Part Buyers Authority Issue #1

INTRODUCTION TO 3D SAND PRINTING When it comes to the foundry industry and the technology that has been utilized 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 therefor 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 of looking at a job. 3D printing is bringing new advantages to the foundry industry for parts buyers to take advantage of and there are 2 that make the biggest impact, shorter lead times and reduced cost. THE PROCESS To most people they are still unsure what 3D sand printing is and how it relates to molding. In its simplicity Viridis3D’s sand printer, as seen in Figure 1, is similar to the modern inkjet printer in homes today. Each print pass can be seen as the next piece of paper that was printed and the binder can be seen as the ink that prints the words on the paper. To go a little more in-depth the sand printer 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 sand printing is very similar to traditional mold making so 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 begin using SolidCast. Running solidification analysis the foundry engineer can design and redesign the rigging (gating and risering) system quickly and efficiently. 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 known theories. With a final rigging system designed and verified, through solidification analysis, mold design can begin after the material shrinkage is added to the casting model. At this point the foundry engineer must envision what the mold is going to look like when printed. It is up to the engineer to create this mold as separate pieces, traditionally known as the cope/ drag. Unlike traditional molding however, 3D printing is not limited to this thinking. With 3D modeling the foundry engineer can create what works best for ETHAN EDWARDS Foundry Metallurgist, TRIDENT ALLOYS 18 PART BUYERS A U T H R I T Y 3D Printed Sand Molds: HOW DOES THIS HELP YOU? TRIDENT ALLOYS Figure 1: Trident Alloys’ Neptune