February 2025 Volume 7

EQUIPMENT & TECHNOLOGY

example, if you have a one-inch piece of cast aluminum and put three teeth into it, it’s going to cut through it without any issues. Too many teeth will cause a problem as well. When cutting two-inch hard, abrasive steels, or compacted graphite iron (CGI) with a 10/14 pitch, it will be a very slow process and the teeth will rip off due to the gullets and teeth loading up with material. When there is a chip load on each tooth, the gullet capacity needs to be adequate so that the tooth can penetrate, fill up the gullet and evacuate the chips. When cutting Inconel, it is so hard that there should be more teeth engaged in the material.

Since Inconel does not produce a big chip, there will not be issues with filling up the gullet. Challenges arise when trying to cut a wide range of materials with one blade, and trying to come up with a middle ground for tooth pitch. It is best to consider the mate rial you are cutting most often and then get yourself within the ballpark. A constant pitch blade (uniform distance from one tooth tip to the next tip) can increase harmonic vibrations. Harmonic vibrations can lead to excessive noise, unde sirable saw or saw blade vibrations and in severe cases, bad cuts. When considering

Starrett Advanz™ FS Carbide-Tipped Band Saw Blades offer precision and versatility for degating and other abrasive processes. Tips for Extending Blade Life Break-in the Blade Taking the time to break-in a saw blade is well spent and we recommend that this step is always performed. The process to break-in a band saw blade will vary depending on the characteristics of the material being cut. While breaking-in a blade, have the machine running at the normal surface feet per minute (SFPM). For harder materials, such as nickel-based alloys including Inconel, or other diffi cult materials such as hardened steels, tool steels and stainless steels, adjust the feed pressure to 75% of the normal cutting rate for 25-75 square inches. Gradually increase the cutting rate to reach 100% after 50 square inches. As the feed pres sure is increased to the 100% cutting rate, be careful to avoid creating vibrations that can occur by increasing the rate too quickly. Cutting Fluid Considerations Cutting fluid, a.k.a. coolants and lubri cants, is important in band sawing opera tions because it cools the blade, lubricates the teeth and washes chips away. Without it, a blade would likely overheat, wearing out the teeth faster with chips filling the blade gullets, which leads to blade stress, tooth breakage and inferior cuts. A rich cutting fluid solution does a better job coating and lubricating the blade throughout the entire cut. Coolant should wash over the blade as it enters and exits

the cut, re-circulating throughout the cutting process. Water will evaporate from the mixed solution, so replace it as needed. Also, keep an eye out for chips that fly into the machine and block coolant flow, as well as system leaks – all of which can also cause problems. When the use of cutting fluids isn’t possible, such as with vertical machines, consider using a lubricant stick to apply on the teeth of the blade. This will reduce heat build up and extend the life of the blade. Proper Feeds and Speeds Proper feeds and speeds are necessary not only for blade life and sawing production, but also for the surface quality of the piece being cut. Blade speed should be estab lished based on the type of material. If the speed is set too low, the teeth can over penetrate which will put excessive stress on them, eventually causing the teeth to strip. Running a blade at too slow a speed will result in teeth with loaded chips, allowing the teeth to “walk”. Too fast a feed rate will also cause the teeth to load, producing a similar outcome. It is also important to refer to cutting recommendations from the saw machine manufacturer. Establish the Right Tension Tension should be set to the machine manufacturer’s recommendations and a blade tension gauge should always be used to check it. Most production machines require between 28,000-32,000 psi of blade tension. Low blade tension allows

the blade to “walk”, bowing the blade as it travels between the guide arms which may cause cracking in the back of the blade. Without adequate and proper blade tension, the beam strength will be insuf ficient to hold the blade straight, resulting in crooked cuts. Brush Off the Blade Most saw machines have a rotating wire brush that clears chips out of blade gullets while the blade is cutting, helping to extend blade life. It is important to keep the brush in good working condition, and it should be positioned close to the drive wheel. The brush needs to be close enough to the blade for the filaments to effectively remove chips from gullets. However, do not set the brush too close to the blade because the hard-hitting filaments could prematurely dull band saw teeth. A brush set too close to the blade could also wear itself out and quickly become useless. The brush should reach in and touch without going beyond the deepest part of gullets. Starrett 682EMZ Saw Tension Gage

FIA MAGAZINE | FEBRUARY 2025 16