Guidelines to follow on the shop floor
August 10, 2004
Because intermittent cutting can be hard on blades, you should find ways to increase blade productivity for your environment. Several guidelines, such as selecting the right blade tooth size, breaking in the blades, and choosing the right blade for the job are ways to help improve the productivity of your band saw blade.
Fabrication, welding, and machine shops frequently use band saw blades to make just a few cuts in a variety of materials. Cuts are made as the need arises rather than based on a predetermined high-volume cutting schedule.
Because this type of intermittent cutting can be hard on blades, you should find ways to increase blade productivity.
The following tips may help you increase blade productivity, saving you time and money.
The tooth size is the single most important choice in optimizing blade efficiency. Remember, a large tooth can work in a small cross section, but a small tooth can't work in a large cross section. If teeth are too small, gullets clog with material before the blade exits the cut. Full or clogged gullets cause teeth simply to rub across the surface, instead of actually cutting. This creates more heat and prematurely dulls teeth.
It's better to be safe by selecting a larger tooth size to ensure chips are removed throughout the cut. As a guideline, between six and 12 teeth should be engaged in the material being cut (see Figure 1).
To choose the right band saw blade for the job, consider the material's width, diameter, or wall thickness to determine how many teeth per inch are needed.
Guideline No. 2 for increasing blade productivity is to break in the blade to prepare the cutting edge before full-speed operation. Picture a highly sharpened pencil. If you put that pencil to paper and apply force, the tip will be damaged and may even break.
The same is true for saw blades. When cutting with a new blade, reduce the amount of force used to push the blade into the material. Feed the blade at half the normal feed pressure for about the first 50 to 100 square inches of material being cut. Breaking in your blade this way can help reduce damage and increase blade life, resulting in more productivity and lower costs.
Matching the blade to the material being cut also increases cutting efficiency and productivity. However, in the real world you often don't have the time or a big enough blade selection to make these blade changes. Instead, consider choosing a good, general-purpose blade that can cut multiple materials. Some blades are suitable for general cutting applications on a variety of different materials. Variable-pitch blades work best. The most popular tooth size for these blades is a 5/8 variable pitch, but 4/6 and 6/10 variable-pitch blades also work well.
General-purpose cutting applications in welding and machine shops usually subject blades to more abuse than production-type applications. Some users cut faster and with more force than recommended, and constantly changing materials is tough on cutting edges. For these reasons, choose a good bimetal blade. Blades made with high-speed steel cutting edges are the most common for general-purpose applications because they can stand up to abuse.
Remember that you can't cut every material at the same speed. Materials with lower machinability are harder to cut and so they need to be cut at lower speeds. The material's machinability depends on its chemical composition. For example, stainless steel, which has large amounts of chrome and nickel, has a lower machinability and must be cut more slowly than carbon steel, which contains only trace amounts of alloys.
To determine your material's machinability, consult a manufacturer's guide or blade catalog. Don't guess; the wrong cutting speed can wear out blades quickly.
Once you know how fast you should be cutting, make sure you actually operate the saw at that speed. If your correct speed is cutting at 10 square inches per minute and you're cutting 10 square inches, your cut should take one minute.
The best way to determine this is to use a stopwatch and time a few cuts to make sure you're cutting at the optimum rate. However, it's common in many welding or machine shops to make only one or two cuts at a time, so it's usually impractical to start timing those cuts.
|Chip Form||Chip Condition||Chip Color||Blade Speed||Blade Feed||Other|
|Thick, Hard, and Short||Blue or Brown||Decrease||Decrease||Check Cutting Fluid and Mix|
|Thin and Curled||Silver||Suitable||Suitable|
|Thin and Tight Curl||Silver||Suitable||Decrease||Check Tooth Pitch|
In addition to the preceding guidelines, you should:
Optimizing band saw blade efficiency isn't hard if you follow a few basic guidelines. These tips will help keep your blades in shape and cut your band saw blade costs.