Choosing between a bush hammer head and a brush hammer head decides how aggressively a floor is profiled before coating, screed overlay or polishing. The bush hammer crushes carbide pins into pits that expose coarse aggregate; the brush hammer sweeps wire or carbide bristles across laitance for a lighter texture. This guide compares structure, impact, removal rate, wear life and spare parts for buyers who stock prep tools.

Scope covers single-disc and ride-on prep machines, portable angle bush hammers and twin-brush rotors on concrete, screed and stone. Reference limits apply to normal-weight concrete at 25 to 45 MPa; high-strength mixes and hard aggregate shorten pin life, so check the machine manual before setting a daily target.

How the Two Heads Transmit Impact

A bush hammer carries a grid of carbide-tipped pins on a rotating drum or disc. Each pin strikes the concrete with a concentrated point load, crushing paste and breaking out particles. The action is percussive and deep: one pass leaves pits 0.5 to 2.5 mm deep and a clearly broken profile.

A brush hammer uses rows of steel wire or tungsten-carbide bristles on a rotor. Bristles flex and slide over the surface instead of punching in, scraping laitance and film while scratching the paste. Removal stays shallow, 0.1 to 0.5 mm per pass, and the profile reads scoured rather than pitted.

Tooth Pattern, Pin Pitch and Contact Geometry

Bush heads are sold by pin count and spacing. Standard plates carry 36, 48, 72, 96 or 120 pins in 4 to 12 rows; pitch between pins runs 10 to 20 mm. Dense pitches of 10 to 13 mm give a finer pit pattern; open pitches of 16 to 20 mm cut deeper on hard concrete. Pin diameters sit between 4 and 8 mm.

Brush rotors are specified by bristle count, wire gauge and diameter. Wire sets run 80 to 240 bristles per rotor at 0.35 to 0.6 mm gauge; carbide blocks carry 12 to 32 tapered tips per segment. Walk-behind rotor diameters range 150 to 250 mm, sweeping a contact band 40 to 90 mm wide.

Removal Depth, Coverage and Working Limits

Productivity separates the two heads more than peak removal. A bush hammer removes 0.3 to 1.2 kg of paste per square meter per pass and covers 30 to 80 square meters per shift; a brush hammer covers 60 to 150 square meters at 0.05 to 0.3 kg per square meter. Profiling to CSP 1 to 2 takes 2 to 4 passes; a light brush pass for CSP 3 to 4 needs 1 to 2.

RPM windows differ too. Bush drum and disc heads work 300 to 900 rpm; brush rotors turn faster, 800 to 1800 rpm, because bristle flexibility limits impact energy. Feed speed sits 2 to 8 m/min for bush hammers and 6 to 15 m/min for brushes. Keep RH at 75 to 80 percent and surface temperature 10 to 30 Celsius.

Matching the Head to Base Condition and Coating

Choose the bush hammer where the base carries hard laitance, oily paste, old tile adhesive 2 to 5 mm thick, or where a 5 to 15 mm polymer screed needs mechanical anchoring. It also prepares stone for anti-slip treatment and opens porous surfaces before densifier.

The brush hammer suits fresh laitance on cured concrete, light membrane residue, thin primer or dust film, and the final scouring between grit passes. A 0.5 to 1.5 mm epoxy or acrylic film comes off cleanly with a brush; anything above 2 mm usually needs the bush hammer first. For a CSP 5 to 7 polishing track, avoid bush hammer profiling: its pits add 2 to 3 extra resin passes.

Wear Life, Servicing and Repair Triggers

Carbide pins last 80 to 200 working hours on normal concrete; on 40 MPa-plus concrete or hard flint aggregate that drops to 20 to 60 hours. When a pin wears below half its exposed length, about 3 mm from the seat, the row develops a flat spot and coverage drops 15 to 25 percent. Replace pins per row; mixing worn and new pins leaves checkerboard marks.

Wire bristles fatigue by fraying. Replace a brush when bristle length drops to 50 to 60 percent of new, after 120 to 300 hours on clean concrete or 40 to 100 hours over adhesive residue. Dress blunt carbide blocks on a soft pad for 5 to 10 minutes, then retire below 2 mm tip height. Inspect every 40 to 80 hours.

Selection Table: Base, Target, Head and Setup

Spare Parts and Stocking List

• Bush hammer plates in two widths: 200 to 250 mm and 280 to 350 mm, each with 48 and 72 pin options.
• Replacement carbide pins by row: 48-pin and 72-pin sets, screw-socket type kept beside press-fit versions.
• Wire brush rotors for 150, 180 and 200 mm heads, plus bristle packs in 0.4 and 0.5 mm gauge.
• Carbide bristle blocks for intermediate profiling, 8 to 16 blocks per fast-moving SKU.
• Fasteners, washers and bearing seals per head model; a stripped thread ruins a new plate on first use.

Pre-Use Inspection and Buyer Checks

Before a shift, spin the empty head and check for bent pins, loose blocks or frayed bundles that catch the drum. Measure head diameter against the machine spec; an undersized worn brush leaves an unscoured band at track edges. Record baseline pin count, bristle length and rotor diameter at purchase.

When ordering, confirm bore diameter, row pattern and mounting interface against the existing head, not by brand alone. Keep replacement sets in the same SKU family for 6 to 12 months so mixed vintages do not appear on one plate. Test profile on a scrap slab before committing a large floor.