Part Buyers Authority Issue #1

It’s a problem every buyer dreads - engineering or production needs a single piece, or maybe just a few, of a part that has not been tooled, tested, or approved for production. They need it in a few weeks, the budget does not allow for large tooling expenditures, and waiting months for tooling to be built, samples produced and final approval is not an option. Until recently, there was no solution that would meet everyone’s needs - but thanks to recent developments in additive manufacturing, and collaboration with investment casting foundries, help is on it’s way. Tech Cast would like to present the following cast study as a perfect example of how you can use this exciting fusion of new and older technology today. Finding the optimum design for pump impellers is critical to making the most efficient, powerful and effective pumps no matter what the application or the market. However traditionally it has been difficult to design and accurately predict how the actual, physical part will perform with so many complex components playing a role. In the past this was accomplished by building a tool, making samples, testing it, and then either making expensive alterations to the existing tool or building a whole new die - all at considerable time and cost. All too often this has resulted in an incomplete development process, with the customer choosing a “good enough” design rather than an “optimized” design. However, in this case Tech Cast, worked with 3D Systems to produce a pattern (See Figure 1) via stereolithography, that would replace the traditional wax pattern used in investment casting. Patterns produced through additive manufacturing, introduced over the past several years, provide increased design versatility without physical constraints of conventional tooling. Because these patterns are created using an additive manufacturing technology, (a process that requires no tooling), this makes it possible to have a prototype pattern created at a fraction of the cost and time required for tooling. Creating patterns using additive manufacturing, enables customers to evaluate several design alternatives inexpensively, and simultaneously, to quickly develop a better performing impeller. STUDY OBJECTIVES This case study had several objectives: • Determine the quality of castings created with SLA (stereolithography) patterns relative to those created with wax patterns. Included in the quality evaluation will be: – Dimensional accuracy – Surface roughness – Surface quality • Determine the relative total cost to create the first casting. • Determine the time required to create the first casting with each method. ANDY BOMBERGER & ANDYMILLER TECHCAST LLC Using Additive Manufacturing to produce Rapid Prototypes through Investment Castings 8 PART BUYERS A U T H R I T Y Figure 1. Pattern created through Additive Manufacturing –in this cast through stereolithography