What Is Garnet?
Garnet is a natural aluminium-iron-magnesium silicate mineral. Its Mohs hardness is 7-7.5 (slightly harder than quartz). It is ideal as a waterjet abrasive: sharp grain structure, low dust, recyclable and harmless to the environment. Because it is a natural mineral it does not carry the silicosis risk that silica sand does (although a mask is still worn).
Garnet Types (by Origin)
| Origin | Type | Characteristics | Typical Use |
|---|---|---|---|
| India (alluvial) | Andradite | The most common, well balanced | General waterjet work — the standard |
| Australia (mined) | Almandine | Harder, more aggressive | Hard metal, thick work |
| China | Mixed | Economical but variable quality | Tight budgets, use with care |
| Türkiye / local | Mixed | Logistics advantage, quality depends on the supplier | The advantage of local supply |
Choosing the Grain Size (Mesh)
| Mesh | Grain Diameter | Use | Advantage / Disadvantage |
|---|---|---|---|
| #50 | ~300 µm | Rough cutting, thick work | Fast and cheap; coarse surface |
| #80 | ~180 µm | The most common — general use | A balance of speed and quality |
| #100 | ~150 µm | Precision cutting, fine detail | A cleaner surface, 15-20% slower |
| #120 | ~125 µm | Very fine, decorative work | The best surface quality, the slowest |
Our Recommendation
For 80% of your production, standard #80 mesh is enough. Use #100 for fine detail or delicate work, and #50 for rough pre-cutting. Stocking more than one mesh is needless complication in most workshops.
Quality Indicators
- MOISTURE CONTENT — must be below 0.2%. High moisture causes clumping and blocks the garnet feed.
- GRAIN DISTRIBUTION — homogeneous and consistent with the mesh specification (for example, 80% of #80 garnet should be around 180 µm).
- SHARPNESS — the grains must be angular; rounded garnet does not abrade.
- DUST CONTENT (passing #200) — must be below 5%. Excess dust blocks the feed system.
- METALLIC PARTICLES — must be checked magnetically and be close to zero (they damage the pump and the nozzle).
- Choose an ISO 9001-certified supplier — critical for consistency of quality.
Consumption Ranges (Qualitative)
Typical consumption ranges in standard waterjet cutting:
- 0.3-0.5 kg/min (while cutting — depending on the pump and nozzle settings)
- 18-30 kg/hour (continuous operation)
- 150-250 kg/day (one 8-hour shift)
- 3,000-6,000 kg/month (a single machine in normal use)
- Monthly consumption varies with production volume and cutting parameters
Garnet Recycling
After a single use, 50-70% of the garnet is still usable. Automatic reclamation systems work as follows:
- The garnet accumulated in the cutting tank is removed
- Screening — the over-fine grains (sludge) are separated out
- Drying — in an oven or by air circulation
- Refeeding — mixed with new garnet at a rate of 30-50%
- Saving: a 30-50% reduction in the monthly garnet cost
The Approach to Reclamation
A garnet reclamation system is a meaningful saving for plants with high consumption. For low production volumes the case for the investment may not stack up; the scope of the investment should be assessed for your own workshop against your monthly consumption.
Storage and Handling
- A DRY ENVIRONMENT — keep it in a closed container with a silica gel pack. Moisture causes clumping.
- It is packed in 25 kg bags; keep them on a pallet, not directly on the floor
- An opened bag should be used within a week (in the climate conditions of Türkiye)
- The garnet hopper must be kept closed — no pigeons or insects (it sounds unlikely, but it happens)
- If clumping occurs — screen the garnet and mix old with new, to eliminate any risk of blockage