Working Hard for You
This section should help to identify some challenges that are inevitable when using Diamond products. Here are some of the possible problems you may encounter, with a guide to any action to identify and eliminate them. It is of paramount importance that all Diamond product specifiers, supervisors and operators are aware of the best practice in products contained within this brochure that will enhance the product’s life, along with operational performance and efficiency.
Diamond segments are attached to the core by brazing with the use of solder positioned between the segment and the core. This is then heated to approximately 2000°C until the solder melts and makes a bond between the two pieces.
High Frequency Welding
By the action of a high frequency electronic current the binder melts and bonds the two parts together.
Laser Welded Segments
Laser welding represents the latest advancements in Diamond blade fabricating technology. Diamond segments are attached to the laser beam. The transitional area of laser weld is even stronger than the segment or the core. Laser welded blades can be used. The requirements of the application or equipment involved
Wet cutting products must be used with water to keep the segments cool during the cutting operation. Water also assists the product to perform at its maximum efficiency. Under no circumstances should you use the product without adequate water OW (see our guide for recommended OW rate chart for wet cutting). Cutting without water on these products will cause excessive heat build up, resulting in poor performance and blade damage in tin the steel centre. The braze transitional area holding the segment onto the centre may melt, resulting in segment loss.
Dry cutting is possible with low horsepower machines for high speed and intermittent use. Although no water is required, blades must be cooled with airflow around the blade to dissipate the heat. Dry cutting blades are only recommended for intermittent cutting. Every 10 -15 seconds the blade should be allowed to rotate out of the cut at maximum rpm for several seconds to allow the blade to cool. Operators should not use dry Diamond blades for long continuous full depth sawing in one single pass. Any cuts deeper than 4cm should be step cut- ie make several shallow passes until the required depth of cut is reached. On asphalt, operators should avoid cutting into the sub-base
The most common problem encountered by diamond blade users is blade wear. It is also the most difficult to accurately evaluate. It is impossible to predict the life performance of a blade that is operating in conditions with so many variables. To consistently monitor the life and performance of the blade it is essential to calculate the variables including the material, inch metres cut, depth of cut, water supply, water quality and quantity used, and the amount of pressure applied by the operator, rather than the hours, days or weeks that the blade has been used. Trying to compare the performance of a blade with another is almost impossible due to the large amount of variables encountered.
- The correct specification blade has been selected for the application.
- The machine selected for the operation is of the correct specification and has been serviced to a standard that complies to the manufacturer’s service recommendations.
- That the machine complies or exceeds all relevant health and safety regulations.
- That the area of operation is clean and tidy and complies with any need for barriers, signs, warning notices, etc.
- That the operator has been properly trained and certified for machine operation and health and safety regulations.
- That in the case of electrically powered machines, the machine is of the correct voltage and that the site supply is adequate both in terms of power supply and compliance to site electricity supply regulations.
- Always ensure that when fitting a blade the machine is disconnected from the power source and the correct tools are used.
- That the site is free of pets and children.
- The blade or bit is operating at the manufacturer’s recommended speed
- The blade or bit is being fed into the work at a suitable rate.
- In the case of wet cutting an adequate supply of water is available.
- The blade or bit is in a suitably undamaged condition.
- The blade is never twisted or forced in the cut.
- The blade is gradually lowered into the material being cut.
- The material being cut is not hand or foot restrained.
- The blade and machine are periodically inspected for wear or damage.
For your personal safety, always ensure that you:
- Wear suitable ear defenders.
- Wear suitable foot wear.
- Wear suitable eye protection.
- Wear suitable protection against dust.
- Wear suitable clothing.
- Read the instructions carefully.
* Based on 9,500 SFPM (Surface Feet Per Minute) the general optimum performance range for cutting concrete and masonry products is = 10%. For hard, dense materials such as stone and tile, the optimum performance speed is 10-25% less than the speeds shown on ‘Maximum blade cutting depths and operating speeds’ table. Blade shaft speeds (RPMs at no load) for most tools will be higher than recommended operating speeds shown on ‘Maximum blade cutting depths and operating speeds’ table. Under normal sawing conditions, the actual blade shaft speed or the tool will slow down under load, and should fall within the optimum speed range. ** This speed RPM represents the recommended operating speed in revolutions per minute at which each blade can be used. Before using any blade, make sure the blade shaft speed of the tool is within the “maximum safe” limit of that blade. All JCB Diamond products are tested to EN13236 specification and guidelines. The maximum recommended cutting speed of all blades must not exceed 100m/sec.
- Blade too hard for the material being cut
- Excessive cutting pressure, caused by too high infeed results in the blade core bending and flexing. Metal fatigue will eventually cause core to crack
- Worn shafts, damaged machine bearings, or blade incorrectly mounted.
Out of Round
- Blade shaft bearing may possibly be worn. Fit new bearing and ensure regular lubrication
- Blade too hard for the material being cut, this will result in the blade hammering and wearing out of round. Choose a blade with a softer bond system
- Machine spindle may have groove scored in it as result of previous blade slipping on spindle.
- Blade has twisted or jammed in the cut because the material was not held firmly
- Machine has been twisted or turned while blade is in the cut
- Blade core has undercut due to cutting below the asphalt into the sub-base
- Blade is too hard for the material being cut, resulting in the blade hammering in the cut
- Blade is deflected in the cut due to the blade flanges being worn or deformed and failing to provide proper support
- Inadequate water supply.
Uneven Segment Wear
- Wet cutting – Insufficient water
- Excessive cutting pressure, caused by too high infeed, results in the blade core bending and flexing. Metal fatigue will eventually cause the core to crack
- Worn shafts, damaged bearings, or blade incorrectly mounted.
Overheating will usually cause black or blueish discolouration on the core.
- In wet cutting – Inadequate water supply due to low water pressure, blocked or damaged water tubes or dust suppression systems being inadequate for wet cut blades
- In dry cutting – Excessive cutting pressure results in heat build up. Allow blade to do work, with hand held machines, use gentle reciprocating action and avoid cutting too deep in a single pass.
- Make sure that the blade specification has offset segments to assist removal of the slurry from the cut
- Make sure that the blade is not cutting below the asphalt into the sub base. Constant rubbing of the loose material causes premature wear and has no beneficial effect on the cut surface
- Make sure that the water supply is correct as increased water flow will wash slurry from the contact area and reduce undercutting.
- Blade core overheated. For wet cut blades ensure sufficient water supply
- Check machine is running at correct rpm, that the flanges are of the correct and same size and that there is no wear on the machine bearing
- The blade is deviating in the cut because it is too hard for the application
- Ensure that the blade is not spinning on the spindle and that it is secure
- Ensure that the blade is cutting in straight lines only.
Blade Not Cutting
- Check that specification is correct for the material. Dull blades can be sharpened by cutting a soft abrasive material
- Machine drive belts need re tightening or the machine has insufficient horsepower for the specification being used
- Check direction of rotation.
Damaged Arbor Hole
- Blade will hammer if it is incorrectly aligned when mounted. Make sure that the blade is mounted on the correct diameter spindle before tightening. Make sure that the pin holes slide over the drive pin
- The blade will spin or vibrate on the spindle if the flanges are not properly tightened
- The blade will pound if the saw shaft is badly worn or grooved.
- Blade specification is causing the diamond to be over-exposed. Use a blade with a harder bond system
- If the blade wears out of round this will increase the wear normally due to bad bearing, worn shaft or the blade specification being too hard for the material
- An inadequate water supply can cause damaged or blocked water tubes
- Softening of the blade specification and low blade speed can be caused by loose drive belts.