Casting Material Study : Volume 1
This year for the Santa Fe Symposium, I have been helping Teresa Fryé at Techform Advanced Casting on a study of CAD/CAM patterns. The study will focus on thermal expansion and how it may relate to casting quality. In 2005 we published a white paper on casting CAD/CAM materials and our hope is to expand and prove out our theories derived from that work. The results from months of work comparing numerous materials are now coming in.
When you take on a scientific endeavor the devil is the details. Teresa is great with details. She set out the DOE ( Design of Experiment ) for all of the worker bees to execute, including yours truly. Our first task was create a “WCS” Worse Case Scenario jewelry design in CAD software intended for casting. Trust me, if you ask a caster for a nightmare design they can tell you more than you wanted to know. I worked with Techform Process Manager, Kevin Mueller to design a ring shape with sharp edged features, triangular holes, pyramid corners, blind holes, and narrow channels with small prongs, all features designed to produce casting failures.
After coffee and the morning meeting, we took 3 of the each material type off to the foundry to be cast in 90/10 Platinum/Iridium. If you have ever tried to cast Platinum you can appreciate how difficult it is to get a perfect casting. That is where Techform has their niche as a boutique caster. As a former medical and aerospace caster, they utilize a proprietary process that is just downright better suited to platinum and palladium than any other in the world. They have close attention to detail there and the facility looks a like a hospital…..
Next step took 1 of each material type for burnout ash residue testing. When we started seeing more CAD/CAM at the turn of the century everyone was saying, “Yeah it’s the ash that made the bad casting.” Well I know there have been changes in these chemistries because I made some myself so, let’s reveal if ash is myth or reality. We did have some interesting results….
The remaining samples we used for our thermal expansion tests. There are several laboratories that specialize in this field measuring a “Coefficient of Thermal Expansion” CTE for any material using a dilatometer. Since we were more concerned about relative expansion of each material when compared to injection wax, we found a more creative in-house solution that seems to shed some light on the answers we have been looking for…..
So, that’s the basis for our work thus far. I will keep you informed over the next few weeks leading up to the Symposium. If you are a professional in jewelry manufacturing and have never attended the Santa Fe Symposium, invest in your knowledge base this year, you will never forget the experience.
Keep checking my blog for the “real” story about Palladium here in the US and abroad. I also had the chance to visit Gemvision and test drive their new Matrix 6.0 software…. I was blown away by some many new features ….more on that later this week….
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