White Fused Alumina for Sandblasting: Grit Size, Surface Finish and Reuse
白色電融アルミナ (WFA) is a hard, clean blasting abrasive used when controlled cutting and low iron contamination are important. It can remove oxide, coatings and surface defects, create a defined profile or prepare selected metal and non-metal parts for coating and finishing.
Good blasting results depend on more than media hardness. Grit size, particle shape, air pressure, nozzle, angle, distance, recycling and the workpiece all affect the surface.
When to Choose WFA
- selected stainless steel and non-ferrous parts where iron contamination must be controlled;
- cleaning and preparation where a white, high-alumina abrasive is preferred;
- precision components requiring a more controlled surface than general-purpose slag media;
- applications where reusable abrasive and consistent grit are economically justified;
- セラミック, glass or hard-material blasting validated for the specific part.
For heavy general steel cleaning, brown fused alumina or another blasting medium may provide better economics. The material should be chosen by surface result and cost per treated area.
How Grit Size Affects the Surface
| Grit direction | General effect | Typical decision |
|---|---|---|
| Coarser | More aggressive impact and deeper profile | Heavy removal, robust parts, thicker coatings |
| Medium | Balance of cleaning rate and finish | General controlled preparation |
| Finer | Finer profile and lower removal per impact | Precision parts and finish-sensitive surfaces |
These are tendencies, not guarantees. Pressure, nozzle, distance, angle and media velocity can change the result. Test on representative parts before approving a grade.
Particle Shape and Bulk Density
Angular WFA cuts and creates a profile rather than peening like spherical shot. Shape also affects breakdown and flow. Bulk density influences the mass fed through equipment, but higher bulk density does not automatically mean a better blasting grade.
Specify the agreed grade, shape-related property where needed and the bulk-density method rather than using the phrase high-density grit alone.
Low Iron and Cleanliness
WFA generally has a lower iron profile than brown fused alumina, but contamination can still enter during crushing, handling, recycling or through dirty equipment. For stainless work, agree chemistry or magnetic-material limits and keep blast pots, hoses and recovery systems separated from carbon-steel media.
Recycling and Breakdown
WFA can be reused in suitable closed blasting systems, but the number of cycles depends on impact energy, part geometry, recovery efficiency, contamination, dust removal and the acceptance profile. Do not advertise a fixed recycling number without application data.
Monitor the operating mix, not only new media. Repeated use changes the size distribution as grains fracture. Dust extraction and controlled additions help maintain stable performance.
Process Variables to Control
- air pressure or wheel speed;
- nozzle type, size and wear;
- stand-off distance and angle;
- media feed rate;
- workpiece material and hardness;
- target cleanliness and roughness;
- recovery, separation and dust extraction;
- cross-contamination from previous media.
WFA vs Other Media
茶色の融合アルミナ: tougher and usually more economical for general heavy blasting. Glass bead: spherical and more associated with peening or satin finishing than aggressive cutting. Steel shot/grit: dense and reusable in suitable systems but inappropriate where ferrous contamination is prohibited. Silicon carbide: harder and sharper, with different breakdown and cost characteristics.
Qualification Checklist
- Define the required cleanliness and surface profile.
- Identify contamination limits and whether dedicated equipment is required.
- Test two or three candidate grit sizes on representative parts.
- Measure cleaning rate, roughness, media consumption and dust.
- Inspect for embedding, discoloration or dimensional change.
- Approve the grade, chemistry and operating window together.
- Track the operating mix and finished surface over multiple cycles.
RFQ Information
- workpiece material and dimensions;
- contaminant or coating to remove;
- target surface roughness/profile;
- pressure blast or wheel blast system;
- current media and quality problem;
- required grit standard, quantity and packaging;
- destination and requested documents.
Read the WFA vs BFA selection guide. Ask Yumo for a blasting-grade recommendation and sample.
