Sawing cuts it close.
Sawing is a streamlined operation in the modern shop. Cold saws, and many bandsaws, too, now machine to the high accuracies of many other machine tools. "Designed with an integrated material-handling system, our saws convert raw material to finished product in accordance with the customer's required tolerances." That's what Bruce Rowland of Metl-Saw Systems Inc, Benicia, CA, told T&P in response to a survey.
Mr Rowland adds, "Our systems allow service centers to take the lead in industry trends. They change steel from a commodity to a finished part, eliminate the customer's need for subsequent machining, and change the focus from price to quality. The industry's future, including its technology and economics, seems to point to more of the current trend: service centers making the transition from cost-adding distribution centers to value-adding producers of finished parts."
Which saw are you most likely to use? The majority of respondents to the T&P survey said that bandsaws are the best choice for most applications. Lloyd Shanks of DoALL Co, Des Plaines, IL, notes, "Although circular saws and hacksaws still maintain niches of effective application, for most cutoff operations, power bandsaws offer the greatest value by far."
Just what is power sawing? According to DoALL, it's the automatic cutting to prescribed length of multiple pieces of steel (or other materials) from round solid bar, pipe, tubing, and structural or other shaped metal stock. But saws can do more. The firm offers contour bandsaws and blades that can perform milling-type operations under CNC control.
Major developments in bandsaw equipment include compact design, NC operation, serviceability, and use of wider and thicker blades to achieve greater beam strength. Compact saws take less floor space and are easier to relocate, and one-piece design can eliminate alignment problems, according to DoALL. For service, modular construction provides easier access to electrical, hydraulic, and coolant systems.
Going a step beyond NC, many firms provide custom-designed power-saw systems with full CNC units, where virtually all machine functions are computer-controlled automatically. Information input includes size and type of raw stock, required length, and number of finished pieces. The computer translates this into specific machine settings, including feeds and speeds, guide-arm and work-height adjustments, and rapid-approach control.
After CNC, the next step is the untended flexible machining cell. According to Marvel, "The 21st century evokes many images. At Armstrong-Blum Mfg Co, Mt Prospect, IL, the upcoming century inspires images of a totally automated factory, a factory under the complete control of only two or three operators who sit atop their control booth removed from the whir and hum of the machinery below. From their computer terminals, the operators command machinery linked together in a network of cells comprised of a collection of components including the Marvel saw.
"This factory exists only in the future; yet some of its modular technology exists today. For example, cells - collections of compatible machines - function in some of today's more sophisticated factories. Marvel engineers have long recognized the value of cells and have succeeded in modifying their saws for integration with other machines."
The firm believes that 90% of all industrial sawing can be accomplished with bandsaws. They require lower initial investment than cold saws, and blade-replacement cost is low. Finally, Marvel says that bandsaws successfully meet the tolerance requirements of most sawing applications.
Amada Cutting Technologies Inc (ACT), La Mirada, CA, offers the Systems Bandsaw, said to provide sophisticated automation without complex engineering. You don't have to completely revamp current operating procedures to use it. And it cuts 12 1/2"-dia rounds, fed by a magazine with 10-ton loading capacity.
The quality cut
Will the best machine tool give you the best quality? Ian Tatham, president of Hyd-Mech Saws Ltd, Woodstock, Ontario, says his machines have a unique swing head that allows the cutting head of the saw to swing from 90 to 40 degrees (five past 45 degrees).
As to quality, Mr Tatham says his machines have high quality in spite of low cost. In fact, he says, "Performance of all the high-quality bandsaws is pretty much equal. Nobody can cut any faster or have a better quality finish than anybody else because we're all limited by the same basic principles."
Nevertheless, he believes you should study the basics when buying a saw. Look at design, performance, and cost. "The design, he says, should be simple. The simpler it is, the easier it is to operate and repair the machine."
What are the real, practical tolerances? Wellsaw Div, Robot Research Corp, Kalamazoo, MI, is announcing the low-cost Wellsaw(R) Model 1216A bandsaw with special control to automatically cut predetermined amounts up to 999 pieces from wafers to 24" length. Part length can be set to 0.001" within the overall cutting range (which can be tripled by multistroke indexing). It handles rounds to 12 3/4" or shapes to 12" x 16".
Analyze your needs
In choosing the best power bandsaw, DoALL offers a free sawing analysis service that can save days and weeks of comparative testing. Using a computer databank of application information gathered over decades of experience, it analyzes existing, or proposed, installation by taking into account all of the many variable factors in power sawing. The resulting analysis provides accurate cost-per-piece figures broken down into machine, blade, cutting fluid, and operating segments. The analysis uses honest assumptions such as a 50-minute hour, single-shift operation, and five-year depreciation, so the results are conservative and justifiable.
CooperTools, Raleigh, NC, a part of Nicholson, The Cooper Group, Apex, NC, offers a similar program for selecting bandsaw blades. The "Service With Advanced Technology" or SWAT team approach uses computer software to help answer questions about blade type, coolant, feeds, and speeds. The computer even offers advice on how to break in the blades and troubleshoot production problems.
Trouble can come from out-of-true wheels, lack of proper bandsaw guides, and improper blade resharpening. Industrial Saw Manufacturing, Compton, CA, offers Tuf-Edge blade reconditioning, which includes resetting and heat treating. The firm also offers ballbearing bandsaw guides, bandsaw tires, aluminum bandsaw wheels, and accessories such as backstand idlers and belt-grinding adapters.
Other items you will need include soluble oils, heavy-duty synthetic concentrates, and cold-air guns for use where liquid coolants are not practical. DoALL's vortex tube, for example, works from shop air and produces 2000 Btu of cooling.
Carbon-steel bandsaw blades are probably on the way out. For instance, American Saw & Mfg Co, East Longmeadow, MA, says its Lenox Diemaster 2 bimetal blades last up to ten times longer than carbon steel when cutting all materials. They resist heat, wear, and fatigue better in high-speed or high-heat operations. High-strength spring-steel backs make the blades last longer and simplify internal contour cutting.
DoALL agrees, noting that some carbon-alloy bandsaw blades may still serve smaller cutoff saws in nonproduction applications, but the more-costly bimetal blades are the most popular for production work.
In recent years, the best cutting-edge materials have included M42 cobalt and matrix-cobalt high-speed steel. "It's not expected that the materials used to make bimetal blades will change significantly in the 1990s," says DoALL's Lloyd Shanks. "Improvements will come from coatings and changes in the shapes of the teeth and the band itself. Of course, TiN coatings on bimetal blades protect the HSS cutting edges by adding a layer of very hard, very wear-resistant, very slippery material. TiN keeps the steel from feeling the effects of the high temperature and pressure in the cut."
Another advance in saw technology will come in greater use of carbide-tipped blades. These blades have been around for some time, says Mr Shanks, but application has been limited. When engineers develop better methods of attaching carbide to the steel body, he believes that carbide blades will begin to fulfill the promise of long cutting life at faster rates on tough materials.
Additional tooling considerations include use of blades with variable pitch to offer smoother, quieter cutting. Amada's Hi-Lo [TM] bandsaw blade cuts work-hardening materials efficiently because it reduces heat by avoiding constant tooth contact on the same cutting plane.
Finally, blades will continue to get wider and thicker to provide greater beam strength. New machines can cut faster while handling larger workpieces, so the bandsaw tools must be stronger to match. On the other hand, the bandsaw machines must have the horsepower and rigidity to fully drive the new band tools to fully tension the blades.
Hot and cold sawing
Most of the responses to the T&P survey talked about bandsawing, but circular cold saws represent an important segment of the industry. Here the individual blades perform much like milling cutters.
Many cold saws include cell systems similar to those for bandsaws. For instance, IBP Equipment Corp, Wabasha, MN, provides the Simec Model 315 circular saw to cut tubular and bar stock in ferrous and nonferrous materials automatically. It cuts tubes up to 4 3/4" dia, and bars to 4", with maximum lengths to 78". The system employs an automatic roll-type material feeder, and its bar infeed works at 46 fpm. A pneumatic anti-burr vise ensures positive workpiece alignment and grip.
Wagner Machinery Corp, Middlesex, NJ, offers the LSCR 140 automatic storage and sawing center, which deals with job-order management, sawing, storing, transporting, and distribution of bar stock and cutoffs. Most models employ the WA-140-CNC circular cold saw with either carbide-tipped or HSS segmental saw blades. But you can also get the system with a bandsaw. Other systems include a CNC Saw/Drill line.
W J Savage Co, Knoxville, TN, redesigned its abrasive saw, which cuts hot and fast. The Guillotine Mark II boasts a horizontal-pivot design that optimizes cutting and clamp geometry.
For wet or dry operation, it slices ferrous-alloy round or square bars to length, and it machines at 1 to 2 sec/sq in. It has smoke-scrubber options, and a laser guide light. Its computer control measures the blade and calculates G ratio after each cut, and it maintains constant peripheral speed.
Kaltenbach Inc, Columbus, IN, points out that no sawing system is complete without proper tooling. The firm's special V tooling helps cold saws cut solid rounds and round tubing at rates to 1995 pcs/hr. Slicing through a stack of tubes or bars, the system holds length accuracy to [+/-] 0.005" per feed stroke, and squareness to [+/-] 0.0015" per inch of height or width. This is precision productivity to rival many machine tools.
PHOTO : Critical cutoff gets a boost from computer guidance. NC also promotes safe operation.
PHOTO : DoALL tungsten-grit band tool at work.
PHOTO : Wagner LSCR 140 automatic storage and sawing center streamlines cutting-room operation. It's shown here with a WE-140-CNC cold-sawing machine. It handles distribution of both bar stock and cutoffs.
PHOTO : The W J Savage Guillotine Mark II abrasive saw features compact design that integrates hydraulics, electrical controls, and coolant into one frame. Waist-high position allows easy blade change.
PHOTO : Kaltenbach V tooling boosts production of rounds 1/4" to 3/4" in dia. Here, it holds 36 solid bars for multiple cuts with an ascending blade.
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|Author:||Miller, Paul C.|
|Publication:||Tooling & Production|
|Article Type:||Cover Story|
|Date:||Oct 1, 1991|
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