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Effect of Binder Composition on the Shrinkage of Chemically Bonded Sand Cores

DSpace at IIT Bombay

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Title Effect of Binder Composition on the Shrinkage of Chemically Bonded Sand Cores
 
Creator KHANDELWAL, H
RAVI, B
 
Subject DIMENSIONAL CHANGES
CASTINGS
Core
Binder
No-bake
Sand
Mold
Casting
Shrinkage
 
Description Modern foundries increasingly use chemically bonded no-bake sand cores and molds because they provide ease of molding, good surface finish, and collapsibility. One of the most popular binder systems is alkyd oil urethane no-bake system comprising three parts: alkyd resin, catalyst, and crosslinking agent. Their amounts and ratios can influence mold shrinkage, and thereby dimensional quality of the resulting casting. With rising emphasis on net-shape casting, there is a need to optimize the binder composition to minimize dimensional errors, while achieving the desired bench life, stripping time and hardness. This work investigates the effect of binder composition on the dimensions of chemically bonded sand cores with respect to time. The maximum shrinkage of 0.15% over length was observed when resin content was 2.4% by weight of sand. The rate of shrinkage increased with the amount of catalyst. Measurement of core hardness and reduction in weight, followed by SEM studies, provided a better understanding of the underlying phenomena, especially formation of resin bridges between compacted sand particles and evaporation of solvent. This work is expected to aid in selection of the most appropriate binder composition for a given set of molding process constraints and cast product requirements.
 
Publisher TAYLOR & FRANCIS INC
 
Date 2016-01-15T08:07:06Z
2016-01-15T08:07:06Z
2015
 
Type Article
 
Identifier MATERIALS AND MANUFACTURING PROCESSES, 30(12)1465-1470
1042-6914
1532-2475
http://dx.doi.org/10.1080/10426914.2014.994779
http://dspace.library.iitb.ac.in/jspui/handle/100/18125
 
Language en