When selecting the segment shape, grit and bond must be matched to the job.
- Repairing rain damaged concrete - as it is soft and abrasive it requires a hard bond with a 30/40 grit to give it the equivalent of a trowel finish
- Removal of thin vinyl glue -use an arrow head segment with a hard medium bond to limit wear. Glues may penetrate concrete requiring a grind of the concrete
- Removal of thick pressure sensitive glue - use a PCD (a polycrystalline diamond is diamond powder formed with carbide; it is a very abrasive resistant and long lasting tool, ideal for thick coatings) to remove the majority and then finish with a 30/40 diamond. The Bond depends on concrete underneath
- Removal of cement based ceramic tile adhesive - this requires a hard bond concrete because tile adhesives are sandy (abrasive)
- Honing of a very hard concrete - a very soft 30/40 followed by a 120g to remove scratches made by 30/40
A diamond segment is made by fusing diamond grit and a metal powder together. Things that determine the grinding and life of a segment are:
- Bond hardness
- Grit Size
- Shape of the segment
- Pressure on segments i.e. number of segments under a machine and the machines weight
- Diamond Concentration
- Material been ground (soft, hard or abrasive)
Bond is the metal (or resin) which holds the diamond segment together. The metal bond is an alloy containing different metals for different hardness's of the bond. The segment is designed to wear away always leaving a new layer of diamond.
There are varying hardness's of metal bonds but typically we use:
Hard bond is resistant to abrasive material such as asphalt, soft/green concrete, and rain damage concrete.
Medium bond can be used on both hard and abrasive materials but will wear more quickly on abrasive materials and not cut as well on hard materials.
Soft bond is ideal for hard materials as the soft metal wears away always exposing a layer of diamonds. If the metal bond is too hard the diamond becomes trapped in the surface i.e. a hard bond on on hard burnished concrete - this is called glazing. If the metal bond is too soft it wears away too quickly i.e. a soft diamond on soft abrasive concrete such as new/green concrete.
Grit is the particle size of the diamond held within the metal or resin bond of a segment. Different companies class their grits differently, typically the sizes are:
- Coarse= 16/20 30/40 grit
- Medium= 50/60 70/80grit
- Fine= 100/120- 140/150grit
Different shaped diamonds are used in different applications.
- Arrow heads are good for glue removal as they create a sharp leading edge for slicing off the glue
- Square segments are good for removal of concrete with a long leading edge
- Round are good for finer grits with less of a leading straight edge
When 'polishing' concrete and stone we need to move onto finer grit diamonds. Beyond 100-150 grit the metal bond itself can scratch or does not give as good as finish as a resin bound diamond. Resin bond allows us to go up to a 3000 grit diamond.
There are many types of resin bound diamonds, as with metal bond there are varying levels of hardness and resin types for different applications. Resin can burn if too much weight or speed is applied and can wear away too quickly on the wrong job.
A full range of diamonds are available for all types of applications in concrete, stone and other surfaces. We stock our own diamond range to ensure optimal quality, performance and wear.
For more information or hire costs for Kennards Diamond Segments, please call or use the IndustrySearch email enquiry for a direct reply.