White Fused Alumina Grit Standards: FEPA F, P, JIS and Micron Sizes

White fused alumina powder is not defined by color and hardness alone. Industrial performance depends on the particle size distribution, chemistry, particle shape, cleanliness and the test method used. A grade described only as 280 mesh or fine powder is not precise enough for many abrasive, lapping or polishing applications.

This guide explains the main white fused alumina grit systems and the information buyers should place on a specification and certificate of analysis.

Material Standard and Grit Standard Are Different

A material specification describes properties such as Al₂O₃ content, Na₂O, Fe₂O₃, moisture, bulk density or magnetic content. A grit standard describes how particles are classified and tested. A product can have suitable chemistry but fail the required particle distribution, or meet a grit distribution but contain impurities that are unacceptable for the application.

A complete purchase specification should therefore identify both the material requirements and the particle size standard.

FEPA F Grades for Bonded Abrasives and General Applications

FEPA F grades are primarily associated with bonded abrasives and general abrasive grain applications. ISO 8486-1 covers macrogrits F4 to F220, while ISO 8486-2 covers microgrits F230 to F2000. The standards define classification and testing requirements rather than a single average particle diameter.

• F4 to F220: macrogrits commonly used in grinding wheels, blasting, refractory products and general industrial applications, depending on the grade.
• F230 to F2000: microgrits used where finer and more tightly controlled particles are required.

Official references: ISO 8486-1 and ISO 8486-2.

FEPA P Grades for Coated Abrasives

FEPA P grades are intended for coated abrasives such as abrasive paper, cloth, belts and discs. ISO 6344-2 covers P12 to P220 macrogrits, and ISO 6344-3 covers P240 to P2500 microgrits.

An F number and a P number that look similar should not be treated as identical. Their distribution limits, production controls and intended products differ. If a coated-abrasive producer requests P-grade material, the supplier should confirm compliance with the relevant P standard instead of offering an F grade based only on an approximate conversion chart.

Official reference: ISO 6344-2.

JIS Grades and Japanese Buyer Requirements

JIS particle size designations are common in Japan and in precision lapping, polishing and electronics-related supply chains. JIS grades should be supplied against the exact standard edition and agreed distribution limits. Do not assume that a JIS number is equal to the same FEPA number.

For Japanese customers, the purchase document should state the JIS standard, grade, sampling method and required report format. When replacing an existing supplier, comparing the actual distribution curves of the approved material and candidate sample is safer than relying on a conversion table.

Mesh and Micron Descriptions

Mesh generally describes the number of openings per linear inch in a sieve system, but different sieve standards can produce different opening sizes. Micron is a unit of length, not a complete distribution specification. A statement such as 10 micron powder may refer to a mean, median, maximum or another point in a distribution.

For fine powders, clarify whether the reported values are D10, D50 and D90, another percentile, a maximum particle size or a standard grade limit. Also specify whether the result comes from laser diffraction, sedimentation, microscopy or another method. Different instruments and dispersion conditions can produce different results on the same powder.

Why Grit Conversion Charts Are Only a Starting Point

Conversion charts are useful for finding a possible replacement grade, but they simplify a full distribution into one approximate value. They do not show oversize tails, fines content, particle shape or method differences. These details can affect scratch rate, cutting speed, coating density, surface finish and slurry behavior.

When changing suppliers or standards, use the chart to select a candidate, then approve the material through a representative sample and the agreed test method.

Key Quality Tests for White Fused Alumina Powder

Not every application needs every test. The correct control plan is based on the failure mode that matters to the customer.

What a Lot COA Should Show

A certificate of analysis is useful only when the buyer knows which results are actual lot tests and which are typical values. A professional COA should include:

• product name and agreed grade;
• lot or batch number;
• test item, method and unit;
• specification limit;
• actual lot result where required;
• inspection or production date;
• authorized approval.

For critical microgrits, consider requesting the particle size report, sieve residue result or microscope image in addition to the standard COA.

How to Write a Purchase Specification

A practical purchase description could follow this structure:

White fused alumina microgrit, grade and standard specified by buyer; agreed chemical limits; particle size tested by the named method; oversize limit defined; moisture and packaging requirements stated; each shipment supplied with lot COA and SDS.

The exact numbers must be agreed for the customer application. Avoid copying a competitor data sheet without checking whether the test method and process requirements are the same.

Choosing the Correct Grade by Application

• Bonded abrasives: start with the appropriate FEPA F grade and confirm chemistry, toughness, shape and bulk density.
• Coated abrasives: specify FEPA P where required and confirm particle shape and coating performance.
• Lapping and polishing: focus on distribution width, oversize control, cleanliness, dispersion and surface results.
• Blasting: evaluate size, shape, low iron contamination, breakdown rate and the required surface profile.
• Refractories: control chemistry, bulk density and the full coarse-to-fine particle packing design.

See our white fused alumina micro powder page, or read how to qualify a white fused alumina powder manufacturer.

Frequently Asked Questions

Is 280 mesh the same as F280?

No. Mesh and FEPA F grades describe size in different ways. A buyer should identify the applicable standard and required distribution instead of assuming they are equivalent.

Is D50 enough to approve a micro powder?

Usually not. Two powders can have the same D50 but different coarse tails and fines content. For scratch-sensitive processes, the upper end of the distribution and oversize control may be more important than the median alone.

Does every batch need a particle size test?

The test frequency should be agreed according to process capability and customer risk. For critical microgrits, actual lot data and retained samples provide stronger control than a generic typical data sheet.

Can a supplier guarantee both FEPA and JIS on one grade?

Only when the tested distribution satisfies both agreed requirements. The supplier should provide evidence rather than add multiple standard names to a product page.

If you need help matching an existing grade, send the current TDS, COA or sample with your application requirements. Ask Yumo for a grade review and qualification sample.