12. Molding and Casting - Landon Broadwell and Alana Duffy¶
The assignment for this week was to read the datasheet for the casting and molding materials used, including their safety procedures, instructions, and other relavent data. The second part of the assignment is to compare the molds and casts for different workflows/procedures/methods.
Datasheets¶
Since most of us had only used two materials during this week, we only looked at the datasheets for them. These two were both Smooth-On products, with the first being Mold Star Series 15 Slow, and the second being Task Series 8.
Mold Material Technical Data Sheets:
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Mold Star 15 SLOW by Smooth-On technical data sheet (the flexible cast material)
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Task 8 by Smooth-On technical data sheet (the hard cast matrial)
Mold Material Saftey Sheets:
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Mold Star 15 SLOW by Smooth-On SDS (the flexible cast material)
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Task 8 by Smooth-On SDS (the hard cast matrial)
| Material | Pot Life | Cure Time | Mix Ratio | Mixing Temp. | Tensile Strength | Color |
|---|---|---|---|---|---|---|
| Mold Star 15 SLOW | 50 Minutes | 4 Hours | 1A:1B | 73F | 400 psi | Green |
| Task 8 | 6 Minutes | 15 Minutes | 1A:1B | 73F | 5840 psi | Off-White |
Additional safety notes:
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Mold Star 15 SLOW: avoid contact with eyes, wear gloves and safety glasses. On contact with eyes, seek medical attention. On contact with skin, though partially skin-safe, remove with soap and water. Keep away from children.
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Task 8: avoid contact with eyes. Wear gloves and safety glasses. On contact with eyes, find immediate medical attention. On contact with skin, remove with soap and water quickly. Keep away from children.
Comparisons¶
Materials¶
To compare the two materials, we used Landon’s casts.
The Mold Star cast was flexible, soft, and a turquoise-ish green, and the Task 8 was rigid, sturdy, and an opaque white. Depending on the type of cast required, both seem to be viable options and both could be used in a variety of ways.
Since Task 8 cures far quicker, it is a better option for mass producing a design, but the process is somewhat messy and seems to have more safety risks, mainly around how skin-safe it is and the high temperatures it gets to when curing. Additionally, unless precisely measured, it is difficult to measure out how much to pour into the mold, as it expands during the curing procedure.
Mold Star 15 has a much slower cure time, but, in exchange, has less safety risks and a significantly longer pot life, making it easier to work with. If too much of the material is poured in, some of it can be scraped out or cut off at the end of the process. Additionally, the temperature changes minimally, decreasing the hazards of coming into contact with it, even with gloves on.
As stated previously, both have individual capabilites and utilizations, so neither can be considered stricly better than the other.
Milled vs 3D Printed Molds¶
The milled molds came out with much more detail than the 3D printed molds, yielding higher quality casts. This is likely due to the ability to adjust the bit size where, on the 3D printers, we are limited by the size of the printer’s nozzle.
In terms of the 3D printed molds, the Prusa MINI molds that used the Prusa filament turned out better than the Formlabs molds that used resin. The resin molds were always slightly sticky no matter how many wash or curing cycles they went through. Additionally, to avoid cupping with the resin prints we had to use supports where, with the prusa mini, we did not. The supports on the resin prints are very hard to remove and leave a rough, bumpy surface when removed, further decreasing the quality of the resin mold’s casts.