DIAMOND GRINDING CUP WHEELS – HOW TO SELECT THE RIGHT WHEEL
How to Select The RIght Diamond Grinding Cup Wheel for the Job
1. The Components of Diamond Wheels
Diamond Grinding Cup Wheels consist of three main components. Generally, small blocks of diamond material called ‘Segments’ are attached by a product called ‘solder’ to a spinning wheel known as a ‘Plate’ or ‘Cup’.
a. Plate (cup)
The Plate or Cup may vary from manufacturer to manufacturer and often incorporates holes or vents to allow for air movement. Larger plates often require balancing (such as 175mm cup wheels and larger). This is generally done by drilling small amounts of material from the surface of the plate.
Plates have a series of blocks called ‘segments’ attached to them by way of high temperature solder. These segments are the component of the Diamond Cup Wheel that does the grinding. Once these are worn completely away, the wheel will no longer be usable.
2. The Fundamentals of Diamond Grinding Wheels
a. Surface area
b. Segment Shape
Diamond Grinding Cup Wheel characteristics are influenced almost entirely by four major factors. The total surface area of the segments attached to the wheel will generally determine the level of aggression or speed. If you measure the cross sectional area of each segment and multiply that by the number of segments you will have calculated the total surface area. The larger the figure, the less aggressive (slower) the wheel will be.
All Preparation Equipment’s blue 175 Rhomboid wheel (DGW7-R24BL) is the least aggressive Rhomboid wheel with 24 segments and is an excellent speedy removal wheel which leaves the surface relatively smooth.
Of course, the reciprocal – more aggressive – is a result of decreasing the surface area. As the total surface area of the segments decreases, more scratching will be evident. More aggressive wheels will deliver a less smooth surface with more scratches. Where segments in the range are identical sizes, less segment wheels will be more aggressive, and more segment wheels will deliver a smoother surface.
All Preparation Equipment’s Red 175 (DGW7-R6RE) wheel is the most aggressive Rhomboid wheel in the range. It’s super-high speed and offers more of a keyed finish rather than smoothness.
Segment shape can affect the aggression of the wheel, as well as dispersion characteristics. This can influence the speed of removal of stickier products like glues, as well as paints or products that can re-activate.
Generally segments with sharper leading edges will deliver more aggression, and tapered shapes will provide better dispersion when oriented in the right direction. All this adds up to superior speed which is why the All Preparation Rhomboid wheels are a premium choice for high speed removal.
Segment bond is critical when it comes to wear rate and performance on harder products. Bond itself suspends the small ‘grits’ of polycrystalline diamond so that they do not fall out onto the surface being ground. The bond is sacrificial – meaning it wears away to allow diamond to be exposed. This is required to sharpen the diamond to allow it to cut. Basically, as the diamond is dragged across the surface of the floor it is slowly blunted by the force of friction. At the same time, bond wears around the diamond exposing it more and more. Once the exposed diamond reaches a certain point, it splits and shatters creating more sharp surfaces which continue to cut.
The rate of exposure the diamond will require to stay sharp will depend on how hard the surface is. In the case that the surface is hard then the diamond will blunt quickly and require constant splitting/fracturing to ensure it stays sharp. A soft bond such as All Preparation Equipment’s 175mm yellow 12 segment soft wheel (DGW7-R12YES) is ideal for hard concrete. Of course, the downside to the need to quickly expose diamond is the increased wear rate.
Alternatively, where the surface is soft or very gritty the opposite problem exists. Because grit and dust is abrasive to the bond it increases the speed of wear. This allows the diamond to become exposed, splinter and re-sharpen well before it blunts. While this does ensure maximum grinding speed, it reduces the lifespan of the diamond wheel. In this case, a hard bond product will ensure wear is slowed to a more reasonable level. All Preparation Equipment offers the 175mm yellow 12 segment hard wheel (DGW7-R12YEH) for softer materials to give maximum lifespan. Some customers have reported up to 500m2 from one of these wheels on spray-pave type gritty surfaces.
The final piece of the puzzle is grit. Grit is generally the easiest component of the wheel to understand. Grit is used as a reference to describe the finishing qualities of the diamond. The lower the number, the larger the piece of diamond (coarser grit). The higher the number, the smaller the piece of diamond (finer grit). Just like sandpaper, as the grit becomes smaller the finish becomes smoother.
Generally in concrete grinding, 30 or 40 grit is about the coarsest required. Coarser than 30 grit can become difficult to maintain sharpness. Finer than 40 grit will create a smooth surface and slow down the productivity. Usually, 60-80grit wheels are used in the process of polishing, with 100-150 being a final cut prior to resin backed polishing pads. All Preparation Equipment provides a coarse grit standard medium bond wheel for high speed removal in 175mm – the yellow 12 segment medium wheel (DGW7-R12YE).
The overall result is that a highly productive wheel will wear much faster than a slow productivity wheel because the grit is always sharp. Slow wheels are not releasing diamond fast enough and are essentially running blunt. Often this is referred to in the industry as “glazing”.
Sometimes it can be important for contractors who have more time and less income to attempt to maximize the lifespan of tooling by running them in the ‘slow’ zone. Longer-lasting wheels are often those with greater surface area and harder bonds.
Longer lifespan wheels often utilize a larger segment. Large segments generally cannot offer cutting ability due to their tendency to ‘float’ up over the surface rather than cut into it. Large segments will rely entirely on grit/bond characteristics coupled with weight or pressure of the machine against the floor.
All Preparation Equipment offers an alternative wheel (Enduro) for this type of scenario. All Preparation Equipment’s Enduro wheel offers a much longer lifespan at the expense of speed. Enduro wheels are also available in higher number grits (60-80 and 100-120) for pre-polishing where excessive aggression is undesirable.
3. Job types
Removal of Paint & Coatings
Removal of surface coatings such as paint is generally performed by the shape of the segment more than any other property of the wheel.
Requirements for rapid removal of surface coatings are cutting (sharpness). Surface area also plays a significant role in the removal of paint and coatings. Too much surface area can encourage the wheel to rise up over the surface rather than cutting into the product and dispersing it. Grit and bond are less important, but the grit does need to be coarse enough to cut the paint where the wheel is unable to slice the surface.
All Preparation Equipment has developed a special paint removal wheel for the Meteor machine in a 250mm (10 inch) wheel which concentrates largely on the first two areas – the yellow 12 segment 250mm wheel (DGW10-R12YE). The speed of removal is extremely fast, up to 4 times faster than traditional wheels and has been verified by numerous contractors. Testimonials on the All Preparation Equipment website testify to this incredible result.
Removal of Glues
Removal of glues and other sticky or potentially reactivated ‘smearing’ products is almost identical in concept to paint removal. However, it relies even less on the grinding characteristics such as grit and bond. Again, the yellow wheels through the range are preferred by contractors due to their speed of removal and outstanding dispersion characteristics.
All Preparation Equipment also recommends the yellow 12 segment 250mm wheel (DGW10-R12YE) for high speed glue removal. The speed of removal is extremely fast, often more than 4 times faster than traditional methods – primarily because contractors traditionally persevere with smearing and re-activated glues due to no other options. Testimonials on the All Preparation Equipment website testify to this incredible result.
Removal of Excess Concrete
High speed concrete removal is achieved by matching all factors to the concrete surface. Surface area, segment size, bond and grit are all extremely important. For fastest removal, minimum segments in the correct shape with matching bond are the most critical. Grit generally should be around #30-#40 to achieve best results.
Traditionally grinding wheels have been designed to focus entirely on grinding which limits their speed. All Preparation Equipment has developed a specialized shape which allows for sharper cutting and increased speed.
For high speed concrete removal All Preparation Equipment recommends the full range of Yellow Medium bond 30/40 grit wheels (DGW4-R12YE, DGW5-R12YE, DGW7-R12YE, DGW10-R12YE). One contractor has publically testified that this technically advanced wheel is capable of removing the same quantity of concrete in half a day where other wheels take 2 days to complete.
The process of leveling surfaces involves the same grinding fundamentals. The significant difference is that a more level surface will arise from a larger diameter contact area. Smaller contact areas will allow the grinding wheel to follow undulations whereas a larger wheel tends to cut through the ‘hills’ so-to-speak.
For most jobs, a high-speed removal wheel is ideal. All Preparation Equipment would recommend the yellow 175mm wheels fitted to a 480mm circumference satellite machine for this type of task.
Where contractors are looking for a wheel which can offer a longer lifespan, one option is to increase the surface area at the expense of aggression. A wheel such as All Preparation Equipment’s 175mm 24Segment Blue (DGW7-R24BL) would generally last twice as long as a 175mm 12 Segment Yellow wheel (DGW7-R12YE) due to it’s property of surface area being doubled.
Another option for longer lifespan is to utilize a wheel with a larger segment. Large segments generally cannot offer cutting ability due to their tendency to ‘float’ up over the surface rather than cut into it. Large segments will rely entirely on grit/bond characteristics coupled with weight or pressure of the machine against the floor. All Preparation Equipment's Enduro range offers exactly that – long lifespan but limited aggression.
The process of polishing starts with the preparation of the surface. Initially, once all surface material is removed, the surface needs to be smoothed out. Often this requires a wheel designed for a smooth finish. Smooth finish requires more surface area, and decreased grit size (increased number).
It is desirable in this case to use a larger segment design. Large segments generally cannot offer cutting ability due to their tendency to ‘float’ up over the surface rather than cut into it. Large segments will rely entirely on grit/bond characteristics coupled with weight or pressure of the machine against the floor.
Just like in sanding applications, grit should be increased incrementally to the maximum available to ensure scratches are minimized. All Preparation Equipment offers ENDURO pre-polishing wheels in 60/80 grit as well as 100/120 grit.
4. Speed & Longevity – Weighing up cost vs speed.
Most modern tasks are centered around speed. Nearly all tasks have a limited time available to complete, and offer a bonus for completing early – or a fine for completing late. Correct diamond tooling can often be critical to ensuring a task is completed on time, but choosing a wheel with excessively aggressive properties can sometimes catch contractors out and cause un-noticed rapid wear.
In all cases we should strive for the fastest possible solution at a price that is acceptable to a client. In most cases, the speed of production can overcome the price of labour per hour.
All Preparation Equipment concentrates on ensuring the fastest possible grinding wheels are available to contractors. Where high-speed is paramount, choose a Rhomboid Diamond Cup Wheel from All Preparation Equipment. If time is readily available and the cost of labour is low, it may be possible to consider the ENDURO wheel from All Preparation Equipment as an alternative.
If you’re about to embark on a new job and would like some free advice on your concrete grinding contract, contact our friendly concrete grinding experts today and we’ll help you choose the right wheel for your job.