Technical article
Casting Powder, Mould Powder, Mould Flux: Three Names for One Product
Buyers, tenders and datasheets use all three names, sometimes meaning different things. What each term covers, where they diverge, how to specify clearly.
Why this confusion costs money
Ask three people in an Indian steel melting shop what they feed onto the meniscus and you will get three words: casting powder, mould powder, mould flux. Ask a European equipment supplier and you will get a fourth, casting flux. Everyone is broadly describing the same consumable, and most of the time the conversation survives the ambiguity.
It stops surviving at two points. The first is procurement: a tender written for "mould flux" and quoted against "casting powder" leaves a purchase committee comparing offers they believe are for different materials. The second is technical — when the terms are used to distinguish genuinely different products and nobody says which distinction is meant.
This post sorts the vocabulary out, because specifying clearly is cheaper than re-tendering.
The terms, in practice
Casting powder is the common usage across Indian mini mills and induction-furnace-based units, and it is the term most buyers search. It covers the whole family: a blended powder or granule fed to the mould that melts to form a liquid slag layer.
Mould powder is the same material, named for where it goes rather than what it does. It is the more common term in integrated plants and in equipment documentation, and it tends to appear in operating manuals written around the caster rather than around the consumable.
Mould flux emphasises function. Strictly, the flux is what the powder becomes — the molten slag that lubricates the strand and controls heat transfer. Some specifications use "flux" for the liquid layer and "powder" for the material as supplied, which is a genuinely useful distinction when discussing slag pool behaviour.
Casting flux appears mostly in imported documentation and should be read as a synonym for casting powder unless the document defines it otherwise.
Our product page uses casting powder because that is how our market asks for it. A specification that says mould powder is asking for the same thing.
Where the terms really do diverge
Two distinctions hide inside the loose vocabulary and matter more than the naming.
Powder versus granule. Both are fed to the mould and both melt to the same slag. Granulated product dusts less, flows more consistently from an automatic feeder, and behaves differently in storage. A tender for "powder" that is quoted with granules is not wrong, but it is a real difference in handling and should be stated.
Mould feed versus open-cast covering. This is the distinction most often lost. Material fed onto a continuous caster meniscus does a different job from material used in open casting, and the chemistry is tuned differently. Both get called casting powder. If your enquiry does not say which route, expect to be asked.
Neither of these is a vocabulary problem. They are specification problems that the vocabulary conceals.
What to actually put in an enquiry
The name matters far less than five facts. Supply these and the term you use becomes irrelevant:
- Route and section. Billet, bloom or slab, with mould dimensions. A powder suited to a 130 mm billet is not the one for a slab caster.
- Casting speed. Low, medium or high, with the actual m/min if you have it. Speed drives the melting behaviour you need more than almost anything else.
- Steel grades. Peritectic grades, high-carbon, stainless and plain low-carbon all pull the chemistry in different directions.
- Steel temperature at the mould. Our grades are specified around 1500–1560 °C operating steel temperature; tell us if you sit outside that.
- Feeding method. Manual, semi-automatic or automatic feeder — this is what decides powder versus granule.
An enquiry carrying those five lines gets a usable grade recommendation on the first reply. An enquiry that says "mould flux, 20 tonnes" gets a phone call asking for them.
Reading a datasheet across the vocabulary
Once you have offers in hand, the names stop mattering and the numbers start. Four parameters carry most of the information:
Basicity (CaO/SiO2). Our grades run 0.8–1.3 depending on grade. Basicity drives crystallisation behaviour in the slag film and therefore heat transfer. It is the first number to compare and the one most often omitted from an offer.
Total carbon. 15–25% in our range. Carbon controls the melting rate — how quickly the powder becomes slag and how the unmelted layer insulates above it. Two powders with identical basicity and different carbon behave quite differently on the meniscus.
Softening and melting range. 950–1150 °C for our grades. This has to suit the heat available at your meniscus and the casting speed.
Bulk density and moisture. 0.75–1.15 g/cc and 0.5% moisture maximum. Bulk density affects feeder behaviour and the depth of the unmelted blanket; moisture matters in an Indian monsoon more than any datasheet conveys.
If an offer gives you a trade name and a price and none of these, you cannot compare it with anything. Ask.
A note on consumption figures
Consumption is quoted in kg per tonne of steel — our range is 0.30–0.60 kg/t — and it is the number buyers most like to compare, because it converts directly into cost per tonne. It is also the easiest number to mislead with, because consumption depends on section, speed, feeding discipline and slag pool management at least as much as on the powder.
A low consumption figure achieved on a slab caster tells you nothing about what the same powder will consume on your billet machine. Compare consumption only against your own route, measured over a full campaign, with feeding practice held steady. Anything shorter is noise.
The short version
Casting powder, mould powder, mould flux and casting flux all describe the material fed to the mould. Use whichever term your plant uses. What actually needs to be unambiguous in an enquiry is the route and section, the casting speed, the steel grades, the mould-level steel temperature and the feeding method — and in an offer, the basicity, carbon, melting range, bulk density and moisture.
Get those on paper and nobody has to guess what anybody meant.
Need a grade recommendation? Send your steel grades, casting route and the problem you are solving. WhatsApp +91 94313 42715 or email info@pkindustries.net.