What precautions should be taken when using a hot melt extruder for pharmaceuticals?

The pharmaceutical hot melt extruder (HME) is a key piece of equipment used in the pharmaceutical industry to prepare solid dispersions, sustained-release formulations, and improve the solubility of poorly soluble drugs. To ensure production safety, product quality, and stable equipment operation, strictly adhering to the operating specifications for pharmaceutical hot melt extruders can ensure stable machine operation.

1. Equipment Preparation and Inspection

Raw Material Pretreatment: All raw materials must meet pharmaceutical standards. Polymer excipients should be pre-dried to a moisture content of <0.5%. Raw materials should be sieved through an 80-100 mesh screen and premixed for at least 30 minutes to ensure mixing uniformity.
Equipment Inspection: Before starting the machine, check that the thermocouples in each heating zone are functioning properly (with an allowable deviation of ±1°C), confirm that the cooling water system pressure is maintained at 0.2-0.4 MPa, and verify that the screw is properly assembled and that no loose threaded components are loose.

2. Process Parameter Control

Temperature Setting: Set a temperature gradient based on material characteristics (generally, the feed section should be 20-30°C below the melting point). Sensitive drugs should be operated under nitrogen protection (oxygen content <100 ppm).
Operation Monitoring: Main motor current should not exceed 75% of the rated value. The pressure sensor display should be stable within the range of 5-15 MPa. Torque fluctuation should be controlled within ±5%.

3. Production Operating Specifications

Startup Procedure: Preheat to the set temperature and maintain for 30 minutes. Start at a low speed (10-20 rpm). Gradually increase the speed after the discharge stabilizes.
Abnormal Handling: Immediately reduce the speed if a sudden pressure rise occurs. Immediately shut down and clean any material overflow. Abnormal temperature fluctuations exceeding ±3°C require interruption of production.

4. Cleaning and Maintenance

Daily Maintenance: Immediately flush with a special cleaning compound (such as PEG400) after production. Check the screw for wear weekly (replace if wear >0.5mm).
Deep Cleaning: Disassemble the die head for thorough cleaning after each batch change. Regrease the drive system monthly.

5. Safety Precautions

Operational Safety: Wear scald-resistant gloves and a face shield when handling molten materials. Do not open the safety door while the equipment is operating.
Electrical Safety: Regularly check the ground resistance (<4Ω). The emergency stop button must remain enabled.