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For hand-held and walk-behind concrete grinding, plan on removing roughly 0.3 to 0.5 mm (10 to 20 mils) per pass with a diamond cup wheel or grinding disc. Heavier machines with larger plates can take 0.5 to 1.0 mm per pass on soft concrete. Trying to remove more in one pass causes disc glazing, motor overload, gouges and uneven surfaces. Build up the depth with multiple overlapping passes instead.
Concrete grinding is a micro-cutting process. Each diamond on the disc chips a tiny fleck of paste or aggregate. If you force too much depth, the diamonds cannot clear the swarf, the disc glazes over, and the motor bogs down. The result is a slow, hot, uneven cut that burns the bond and shortens disc life. Working shallow keeps the diamonds exposed, the motor cool, and the surface flat.
A 125 or 180 mm angle grinder removes about 0.2 to 0.4 mm per pass. These machines are light and rely on operator pressure, so they cannot take deep cuts. They are used for edges, high spots, coating removal and small patches, not for grinding a whole floor in one go.
A single-head floor grinder (250 to 400 mm disc) with a 3 to 7.5 kW motor removes 0.3 to 0.6 mm per pass on normal concrete. Add weight plates and the cut depth can go to about 0.8 mm on soft mix.
Planetary or triple-head grinders (500 to 800 mm) are the production machines. On soft to medium concrete they can remove 0.5 to 1.0 mm per pass, and on very soft mixes up to 1.5 mm. On hard, dense concrete they back off to 0.3 to 0.5 mm.
If you need to take off 2 mm or more, do not try to do it in one pass. Plan the job in stages:
For thick coatings (epoxy, glue, bitumen), use a PCD disc first to strip the coating, then switch to a metal-bond diamond disc to clean up the residual layer.
Watch for these warning signs that you are pushing too hard:
When you see any of these, lift the machine, let the disc breathe, and resume with lighter pressure and shallower passes.
Before you start, mark a reference line or use a straightedge to identify the high spots. After each pass, run the straightedge across the floor and feel for gaps. For more accuracy, use a depth gauge or a laser level. Do not rely on visual inspection alone; the human eye is poor at judging small height differences on concrete.
Wet grinding washes away swarf and keeps the disc cool, which lets the diamonds stay sharp longer. The trade-off is that water also adds a layer between the disc and the concrete, so each pass removes slightly less than dry grinding on the same machine. Plan on about 20 to 30 percent less depth per pass when wet, and be prepared to make one extra pass. The benefit is a much cleaner cut with less dust, a cooler disc and a more consistent scratch pattern. Wet grinding also reduces the risk of burning the bond on hard concrete, which is the most common cause of premature disc failure.
Before you start cutting, work out how many passes the job will take. Divide the total depth you need to remove by the per-pass depth for your machine and grit. For example, if you need to remove 1.5 mm and your machine takes 0.4 mm per pass, plan on four passes: two in one direction, two perpendicular. Add 20 percent for cleanup and blending. This planning keeps you from guessing on the floor and from pushing one pass too deep because you are behind schedule.
Plan on 0.3 to 0.5 mm per pass for most concrete grinding work. Adjust up or down based on machine size, grit and concrete hardness. Build depth with multiple passes rather than forcing one heavy cut, and watch for the signs that you are overloading the disc. Shallow, consistent passes give a flatter floor, longer disc life and a safer job.
Written and reviewed by JOY TECH - an SGS & BV audited, CE/RoHS certified diamond tools manufacturer founded in 2004, exporting to 50+ countries.
Our factory and quality management system are audited by SGS and Bureau Veritas. Products meet CE/RoHS requirements and every piece is 100% inspected before packing.
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