA) costs $100,000.
"Because they cost less, Fadal machines reduce the risk," Shaffer says. "And, they can do the same work as a machine costing three times more. Fadals reduce the risk of a big cash outlay and higher overhead."
Campro routinely works with tough workpiece materials such as 17-4 PH and type 316 stainless steels. The Fadal machines use heavy cast-iron box ways with nonmetallic liners that provide better vibration damping and rigidity under load than linear guides. According to Fadal, positive-displacement lubrication over the full length of the way surfaces effectively eliminates stick/slip, preserving positioning accuracy and extending machine life.
Offshore competition is an increasing problem for many shops in the United States, and Shaffer says Campro is no different. "It's apparent offshore competitors are impacting many markets throughout the US," he says. "Customers with jobs that are not time-sensitive are sending contracts offshore for parts that once would have gone to US job shops.
"While a lot of job shops are resigned to cutting shop rates to compete with offshore firms, there is a silver lining," he continues. "If you really concentrate, rather than cut shop rates and make less money, you can figure out a way to make parts for less money and just as good. The key is how to build the part faster and therefore cheaper and still maintain the quality. You have to know which machine-tool and cutting tool technologies to use for a part, and how to get cycle times down. Sometimes we have to cut shop rates, but not always. Most of the time we still make our hourly rates."
According to Shaffer, the processing speed and ease of use of the Fadal MP CNC supports Campro's cycle-time reduction efforts. "The Fadal is one of the easiest controls on the market to teach," says Shaffer. "You can get used to other controls, and there's nothing wrong with them. But they're cumbersome and require too many steps to get from point A to point B. With the Fadal control, we can get our VMCs up and running much faster than our high-end machines."
The control features a utility menu with options for digitizing of tool offsets and fixture offsets, which allow tool and fixture offsets to be loaded by answering several simple questions. This saves time and reduces errors caused by manually inputting offsets.
"The control has a number of functions that are very helpful," says Shaffer. "For example, the mid-tape startup function allows you to start in the middle of a program on a tool on a certain line. On other controls, you have to go through the program line by line, pick up the offsets, then stop and put the cursor where you want it. You have to run through a lot of tricky steps. One mistake can crash the machine, scrap a part, break a tool or fixture, and other bad stuff. With the Fadal, as long as the tool you need is in the spindle, you can start on any line you want."
Campro now operates three Fadal VMC 4020 machines, and recently installed a VMC 8030. "The larger machine will allow us to run bigger parts and multiple parts at the same time, which will make even more machining strategies available to us," Shaffer explains.
Clean Coolant Key to Shop Operations
Synventive Molding Systems (Peabody, MA), a manufacturer of advanced hot-runner systems for plastic injection molding, recently expanded and upgraded its facility with the addition of 10 new CNC machines.
Company managers took the opportunity to review shop operations, and one of the first areas they studied was coolant selection and maintenance. Michael Venable, Milling Department operations supervisor, explains: "Coolant quality has a major effect on overall shop efficiency. Selecting a coolant based solely on price could be a very costly decision."
Synventive managers also realized the need for clean coolant. Metalworking fluids loaded with tramp oil and chips impact machining throughput, part surface finish, and tool life. And, according to Venable, dirty coolant sends the wrong message to machine operators.
"That message is that, to save the relatively small investment in coolant cleaning equipment, we are satisfied to have them deal with oily parts, dirty machines, a smoky environment, and increased chance of contact dermatitis," he says.
"Clean coolant is an essential requirement for achieving maximum shop efficiency and maintaining employee relations," Venable continues. "For that reason, finding a practical method to keep the coolant clean was a top priority in our shop optimization program."
Synventive managers wanted a coolant cleaning device stationed permanently at each machine sump rather than portable units. Dedicated sump cleaning units allow each operator to maintain control over his work environment. However, this setup depends on cleaning devices that require minimal operator attention.
Venable tested belt skimmers, but found they were ineffective for removing tramp oil from relatively large sumps, particularly when the machine tool is operating. The devices also were unable to remove floating chips.
Small pump/separator units tested did not adequately split out tramp oil, and required operator attention to deal with shutdowns and maintenance problems caused by solids being drawn in with the oily coolant.
Synventive then installed a model #255 pump/separator unit from Keller Products Inc. (Lexington, MA) on one sump. Venable says the unit had several features that suited it to his application, including permanent plastic oil-separator elements, a high-capacity bag filter to remove suspended chips and fines, and an air-operated diaphragm pump that required no electrical hookups.
Venable reports that the Keller unit effectively cleaned tramp oil from the sump in a few hours, whether the machine was operating or idle. The unit also required little attention. Operators drained separated tramp oil once a day, and the filter bag is changed about once a month--a task that takes about five minutes, at a cost of $4 per bag.
After operating the device for about a month, Synventive installed a model #255 on each of 12 machine sumps. "We're getting significant cost savings as a result of increased tool and coolant life," Venable reports. "But the major benefit is that our operators can work with clean parts, clean machines, in a clean shop, and take pride in their work.
"As a result, we're maximizing the return on our machine tool investment, and that's the objective we set for ourselves when we started our coolant and coolant maintenance program," he concludes.
Machining Centers Key Niche Market Success
Things didn't exactly start on a global level for Marten Machining (Stevens Point, WI). Operated by Al and Deb Marten, the company grew slowly and eventually built up its current reputation.
"Even though we're based in a rural area, with all the shipping services and Internet capabilities we are as connected here as we would be anywhere else," Deb Marten says. "This is better than actually being next door to our customers."
Al Marten began his manufacturing career with a two-year degree, and gained valuable industry experience with a 10,000-hr journeymanship at Remmele Engineering (New Brighton, MN; see the article "Changes: Remmele Evolves from Job Shop to Contract Manufacturer" on page 57 of the May 2003 issue of Manufacturing Engineering). He founded Marten Machining in 1984, and the company moved to its present location in 1990.
In many ways, Marten Machining is emblematic of the changing face of modern machining technology. "We receive all of our CAD files by e-mail these days," Al points out. "We have what we need seconds after it leaves the customer's hands. We can then use our CAM system to input the data into our machines."
At the heart of Marten's machining operation are three-, four-, and five-axis machining centers supplied by Hermle Machine Co. (Franklin, WI). "We've always been fans of Hermle," Al Marten says. "I think we bought one of their first American machines back when we were starting out." One machine still actively producing parts in the shop is painted the original Hermle green color.
"The main reason we have such a long history with Hermle is precision," Marten continues. "I mean, the controls are easy to learn and to use, but the exceptional precision and versatility of these machines is what sets Hermle apart."
Marten uses the machining centers to turn out a wide variety of prototypes and repeat parts, although he says only about 20% of the shop's business is based on repeat orders. The company's bread and butter is machining of highly complex prototypes and special machine parts in materials ranging from plastics and tungsten to stainless steel and aluminum.
The geometric complexity of many of the parts, for medical, automotive, tooling, and scientific research and development applications, has driven Marten toward advanced machining capability. "As the designs have increased in complexity, we've found that five-axis is the only way to go," he says. "Setup time is shorter, and less special tooling is required."
Shrink-Fit Switch Pays Off
AISIN Drivetrain Inc. (Crothersville, IN) is a high-volume supplier of auto parts whose customers include GM, Toyota, and Nissan.
Process engineer Dave Baker manages the line that machines transmission cases. Kerry Edwards is the process engineer for the brake master cylinder production line. To meet the company's need for increased production, both men had to find solutions to machining problems in their lines.
Baker's problem was a high scrap rate on transmission cases. "There is a 22-mm diam hole in one of the shafts of our transmissions," he explains. "We have to reach way back into the case to get to that hole, so the drill is sticking out probably 200 or 250 mm from the holder."
Baker says roughness inside the hole resulted in 3 - 5 pieces of scrap per day. The hole was being produced using carbide drills in end mill holders, and excessive runout was the problem.
Edwards needed to extend tool life of an expensive polycrystalline diamond (PCD) tool used to machine brake master cylinder bores. "This tool has 12 PCD inserts and costs several thousand dollars, so tool life was my first concern," he says. The tool was used with a hydraulic holder.
Both engineers were skeptical about shrink-fit toolholders. After consulting with a distributor and toolholder supplier, however, both decided to test shrink-fit tooling supplied by Techniks Inc. (Indianapolis).
According to Baker, a trial run resulted in immediate process improvements. "Speeds and feeds went up 20 - 30%," he recalls. "We had longer tool life, better runout, and a better hole." Since converting to shrink-fit a year ago, the transmission case line has experienced no scrap for that tool. Output has nearly quadrupled from 900 pieces to 3500 pieces. Cycle time for the boring operation improved by 60%.
The one-piece design of shrink-fit holders also yielded benefits, eliminating the need to stock collets, nuts, and coolant disks and minimizing training. "With collet chucks, new people want to really over-torque those nuts," Baker says. "So we were stripping out nuts and holders. We had to keep back-up holders, but not with these."
Edwards tested shrink-fit holders for three months before presenting his results. "When I went before management, I was at 4 X tool life, and the tools were still running," he reports. "The results were so good I was afraid they weren't going to believe me. There I was, asking for money to purchase equipment that we'd already saved enough money to justify, all on that one tool! Techniks claimed shrink-fit could increase tool life 4 - 7 X on PCD tools. That was a bold statement, but they delivered," he concludes.
Briquetter Makes Quick Work of Chips
Eagle Bridge Machine & Tool Inc. (EBM; Eagle Bridge, NY) has found a niche machining large and complex workpieces, including castings for rail car components and heavy machinery industry. The company's growing reputation has resulted in increased business and long-term contracts.
That's the good news. On the flip side is making sure EBM can get the work done profitably while maintaining delivery, cost, and quality requirements.
To that end, in the last three years the shop has replaced over half of its stand-alone machine tools with a pair of two-machine automated cells, reducing the number of machines in the shop from 23 to 12.
For a 30-employee shop, the large capital expenditure was quite a risk. But the investment is paying off, according to production manager Tony Farrara. "Thanks to these two cells, we've made considerable gains in productivity and cost savings due to faster machining cycle times, reduced setup and loading times, and our ability to run unmanned operations overnight," he says. "But, with our jump in production of machining large cast steel, cast iron, and stainless steel components, we were concerned with the increased volume of metal chips. Our part production went up 40%, but our chip volume increased by nearly 50%."
EBM deals with more than one-and-a-half tons of chips every day, and uses a chip compactor system to reduce chip volume. Supplied by Mayfran International (Cleveland, OH), the system consists of a briquetter, a vertical chip crusher, and two conveyor units. It transforms metalworking chips, strings, nests, fines, and sludge into dense, dry, and compact briquettes.
The model RB4/2500/60 briquetter can handle 350 lb/hr (158 kg/hr) of chips, and delivers a 5.5:1 compaction ratio. The machine eliminates cutting fluid and coolant spill-liability risks during transport, increases the amount of fluids reclaimed, eliminates the need to have large areas for scrap storage, and increases the value of the scrap material.
"Previously, we gave away the scrap just to get rid of it, but now we are paid for the compacted chips by our local recycling center," says Farrara. "Before the system was installed we had a 30-yard dumpster that held about a week's worth of loose chips. Now, a 12-yard container holds up to 20,000 lb [9000 kg] of briquettes.
"We've yet to fully calculate our payback on the system," he continues. "Part of the reason for that is trying to monetarily quantify having additional storage room, cleaner machining operations and a clean storage area. It's hard to put a dollar amount on what these improvements contribute to our overall efficiency."
Coolant Management Propels Productivity
Consolidating to one coolant and using proper coolant management techniques helped Schwab's Screw Machine Products improve part quality and cut costs.
The family-owned manufacturer started in 1987 with only two screw machines. Today, more than 50 people work in the plant, which is located on the Nez Perce Indian reservation in Lapwai, Idaho. The company makes everything from automotive and aerospace components to parts for wood stoves to outdoor gear using saws, CNC grinders and turning machines, and other equipment.
"We used to change coolants every month or every other month," recalls supervisor Bill Winker. "Since we switched to Rustlick Ultracut 370R a year ago, we have not changed the coolant in the sump."
Rustlick Ultracut 370R is a biostable semisynthetic cutting fluid from ITW Rocol North America (Glenview, IL). Schwab's now uses it for metal cutting and forming operations throughout the plant, including forming, sawing, drilling, and other processes. The fluid is also compatible with all Schwab's work materials, including brass, aluminum, stainless steels, and plastics. According to ITW Rocol, the coolant's long sump life is due to its exceptional biostability and rust protection.
Winker also credits the fluid for eliminating secondary processing on one of Schwab's more unique products, ice-screws for use in mountain climbing. Surface finish is critical, and the parts previously required both rough and finish milling to meet surface finish requirements.
"We tried a variety of coolants, along with various recommendations from carbide insert suppliers, to get the finishes required on the ice-screws and on type 403 stainless steel parts," Winker recalls. "After we switched to Rustlick Ultracut 370R, we were able to achieve the required finish with our normal tooling in one operation while increasing the speed and feed of the machines."
Proper coolant management is an important part of Schwab's successful coolant switch, Winker adds. "We check refractometer readings once a week in each of our sumps to make sure we have the right coolant concentration, and we make sure to remove tramp oils," he says. Removing tramp oil prevents rancidity and "Monday morning odor," and reduces coolant replacement and disposal costs.
Schwab's removes tramp oil with a Rustlick SC3000 portable separator, also from ITW Rocol. "We run it for two to three hours every other week," Winker says. "The portable design makes it easy to relocate and share the unit for multiple machines. It can be moved simply by making one hose connection and a compressed air line connection. The unit can be run while the machine tool is operating to avoid machine downtime, he adds.
This article was first published in the June 2004 edition of Manufacturing Engineering magazine.