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Green Sand Metalcasting Foundry News

Cast in Place: Integrating Non-Cast Components into Castings

Posted by Hill and Griffith Company on Feb 11, 2020 8:00:00 AM

Article excerpt from the August 2017 issue of Modern Casting by Geoffrey D. Korff and Travis B. Stewart.

Steam turbines are built using a variety of castings ranging from standard class 25 gray iron to 400 series stainless steels. A typical single-stage turbine can contain up to 21 castings of different variations for the base design, while a typical multi-stage turbine can contain 30 castings or more. This does not include any castings that would be used for add-on equipment, such as trip and throttle valves and aftermarket governors or for other equipment on the equipment train.

The casting material is determined based on the temperature, pressure, environment, and steam conditions for the turbine application. In many cases, casting materials are interchangeable depending on these factors. For example, iron castings may be used in some applications for their thermal properties and ductility/dampening, while stainless steels may be used in other applications where it is needed for corrosion resistance. Material selection is important not only for the operation of the unit, but also for servicing the unit. Depending on the operating temperatures, there may be requirements for J-Factor calculations to avoid embrittlement in the time vs. temperature designs. Charpy impact testing may be required for low temperature service. For turbines, this is mostly environment-based and not dependent on operating temperatures.

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Tags: Green Sand Casting Products, Green Sand Foundry Supply, Foundry Supply, Green Sand Release Agents, Foundry Supplies, Modern Casting Magazine

Predicting, Preventing Core Gas Defects in Steel Castings

Posted by Hill and Griffith Company on Jan 28, 2020 8:00:00 AM

Modeling and analyzing core gas evolution and metal solidification behavior can aid in the prediction and prevention of porosity caused by core gas.

Article excerpt from the Modern Casting September 2014 issue by L. Xue, M. Carter, A. Catalina, Z. Lin, C. Qiu and C. Li.

Porosity is a common but serious casting defect. One type of porosity is a result of core gas that has evolved and become trapped in the casting during solidification. Detailed information is needed to reduce or eliminate core gas-related defects regarding the core gas generation, flow and venting in the core, and the metal flow and solidification behavior in the mold. In a recent study, numerical simulations were conducted based on a prototype design for a steel casting for Caterpillar. Core gas and porosity defects calculated in the simulations were analyzed and compared with the real casting results.

The gases dissolved during solidification can be caused by hydrogen or nitrogen in the initial liquid or core gas decomposed from the sand core and vented to the liquid, and they play a major role in porosity formation in castings. For all the analytical models developed to predict porosity defects in castings, most are based on tracking the evolution of dissolved gases in the initial liquid. Due to the complicated physics involved, modeling the core gas evolution in castings is difficult. However, without the consideration of core gas, predictions of porosity defects are insufficient.

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Tags: Green Sand Casting Products, Green Sand Foundry Supply, Foundry Supply, Green Sand Release Agents, Foundry Supplies, Modern Casting Magazine

Defect Detective: Common Green Sand Flaws

Posted by Hill and Griffith Company on Oct 22, 2019 3:47:48 PM

Green sand quality control, including good critical visual inspection, helps avoid scrapped castings.

Excerpt from the July 2018 issue of Modern Casting by the AFS Institute

Quality control begins with prevention. Metalcasters can control five areas of green sand mold making in order to prevent mold defects:

  • The selection of type of sand and clay and the amount of moisture needed to make the mold. 
  • Consistent mulling, using the right sequence of raw materials, and selecting the right temperature of the sand.
  • The cleanliness and condition of horizontal and vertical patterns, as well as core placement.
  • Selection of scrap metal and determining what can be reused and what must be discarded.
  • Testing for quality ensures the part meets the requirement of the buyer. While casting can be tested many ways, one of the major casting quality tests used after the casting is made is visual inspection.


Nine common types of green sand casting defects can be visually identified:

  • cracks
  • holes
  • rough surfaces
  • tear-up/drop
  • friable edges
  • excess parting spray
  • missing components
  • loose sand
  • sand contamination
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Tags: Green Sand Casting Products, Green Sand Foundry Supply, Foundry Supply, Green Sand Release Agents, Foundry Supplies, Modern Casting Magazine

Green Sand Foundry System: Go With the Flow

Posted by Hill and Griffith Company on Oct 1, 2019 8:00:00 AM

Excerpt from the October 2015 issue of Modern Casting

Every metalcasting facility is unique, but a department-by-department examination may highlight ways to improve operations and reduce costs.

No matter the size of a metalcasting operation, whether it’s a small, family-run shop or a mega facility with volumes in the millions, the question of modernization is not an “if” but a “when.” Machinery fails. Maintenance gives way to replacement. Upgrades need to be made.

Projects can be as simple as swapping out an old welding machine for a new one. They also can involve many more moving parts, such as a new molding line, which requires engineering and logistical planning far more advanced than simply sticking a plug in the wall. Every improvement project requires planning and engineering to ensure it fits into the broader facility-wide material flow and handling.


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Tags: Green Sand Casting Products, Green Sand Foundry Supply, Foundry Supply, Green Sand Release Agents, Foundry Supplies, Modern Casting Magazine

Article Excerpt: "Does Water Quality Affect Green Sand Properties"

Posted by Hill and Griffith Company on Aug 20, 2019 11:13:53 AM

Originally published in the June 2018 issue of Modern Casting.

by Bo Wallace, Sairam Ravi, Jerry Thiel

Water-soluble salts or electrolytes are just some of the mineral contaminants found in everyday tap water used by foundries across the U.S for their green sand systems. Bentonite is the main bonding compound of green sand systems, and for it to have quality bonding, it first must be activated with the use of an agent. A good activating agent must fulfill three requirements:  

  1. Be distinctly soluble in water, having a solubility of at least 1 g/100 g of water.
  2. Be composed of anions, which react with cations (Na+) to give insoluble compounds.
  3. Supply small, univalent cations for ion exchange.

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Tags: Green Sand Casting Products, Green Sand Foundry Supply, Foundry Supply, Green Sand Release Agents, Foundry Supplies, Modern Casting Magazine

Article Excerpt: "Dynamic Testing of Green Sand"

Posted by Hill and Griffith Company on Aug 13, 2019 3:24:51 PM

Can Metalcasters Better Monitor Sand Properties by Adopting Additional Testing Methods?

Originally published in the September 2015 issue of Modern Casting.

by Sam Ramrattan, Mo Khoshgoftar and Hiroyasu Makino

Sand property testing tells a metalcasting facility how well it is controlling its green sand system. Many of these current tests do not provide as timely results as desired, but certain laboratory tests are essential in properly controlling processes. Due to the nature of the variables that are being monitored, some test data, such as loss on ignition (LOI) values, tend to change slowly, while other test results, such as green compression strength and compactability, may fluctuate more abruptly. Current sand testing provides insight into sand quality, but the metalcasting industry as a whole would benefit from methods to better and more quickly quantify the effectiveness of sand-clay bond strength in green sand molds.

The green sand samples subtly change color after thermal erosion tests (TET) for various temperatures.

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Tags: Green Sand Casting Products, Green Sand Foundry Supply, Foundry Supply, Green Sand Release Agents, Foundry Supplies, Modern Casting Magazine

Article Excerpt: "Green Sand Testing Aptitude"

Posted by Hill and Griffith Company on Jul 30, 2019 3:32:42 PM

Originally published in the July 2014 issue of Modern Casting.

The dilution of core sand and other additives into greensand is a popular topic of discussion in the metalcasting industry. In the 1960s and 1970s, industry experts debated whether core sand was a contamination in greensand. But core sand or other additives (new sand) are not considered contaminations because these materials are added into the greensand by design, not by accident. Today’s sand casting facilities treat core sand and new sand as an additive that is monitored, and it is adjusted to compensate for variations in the process.

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Tags: Green Sand Casting Products, Green Sand Foundry Supply, Foundry Supply, Green Sand Release Agents, Foundry Supplies, Modern Casting Magazine

Article Review: "Avoiding (Green Sand Foundry) Coating Related Defects" - Part 2

Posted by Hill and Griffith Company on Jul 9, 2019 12:30:08 PM

Refractory coatings exist to improve casting quality, but when not properly applied, they can cause unwanted characteristics in the final casting.

By Jay Morrison, Carpenter Brothers (Mequon, Wisconsin)

Applying a refractory coating to molds and cores can be a useful step to improve surface finish, control the heat transfer characteristics and thus the microstructure in the casting, improve core venting and prevent certain defects in the casting. As with any process step, proper techniques in applying the coating are paramount in achieving the desired effects and avoiding the cause of new quality issues. Metalcasters can apply coatings to their sand molds in four main ways, all with varying advantages and disadvantages.

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Tags: American Foundry Society, Green Sand Casting Products, Green Sand Foundry Supply, Foundry Supply, Green Sand Release Agents, Foundry Supplies, Modern Casting Magazine

Metal Casting Systems - Choosing Between Nobake and Green Sand

Posted by Hill and Griffith Company on Jul 2, 2019 5:35:28 PM

Navigate the differences in capabilities and cost factors between nobake and green sand metal casting molding processes to ease your sourcing decision.

Opting for a sand casting process over permanent mold, diecasting, or investment casting is step one in sourcing a casting. But sand casting encompasses several methods, each of which carries its own advantages and disadvantages. The two most common processes used are green sand and nobake molding, and sourcing between the two is not always cut and dry.

Forty-two percent of North American metalcasters employ the green sand molding process.  Its popularity stems from its affordability, ability to be used for most metals and flexibility for low to high volume production.

Green sand molding does not hold the tightest tolerances or achieve the finest surface finish of all the casting processes; however, in general, it meets most of the qualifications desired to produce a high quality casting with a good finish.

Nobake sand casting, which is utilized by 40% of North American metalcasters, also is known for its versatility. Virtually all metals can be cast via nobake molding, a wide range of sizes can be produced, and the rigid mold walls provide good dimensional tolerances and control.

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Tags: Green Sand Casting Products, Green Sand Foundry Supply, Foundry Supply, Green Sand Release Agents, Foundry Supplies, Green Sand System, Green Sand Metalcasting, Modern Casting Magazine, Metal Casting Design & Purchasing

Article Review: "Avoiding (Green Sand Foundry) Coating Related Defects"

Posted by Hill and Griffith Company on Jun 25, 2019 5:26:42 PM

Refractory coatings exist to improve casting quality, but when not properly applied, they can cause unwanted characteristics in the final casting.

By Jay Morrison, Carpenter Brothers (Mequon, Wisconsin)


Brushing coating on molds is useful when extra care needs to be given to certain areas.

Applying a refractory coating to molds and cores can be a useful step to improve surface finish, control the heat transfer characteristics and thus the microstructure in the casting, improve core venting and prevent certain defects in the casting. As with any process step, proper techniques in applying the coating are paramount in achieving the desired effects and avoiding the cause of new quality issues. Metalcasters can apply coatings to their sand molds in four main ways, all with varying advantages and disadvantages.

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Tags: American Foundry Society, Green Sand Casting Products, Green Sand Foundry Supply, Foundry Supply, Green Sand Release Agents, Foundry Supplies, Modern Casting Magazine

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