Mixing Beyond Metals – Solving Compatibility Issues by Printing Ceramics.
Case study on a model mixer blade in zirconia. Note that this mixer design was made internally and intentionally designed to be shareable. Customer examples are somewhat contrived, but are still realistic.
Loaded epoxy resins are often used to provide structural reinforcement and tuned properties in various assemblies. Additives can range from simple silica that is used to decrease sag to specialized metal fillers that are commonly used to repair cracked metals, even in extreme situations like engine blocks.
Manufacturing these resins can prove difficult, since they require high shears to successfully incorporate the fillers fully into the liquid, and can require long mixing times since the fillers are prone to settling out. These fillers effectively turn the resin into a liquid sandpaper, grinding away at anything that is moving within it. This particularly applies to the walls and the mixing blades used to contain it.
A manufacturer working in mass producing resin discovered that over the course of a couple of hours, significant impurities began to appear as gray streaks in the liquid – the stainless steel mixing blade was being ground away as it spun at high rpms through the resin. This steel impurity caused resin batches to change properties, causing several batches to be lost and costing the company thousands of dollars.
Plastic blades were tried and ultimately failed, as were coatings on the stainless. In both cases the plastic wore down even faster, and introduced a different set of impurities. In search of a better option, they moved on to ceramic materials.
Both alumina and zirconia are highly wear resistant ceramic materials. The first stop is always alumina, which is by far the most common technical ceramic material, and is usually the cheapest. Unfortunately, since there is a high start up torque and flex force, alumina parts risked shattering in the mixing process, and so were ultimately discarded. 3Y Zirconia, however, with a flexural strength of almost 1000 MPa, seemed to fit the bill perfectly.
Since the need was only for 10-100 parts per year, setting the part up for ceramic injection molding or hot pressing was completely out of the question – with mold costs at almost $150,000, it simply wasn’t economical. Ceramic machining was more reasonable, with parts only costing a few thousand dollars each, but the timeframes and costs were still high.
At this point they reached out to Sinto Advanced Ceramics to see if 3D printing could help. Not only would parts be possible to print with any quantities, but the first articles could be turned around in only a few weeks and immediately put into production.
| CIM | Ceramic Machining | 3D Printing | |
|---|---|---|---|
| Total Cost for 80 Blades | $160,000 | $150,000 | $6,000 |
| Cost / Part for 80 Blades | $2,000 | $1,875 | $75 |
| Lead Time for 80 Blades | 8-12 Months | 12-15 Weeks | 4-5 Weeks |
When parts arrived, the fit easily onto the shafts, with the fit nearly as close as the original stainless propellers. The parts were able to spin up to 1500 rpm without issue, and have been mixing resin successfully with no signs of degradation into the material at all.
Sinto Advanced Ceramics, USA
If any of this is of interest to you, we encourage you to reach out to our engineers and sales representatives. They are experts in the field of ceramic 3D printing, and are happy to help you to realize your ceramic part needs.
Learn more about Sinto Advanced Ceramics USA online here.
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