How to resolve capsule filler dosing problems

2025-04-02 Visits: 39 +

How to solve the capsule separation problem and filling dosage problem?

The NJP series represents an integrated electromechanical-pneumatic automation system. Driven by a main motor through a indexing box and cam-linkage mechanism, it coordinates multiple stations to achieve capsule separation, material filling, waste removal, capsule closing, product ejection, and mold cleaning. Key features include:

  • Compact structural design

  • Advanced automation level

  • High operational availability

    Dosing accuracy ≤±3%

  • Material recovery rate ≥99.5%

  • Quick mold changeover (<15 min)

  • Low noise operation (<75 dB(A))

Dosing accuracy serves as the critical performance indicator. Our machine employs a ‌plug-type dosing mechanism‌ where filling volume is determined by the diameter (Φ2.5-Φ12mm) and thickness (3-15mm) of measuring disc holes, correlated with material bulk density (0.4-1.2 g/cm³). Notably, dosing precision is influenced by both machine parameters and environmental/material factors.


I. Production Environment Requirements

ParameterSpecificationSpecial Cases
Temperature21±3°CReduce for high-sugar/fat content materials
Humidity40-60% RHReduce for hygroscopic materials

Critical Control: Maintain environmental stability to prevent material adhesion to punches, which may cause weight variation exceeding ±5%.


II. Material Characteristics

Optimal Specifications‌:

  • Particle size: 80-100 mesh

  • Uniform granulation (CV <5%)

  • Homogeneous density (RSD <3%)

  • Moisture content: <3% w/w

  • Flowability: 25-35° angle of repose

  • Anti-static properties

  • Compactibility index: 0.8-1.2

Process Recommendation: Adjust formulation excipients (e.g., add 0.5-1% colloidal silica) to approach these parameters when pharmaceutically permissible.


III. Structural Factors & Adjustments

1. Surface Finish of Mold Components

  • Critical Inspection Points‌:

    • Measuring disc holes (Ra ≤0.4μm)

    • Filling rod tips (Ra ≤0.2μm)

  • Acceptance Criteria‌: No visible scratches, dents, or foreign particles under 10× magnification

  • Optimization‌: Electrolytic polishing can reduce material adhesion by 30-40%.

2. Clearance Control

ComponentStandard ClearanceAdjustment Range
Copper ring ↔ Measuring disc0.08-0.12mm≤0.2mm (sticky materials)
Partition block ↔ Measuring disc0.05-0.10mmNon-contact operation

Technical Note: Maintain contact surface finish (Ra ≤0.8μm) to prevent powder leakage exceeding 0.5% of batch weight.

3. Filling Rod Pressure Consistency

Verification Protocol‌:

  1. Clean rod seats (ultrasonic cleaning recommended)

  2. Spring force test:

    • Vertical droop deviation: <1mm

    • Swing amplitude variance: <15%

  3. Replace springs with >10% force variation

4. Material Level Control in Powder Ring

  • Sensor Calibration‌: 5-8mm detection range with 0.1mm repeatability

  • Feeding Strategy‌:

    • Delay time: 1-3s (adjustable via HMI)

    • Frequency: 8-12 feeds/min

  • Material Flow Aids‌:

    • Install agitator discs (rotation speed: 15-30 rpm)

    • Optimize machine speed: 2,000-2,800 cph

5. Compacted Column Characteristics

Column TypeWeight CVMachine LoadRecommended Action
Solid Column≤2%High (≥85% rated)Optimize punch taper angle
Semi-column3-5%MediumUse smaller disc holes (ΔΦ-0.5mm)
Granular≥8%LowActivate anti-leakage kit

6. Material Adhesion Mitigation

Corrective Actions‌:

  1. Environmental control:

    • Dehumidify to ≤35% RH for hygroscopic materials

    • Cool to 18-20°C for fatty compositions

  2. Mechanical adjustments:

    • Cam phase optimization (±5°)

    • Implement scraping mechanism (0.05-0.1mm clearance)

7. Weight Deviation Analysis

Utilize dual-channel weighing system (accuracy: ±0.1mg) to:

  • Detect front/rear row variations (>±3% indicates alignment issues)

  • Identify left/right deviations (>±2% suggests uneven compression)


IV. Dosing Accuracy Principles

  1. Finer disc holes offer better stability than coarser ones

  2. Thinner discs (3-8mm) outperform thick discs (>10mm)

  3. High bulk density materials (≥0.8g/cm³) show 40% lower CV

  4. Maintain powder level ≥80% ring height

  5. Surface flatness tolerance: ≤1mm/m²

  6. Level fluctuation should be controlled within ±3mm

Conclusion‌: Capsule weight uniformity (typically RSD 1.5-4.5%) is collectively determined by equipment condition (40%), environmental control (30%), and material properties (30%). Comprehensive process validation (≥3 consecutive batches) is recommended for critical formulations.


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