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The classification and nature of the nodulizer for ductile iron

Nodulizer is the primary mean of accessing to ductile iron. This article will briefly analyze the classification and nature of the nodulizer.

The classification of the nodulizer

Divided by production of ductile iron castings, nodulizer can be classified as alloy-like nodulizer, massive nodulizer, core line nodulizer, power nodulizer.

1. Alloy-like nodulizer

Including Mg-Si alloy, magnesium silicon alloy, calcium alloy (Japanese use more), nickel magnesium alloy, pure magnesium alloys and rare earth alloy.
Currently the world's most widely used alloy is rare-earth-Mg-Si alloy.

But the ratio of rare earth divided by Mg in China foundries ranges from 0.5 to 2.2, in foreign this ratio ranges from 0.1 to 0.3.

1.1.1 Calcium alloy

The calcium and magnesium nodulizer is mainly used by Japan casting producers.

The production of Shin-Etsu (SHIN-ETSU), NC5, NCl0, NCl5, NC20, NC25, the content of magnesium changes from 4 to 28%. But there are small changes in calcium content; the range is from 20 to 31%. Chilling tendency of such alloys is small, but it requires a high processing temperature and large amount of residue after treatment.

1.1.2 Nickel magnesium alloy

Nickel magnesium alloys is produced by International Nickel Company. The content of nickel is up to 82 ~ 85% while Ca is 20 % and Mg is 13%-16 %. But nickel is 57 to 61% minimum (which Mg 4 .0 ~ 4.5 %, Ca <2.5 %, Fe 32 ~ 36 %). German chemical company produces nickel-metal magnesium alloy in which Ni 47 ~ 51 %, Mg l5 ~ 17 %, C1.0 % Si28 ~ 32 %, RE1.0 %. The advantage of these alloys is heavy, reaction steady and nickel alloy can play a role in alloying. But it is characterized by expensive, this alloy in China, basically is not applied in China foundries.

1.1 Nickel-silicon alloy

Nickel-silicon alloy is currently not applied in China basically.

1.2 Pure magnesium alloy

Pure magnesium alloy processing need a dedicated pressure make magnesium package, and the magnesium absorption rate is high. But it needs very strict security dealing measures leading to a smaller proportion of the production application.

1.3 Rare earth

Rare earth is used when iron foundry invented ductile iron, which promotes the process of ductile iron industrial applications greatly.

But the price is high, and it has a large chilling tendency. If the mount is over, it will make graphite metamorphosis .So now it is no used alone as nodulizer, only as an auxiliary elements.

2. Massive nodulizer

Press magnesium and iron and silicon content designed directly into compression molding. Silicon in this nodulizer is very low. So it is referred to as a low pressure block nodulizer, which provides subsequent room and conducive to production of cast iron. But this alloy is easy to float, the effect of treatment is volatile. So it is better to use with massive nodulizer

3. Core line nodulizer

Coat the magnesium powder, iron powder in a thin steel plate or steel plate and cast it into the molten iron to achieve the purpose of balling. But this nodulizer is expensive, the investment in equipment is large and the absorption rate of alloy is high, so the cost of processing ductile iron is almost no increase.

4. Power nodulizer

Power nodulizer is a Russian patent. Mix with the magnesium powder and inhibitors into the bag. Make the molten iron flow through the surface of alloy, reacting with alloy layer and layer. Iron foundries call this special process MC.

Each nodulizer has its own advantages and disadvantages, iron foundries should base on their products and production process to choose appropriate nodulizer, in order to decrease the cost of investment and increase the production efficiency.

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