Metal Cutting Bandsawing Myths
A positive rake tooth is weak
It is true that the cross-section of a conventional tooth has more “beef” than a milled positive rake tooth. However, the positive rake angle reduces the force that can chip or strip a tooth creating an advantage and the need for the extra cross-section as it does not need to have the same strength to get through the material being cut. The best use for a positive rake tooth is on difficult to cut materials.
On larger cross-sections (long workpieces) a skip and/or hook tooth blade should be used because they have a larger gullet than their counterparts.
The total gullet area for a hook or skip tooth on a bandsaw blade is approximately 60% that of a conventional hook tooth. The usable gullet area of a hook or skip on a band saw blade is only about 38% of a conventional tooth with the same pitch. Therefore, the appearance of a larger gullet is only an optical illusion.
D-2 must be cut dry
D-2, a high carbon – high chromium steel, contains a large amount of carbide in its annealed condition. This makes it quite difficult to penetrate and work hardening can become a problem because of its chemistry. Often, too much lubrication from cutting oil can worsen the problem. The best way to cut D-2 is with a water-based soluble oil which will also prolong blade life.
Band tension should always be set at 30,000 P.S.I.
False. It depends on what material you are cutting.
It is true, for most sawing applications a band tension of 30,000 P.S.I. is recommended. This is because higher blade tension makes straight cutting at a higher feed force possible. Increased tension, could then lead to early fatigue or failure. Thus, knowing this, an operator is able to adjust the band tension on the bandsaw blade to suit their own needs.
However, when dealing with a material that is difficult to cut and where tooth life on the bandsaw blade is expected to be shorter, higher tensions such as 40,000 P.S.I. should be used. This is because it will be able to achieve straighter cuts and alow for a higher speed force.
Alternatively, if the material is easy to cut material and the feedforce does not need to be high, then a lower band tension can be used to prevent fatigue failure and prolonging bandsaw blade tooth life.
I have a bandsaw blade that is honed, I don’t need to break it in.
False. The idea of a break-in procedure is to remove any sharp edges and burrs from the band saw tooth. A honed blade is already supposed to have this removed. However, upon testing it has shown that break-in procedure is beneficial and necessary for both honed and unhoned bandsaw blades leading to prolonged blade life.
How to Prolong Bandsaw Blade Life
The most important thing is for you to know what you would like to achieve with your band saw blades in order to select the right blade. These are the factors that must be considered.
It is important to use proper speeds and feeds for the application you are working on as incorrect settings can damage a bandsaw blade.
Not all band saw machines have a speed and feed indictor, the best scenario would be for the metal cutting band saw machine to have a variable cutting speed adjustment, a feed rate regulator and an automatic feed force regulator which can easily help to correct parameters. However, in other cases the saw may just have two speeds, no feed regulator and the band saw blade is the weight of the head.
These are the main choices of coolants:
1. Water-soluable oils
2. Semi-synthetic cutting fluids
3. Synthetic metal cutting fluids.
The best choice depends on the type of metal you are cutting. However, semi-synthetic does work for most applications and is easier to maintain than water-soluable oils and synthetic cutting fluids and is the most widely used coolant.
The operator is also an extremely important the cutting process as they are the most variable piece in the process.
It is integral for them to understand the proper parameters for the band saw blade and the material being cut. If not, there can be a large discrepancy between performance and band saw blade life. Each time the material being cut is changed, the parameters should be adjusted. This could also include a change to the bandsaw blade being used. If the operator does not understand this, then the metal cutting band saw blade can be destroyed in seconds.
The best cutting results can only occur if the metal cutting band saw is in good working order. The following components influence the performance, accuracy and band saw blade life. See our machine maintenance FAQ.