D.Ghosh of Forace Polymers, India has written a paper on the Alphaset (APNB) process for mould and core making in foundries, one of the two most widely used self-set processes practiced across the globe at this time.
In this paper, attempts have been made to relate few variables in APNB formulations to physical, chemical and sand mix properties, at ambient and elevated temperature. Major variables in APNB formulations are mole ratio of phenol to formaldehyde, total alkali content, ratio of two alkalis NaOH and KOH, non-volatile content and extent of reaction. Total eight formulations A-H were made by varying ratio of two (NaOH and KOH) alkali and extent of reaction (molecular weight). Other variables were kept unchanged.
All these formulations have been studied for physical, chemical and sand mix properties, at room and elevated temperature over a period of time. This study may help to correlate essential parameters like increase in resin viscosity, decrease in bench life and drop in strength of mixed sand with resin ageing on storage. Efforts have been made to identify strength requirements of moulds at various stages right form stripping to post pouring and simulate same with laboratory strength values. Special efforts have been made to understand difference between Na and K as alkali in resin formulations on sand mix properties, a widely asked question in foundries.
Studies in this paper conclusively proves that quality of thermal reclamation chemical is the sole variable contributing to quality of thermally reclaimed APNB bonded sand produced from standpoint of stability. Using proper chemical, thermally reclaimed sand generated maintains essential properties like bench life, strip time and strength properties like that in fresh sand. Otherwise, if chemical is not proper, reclaimed sand generated works at beginning, say one or two days, then properties drop continuously making it totally in effective within as quickly as one week.
Fo a full version of the paper contact Joel Mutero of FP Specialty on TEL: 011 865 2845
Mobile: 060 570 0035