Masonry Magazine November 2004 Page. 26
Saw BLADES
Manufacturers produce blades for specific applications.
The American National Standards Institute (ANSI) Code B7.1 and B7.5 guidelines set maximum operating speeds. Never operate a blade above the maximum or "Do Not Exceed" revolutions per minute (RPM) stamped on the blade. Failure to comply with this warning is dangerous and can result in injury or death. When in doubt about the correct operating speed for a particular material, it is better to choose a lower speed rather than a higher speed. Once the blade is cutting well, the speed can be increased to optimize the life of the diamond blade.
Material to be Cut
KNOWING AS MUCH as possible about stone, brick, block, ceramic or combinations of these masonry materials can be of enormous benefit to the cutting operator and the tool manufacturer.
Blades used to cut hard masonry materials should have segments with tough diamonds and a soft metal bond matrix. Otherwise, the diamond particles will wear even with the bond surface and the blade will glaze over and be unable to cut. Likewise, segments for cutting soft materials should have hard metal bonds so that the diamond particles are not lost before their cutting life is used up.
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DIAMOND BLADE OPERATING SPEEDS
| Blade Diameter (inches) | Blade Diameter (mm) | Operating Speed (RPM) | Maximum Safe Speed (RPM) |
|---|---|---|---|
| 4 | 102 | 9,072 | 15,000 |
| 4½ | 114 | 8,063 | 13,300 |
| 5 | 127 | 7,257 | 12.000 |
| 6 | 152 | 6,048 | 10,000 |
| 7 | 178 | 5,184 | 8,500 |
| 8 | 200 | 4,536 | 7,500 |
| 9 | 228 | 4,032 | 6,800 |
| 10 | 254 | 3,629 | 6,100 |
| 12 | 305 | 3,024 | 5,100 |
| 12 High Speed | 306 High Speed | 6,300 | 6,300 |
| 14 | 358 | 2,562 | 4,400 |
| 14 High Speed | 356 High Speed | 5,400 | 5,400 |
| 16 | 406 | 2,258 | 3,800 |
| 18 | 457 | 2,016 | 3,400 |
| 20 | 500 | 1,814 | 3,000 |
| 22 | 500 | 1,548 | 2,800 |
| 24 | 610 | 1,512 | 2,500 |
| 26 | 660 | 1,396 | 2,300 |
| 28 | 711 | 1,296 | 2,300 |
| 30 | 762 | 1,210 | 2,000 |
| 32 | 813 | 1,134 | 1,900 |
| 36 | 914 | 1,008 | 1,800 |
| 42 | 1,067 | 854 | 1,500 |
| 48 | 1,219 | 756 | 1,200 |
Figure 5- Diamond blade operating speeds
Troubleshooting
IN THE EARLY DAYS of cutting there were many misconceptions based upon a lack of technical knowledge. The introduction of synthetic diamond has allowed the industry to advance its technology and professionalism; however, there are still a number of common problems encountered in the field today.
Loss of Tension
THE LOSS OF TENSION in a diamond blade can be caused by many factors. The blade core could have become overheated from a lack of sufficient water being applied to the blade or a lack of side clearance that results from uneven segment wear. The operator should check that the water supply is adequate and that it is reaching the core near the collars and sheeting out to the cutting area. The operator should use a blade with more side clearance and suited to the cutting application.
Blade tension may also be lost when a blade is not aligned correctly on the saw, the blade flanges are not of the proper size, or the blade is not properly mounted on the arbor shoulder, causing the blade to bend when the flanges are tightened. The operator should make certain that the flanges are clean, the proper size, and properly mounted and secured.
Segment Loss
OVERHEATING OF THE BLADE can cause segment loss. This is often the result of a lack of enough water being