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RED TURBO - GP saw blade for Brick, Block, Cured Concrete, Field Stones, Roof  Tile, Pavers
RED TURBO - GP saw blade for Brick, Block, Cured Concrete, Field Stones, Roof Tile, Pavers
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Troubleshooting Diamond Saw Blades
Core Cracks

One of the most common blade failures is core crack failure. Core Cracks are a result of the stress put on the core at the root of the notch or gullet from the segments being pushed into the material at the point of initial contact and being pulled out of the cut at the end of contact with the material. This is analogous to bending a piece of wire back and forth till it breaks. Core cracking can not be stopped or eliminated. Blade manufacturers design the blade under normal operating conditions. If during cutting operations the blade is subjected to pounding, twisting, overheating, or other abnormal stresses, core cracks will develop prior to the blade being worn out. The presence of a visible core crack will render the blade unusable. The danger in using a core cracked blade is that for every visible crack there are several cracks that are not visible. Continuing to use a core cracked blade will result in catastrophic failure of the core causing large sections of the core to fly off at energy levels equal to a 22 caliber bullet. A core cracked must not be used . Fig 5 shows a core cracked blade that has two major cracks and several small cracks that under visual inspections may not be visible.

diamond saw blade
"Cracked Core"

diamond saw blade
"Core Crack progression"
 The failure occurs almost instantaneously because the cracks progress slowly until the material separating the cracks can no longer withstand the stresses to it and then failure occurs at the speed of sound in steel which is 19,533.81ft/sec.

One of the leading causes of the core cracks is that the blade specification is to hard for the material being cut. The saw operator has a tendency to push the blade very hard in order to “make” it cut. Eventually something has to give, and many times it is the steel core which cracks. The solution is to check the blade specification and make sure it is the correct one for the material the user is cutting. If the blade has become dull, sharpen it by cutting some soft abrasive material such as asphalt, block or mortar before sawing again.

A misaligned saw or excessive side pressure put on the blade while cutting can cause core cracks. A misaligned saw or excessive side pressure can be detected by uneven signs of wear on one side of the blade core. To prevent this problem make sure that your saw is properly aligned and cuts in a straight line. If, for whatever reason, the blade begins to saw “off-line”, its is easier on the blade (and generally faster), to take the blade up out of the cut and restart the cut on-line. Continually trying to make alignment correction while the blade is in the cut will cause core cracks.

A worn blade shaft or blade shaft bearing can set up a “pounding” effect. Be sure that your saw is properly maintained and that worn blade shafts or blade shaft bearings are replaceed immediately.

Segments Loss

Except for rare instances such as bad weld or undercutting, the reasons that diamond blade segments are lost are impact damage or extreme stress. Let's look at some of the common causes for segment loss.

Material slipping and jamming itself against the blade is a common cause for segment loss, particularly in masonry or tile sawing applications. Many times the break itself will appear very jagged, and damaged to the core itself will be obvious. To prevent this type of damage, the saw operator must make sure that the material is “seated” securely on the saw, and that he holds the material firmly through the entire cutting stroke.

A worn blade shaft or blade shaft bearing is another common is another common cause of segment loss. In addition to loose or broken segments, Theses blades will sometimes show signs of eccentric or uneven segment wear caused by the “pounding” effect in the blade in the cut.

A worn blade shaft can be the result of blades spinning on the shaft which wears a groove in the shaft at the point where blades are normally mounted. With a grooved shaft, The blade drops into the groove when it is mounted on the saw. This means the blade is mounted “off center” and will be jumping up and down in the cut.

This same type of “pounding” effect can be caused by worn blade shaft bearings which allow the blade shaft to move up and down inside the bearing housing.
Both the blade shaft and the blade shaft bearing should be checked regularly. At the first sign of wear damage, Those parts should be replaced.

Inadequate water supply or air coolant is a frequent cause of blade damage. If diamond blades are not properly cooled, they can generate a tremendous amount of heat from friction in the cut. It is critical that saw operators constantly monitor water flow on wet cutting diamond blades, and the entire water system should be checked regularly, including the water pump, water tubes and water jets in the blade guard.

For dry cutting diamond blades, the operator's sawing technique is critical in making sure that there is plenty of cooling air flow around the blade. Dry cutting diamond blades should not be used for one-pass, deep cutting or subjected to continuous cutting pressure. It is important to remember that dry cutting blades are cooled with air, and must be given periodic rest periods (i.e. Removal of cutting pressure) to allow air to remove the heat generated in the cut.

The effects of inadequate water or air coolant on a diamond blade are obvious. Blades will typically have black and blue discolorations around the edge of the blade. An overheated blade can also show other signs of damage such as segment loss, loss of tension and core cracks.

Preventing overheating problems on wet cutting diamond blades is really very simple. The operator must make sure that he has adequate water flow on both sides of the blade at all times. Many times it only takes a few seconds without water for blades to be damaged.

For dry cutting blades, saw operators should make intermittent shallow cuts. If full depth cutting is required, the operator should make several shallow passes (step cut). Dry cutting diamond blades should be used only for intermittent sawing. This means that the blade should be allowed to run free by taking cutting pressure off the blade every few seconds and allowing it to run back up to full speed. The operator must allow air to flow around the blade core to keep it cool.

A miss-mounted diamond blade or loose blade flanges can cause segment loss. The nut or bolt which holds the flanges and blade shaft together on the shaft must be “wrench tight”. If the blade shaft bolt or nut is not tightened securely, the blade may “flutter” on the shaft at high speed. Diamond blades which have lost segments due to loose flanges will sometimes have damaged or distorted arbor holes or drive pin holes.

If foreign material such as dirt sand is between the blade flanges, or if the blade is miss-mounted on the shaft, the blade still may “flutter” on the shaft- even though the blade shaft nut or bolt feels “tight”. Often there is evidence of debris on the blade or flanges, or marks around the arbor hole as evidence of miss-mounting.

Excessive Wear

Sooner or later everyone using diamond blades hears about this one... “the blade wore out to fast”. Before you get to far, make sure that you indeed have a problem. Every user seems to have a different opinion about what is acceptable diamond blade life. Just make sure you understand what is considered good blade life, and what is considered bad blade life.

Assuming there is a problem, the most common cause is simply using the wrong blade specification. If you buy a “hard cured concrete” blade specification, and then uses it to cut asphalt, the blade will wear out very fast. Check the application and then check and make sure you have the right blade for the job.

Insufficient water supply or cooling air can cause excessive diamond blade wear. Make sure that there is plenty of water for cooling wet cutting diamond blades, and make sure proper sawing techniques are used with dry cutting diamond blades. Saw operators need to get into the habit of making sure that there is proper coolant on the diamond blade.
Another cause for excessive diamond blade wear is insufficient power or speed to the blade. Whenever a blade is turning well below the recommended speed range, the blade will tend to wear fast. This condition can be caused by loose drier belts, a lack of power from the engine, or low voltage/amperage going into the electric motor.

To correct this condition make sure that you have adequate voltage and amperage going into your electric motor. Also check belt tension regularly. Voltage and amperage should be checked at the motor. For gas or diesel engines, make sure that they are properly tuned and that they are running at full speed when sawing. The blade user should make sure to match the diameter of the blade to the blade shaft speed of the saw. While it acceptable to use a slightly smaller blade on a given capacity saw, [such as using a 12” (300mm) diameter on a 14” (350mm) capacity saw], A substantially smaller blade used on a larger capacity saw will cause the smaller diameter blade to be turning at a very low speed, decreasing blade life.

Undercutting

Undercutting is a common found in almost every blade application involving the sawing of abrasive materials. Undercutting is caused by abrasive slurry wearing away the steel core, just beneath the diamond segment. The steel core can wear to a “knife edge” which will cause the diamond segments to separate from the core. This condition is found mostly on diamond blades used for asphalt or green concrete pavement sawing. Undercutting can be greatly accelerated when the diamond blade cuts completely through the pavement and into the loose sub-base

While the undercutting problem on a diamond blade is easy to diagnose, preventing undercutting on diamond blades is impossible. A certain amount of undercutting is normal and acceptable on green concrete or asphalt sawing. Further, by adding some type of undercut protection, such as recessed segment blade cores or undercut retardant inserts, the undercutting wear can be slowed down to the point that the user can get full use out of his diamond segments before the steel core wears completely through.

Another means of slowing down undercutting action is to be sure to use plenty of water on the diamond blade. This will help keep abrasive slurry washed out of the cut. When sawing, the user should take care not to cut completely through the pavement into the sub-base. One way for the operator to keep the blade out of the sand and dirt is to watch the color of slurry which flows up out of the cut behind the blade. When this slurry starts becoming very muddy and sandy, he should raise the cutting height of the blade until the water starts to run more clearly. The operator can the proceed with the cut, checking the slurry coming out of the cut frequently.

Other Diamond Blade Problems
The problems we have discussed cover the most common blade problems encountered. The following are a list of other blade problems that you will encounter and are presented in a cause of Remedy format:

Loss of Tension

Cause Blade is used on a misaligned saw
Remedy Check for proper saw alignment.
 
Cause Blade is excessively hard for the material being cut, creating stress on the steal center.
Remedy Make certain that the blade is correct for the material being cut. (consult manufacturer''s recommendation chart or see your dealer)
 
Cause Material slippage causing the blade to twist and become kinked or bent.
Remedy Maintain a tight grip on the material while sawing
 
Cause Utilizing blade flanges that are under size or not the same diameter, creating uneven pressure to the center.
Remedy Make certain that the blade are of proper size and identical diameter.
 
Cause Blade is used at improper RPM, over speeding.
Remedy Make certain the blade shaft is turning at the proper RPM by using a tachometer. This is especially important with concrete saws.
 
Cause Blade is used on a misaligned saw when the flanges are tightened.
Remedy Hold the blade securely on arbor shoulder until the outside flange and nut are firmly tightened.
 
Cause Blade core is overheating from lack of side clearance due to uneven or too rapid segment wear.
Remedy Specify a blade with a greater side clearance or a specification more suited to the material being cut.
 
Cause Blade core is overheating from lack of adequate coolant.
Remedy Check water supply system for even water flow on both sides of the blade. For dry cutting, make more shallow, intermittent cuts allowing for air to cool the blade.
 
Cause Undercutting is a condition in which the steel core wears faster than the diamond segment, especially in the areas where the segment and core are joined. The condition is caused by highly abrasive material grinding against the blade during the sawing operation. Usually material containing sand are responsible for causing this condition.(see section on segment loss).
Remedy The flow of slurry (abrasive cuttings) must be distributed over a wider area, away from the critical segment area. On most occasions this can be accomplished by using undercut protectors specially positioned around the steel core to change the pattern of abrasion. Although successful in most cases, undercut protectors do nut provide 100% protection. Use high water flow to thin the slurry and flush away sand particles.
 
Cause With a floor saw, sawing all the way through the material, allowing the blade to pick sub-base material.
Remedy Set the cutting depth slightly less than or equal to the total thickness of the slab.
 
Uneven Segment Wear
Cause Segments worn on one side reducing side clearance. Usually caused by misalignment of the saw or a lack of sufficient water on both sides of the blade.
Remedy Check the saw alignment. Clean the water system, making certain that water is properly applied to both sides of the blade. check to see if the pump is supplying sufficient water.(see excessive wear section)
 
Cause Blade is worn out of Round due to bad bearings, worn arbor, missing bushing, arbor hole larger than arbor, cleanliness of or damage to flange surfaces or excessively dull condition.(see section on excessive wear)
Remedy Replace the bearings or worn arbor as required. Inspect the flanges for damage and foreign materials: replace if necessary. Do not remove drive pins when supplied with blade flanges.
 
Excessive Wear
Cause Blade is not perpendicular to material being cut.
Remedy Recommended the proper blade specification for abrasive material.
 
Cause Lack of sufficient water to the blade. Often detected by examining the segment and noting overexposed or highly exposed diamonds.
Remedy Clean up the water system. Make certain the water pump is functioning properly.
 
Cause Wearing out of round accelerates wear. Usually caused by bad bearings, worn shaft or using a blade to hard for the material being cut.
Remedy Check the bearings and arbor. If worn, replace with new parts before installing another blade; select the proper blade for the application.
 
Cause Insufficient power caused by loose v-belts, Inadequate voltage/amperage, or improper RPMs.
Remedy Tighten belts (taunt). Replace worn belts. Check voltage/amperage. Use proper size extension cord.
 
Cause Blade shaft RPM is too low.
Remedy Check the operating RPM of the blade shaft. If necessary, change equipment or modify the blade shaft speed.
 
Cracked Segments
Cause Blade is to hard for the material being cut.
Remedy Use a blade with a softer bond.
 
Cause Blade is being flexed in the cut by misaligned saw, or operator making dramatic saw course corrections.
Remedy Align saw. If cut has slightly wandered off line, gradually steer the saw back on line. If the cut is way off line, plunge the blade to proper cut depth and resume sawing.
 
Cause Blade is overheated.
Remedy Apply proper cooling.
 
Cracked Core
Cause Excessive cutting pressure, or jamming or twisting the blade in the cut can cause the blade core to blend or flex . When subjected to extreme stress and metal fatigue, the blade''s steel core will eventually crack.
Remedy The saw operator should use steady, even in feed pressure, and be careful not to twist or jam the blade in the cut.
 
Cause Overheating through inadequate water supply or improper use of dry cutting blades.
Remedy Use adequate water to cool wet cutting diamond blades (for example, 2 to 5 gallons per minute (7-18 liters per minute) for concrete saws). Allow adequate airflow around dry cutting diamond blades to prevent overheating.
 
Cause RPM is too high.
Remedy Check the operating RPM of the blade shaft. Change equipment or blades if necessary.
 
Cause Blade is out of tension.
Remedy Replace the blade or have the blade retensioned by manufacturer.
 
Eccentricity (Blade out of Round)
Cause The bond is to hard for the material being cut. The hard bond retains the diamonds, which begin to round off, causing the blade to become dull. Instead of cutting, the blade begins to pound, causing the blade to wear out of round.
Remedy Change to a softer bond, which will wear away more readily, allowing the dull diamonds to be released and sharp, new cutting edges to become exposed.
 
Cause The saw''s blade shaft my have a groove scored in it, caused by a blade spinning between the flanges. A new blade, installed on the arbor shaft, will seat into the groove, and immediately run eccentrically when the saw starts.
Remedy Replace the worn shaft.
 
Cause If the blade shaft bearings are worn, the shaft and mandrel will run eccentrically, causing the blade to wear out of round. Can happen with concrete saws when proper lubrication of the bearings is neglected.
Remedy Install new blade shaft bearings. In some cases it might also be necessary to replace the blade shaft if it worn or out of alignment.
 
Segment Loss
Cause Blade is too hard for the material it is cutting, causing excessive dullness, which causes the segment to pound off or fatigue.
Remedy Use a softer blade specification.
 
Cause Worn blade flanges fail to provide proper support, causing the blade to deflect.
Remedy Replace both flanges.
 
Cause Overheating. Usually an easily detected bluish color on the steel center, generally confined to the area where the segment was lost.
Remedy Check the water system for blocked water passages. Test the pump to see if it is functioning. For dry cutting it may be necessary to make shallower cuts and allow the blade to run free every few minutes to let the air cool it.
 
Cause Segment is subjected to sudden, sharp jolting while moving the machine or when contacting the material being cut.
Remedy Avoiding jarring the blade when transporting the machine. Contact the material with slow, even movements.
 
Repair note: It is possible to replace two or three missing diamond segments, providing the steel center is not cracked or undercut badly. If many segments are missing, or if there is less than 50% blade life remaining, Repairing the diamond blade may not be economical. Be certain to eliminate mechanical or operational problems before installing replacement blades.

Overheated Blade
Cause Adequate coolant was not provided.
Remedy Check the water supply for an adequate volume and for obstructions through water system. Use dry blades only for shallow cutting. Allow the the blade to run free every 10 to 15 seconds to increase cooling airflow.
 
Cause Using improper specification for the material being cut.
Remedy Consult the manufacturer''s specification chart for the proper blade.
 
Arbor Hole Out of Round
Cause Saw arbor badly worn due to blade being improperly mounted.
Remedy Be certain the blade is properly mounted on the arbor before tightening the flange.
 
Cause Blade flanges have been improperly tightened, permitting the blade to rotate on the shaft.
Remedy Always wrench tight the arbor nut. Never hand tighten. Always use hexagonal nuts. Never use wing nuts.
 
Cause Blade flanges , drive pin or the arbor shaft are worn and not providing proper blade support.
Remedy Check the blade flanges, arbor shaft and drive pin for wear, foreign matter and proper tightness. Both flanges should be no less diameter then recommended by the manufacturer. Replace worn parts.
 
Note: If the out of round condition of the blade is not to serious, return the blade to the factory for possible repair.

Blade Wont Cut
Cause Blade is too hard for the materials being cut. (examples: block or general purpose blade being used for extended period on hard brick. Asphalt blade being used to cut hard concrete.)
Remedy Consult the dealer or manufacturer for the proper blade to cut materials on the job.
 
Cause Insufficient power to permit the blade to cut properly. (Loose V-belts, low voltage, motor lacks horsepower).
Remedy Check belts, voltage/amperage and horsepower.
 
Cause Check belts, voltage/amperage and horsepower.
Remedy Some blades have a non-diamond bearing section in a backing at the base of the diamond segment for better adherence to the steel core. A blade used to this stage has worn out in the normal manner and should be replaced
 
Cause Blade becomes glazed due to excessive RPM
Remedy Match blade specification and diameter to the machine RPM and cutting conditions.
 
Cause Blade becomes glazed due to inadequate pressure against the material being cut.
Remedy Ensure the proper pressure to keep the blade sharpened, while avoiding an excess of pressure.
 

Glazed Blade
     Glazed Blade: Surface of segment and diamond are smooth.
     Reasons:
  • Diamonds are to friable
  • Bond is too hard
  • Blade speed is too high
     Results:
  • Blade initially cuts, slows and then stops cutting
  • If cutting conditions are not modified, overheating, segment loss, segment breakage, core cracking or tension loss will occur

Over-exposed Diamonds
     Over-exposed Diamonds: Diamonds protrude from bond with minimal support from bond.
     Reasons:
  • Abrasive resistance of bond is incorrect for the material being cut
  • Diamond concentration and bond type are unsuitable for the application
     Results:
  • Blade cuts fast
  • Blade life is short due to premature loss of diamonds
Heavy Premature Diamond Loss
     Heavy premature Diamond Loss: Surface of segment has a high percentage of missing diamonds.
     Reasons:
  • Abrasive resistance of bond is incorrect for the material being cut
  • Diamond concentration and bond type are unsuitable for the application
     Results:
  • Blade cuts very fast
  • Blade wear is high
  • Short blade life
Crushed Diamonds
     Crushed Diamonds: Majority of diamonds show heavy fracture
     Reasons:
  • Diamonds are too friable
  • Diamonds are too large
  • Excessive pounding or vibration
     Results:
  • Blade cuts fast
  • Blade life is short due to premature loss of diamonds if bond cannot hold the crushed diamonds
Polished Segment
     Polish segment: Diamonds are smooth or have flat tops and protrude from the bond surface
     Reasons:
  • Diamonds have too high impact
  • Diamonds size is too large
  • Diamond concentration is too high
  • Insufficient workload on diamonds
    Results:
  • Blade initially cuts, slows and then stops cutting
  • If cutting conditions are not modified, overheating, segments loss, segment breakage, core cracking or tension loss will occur
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GP TURBO - 15mm Seg general purpose diamond blades
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