Abstract:
The traditional sand casting begins with the manufacturing of a physical pattern which is then used to develop a mold. The process however may require a lead time of days, or even weeks sometimes, depending on the size & complexity of the part to be cast. Furthermore, the foundry has to deal with the storage of the pattern so that it can be used again to make a new mold when a new batch of production or order is placed again. The foundry is actually paying to have them warehoused. It also requires a great skill and a lot of effort and time is wasted for making a pattern and small mistakes results into complete loss of pattern and it has to be made again.
To address the issue different techniques have been developed out of which a promising one is Additive Manufacturing. The technique in principle joins materials to make parts from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing. While the process has been used for rapid prototyping, its application in the field of manufacturing of sand molds for direct casting is rather new and unexplored. It holds quite a promise to reduce the lead times of cast parts since it can create complex and accurate sand cores and molds directly from CAD data, thereby eliminating the need for a physical pattern.
The research carried out hence focuses on the determination of the factors which affect the printability of a sand mold and the Design and Development of a 3D Sand Mold Printer using locally available/used sands and binders. The setup developed makes use of inkjet printing technology to spray the binder on the sand layers. The process begin with distributing a fine layer of sand, pre-mixed with the catalyst, and followed by spraying binder in the selected area of the deposited sand layer. Curing reactions taking place make the sand particles stick together only within the region where the binder will be sprayed. The process is repeated as the platform moves downward by a set distance until all of the layers of the part are completely printed and a final sand layer is spread.
