Core making is an important branch in any foundry and the choice of core making depends on various factors. To name them are depending on type of metal to be cast, depending on the size of casting, choice based on complexity involved in a casting process, depending on the requirement of quality in final product, depends on equipment used for production and energy source.Common Technologies in Core Making :
There are six most common technologies involved in core making. They are
- Oil as the sand binder
- Green sand
- Shell process
In each of the above technologies there are various advantages and drawbacks.Requirements and Features of Common Technologies in Core Making :
When each of the above technology is ranked based on the usage of energy per unit of product ranking from greatest to lowest amount the order is oil as the sand binder being the highest followed by green sand, hotbox, coldbox, nobakes and shell process being lowest usage of energy in ranking.
That is when rated in percentage the technology of oil as the sand binder uses the maximum energy of hundred percentage and green sand used 85% followed by hotbox with 75%, coldbox with 58%, nobakes with 38%. The least energy usage is made by shell process technology with 35% recorded as usage.
The oil as the sand binder as well as the green sand technology uses high energy because it needs high temperatures for the process of curing and refractory coating and pasting has to be carried out on cores. The hotbox technology gives output as solid cores and needs hot curing for the process of binder setting. The technology of coldbox is carried out with the usage of heated sand and amine gas mixture.
Nobakes technology operates at accurately controlled setting. The least usage of energy is by shell process technology in which no coating is necessary.
Process change to any foundry must be taken only after careful projection on various factors being taken into account. Some to name in this direction are processing change results on costs like fixed and variable, investment or capital cost, payback needed and so on. In a similar way per actions towards energy consumption must be made for achieving system efficiency, which must also focus on step towards consistent usage of such energy consumed to be used efficiently.
Some of the steps suggested for workforce in this aspect are avoiding wastages of shell sand, usage of equipments producing heat only when needed, analyzing and taking steps towards vital defects, making economical usage by switching of unwanted machineries.
Some of the process improvements that could be made at reduced cost towards this direction are taking steps for oven insulation, going for moisture sensors installation, taking steps towards process improvements like reviewing for reusable products like steel cores which increase productivity and helps in achieving greater quality with cost cutting.
The high cost up gradations that could be taken in the direction for system efficiency are going for improvements in drying process by making use of either infrared heating or microwave heating, making use of technique of continuous drying, reuse of heat recovered, taking steps towards heat recovery like recovery of heat from exhausts attached in the drying or baking oven.