Pursuing a plate-cutting saw
Employees team up to make a buying decision
Metal Cutting Service, City of Industry (Los Angeles), Calif., specializes in sawing metals. President David Viel explained the company's strategy: "We do not buy or sell anything, we just add value to others' products." Although it does very little advertising, the 26-employee company has customers throughout the U.S., Europe, and Asia, even though the cost to ship material can be substantial.
|Metal Cutting Service's custom-made saw has a built-in laser that aids setup.|
The nature of the company's business shifted substantially during the 1990s. To adjust to the changes, Viel recognized that the company would need to research, specify, and purchase a new saw. He also recognized that the best people to help with such an ambitious project were the company's employees.
Shifts in the Business
A large portion of the shop's business comes from aerospace companies and metal distributors. Shifts in product demand in these two customer segments necessitated a change in equipment to meet their changing needs. For instance, throughout the 1990s aerospace manufacturers moved toward using thicker, wider pieces than they previously used. A trend among metal distributors was reducing inventory of barstock by replacing it with larger inventories of plate, which can be cut in many different sizes.
Viel attributed the inventory shift to three factors. First, steel mills were producing less barstock, so it became more difficult to buy the variety of sizes needed to meet customer demand. Second, storing plate rather than several sizes of bar of the same alloy reduced the amount of inventory. Third, more service centers were filling a niche by providing economical, accurate sawing and timely deliveries.
To establish specifications and select a new plate saw, Viel assembled a team of employees who would use the new equipment. The team comprised the plant foreman, the proposed saw's operating manager, maintenance personnel, and the company's CEO.
To begin the selection process, the team compiled a list of the features they wanted in the new plate saw. Among the most important were extended-length capability, thicker-plate capacity, and the ability to operate the saw by remote control.
|Operators use a remote control to position workpieces on the saw bed.|
Team members spent four and a half months evaluating potential suppliers and visited seven saw manufacturers in the U.S. and Canada. They discussed what they wanted and got suggestions regarding what could be designed and built that would improve the company's plate-sawing capability.
The team selected DoALL Co. to build a custom saw capable of cutting material up to 20 feet long, 50 inches thick, and 97 in. wide and with a table that could handle stock weighing up to 48,000 pounds. This was a substantial step up for the company; the maximum cutting capability of its existing equipment was 13 ft. long, 35 in. thick, and 48 in. wide; the maximum workpiece weight was 30,000 lbs.
The remote control, a requested feature, would assist with cutting unusual shapes.
"The remote control unit is like the control box for a radio-controlled airplane. With the blade shut down, the operator can stand on the cutting table and use the controller to position the workpiece precisely where it's needed to make a cut. It's an important feature for us since many of the jobs we do call for sawing irregularly shaped polygons from thick plate," Viel said.
|Operators can program up to 9,999 cuts for unattended operation.|
Notch-cutting capability was another feature the design team required. The saw was designed with controls that can be set to make notch cuts. A sensor finds the beginning of the cut and a linear scale measures the cutting length.
Getting the Most From the Saw's Features
An operator loads plate onto the saw bed via a forklift. Pneumatically powered lift rollers help the operator move the plate against the backgauge assembly.
The operator is aided by a built-in laser marker that shines a bright line down the length of the stock. This helps ensure the top crop removes only the undesirable portion of the workpiece. After trimming, the controls can be set to run the saw unattended. The control can store instructions for cutting up to 20 different widths and a maximum of 9,999 cuts. Because the saw is fitted with a band break safety switch that automatically stops the machine when a blade breaks, it can be programmed for unattended sawing for multiple-piece cutting jobs.
Many industrial band saws use either 1 12- or 2-in. blades. This saw is unusual in that it can use either a 2- or a 2 58-in. blade. The 2 58-in. blade is stronger than a standard blade so it can be tensioned at greater pressures. While many blades are tensioned at 30,000 pounds per square inch (PSI), the new saw is factory-preset with an internal hydraulic band tension system at 39,000 PSI. Greater tension means greater blade beam strength and less blade deflection.
The saw head is designed to accommodate quick blade changes, and experience has made quick changes quicker still. Since getting the saw, employees have learned to cut the blade-changing time by more than half. "When we started out, it took us about 20 minutes to change blades. We're experienced enough now that we've cut changeover time to just under nine minutes," Viel said.
"We've used this new plate saw to cut about every metal imaginable," Viel added. "And we're picking up jobs now that previously we were unable to handle. Not long ago we received some bimetal plate that had a 2 12-in. steel core and a 1 18-in. stainless cladding. The plate measured 120 in. wide by 250 in. long, and we were asked to cut it to 13-in. strips. It wasn't a problem. Since the saw head moves along linear ways while the workpiece remains stationary, all we had to do was put the plate on the table and start sawing.
|The saw cuts workpieces up to 20 ft. long, 50 in. thick, and 97 in. wide. It accommodates up to 48,000 lbs. of stock.|
"If the saw head was stationary while the workpiece moved through it, we wouldn't have been able to do the job. It would have meant starting at one end of the stock extending 250 in. from the saw head and then pushing the workpiece through until it extended another 250 in. out the back of the head. That's over 40 ft., which is more than we have room for in our facility. This saw takes up only half that amount of space.
"Other jobs we've done with it are sawing a 46-in.-high stack of aluminum alloy and a 10-in.-high stack of 2-in. titanium plates. With the positive feed of the blade, stacking plates is not a problem as long as they're flat. When sawing multiple plates that are not perfectly flat, we use the T-slots built into the saw's bed to attach clamps that hold the workpieces.
"Another of the more unusual jobs was splitting titanium plates into two pieces. The stock was only 5 in. thick, but it came in 33-in. by 75-in. plates. To split it, we stood it on the 75-in. edge so the plates were 33 in. high by 5 in. thick. We cut the plates into two pieces each nominally 2 12 in. thick and were able to do the job at 6 sq. in. per minute using a carbide blade.
"When we move to a metal like aluminum, we can adjust the blade speed up to its maximum 360 feet per minute and get cutting rates in the 30- to 50-sq.-in.-per-min. range, as we recently did with a 20-in.-thick aluminum workpiece."
A Home Run for the Home Team
Viel said that if he had to go through the process of buying another plate saw, there is little he would change. He'd still form a team to set the specifications and let them make the buying decision. Since the day the machine arrived at Metal Cutting Service, the employees using and maintaining the machine are more than satisfied with its performance because they helped design it. It imparts a feeling of accomplishment.
"When you let workers decide what they need to get a job done, they do a thorough job of evaluating their needs. After all, they're the ones who have to live with the decision day in and day out," Viel added.
Metal Cutting Service, 16233 E. Gale Ave., City of Industry, CA 91745, 877-METALCUT, fax 626-333-4051, www.metalcut.com.
DoALL Co., 254 Laurel Ave., Des Plaines, IL 60016, 800-955-8191, fax 847-824-4340, www.doall.com.
The FABRICATOR is North America's leading magazine for the metal forming and fabricating industry. The magazine delivers the news, technical articles, and case histories that enable fabricators to do their jobs more efficiently. The FABRICATOR has served the industry since 1971.