Experimental Investigation of Pattern-less Casting ... - MIT Publications

MIT International Journal of Mechanical Engineering Vol. 1, No. 1, Jan 2011, pp 17-25ISSN No. 2230 – 7699 © MIT Publications 20days [22]. ZCast provides three basic methods tofabricate moulds to produce casting rapidly [23].Reference [15] reported that the accuracy and surfacefinish are consistent with sand casting by using ZCastprocess.Feed RollerBinderCartridgeBinderComponentF. Major Features of ZCast:• ZCast501 mold is recommended for non ferrous metalswith pouring temperature below 1100 o C• The recommended shell mold wall thickness range isminimum12.5mm and maximum 25.4mm [24].• Before pouring, ZCast moulds must be baked in anoven from 180 o C to 230 o C for between 4 and 8 hours(based on volume), until it is “bone” dry.• Customers cast metal into these 3D printed molds forprototype evaluation or fully functional parts.Feed Material(Powder)PistonBuild ChamberFig.2(a) 3DP process [18]STARTLAYER OF POWDERDEPOSITED AUTOMATICALLYPRINT HEAD APPLIESRESIN TO POEDER LAYERPOWDER LAYER DRIESALMOST IMMEDIATELYADD ANOTHER LAYER?NOREMOVE COMPLETEDMODELFINISHFig. 2(b) Complete 3DP process cycleExcess MaterialChuteYESG. ZCast Methods(TM)• Direct Metal Casting (ZCast): The ZCast DirectMetal Casting consists of materials and processes thatallow designers and engineers to build moulds (copesand drags) and/or cores directly from a CAD file. Iteliminates the pattern creation phase of the traditionalsand casting process in a revolutionary way, resulting ina drastic reduction of the casting lead time from weeks todays. The process involves the design of basic partinglines and coring. A 3D mould shell approximately25(mm) thick is printed using ZCast plaster-ceramiccomposite material. If necessary, the shell is created withribbing and backfilled with traditional foundry sand togive added strength while minimizing material cost.• Loose Pattern Method (LP): The Loose Pattern (LP)method is a familiar and well-established technique inthe casting industry. The steps of this process are shownin Figure 1b. According to conventional techniques, thepatterns are usually made of wood or plastic.Implementing modern technologies, these patterns canbe produced using 3D Printing. Printed parts, havingbeen infiltrated, are aligned on a joint board. Around thepattern, a dividing surface (split line) has to be createdmanually by using resin mixed foundry sand or similarmaterials. The pattern stays loosely seated so that theprocess of creating the split line can be repeated for theother mould half, using the same pattern. The two jointboards are framed with wood which, along with the 3DPrinted pattern, constitutes the final foundry tool. Mouldhalves are then created separately by interchanging thepattern between the two core boxes.• Production Intent Casting (PIC): This method is acombination of the zp102 plaster material for creatingpatterns, and ZCast material for creating cores. It firstinvolves the creation of the foundry tooling as it wouldbe designed for the production foundry process,including core prints, offset partings, and clearances. Thepattern equipment is then printed with the zp102material, infiltrated with epoxy, and if necessarybackfilled with a rigid plastic filler for added strength. Ifcores are required, they may be produced using theZCast material.