Settings and process
Setting up your extruder
When setting up your extruder, you need to adjust the temperature and speed based on the type of polymer you are processing. These settings vary between different polymers, and even within the same polymer, different colours can behave differently.
Key factors affecting extrusion settings
- Polymer type: Different plastics melt at different temperatures and require different extrusion speeds.
- Colour variations:
- Black HDPE is often an impure mix of polymers, so it tends to melt at a lower temperature than other colours.
- Yellow HDPE, by contrast, is usually purer and may require slightly different settings.
- Melting flow index (MFI):
- PP has a low MFI, meaning it flows easily and requires a faster extrusion speed.
- HDPE has a higher MFI, so using the same speed as PP would cause uneven melting.
Extrusion settings
Below are the temperature and speed settings we use for different polymers. The values are based on a standard 6×1 mould.
- Temperature: N/A
- Speed: N/A
- Cooling times (in a cooling bath): N/A
- Temperature: 220 – 245°C (428 – 473°F)
- Speed: 11 – 25 Hz
- Cooling times (in a cooling bath): 20 – 25 minutes
- Temperature: 160 – 200°C (320 – 392°F)
- Speed: 15 – 35 Hz
- Cooling times (in a cooling bath): 10 – 15 minutes
- Temperature: 160 – 200°C (320 – 392°F)
- Speed: 15 – 40 Hz
- Cooling times (in a cooling bath): 10 – 15 minutes
Extrusion process
The extrusion process happens in three main stages: Pre-extrusion, Extrusion, and Post-extrusion.
1. Pre-extrusion (Preparation stage)
- Prepare your material – Ensure plastic flakes, pellets, or agglomerates are ready.
- Check tank levels – Make sure there is enough material for a full run.
- Set heating – Adjust the temperature settings and wait for the barrel to heat up.
- Clear the barrel – Pre-extrude any leftover material from the last run.
- Select your moulds – Choose the right mould size and shape.
- Prepare the extrusion table – Ensure it is stable and ready for use.
- Attach the mould to the universal die.
- Switch on the VFD (Variable Frequency Drive) to control speed.
2. Extrusion (Forming the product)
- Fill the hopper with plastic material.
- Wait for the mould to fill completely.
- Switch off the VFD once extrusion is complete.
- Unbuckle the mould and hoist it into the cooling bath.
- Repeat the process with a new mould.
3. Post-extrusion (Cooling, demoulding, and storage)
- Hoist the mould onto the demoulding table.
- Unbolt the back stopper.
- Attach the hydraulic jack.
- Select the correct demoulding bar.
- Engage the jack to push the product out.
- Close the mould and hoist it back to the waiting bay for reuse.
- Weigh and label the extruded material.
Store safely for further processing or sale.
