Extrusion

Many engineering plastics absorb moisture from the surrounding air during storage and handling. If these materials are processed without proper drying, moisture can lead to polymer degradation, surface defects, bubbles, reduced mechanical properties and inconsistent product quality. Drying the material to the recommended residual moisture level is therefore an essential step before extrusion.

Accurate dosing of virgin material, regrind, masterbatch and additives is critical for maintaining consistent product properties. Variations in material flow or bulk density can alter the recipe and result in colour deviations, fluctuating mechanical properties or unnecessary material consumption. Gravimetric dosing systems help maintain precise formulations throughout production.

Contamination can occur during material transport, storage or manual handling. Dust, foreign particles or material mix-ups may affect product quality, increase scrap rates and lead to production downtime. Closed and automated material handling systems help reduce contamination risks and improve process reliability.

Extrusion lines often operate under changing production conditions. Variations in throughput can influence dosing accuracy, melt quality and process stability. Continuous monitoring and automatic process control help compensate for these fluctuations and maintain consistent production.

Regrind plays an important role in improving material efficiency and reducing waste. However, inconsistent particle size, moisture content or mixing ratios can negatively affect product quality. Controlled handling and precise dosing of regrind help ensure a stable production process while supporting sustainability goals.

Drying systems, conveying equipment and auxiliary machinery account for a significant share of the total energy consumption in extrusion plants. Optimising these systems can reduce operating costs while maintaining reliable production performance. Energy-efficient technologies and process optimisation therefore play an increasingly important role in modern extrusion facilities.

In many industries, including automotive, medical and packaging, complete traceability of raw materials and production batches is becoming increasingly important. Automated material management systems support documentation, recipe management and quality assurance throughout the production process.

Consistent product quality starts long before the material enters the extruder. Reliable conveying, efficient drying, accurate dosing and automated material management contribute to stable processes, reduced waste and improved production efficiency. An integrated material handling solution helps manufacturers maintain consistent quality while increasing productivity across the entire extrusion process.

Plastic extrusion is a continuous manufacturing process in which plastic material is melted and forced through a shaped die to create products with a constant cross-section. Common applications include pipes, profiles, sheets, films, cables and medical tubing. The quality of the finished product depends on consistent material preparation, stable processing conditions and precise control of the extrusion line.

Gravimetric dosing is a method of feeding raw materials based on weight rather than volume. The system continuously measures and adjusts the material flow to maintain the specified recipe, even when bulk density or throughput changes.

Compared with volumetric dosing, gravimetric systems provide higher accuracy, improve product consistency and reduce material waste.

Material conveying transports plastic pellets, regrind or additives from storage silos, containers or drying systems to the extrusion line. Most modern extrusion plants use vacuum conveying systems that automatically deliver the required material while minimizing contamination and operator intervention.

Centralized conveying systems can supply multiple extrusion lines simultaneously and improve overall production efficiency.

Many hygroscopic polymers require drying before processing because they absorb moisture during storage and handling. Common examples include:

• PET 
• PA (Nylon) 
• PC 
• PBT 
• TPU 
• PMMA  
• ABS (depending on grade) 
• PLA 

Non-hygroscopic materials such as PE and PP generally do not require drying, although removing surface moisture may still be beneficial under certain environmental conditions.

Volumetric dosing measures material by volume. It is a simple and cost-effective solution but may be affected by changes in bulk density, material shape or flow characteristics.

Gravimetric dosing measures material by weight and continuously compensates for process variations. This results in greater dosing accuracy, more consistent product quality and improved traceability.

For applications with tight quality requirements, gravimetric dosing is generally the preferred solution.

Material waste can be minimized by improving the consistency of the entire material handling process. Important measures include:

• Accurate gravimetric dosing 
• Proper resin drying 
• Stable material conveying 
• Controlled use of regrind 
• Automated recipe management 
• Continuous process monitoring 

Reducing process fluctuations helps lower start-up scrap, minimize off-spec production and improve material utilization.

A complete extrusion material handling system typically includes:

• Raw material storage 
• Material conveying 
• Drying systems (for hygroscopic materials) 
• Gravimetric or volumetric dosing units 
• Mixers  
• Extruder feed systems 
• Process control and automation 
• Material management software 

The exact configuration depends on the processed materials, production capacity and quality requirements. Integrated material handling solutions help ensure reliable operation, consistent product quality and efficient use of raw materials.