How to Read a Brown Fused Alumina Batch Test Report Before You Buy

A product data sheet tells you what a grade of brown fused alumina is designed to meet. A batch test report tells you what one actual lot measured. Approving a shipment from the data sheet alone means approving a promise; reading the batch report means approving evidence. This guide walks through a batch report in reading order, using published specification values from real product pages as reference anchors, and assumes you already have an agreed specification in writing.

Start With Identity: Lot, Grit and Grade

Read the header before any numbers. It should identify the product, grit designation, grade column, lot number and issue date.

Each field does a job. The grit designation — for example F36 — ties the lot to one size standard and one set of sieve limits. The grade column matters just as much: in the brown fused alumina F-grit series, grades are published in two columns, A and A-B, with different chemistry windows. A result that passes as A-B may sit outside the A window, so a number is meaningless until you know which column it is judged against.

The lot number is your traceability link. It should match the bag labels and packing documents. If the lot on the report and the lot on the bags differ, stop and clarify before discussing chemistry — the report may be accurate, but it would describe a different lot.

The Chemistry Block: What Each Line Tells You

The chemistry section rewards a line-by-line reading rather than a glance at alumina alone.

Alumina (Al2O3) is the headline figure. As a published reference, F36 and F46 grade A are specified at 95.00–97.50% Al2O3, while the A-B column starts at a minimum of 93.00%. Compare the lot result against the column you ordered, not against a generic expectation. Context also matters by size: fine grits in the F150–F320 range normally run lower, around 93%, because of how fine grain is produced and classified. Judging a fine grit against a coarse-grit expectation creates a problem where none exists.

Titania (TiO2) is part of the character of brown fused alumina, not an impurity to wish away. In the same published tables, titania is held at 1.50–3.80% for grade A and 1.50–4.20% for A-B. A result far outside the agreed window, in either direction, is a reason to ask how that lot was produced.

Silica, iron oxide and calcium oxide (SiO2, Fe2O3, CaO) are read as control lines. For grade A, a CaO limit of 0.45% or below is published for F36 and F46. Where your process is sensitive to one of these oxides, make sure the limit is written into the agreed specification, so the lot is judged against it.

The habit to build is simple: never read a result without its agreed limit beside it. Acceptance comes from comparing measured values with the specification fixed when the order was placed.

Particle Size Distribution: The Section That Predicts Behaviour

Many performance surprises blamed on chemistry actually start here. Two lots can share the same nominal grit and similar chemistry, yet behave differently in a wheel or a blasting cabinet because their size distributions differ.

A distribution table lists how much of the lot sits on or passes each sieve. Read it in three parts:

• Oversize fraction — material coarser than the nominal range. Elevated oversize shows up as scratches, uneven finish or localised wear in bonded tools.
• Main fraction — the share inside the target range. A stable main fraction is what makes one lot feel like the previous one.
• Fines fraction — material finer than the range. Excess fines change dust behaviour in blasting and packing and bond demand in wheel making.

On product pages such as brown fused alumina F36, fixed distribution percentages are not published as universal figures: distribution limits are confirmed in the agreed technical specification and the batch is tested against them. Check each sieve line against the limits in your order document, and watch the two ends of the distribution, where drift tends to appear before it shows in the main fraction.

For refractory section sizes, the same logic applies in millimetre ranges rather than F numbers. The refractory grain range is read by its own size bands and chemistry, but the method is identical: identity, chemistry against the agreed column, then distribution.

Magnetic Content and Other Physical Lines

Magnetic content looks like a minor line and is easy to skip. For resin and vitrified wheel makers it deserves attention, because magnetic particles carried into a wheel can affect tool quality and appearance. Published limits tighten as grit gets finer: for F36 the limit is 0.0340% for grade A and 0.0620% for A-B, and for brown fused alumina F46 it is 0.0300% for grade A and 0.0580% for A-B. Read the lot result against the limit for its own grit and grade.

Treat bulk density with a different lens. Check whether a density figure is a specification limit or a reference sample value. On the F46 product page, 1.85 g/cm3 is published as a reference sample result. It helps you see where a tested lot sits, but it is not a guaranteed limit for every batch and should not be used as a pass-or-fail line unless the agreed specification makes it one.

A Five-Minute Check Before You Approve a Lot

Before a trial or a repeat shipment is approved, run through these checks in order:

1. Do the product name, grit and grade column on the report match the order exactly?
2. Does the lot number on the report match the bags and packing documents?
3. Is every chemistry result inside the agreed window for the grade column ordered?
4. Are oversize and fines within the distribution limits fixed in the specification?
5. Is magnetic content within the limit published for that grit and grade?
6. Have you kept a copy of the report with a retained sample from the same lot, so any later question can be checked against both?

If any answer is unclear, ask for clarification while the lot is still identifiable. A question raised at this stage is a paperwork exercise; the same question after the grain has entered production is a much harder investigation.

The Bottom Line

Reading a batch report well is not about memorising numbers. It is about matching three things: the lot in front of you, the grade column you ordered, and the limits you agreed before production. Chemistry confirms the grade, distribution predicts behaviour, magnetic content guards wheel quality, and the lot number holds the chain together. Judge each line against its own agreed limit, keep the report with a retained sample, and confirm behaviour with a trial in your own process.

Luoyang Naibao New Materials Co., Ltd. has produced brown fused alumina since 1999 and supplies batch test documentation with its lots, with product data sheets available for each grade. If you are preparing an order, send the grade, grit size, quantity, packing and destination port, and the quotation and specification will be prepared against those exact requirements.