3.3 KiB
Sheetpress Experiments - Cassandra - 650 - EDC - RC1
10 mm
A one-stage process, suitable for up to 10 mm thickness, requires careful setting and timing to avoid warping effects.
Description
One-stage process for plastic sheet pressing.
Settings
- Temperature: 155-160°C
- Cool-down temperature: 130°C
- Duration: 1 hour for mold closing, 30 minutes for cool-down
Requirements
- Place a stainless sheet inside the mold.
- Fill with plastic, carefully pressing.
- Avoid contact between the mounting edge and the mold.
- Wait 10 minutes before full pressing.
- Wait 1 hour for full mold closure.
- Cool to 130°C and wait 30 minutes.
- Remove the mold and access the formed sheet.
- For shiny/flat finish, press again with a harder surface.
Results
- Small flatness errors (0.5-1 mm) based on press quality and plastic characteristics.
Problems
Warping and material shrinking, especially in corners.
Proposed Solutions
Add reheating steps at 140°C and press again to minimize shrinkage and warping.
| Mould |  |
| Top-side | |
| Back-side | |
20 mm
A two-stage process for thicker sheets with a more controlled heating and pressing cycle.
Description
Two-stage process for enhanced material control and heating distribution.
Settings
- Temperature: 155°C, cooling at 130°C
- Duration: 90-100 minutes for initial heating, 30 minutes cool-down with die insertion
Requirements
- Reheat the plastic to 130°C.
- Insert a die with 3-4 mm thickness once melted.
- Cool the mold for 30 minutes before opening.
- For thicker molds, ensure the press has 20 tons of power.
Results
Reduction in warping and improved flatness by using intermediate dies.
Problems
Requires a significant amount of time to ensure proper penetration of heat.
Proposed Solutions
Incremental heating and die insertion at controlled temperatures to minimize air pockets.
| Mould |  |
| Top-side | |
| Back-side | |
40 mm
A challenging process with long melting times, leading to potential warping and deformation.
Description
3-stage process for very thick sheets. Manual handling needed to prevent air pockets and deformities.
Settings
- Temperature: 175°C
- Duration: 2 hours of heating, 3 hours cool-down
- Mould: 55mm
- Die: 10mm
Requirements
- Heat to 175°C for at least 2 hours to melt the thick plastic layers.
- Insert a die (10mm) to ensure no air pockets form.
- Let the plastic cool with a 3-hour rest while engaged with the die.
- Reheat corners at 140°C and press again, for 15 minutes, with no mould (careful).
Results
Height differences up to 5 mm on die-engaged side.
Problems
Long melting times, air pockets, and corner deformities leading to warping on one side.
Proposed Solutions
Intermediate reheating and more controlled cooling periods to mitigate height differences.
| Mould |  |
| Top-side | |
| Back-side | |