Injection + Heat Molding Trials: Local studio visits

FORMATION BX STUDIO

1. Circular Tray A

  • Bonding Agent: PLA (30%) + PEN-100 (60%)
  • Carbon: CaCO3 (10%)
  • Process: Thermoform @ 405 F: Silicon mold in toaster oven. Hand pressure applied
  • Results:
    • Some PLA granules in center still visible, most became totally liquid.
    • Material began smoking before reaching + sustaining melting point for PEN-100.
    • Virtually all PEN-100 granules deformed yet still distinct from each other. Some burned.
    • CaCO3 is suspended in melted PLA. Some collected on surface of PEN-100 granules and cannot be washed off but can be scraped off.
    • Some excess CaCO3 remained after cooling and was washed off. Agitating the material while heating helped.
    • Object has overall good strength, but poor aesthetic quality.


2. Circular Tray B

  • Bonding Agent: PS (85%)
  • Carbon: CaCO3 (15%)
  • Process: Thermoform @ 350 F: Silicon mold in toaster oven. Hand pressure applied
    • Limonene was mixed into EPS, reacting and dissolving it into a suspension of liquid PS polymer and limonene. This suspension was dried out for a week to become a block of solid yet flexible, clear PS with a yellow tint. The material was heated until it started becoming more formable, taken out and CaCO3 was added + kneaded in, the mixture was returned to the oven and pressed into the mold over time by hand.
  • Results:
    • Great strength and surface quality of mold face
    • Further agitating and mixing material while at temperature yielded high level of mixture and the vast majority of CaCO3 being suspended in PS, with a desirable β€˜tie-dye’-like pattern. Remaining limonene in the PS burned, giving the plastic a light brown color.
    • Poor surface quality on open face of mold - heating material has consistency of kneaded dough


3. Square Disc

  • Bonding Agent: PS + Limonene (43%)
  • Carbon: CaCO3 (28.5%)
  • Filler: Sawdust (28.5%)
  • Process: Wet mixture of limonene + EPS - Reaction to become liquid PS - Added CaCO3 + saw dust packed into silicon mold - Air dry
  • Results:
    • No update on dried end result

4. Hex Disc

  • Bonding Agent: PS + Limonene (48%)
  • Carbon: CaCO3 (30%)
  • Filler: Sawdust (22%)
  • Process: Wet mixture of limonene + EPS - Reaction to become liquid PS - Added CaCO3 + saw dust packed into silicon mold - Air dry
  • Results:
    • No update on dried end result





DAVE MARIN STUDIO

5. Injection Molded Tags A

  • Bonding Agent: Shredded Yellow PP (91%)
  • Carbon: CaCO3 (9%)
  • Process: Hydraulic Injection mold @ 385 F into aluminum mold
  • Results:
    • x6 samples produced, of varying concentrations of CaCO3 depending on the
      level of mixture in the heating barrel, which was difficult to maintain consistency.
    • Material was left to reach liquid point in the heating barrel and the material was injection into the mold at about 0.5 oz. at a time
    • After 1 initial shot, the material had visible streaks of CaCO3, a very subtle difference in color, and a slightly but discernably softer surface texture
    • When purging the remainder of the heating barrel, it appeared to contain some larger concentrations / clumps of CaCO3, suggesting difficulty passing through the nozzle / mold opening




6. Injection Molded Tags B

  • Bonding Agent: Shredded Clear PP (89%)
  • Carbon: CaCO3 (11%)
  • Process: Hydraulic Injection mold @ 385 F into aluminum mold
  • Results:
    • x3 samples produced, of varying concentrations of CaCO3 depending on the level of mixture in the heating barrel, which was difficult to maintain consistency. Yellow PP remained in the barrel held back, appearing in samples, presumably held back by clogged CaCO3
    • Material was left to reach liquid point in the heating barrel and the material was injection into the mold at about 0.5 oz. at a time
    • The 2nd sample of this batch showed a clear mixture + suspension and successfully demonstrates the ability to sequester CaCO3 in PP
    • It became immediately clear however that the CaCO3 was clogging the barrel / nozzle, yielding several blank shots
    • The nozzle was taken off and barrel cleared, showing leftover yellow PP and a significant amount of CaCO3 clumps which where stuck inside and obstructing the flow of material
    • The conclusion of injection molding trials was that while CaCO3 can be mixed with and suspended within PP without sacrificing any noticeable material properties, and permissible visual changes, the difficulty of getting a homogenous mixture and passing material through a small nozzle / pathway makes the process error-prone and not practical
    • Additional trials needed to explore methods of keeping CaCO3 from clumping (humidity/physical pressure) and enabling better mixture. Smaller nozzle sizes (under 3-4 mm in diameter) do not seem to be a promising path, but rather forming with larger nozzle sizes and / or casting / thermoforming


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