Boosting band saw blade life
Guidelines to follow on the shop floor
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.
Select the Right Tooth Size for the Job
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.
Break in Blades
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.
Choose the Right Blade
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.
Consider Material Machinability
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.
Check Your Speed
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:
- Inspect the chips. Typically, chips should be brightly colored, not blue or brown. Chips should have some mass to them, be moderately or tightly curled, and never be powdered (see Figure 2).
- Listen to the machine. Squealing or grinding sounds often are indications of overfeeding and blade strain.
- Make sure the coolant flow is sufficient and covers the cutting surface. Follow your coolant supplier's recommendations concerning how rich the cutting fluid concentration should be for different materials.
- Keep the machine clean. Make sure the chip brush is working. This is the wire brush that helps clean chips stuck in the gullets. The brush also prevents chips from building up in the band wheel drive mechanism. If the blade comes back around with chips loaded in the gullets, the blade will rub the material rather than cut it.
- Follow manufacturer-suggested maintenance schedules and safety recommendations. It's worth the time and ultimately can save you money in machine downtime and injuries.
- Take care of blades when they are not in use. A few commonsense guidelines can help you improve blade performance and cut your costs even when blades are not in use. For example, it helps to release the tension on blades when they are idle during off-shifts. When storing blades for longer periods of time, it's a good idea to spray them with a common rust preventive. This usually isn't necessary for new blades because most are coated before they are shipped.
- Be careful when handling your blades. The fastest way to cut a blade's life short is to drop it on a cement floor.
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.
Practical Welding Today
Practical Welding Today was created to fill a void in the industry for hands-on information, real-world applications, and down-to-earth advice for welders. No other welding magazine fills the need for this kind of practical information.