Part Buyers Authority Issue #5

12 PART BUYERS A U T H R I T Y INTRODUCTION When it comes to the foundry industry and the technology that has been used to create prototypes and production castings, there have been minimal changes. The technology of the foundry industry is one of the most researched areas within the respective engineering discipline and therefore it beckons the phrase “If it isn’t broke don’t fix it.” 3D printing is beginning to change that line of thought by introducing new ways to manufacture a casting. The first being the use of 3D printed sand, which requires no hard tooling and can be easily changed to accommodate product design changes throughout the life cycle of the part. The second is the use of 3D printed plastic for hard tooling versus expensive wooden tooling. Both 3D printing methods are bringing new advantages to the foundry industry which are passed on to the parts buyers to take advantage of to reduce their costs and shorten lead times. 3D SAND PRINTING Many people are still unsure of what 3D sand printing is and how it relates to molding. The Viridis3D robotic sand printer, as seen in Figure 1, uses binder jetting technology in which furan binder is deposited in specific patterns to bond individual layers together to create the mold. This mold is comparable to existing no-bake technology in strength and surface finish – all without the need for an expensive wooden/metal/polymer pattern. The process flow for 3D printed sand is very similar to traditional mold making, therefore any large production orders can be transitioned flawlessly if the need arises. The part begins as a 3D model or 2D drawing provided by the customer, once a satisfactory casting model is achieved (i.e. machine stock added, fillets added) solidification analysis can be used to design an efficient rigging system. The major advantage to this is that when the part goes to the foundry floor there is a high confidence that the casting will be sound as the solidification software has predicted/shown where risering was needed and a proper gating system calculated based on established formulas. With 3D modeling the foundry engineer can create what works best for that particular casting by cutting the mold into several sections to allow for easier cleaning and handling or even removing mold material in areas that are unneeded to reduce cost and weight on the final mold. This can be seen in Figure 2, which shows a partially assembled mold that was printed in 4 separate sections. The 3D printer can run autonomously with very limited outside action needed by an operator. With Viridis3D’s current printer technology the rate of printing is 2.25 inches per hour on average and a curing time of 2 hours depending on the size of the mold printed, it is typical to print a mold and pour it the next day. One of the largest complaints with 3D printed sand ETHAN EDWARDS Foundry Metallurgist TRIDENT ALLOYS INC. Figure 1: Trident Alloys' Neptune