Green Sand Metalcasting Foundry News

Effects of Chemical Surfactants on Clay-Bonded, Green Sand Foundry Sand Control Systems

A 1-1/2 year research project by several companies lends help to understanding the role of chemical surfactants to the industry

AFS Foundry Sand Additives Committee (4-H) 

Searching for the most direct method to determine the effect of chemical surfactants (wetting agents) on clay-bonded systems, member companies of AFS Committee 4-H decided a series of L-8 orthogonal arrays would be the ideal technique.

Once the orthogonal array was se­lected, the variables and levels were determined (Table 1).

During the laboratory experimental evaluations, a series of chemical surfactants was evaluated. These surfactants were selected from products used in the foundry industry.

Prepared sand mixtures were com­pleted in a research environment A testing laboratory muller with a 20-lb capacity was employed. The sand mix­ture was consistently prepared by mulling a four-screen silica sand for 10 min­utes with 7% bentonite. A total of 60 L-8 designed experiments were completed during the evaluation phase.

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Tags: Metal Casting, Green Sand Casting Products, Green Sand Foundry Supply, Foundry Supply, Green Sand Release Agents, Metal Casting Supplies, Foundry Supplies, Green Sand Metal Casting, Green Sand System, Green Sand Metalcasting, Foundry Core Coating, Vein reduction

Reducing Surface Defects With Proper Vein Reduction

While green sand foundry vein reduction compounds can lead to improvements in iron castings — such as reduction in metal penetration and core erosion — they can result in varying degrees of tensile property reduction.

As casting surface quality becomes increasingly important to end-users, foundries have to find new and effective methods of eliminating surface defects in iron castings.

One method — vein reduction compounds — is used primarily to reduce or eliminate expansion defects, which show up as “veins” on the surface of the casting. Foundries have achieved reductions in expansion defects and imprints in casting quality with mixtures of 90% prepared sand and 10% vein compounds.

However, the key to vein reduction compound use is to be careful when adding the compounds into core sand mixtures, as they can result in varying degrees of reduction in mold tensile properties. This reduction is due primarily to the composition of the materials and the sizing.

This article will take a look at the process of vein reduction and what casting surface quality improvements can result.

Fig. 1. The middle location on this test casting was made with a phenolic urethane binder without the addition of a vein reduction compound. The locations at the left and right both used vein reduction compounds.

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Tags: Metal Casting, Green Sand Casting Products, Green Sand Foundry Supply, Foundry Supply, Green Sand Release Agents, Metal Casting Supplies, Foundry Supplies, Green Sand Metalcasting Foundry, Green Sand Metal Casting, Green Sand System, Green Sand Metalcasting, Foundry Core Coating, Vein reduction, metalcasting