Concrete

Metal Bond, Resin Bond and PCD Tooling Compared

What metal bond, hybrid, resin bond and PCD tooling each do, where one hands off to the next, and why PCD is a removal tool only.

Updated · 2 min read

Grinding tooling comes in four families, and each has a specific job. Metal bonds grind and flatten, resin bonds polish, hybrids bridge the two, and PCDs remove coatings. Most problems come from using one family for another's job.

The four families

Each family has one job.

Tooling Job Typical grits
Metal bond Grinding, flattening, removing thin coatings and adhesive, exposing aggregate Up to about 120[1]
Hybrid / transitional Removing metal-bond scratches before resin About 100 to 400[3]
Resin bond Honing and polishing Up to 3000[3]
PCD Removing thick coatings, epoxy, mastic and elastomerics Not graded by grit

Metal bond

Metal bond is the workhorse of floor prep. Match the bond inversely to the concrete: soft-bond segments for hard concrete, hard-bond segments for soft concrete. The right bond prevents glazing and early wear.[1] If segments glaze, lower the speed a step at a time until the glazing stops.[1] The full bond and grit guide is in Diamond tooling: bond hardness and grit selection.

Hybrid and resin

These are finishing tools for polished concrete.

  • The usual sequence: metal bond for rough grinding (#25 to 100), resin or hybrid tooling for honing out the metal scratches (#100 to 400), then resin polishing (#800 to 3000).[3]
  • Manufacturers don't agree on a single RPM rule. A common rule of thumb is that the finer the grit, the slower the grinder should run,[1] but follow the settings for your machine and tooling.

PCD

PCD is a removal tool. It scrapes and chips off thick coatings that would load up metal-bond segments, and PCDs will usually profile the concrete under the coating as they remove it.[1]

  • Lavina (Superabrasive) sells PCDs with and without sacrificial bars. Without them, PCDs are very aggressive and leave a coarse profile; with them, they cut gentler and don't damage the concrete.[4]
  • Run PCD tools at low RPM.[4]
  • Always follow PCD with metal bond to clean up and even out the surface.

More in Removing epoxy and coatings.

Tool life

On a GP500 or GP700 with added head pressure, metal-bond diamonds average 8,000 to 10,000 sq ft, while tooling on smaller machines lasts around 2,500 sq ft. A bond that doesn't match the concrete wears faster.[2]

Actual life depends heavily on the slab, the machine and the operator.

Common mistakes

These waste the most tooling.

  • Metal bond on thick epoxy. It loads up and polishes. Start with PCD.
  • Skipping hybrids. Resins can't remove deep metal scratches.
  • Running resin too hot or dry.
  • Finishing with PCD. It leaves a rough, torn surface.

Tooling we carry

These are National's planetary grinder tooling styles.

References

  1. National Flooring Equipment: Grinder tooling guide
  2. National Flooring Equipment: Top tooling tips
  3. Husqvarna: Concrete grinding and polishing guideline
  4. Superabrasive (Lavina): PCD tools

Linked PDF documents are archived copies saved by PreFloor Tools so they stay available if the publisher moves or removes them. Check the publisher's website for the latest revision.

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OEM replacement parts, organized by assembly, with the manual for each machine.