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HomeMy WebLinkAbout306.010 - Diamond BladesSection 306.010 ADA Effective Date: November 2008 Current Revision Date: 3/30/2022 Next Revision Date: 3/30/2024 Page 1 of 7 300 Training and Equipment Manual SECTION 306.010 DIAMOND BLADE PURPOSE The purpose of this policy is to provide Fresno Fire Department (FFD or Department) members with guidelines for safe operation of saws with diamond blades. APPLICATION Contents of this policy apply to all members while operating saws with diamond blades during maintenance, training, or emergency operations. OPERATIONAL POLICY This section intentionally left blank. OPERATIONAL GUIDELINE This section intentionally left blank. PROCESS Set Up: Diamond blades are for use on the K-12 or the K-950 saws. They have a removable arbor just like the metal and masonry blades. The K-12 saw uses a 7/8-inch arbor and the K-950 saw uses a 1-inch arbor. (See Figure 1.) Figure 1 Fresno City Fire Department Section 306.010 ADA Effective Date: November 2008 Current Revision Date: 3/30/2022 Next Revision Date: 3/30/2024 Page 2 of 7 Remove the blade just like the metal or masonry blades and replace with the diamond blade. (See Figures 2 and 3.) Figure 2 Figure 3 Diamond Tool Construction: There are three main methods by which diamond blades are made. 1. Sintered This is the least costly method of making a diamond bit or blade. The entire tool is heated along with the metal containing the diamonds and the metal matrix “fuses” to the steel core in a permanent mold, reducing “build time.” (See Figure 4.) Figure 4 2. Brazed Section 306.010 ADA Effective Date: November 2008 Current Revision Date: 3/30/2022 Next Revision Date: 3/30/2024 Page 3 of 7 The brazing process allows for much denser and higher temperature manufacturing of individual segments. These segments are then individually brazed, or silver soldered to the steel core of the diamond tool. This is a much more labor-intensive process but allows much flexibility in how hard or soft the metal matrix is. (See Figure 5.) Figure 5 3.Laser Welded Like the brazing process, each segment is individually made and then welded (fused) to the steel core of the diamond tool with a high- powered industrial laser machine. This is a quick process but requires a machine costing several hundred thousand dollars. (See Figure 6.) Figure 6 Cutting Process: The process of “cutting” with a diamond tool is not a cutting process at all, but instead is a grinding process where the diamonds scratch the concrete into fine powder. (See Figure 7.) Section 306.010 ADA Effective Date: November 2008 Current Revision Date: 3/30/2022 Next Revision Date: 3/30/2024 Page 4 of 7 Figure 7 Dry vs. Wet: Whenever possible, it is preferable to cut wet instead of cutting dry because of the respiratory danger associated with breathing dust and the possibility of over-heating the tool if using a powerful machine. Dry blades work better at higher rpm, so air cools them better and dust gets thrown off the tool faster, reducing friction. Cutting with a dry tool is a process using low to medium pressure for a few seconds and then free spinning the tool in the air for a few seconds, allowing the tool to cool. (See Figure 8.) Figure 8 Cutting Characteristics: There are many factors which affect the cutting speed and wear rates of diamond tools. Some of the most important factors are: 1.Diamond Tool RPM (See Figure 9). a.If the tool does not wear at the proper rate, the diamonds cannot fall out at the proper rate and eventually the cutting of the tool can slow down as the diamonds lose their sharp edges. b.If the diamond tool rpm is too low, the metal matrix may wear faster than necessary, allowing the diamonds to fall out of the Section 306.010 ADA Effective Date: November 2008 Current Revision Date: 3/30/2022 Next Revision Date: 3/30/2024 Page 5 of 7 matrix before their ability to cut is fully utilized. Figure 9 2.Tool pressure against the material being cut. (See Figure 10.) a.Light tool pressure may allow the diamonds to dull without exposing new diamonds quickly enough, causing the tool to cut slowly. b.If excess pressure is used, the matrix may wear away too fast, allowing the diamonds to fall out of the matrix too quickly, causing the tool to wear out quickly. Figure 10 3.Type of aggregate in the asphalt or concrete being cut. (See Figure 11.) a.Limestone aggregates are soft and usually only slightly abrasive and can be cut at higher rpm for good tool life and fast cutting speed. b.Flint and chert aggregates are hard and usually cut better at Section 306.010 ADA Effective Date: November 2008 Current Revision Date: 3/30/2022 Next Revision Date: 3/30/2024 Page 6 of 7 lower rpm. Figure 11 4.The type of sand in the mixture of asphalt or concrete. (See Figure 12.) a.Sharp sand wears away the metal matrix more quickly than rounded (riverbed) type sand. Use higher diamond tool rpm, less tool pressure, and lots of water (if wet cutting) to help minimize this matrix wear. b.Dull sand may cause the matrix to wear away too slowly, causing the tool to cut slowly. Slowing the rpm down, putting more pressure on the tool, and minimizing the cooling water flow can help keep the tool “open” and cutting properly. Figure 12 5.The toughest cutting is a situation where the aggregate being cut is very hard and the sand is very sharp. (See Figure 13.) a.This situation is difficult and requires careful operator attention to the cutting pressure, rpm, and water flow (if wet cutting) to get a reasonable balance between cutting speed and tool life. This type of cutting situation can cause diamond tools to be used up at two to five times the normal rate. Section 306.010 ADA Effective Date: November 2008 Current Revision Date: 3/30/2022 Next Revision Date: 3/30/2024 Page 7 of 7 Figure 13 INFORMATION This section intentionally left blank. DEFINITIONS This section intentionally left blank. CROSS-REFERENCES No cross-references recognized.