Sand Casting for Power Generation Equipment Applications - Impro Precision


Sand Casting for Power Generation Equipment Applications

June 13th, 2023

Many components of power generation equipment perform best when produced in cast iron. It’s a metal that can dampen vibration, distribute heat, hold up to wear and withstand high loads. Impro sand casts an extensive range of components in iron for power generation equipment manufacturers and applications.

Cast Iron Metallurgy

In the oldest form of cast iron, gray iron, a high carbon content results in graphite flakes forming in the metal matrix. While strong in compression and possessing excellent damping and heat transfer characteristics, this type of cast iron is too brittle for many applications.

Ductile iron, where inoculating the metal with magnesium at pouring makes the carbon form spheres or nodules, is stronger, but inferior in terms of damping and thermal conductivity.

Between the two is compacted graphite iron (CGI). Like ductile iron, this is produced by inoculating the melt, but at a lower level. The result is a vermiculite structure that’s stronger, stiffer and lighter than gray iron but still with good damping and conductivity.

Two additional forms of cast iron used for power generation equipment components are SiMo Ductile and ADI.

SiMo ductile contains elevated proportions of silicon and molybdenum, which increases resistance to thermal cycling fatigue. ADI is the abbreviation for austempered ductile iron. This refers to austempering heat treatment, a complex process involving controlled quenching. Austempering results in a very strong yet light material, wear-resistant and with good damping behavior.

Sand Casting Capabilities at Impro

Impro’s foundries carry out both green sand and resin casting of cast iron. Green sand casting is the older, more traditional form where a clay binder holds the sand mold together. Resin sand casting is a newer development that replaces the clay with a resin coating on the sand particles.

Resin sand casting has two advantages over green sand. First, there’s less moisture in the mold, which means fewer problems with porosity. Second, resin produces a mold that’s harder and denser, which helps improve geometric accuracy.

When casting CGI, inoculation with magnesium is key to achieving the required properties. CGI is especially sensitive to both the quantity and timing of the magnesium addition: Impro handles this by using some of the most advanced sand casting equipment available.

Iron Inoculation in Impro Foundries

Impro casts CGI on equipment made by the Swedish company, SinterCast. SinterCast is considered the industry leader in iron inoculation, thanks to the sampling and magnesium addition technology they developed. Impro uses both SinterCast System 3000 and the newer System 4000 equipment.

Power Generation Equipment Castings

Impro sand casts many of the major components used in power generation equipment. For generators this includes cylinder blocks and heads, plus manifolds, pistons and various frames and brackets. Most are cast in CGI or ductile iron, but exhaust manifolds typically employ SiMo ductile iron to better handle the thermal cycling.

Other power generation parts produced include torque arms for wind turbines (cast in ADI,) and components for gas turbines. This last category however tends to use investment cast superalloys rather than sand cast iron.

Experts in Sand Casting and Cast Iron

Though sometimes considered an “old-fashioned” metal, iron has advantages over steel and aluminum in power generation equipment applications. Particularly in CGI and ADI form, it has a high strength-to-weight ratio, good thermal conductivity, and machines well. Its most notable characteristic though is an ability to absorb and dampen vibrations like those from combustion. This reduces noise, which is an important consideration in the marketplace.

Impro has extensive experience in casting iron and has both the technology and systems needed to produce high quality parts on a consistent basis. Whether you need a source for power generation equipment components or are looking to have parts cast in gray, ductile or CGI iron, we can help. Contact us for more information.


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