Part Buyers Authority Issue #4

Additive Manufacturing (AM) or 3D printing is an exciting technology that creates solid objects from a 3 dimensional CAD model. 3D sand printing (3DSP) falls under the Binder Jetting category of additive manufacturing. Molds or cores are produced by jetting a chemical activator over a bed of blended silica sand and dry acid binder to create a mold or core in accordance with the 3D model design. The mold or core is constructed one layer at a time as the jetted activator reacts with the dry acid to create a chemical bond joining one particle of sand to another. Computer software manages the construction process by controlling the deposition of the activator only where needed. Upon completion, the mold or core is removed from the print table and any blended sand that has not been treated with the jetted activator is removed from the build envelope. In some cases, this untreated blended sand is collected and recycled for reuse in subsequent prints. As with any of the other well known and understood molding and core making methods, 3D printing can be an effective solution when this technology is properly applied to the manufacturing problem. The additive production methodology produces sand molds and cores directly from a computer generated model thus eliminating the need for patterns and coreboxes. This makes the additive method of mold and core production uniquely suited for casting production when shortened delivery cycles are needed or when fixed tooling is not available. With Additive Manufacturing receiving so much attention, it is easy to get caught up in the excitement. It is important to understand when AM is appropriate. This is especially true for 3D sand printing. While there are many advantages to 3D sand printing, the incorrect application of this technology can add considerable cost without a realized benefit. TONY BADAMO President & CEO HAZLETON CASTING COMPANY 6 ROBOTIC 3D PRINTING FOR METAL CASTING Prototyping and design confirmation projects are very often the first thing that comes to mind when the subject of 3D sand printing is discussed. In many cases, sample pieces can be produced and tested in less time that is required to produce conventional tooling. Additionally, subsequent product design modifications can be effected in days through a revision to the digital files as opposed to time consuming and costly modifications to wood patterns. 3D sand printing is also widely recognized as an effective solution for timely production of castings that are needed in very low quantities or single use requirements. In these situations, the cost of fixed tooling can be difficult to justify from a cost and lead time perspective. It should also be noted that 3D sand printing does not need to be a stand-alone solution. Perhaps 3D sand printing offers the most benefit when this technology is integrated with conventional foundry practice. Cost savings can be realized when utilized in conjunction with traditional molding methods. Additionally, sand printing molds and cores provide a near infinite amount of design freedom to equipment designers and engineers. Conventional foundry processes often limit available geometries due to the need for tooling to be constructed with PART BUYERS A U T H R I T Y