nouvelles de l'entreprise South Korea | How Should Machinery Foundries Select MgFeSi Particle Size for Consistent Spheroidization?

Particle size is the variable that turns one MgFeSi grade into several different treatment behaviours. In a sandwich ladle, 10 to 50 mm lump gives a reaction of roughly 60 to 120 seconds, which is enough to stir the bath without blowing magnesium out through the slag. In an in-mould system, the same alloy in 3 to 6 mm granule reacts within seconds, which is the point of the process. Korean machinery foundries that repeat spheroidization results choose the size band from the treatment method first and from the grade second, then verify the band by sieve rather than by eye.

Machine tool beds, hydraulic valve bodies and pump housings cover a wide section range, and they are often produced on lines that also run small parts. A single size band cannot serve both a covered ladle treatment and an in-mould conversion. Selecting size properly means accepting two or three stocked bands, each tied to a process, rather than buying one coarse product and adjusting the weight.

Reaction speed scales with surface area, and surface area scales inversely with particle diameter.

A 10 mm lump has a small surface to volume ratio, so magnesium is released over a longer period and the boil stays controlled. A 3 mm granule releases its magnesium quickly, which suits a process where the iron is already in the mould and mixing happens in a small cavity.

The treatment method sets the residence time available for the reaction, and the size band has to fit inside it.

Two bands are enough for most machinery foundries: a lump band for ladle work and a granule band for in-mould or tundish work. Stocking a third intermediate band is justified only when heats vary widely in tapped weight.

A band with a wide spread behaves like a mixture of alloys, so uniformity is a quality property in its own right.

Undersize is the more damaging of the two extremes in ladle work, because the magnesium that leaves early cannot be recovered later in the treatment. Oversize is more damaging in in-mould work, because the mould cavity has no time to dissolve a large lump.

Verification needs a sample, a sieve set and a decision rule, and it takes minutes.

1. Draw a sample from at least three bags per lot, from different container positions

2. Screen through the two sieves that define the band, for example 10 mm and 50 mm

3. Record the mass retained on each sieve and the undersize fraction

4. Compare against the agreed tolerance for undersize and oversize

5. Check for dust and broken fragments, which indicate handling damage

6. Retain the record with the lot certificate for the life of the delivery

A tolerance of a few percent undersize is normal in lump products. The point of the check is to detect a change, not to demand a perfectly monodisperse product.

The defect pattern is specific enough to identify the mismatch without a chemistry report.

The specification should describe the band in the language a sieve can test.

• Nominal band, expressed as the two sieve sizes that bound it

• Maximum undersize percentage and maximum oversize percentage

• Sampling method and the sieve set to be used for the check

• Packing format, since 1 MT big bags protect the band better than small sacks during handling

• Moisture protection and a statement that the product is delivered dry

• A clause covering handling damage, so that fines created in transit are a supplier responsibility

Writing the band as a sieve specification rather than as a descriptive phrase removes most of the arguments that follow a change in behaviour.

For most covered ladle work, 10 to 50 mm lump gives a controlled reaction of about 60 to 120 seconds. Large heats with deep ladles can use 50 to 100 mm lump.

Because the reaction has to complete inside the mould cavity in seconds. A 3 to 6 mm granule dissolves fast enough, while a lump would still be reacting when the metal solidifies.

No. Finer material reacts faster and loses more magnesium to the slag in an open ladle. Recovery depends on the match between size and process, not on fineness alone.

A small percentage is normal from handling. The acceptable figure should be agreed in the specification and checked per lot, because a rising undersize share is the first sign of a change in screening practice.

It is technically possible and practically a bad idea, because the reaction becomes a blend of two speeds that cannot be tuned. Use one band per treatment station and adjust the weight instead.

Big bags with proper liners protect the band during handling and transport better than small sacks, and they reduce the fines generated by repeated transfers.

Both matter, but size errors produce faster and more visible failures. A wrong band shows up in the first heat, while a grade error sometimes shows up only in a specific section thickness.

Trial the band on a single pattern for three consecutive heats, with the grade and weight held unchanged, and judge it on boil duration, residual magnesium at a fixed sample point and nodularity against the band already in use.

ZhenAn supplies FeSiMg in 10 to 50 mm and 50 to 100 mm lump, plus granule and powder forms, with magnesium from 5 to 11 percent and rare earth from 0.5 to 8 percent, ISO 9001:2015 certified, packed in 1 MT big bags at 20 to 25 MT per 20 foot container.

Send the treatment method, size band and monthly tonnage to receive a matched quotation.

Size bands are listed across the 10-50 mm FeSiMg lump page and the 3-6 mm FeSiMg granule page, with the coarser alternative on the 50-100 mm FeSiMg lump page.