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How to Select the Right Diamond Grinding Cup Wheel for the Job

Date: 19-08-2021

 

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'.

  • Plate (Cup)
  • Solder
  • Segments

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 ones). 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 through high-temperature soldering. These segments are the components of the Diamond Cup Wheel that does the grinding. Once these are worn away completely, the wheel will no longer be usable.

 

The Fundamentals of Diamond Grinding Wheels

  • Surface area
  • Segment Shape
  • Bond
  • Grit

 

Surface Area

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 that leaves the surface relatively smooth.

Of course, the reciprocal – more aggressive – as 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, fewer 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

Segment shape can affect the aggression of the wheel as well as dispersion characteristics. This can influence the removal speed of stickier products like glues and paints or products that can reactivate.

Generally, segments with sharper leading edges will deliver more aggression, and tapered shapes will provide better dispersion when positioned 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

Segment bond is critical when it comes to the wearing rate and performance on harder products. The 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 the diamond to be exposed. This is required to sharpen the diamond to allow it to cut. 

As the diamond is dragged across the surface of the floor, it is slowly blunted by the force of friction. At the same time, the 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. If the surface is hard, the diamond will blunt quickly and need constant splitting/fracturing to stay 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 diamonds is the increased wear rate.

Alternatively, where the surface is soft or very gritty, the opposite problem exists, because grit and dust are 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.

 

Grit

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 pieces 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 challenging to maintain sharpness. Finer than 40-grit will create a smooth surface and slow down productivity. Usually, 60 to 80-grit wheels are used in polishing, with 100 to 150 being a final cut before using 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 diamonds fast enough and are essentially running blunt. This is often referred to in the industry as "glazing".

Sometimes it can be important for contractors who have more time and less income to maximise 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 utilise 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 the 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 provides 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.

 

Job types

  • Removal
  • Levelling
  • Pre-Polish

 

Removal of Paint & Coatings

Removal of surface coatings such as paint is generally performed by the shape of the segment more than any other wheel property.

The surface area also plays a significant role in the removal of paint and coatings. Requirements for rapid removal of surface coatings are cutting (sharpness). Too much surface area can encourage the wheel to rise over the surface rather than cutting into the product and dispersing it. 

Grit and bond are less critical, but the grit needs to be coarse enough to cut the paint where the wheel cannot slice the surface.

All Preparation Equipment has developed a unique paint removal wheel for the Meteor machine in a 250mm (10-inch) wheel, concentrating mainly on the first two areas – the yellow 12-segment 250mm wheel (DGW10-R12YE). The removal speed 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 attest 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 removal speed is breakneck, often more than four times faster than traditional methods – primarily because contractors traditionally persevere with smearing and reactivated glues due to no other options. Testimonials on the All Preparation Equipment website attest 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 vital. For the fastest removal, minimum segments in the correct shape with matching bonds are the most critical. Grit generally should be around 30 to 40 to achieve the best results.

Traditionally, grinding wheels have been designed to focus entirely on grinding, which limits their speed. All Preparation Equipment has developed a specialised shape that allows for sharper cutting and increased speed.

All Preparation Equipment recommends the full range of Yellow Medium bond 30/40 grit wheels (DGW4-R12YE, DGW5-R12YE, DGW7-R12YE DGW10-R12YE) for high-speed cutting. One contractor has publicly testified that this technically advanced wheel can remove the same quantity of concrete in half a day, where other wheels take two days to complete.

 

Levelling

The process of levelling 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 task.

Where contractors are looking for a wheel that 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 24-Segment Blue (DGW7-R24BL) would generally last twice as long as a 175mm 12-Segment Yellow wheel (DGW7-R12YE) due to its property of surface area being doubled.

Another option for a longer lifespan is to utilise 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 the weight or pressure of the machine against the floor. All Preparation Equipment's Enduro range offers precisely that – a long lifespan but limited aggression.

 

Pre-Polish

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. A 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 the weight or pressure of the machine against the floor.

Like in sanding applications, grit should be increased incrementally to the maximum available to minimise scratches. All Preparation Equipment offers ENDURO pre-polishing wheels in 60/80-grit as well as 100/120 grit.

 

Speed & Longevity – Weighing up Cost vs. Speed

Most everyday tasks are centred 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.

We should strive for the fastest possible solution at an acceptable price to a client in all cases. In most cases, the speed of production can overcome the cost 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 labour cost 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.