Extruder feeding with an Extruflow Gravi line

A leading manufacturer of electrical and optical cables asked Palamatic Process to design a feed line for its extruder.

The main objective was to optimize the production of technical plastic granules used as insulation for electrical cables.

Once extruded, these granules are then taken to a second line to cover the bare cables.

Challenges identified:

• Ensure a continuous and consistent feed to the extruder to avoid variations in the quality of the plastic granules.
• Optimize the dosing and mixing of raw materials to ensure a consistent compound composition.
• Minimize dust emissions and ensure compliance with industrial safety and hygiene standards.

Palamatic Process has designed an Extruflow Gravi line, enabling gravity feeding from a multi-level structure.

This solution eliminates the need for complex mechanical conveyors and ensures a smooth feed of raw materials to the extruder.

Integrated equipment:

• EasyFlow® 125 big bag emptying with sealed connection and pneumatic cylinder assistance.
• Manual bag emptying stations for powders and additives (powder No. 1, powder No. 2, premix).
• High-precision weight feeders (± 0.5%) to ensure accurate dosing of granules and powders.
• Integrated mixer to homogenize materials before feeding into the extruder.
• 1,000 L weighed buffer hopper with integrated dosing unit, ensuring a stable flow to the extruder.
• Herding cyclofilter filtration system to minimize dust emissions.
• Palamatic PLC with touchscreen interface, ensuring real-time control and supervision.

1. Storage and emptying of raw materials

The raw materials used in the process include:

• Granules No. 1 to No. 5 (apparent density: 400 to 1,100 kg/m³, particle size: 3 to 10 mm).
• Powders and additives (apparent density: 200 to 600 kg/m³, particle size: 2 to 20 µm).

The big bags are emptied via an EasyFlow® 125 station, equipped with a pneumatic massage system and a sealed connection.

The powders and additives are fed via bag emptying stations with controlled extraction to limit the dispersion of fines.

2. Dosing and weighing of materials

Each material is weighed individually using weighed buffer hoppers with precision scales accurate to ± 200 g.

The granules are dosed via D1310 single-screw feeders, capable of handling flow rates from 481 to 5,781 L/h.

Powders and premixes are dosed by a D14 twin-screw feeder, with an adjustable flow rate from 29 to 3,854 L/h.

3. Mixing and homogenization

A buffer hopper mixer is used to ensure perfect homogenization of the materials before extrusion.

The buffer hopper is equipped with vibrators and a weighing system to ensure smooth flow and accurate dosing.

4. Extruder feed

The mixed materials are released into a 1,000 L weighed buffer hopper, equipped with a single loading feeder.

The extruder feed rate is adjustable between 10 and 500 kg/h, depending on production requirements.

5. Control and supervision

The entire process is managed by a Palamatic PLC, ensuring:

• Real-time monitoring of flow rates and dosing.
• Optimization of recipes for maximum repeatability.
• Complete traceability of batches produced.

• Optimized quality of plastic pellets, ensuring uniform insulating properties.
• Improved process consistency thanks to continuous and homogeneous flow.
• Reduced material losses and optimized formulations thanks to the ultra-precise weighing system.
• Compliance with safety standards and reduced dust thanks to the Herding cyclofilter system.
• Advanced automation, limiting manual intervention and reducing the risk of human error.

This case study demonstrates the performance and reliability of the Extruflow Gravi line for optimized extruder feeding and total control of the compounding process.