Green Sand Metalcasting Foundry News

Excerpt from the January 2017 article in International Journal of Engineering Research and Technology by M.R. Latte and P.D. Chougule. 

Abstract

In this research paper, the blow-hole defect analysis of MH1-VST 4-cylinder block fitted on tractors is presented as a case study. An MHI-VST 4-cylinder block is the central component of a tractor or any vehicle. It plays an important role in lubrication, temperature control and stability of the engine. It must be of the highest quality so there is no room for shortcuts. In this case study, parts pre- and post-analysis is done by using quality control (QC) tools such as Pareto charts and cause/effect diagrams. A DMAIC approach is followed and proper actions are taken to reduce the defect and rejection rate at the factory end. The work is done under two phases:

Phase 1: identifying drastic effects of blow holes in production; 
Phase 2: sorting out the issues by using various QC tools and expert opinion.

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This article focuses the application of green sand in large scale infrastructure projects.

Excerpt from the Thomas Register article defining the different casting processes. 

Casting manufacturing is a process in which liquefied material, such as molten metal, is poured into the cavity of a specially designed mold and allowed to harden. After solidification, the workpiece is removed from the mold to undergo various finishing treatments or for use as a final product. Casting methods are typically used to create intricate solid and hollow shapes, and cast products are found in a wide range of applications, including automotive components, aerospace parts, etc.

 

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This article focuses the application of green sand in large scale infrastructure projects.

Excerpt from the December 2011 principle investigation by Craig H. Benson and Sabrina Bradshaw from University of Wisconsin-Madison's Recycled Materials Resource Center. 

Introduction

Foundry sand is high-quality uniform silica sand used to make molds and cores for ferrous and nonferrous metal castings. The metal casting industry annually uses an estimated 100 million tons of foundry sand for production. Over time, foundry sands physically degrade until they are no longer suitable for molds. Consequently, 9 to 10 million tons of sand are discarded each year. However, the discarded foundry sands have remarkably consistent composition and are typically considered a higher quality material than typical bank run or natural sands used in construction. Currently, an estimated 28% of discarded sand is reused in primarily construction related applications, while the remaining sand is discarded in landfills (American Foundry Society 2007). Recycling of foundry sand can:

• save energy
• reduce the need to mine virgin materials
• may reduce costs for both producers and end users

Use of foundry sand as a fine aggregate in construction applications offers project managers the ability to enhance green sustainable construction by reducing their carbon footprint, while also qualifying for LEED credits. The USEPA recently estimated that at the current recycling level 20,000 tons of CO ₂ emissions are prevented while 200 billion BTUs of energy are saved. Support for increased reuse of foundry sand has brought together the USEPA, the Federal Highway Administration, the US Department of Agriculture, the Recycled Materials Resource Center (RMRC), state environmental agencies, the foundry industry and end users to develop the tools and resources needed to increase foundry sand recycling to 50% by 2015.

 

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This article focuses on the nobake process and when it would be appropriate for use.

An MCDP Staff Report
Click here to see this story as it appears in the January/February 2018 edition of Metal Casting Design & Purchasing

Dozens of chemically bonded sand molding methods exist, but they can be divided into three main categories: coldbox, heat-activated and nobake. The basic principle is that a binder and catalyst are mixed with the sand to help form the mold into a "brick-like" product when cured. The differences in the process focus on the sand resin binder and catalyst used and how the mold or core is cured.

Coldbox—with this method, sand is coated with one of several binders, such as liquid sodium silicate or phenolic urethane, and catalyzed by a gas (such as carbon dioxide or sulfur dioxide) passing through the sand. This causes the resin binder to harden (cure) and lock the sand grains in place to maintain a solid mold wall.

Heat-Activated/Shell (also called hotbox and warmbox)—heat is used as the curing means in shell molding. Plastic resin-coated sand is compacted around a pattern and allowed to rest until a "shell" forms. The mold then is heated to temperatures higher than 500F (260C) to cure the mold.    

Nobake (also called airset, dry sand and precision sand)—like coldbox, several binders are optional. However, a liquid catalyst is used. The sand is processed in a continuous mixer and then formed around the pattern until it is fully cured.

Mold coatings are applied to more than 75% of noble molds. The coatings help prevent defects and improve surface finish.

Read More

This article focuses on the nobake process and when it would be appropriate for use.

An MCDP Staff Report
Click here to see this story as it appears in the January/February 2018 edition of Metal Casting Design & Purchasing

Dozens of chemically bonded sand molding methods exist, but they can be divided into three main categories: coldbox, heat-activated and nobake. The basic principle is that a binder and catalyst are mixed with the sand to help form the mold into a “brick-like” product when cured. The differences in the process focus on the sand resin binder and catalyst used and how the mold or core is cured.

Coldbox—with this method, sand is coated with one of several binders, such as liquid sodium silicate or phenolic urethane, and catalyzed by a gas (such as carbon dioxide or sulfur dioxide) passing through the sand. This causes the resin binder to harden (cure) and lock the sand grains in place to maintain a solid mold wall.

Heat-Activated/Shell (also called hotbox and warmbox)—heat is used as the curing means in shell molding. Plastic resin-coated sand is compacted around a pattern and allowed to rest until a “shell” forms. The mold then is heated to temperatures higher than 500F (260C) to cure the mold.    

Nobake (also called airset, dry sand and precision sand)—like coldbox, several binders are optional. However, a liquid catalyst is used. The sand is processed in a continuous mixer and then formed around the pattern until it is fully cured.

Mold coatings are applied to more than 75% of noble molds. The coatings help prevent defects and improve surface finish.

Read More