What is your facility cut out for? Circular and band saw purchases depend on application requirements

THE FABRICATOR® APRIL 2001

April 24, 2001

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What cutting equipment you buy depends very heavily on what area of industry you are supplying, throughput requirements, and, not least, finances. Don't let preconceived notions prevent you from making the very best possible decision.

The debate about whether to use a band saw or circular saw has been a long-running and faulty one. A more valid question is which saw is better for a particular job. The two technologies offer advantages for different applications.

Neither application is fundamentally better. Each type of saw exhibits strengths in different areas. You must determine what you want your metal saw to do and make your purchase based on a technical and commercial appraisal of the equipment available.

A fair comparison between band and circular sawing assumes a level playing field. All comparisons made in this article assume state-of-the-art machinery. Likewise, it should be understood that modern, high-quality band saws and circular saws both offer outstanding technical specifications, are capable of superb results, are easy to set up and operate, and are safe.

Comparison Criteria

The basic criteria for comparing band and circular sawing are:

  1. 1. Industrial sector, materials, and surface finish.
  2. 2. Cost per part.
  3. 3. Throughput requirements (parts-per-unit time).
  4. 4. Operational flexibility.
  5. 5. Percentage of miter (angle)cutting.
  6. 6. Financial considerations.
  7. 7. Personal preference.

Industrial Sector, Materials, and Surface Finish

When deciding which saw to use, the first area to consider is the industrial sector in which the machine will be used. In many cases, this dictates automatically which criteria are important.

For example, when handling aluminum profiles, excellent surface finish, very close tolerances, and fast cycle times almost always are paramount. Flexibility is secondary, because the machine always will cut the same type of material. This is circular saw territory, pure and simple.

Carbide-tipped circular machines, running at speeds up to 20,000 surface feet per minute (or speed of the tooth through the cut), make short work of aluminum profiles, and a good machine can provide extremely close tolerances, as well as a mirror surface finish, with a low cost per cut.

As an added bonus, switching to carbide-tipped circular sawing can completely eliminate one or more subsequent machining operations, resulting in cost savings.

In steel service centers, the picture is different. Because of the array of grades, shapes, and specializations handled by the service center, a saw must be all-purpose. The band saw, with a few exceptions, can do most everything.

A high-quality, modern band sawing machine can be thought of as the pickup truck of the metal sawing industry. It never wins the Indy 500, but it gets most jobs done. It also is versatile and relatively inexpensive in terms of initial outlay. In many cases, these qualities count for more than speed, surface finish, or absolute tolerances.

Cost per Cut

Ultimately, of course, speed matters because time is money. Likewise, surface finish and tolerances are subjective, and this is where the gray areas creep in. Reviewing a particular application establishes which sawing technology best suits that application and is based on user requirements.

Each application may have different requirements. Whereas surface finish may be critical to one customer or for one application, it could be irrelevant in another application. This is why a full review of each application is necessary to determine which needs are essential. In turn, this review will determine which technology--circular or band--is more appropriate.

Sometimes, a specific need points to a certain technology. For example, structural sections that are going to be welded do not need to exhibit near-perfect squareness or superb surface finish. Columns for high-rise buildings, on the other hand, do. Either sawing technology can handle both of these jobs, but the circular saw has an inherent advantage in sawing big columns. It will cut them cleaner, straighter, and faster.

If a certain technology isn't indicated by the needs assessment, the commonly used benchmark for choosing a saw is cost per cut, which should take into account all the financial factors that make most applications unique. One important factor that often is overlooked is the efficiency of existing machinery. A new machine under review might be ideal for 85 percent of the proposed work load but useless for the remainder of the work.

If these other jobs can be handled by existing machinery, choose the machine best-suited for the bulk of the work load to avoid an inefficient and ultimately costly compromise. Often, a mixture of technologies is the best solution, assuming that all the necessary machines are readily accessible.

Throughput Capacity

On average, for every ton of structural steel a band saw cuts, a circular saw can cut almost 2 tons. The bigger the standard beam size is, the greater the advantage of using a circular saw to cut it.

This throughput capacity difference might be a deciding factor in what technology to choose if, for instance, your current band saw cannot keep up with the level of cutting you need to do. Options are to:

1. Buy an additional band saw (plus additional handling equipment, space, and labor) or

2. Replace it with a circular saw that uses the same handling equipment, space, and labor but that can produce almost twice the amount of cut steel per unit time.

Operational Flexibility

The band saw is an all-purpose tool. The circular saw, on the other hand, usually is customized to some degree to suit a particular task. Accordingly, the circular saw performs that task more efficiently than the band saw does but loses out on overall flexibility.

Percentage of Miter Cutting

Particularly on smaller materials, a miter-cutting circular saw can be made very compact--yet strong and precise--and therefore easier and quicker to set up on the miter. This is especially true with upstroking machines.

Financial Considerations

For the same material capacity, circular saws are more expensive than band saws in terms of initial investment. However, in many cases, this investment can be offset by the circular saw's higher throughput. In structural steel applications, cost per cut (which takes into account almost all expenses associated with sawing) is lower with a circular saw as long as you assume a full work load.

Financial costs taken into consideration when determining the cost per cut include initial outlay, blades and other consumables, labor-hours, power consumption, maintenance requirements, and life expectancy. Circular saws typically outlast band saws because of their more robust build.

Personal Preference

While seemingly obvious, personal preference should not be underestimated. Some operators are circular saw fans, while others are very loyal to the flexible band saw. This loyalty can be so deep that band saw adherents wouldn't dream of working with a circular saw. Likewise, circular saw followers wouldn't dream of working with a band saw.

Making the Purchase

In terms of metal removal rates per dollar outlay, saws generally are at or near the top of the pile in almost all industrial metal cutting environments, and current high-end sawing machinery offers a sophisticated level of control that matches most mainstream machine tools. While saw purchasing criteria are basic, many factors contribute to the decision because each cutting application is unique. Establishing which technology, or combination of technologies, is right for your operation demands a blend of technical expertise, industrial experience, and commercial acumen.

By evaluating your needs according to the purchasing criteria outlined in this article, you should feel confident that you've made the right purchase.



David McCorry

President
Structural Machinery Solutions Inc.
6775 Inwood Drive
Columbus, OH 47201
USA
Phone: 800-TALK-SAW

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