Optimizing Tablet Compression Parameters: Pressure, Speed & Properties in Pharma

‌1. Pressure Parameters‌

‌Main Compression Pressure‌ (Unit: kN)

· ‌Definition‌: Primary force applied by upper and lower punches to the material in the die cavity.

· ‌Impact‌:

· Insufficient pressure → Low hardness, crumbling, or loose tablets.

· Excessive pressure→ Hard tablets with delayed disintegration or dissolution (critical for pharmaceuticals), increased die wear, or capping (uneven pressure distribution).

· ‌Adjustment‌: Higher pressure required for poorly compressible materials (e.g., crystalline drugs).

‌Pre-compression Pressure‌ (10%-30% of main pressure)

· ‌Function‌:

· Expels air to prevent capping.

· Ensures uniform pressure distribution.

· ‌Use Case‌: Recommended for air-sensitive materials (e.g., lightweight powders) or formulations prone to capping.

‌2. Speed Parameters‌

· ‌Compression Speed‌ (Tablets/min)

· ‌Effect‌:

· High speed → Poor filling, weight variation, and density inhomogeneity (especially for sticky materials).

· Low speed → Reduced efficiency, suitable for high-precision batches (e.g., high-potency drugs).

‌3. Tablet Physical Properties‌

‌Tablet Weight‌

· ‌Control‌: Adjusted via fill depth (lower punch position).

· ‌Tolerance‌: Typically ≤±5% variation.

‌Thickness/Diameter‌

· ‌Determined by‌:

· Thickness → Pressure, material density, and weight.

· Diameter → Mold size (fixed parameter, e.g., φ5mm, φ8mm).

‌4. Material Properties‌

‌Particle Size‌

· ‌Issues‌:

· Uneven size → Poor flow and weight variation.

· Too fine → Electrostatic adhesion or poor filling.

· Too coarse → Density inhomogeneity and delayed disintegration.

‌Moisture Content‌ (3%-8%)

· ‌Effect‌:

· High moisture → Sticky material, sticking, or tablet softening.

· Low moisture → Brittle material, powdering, or capping.

‌Lubricant Level‌ (0.1%-1%, e.g., magnesium stearate)

· ‌Impact‌:

· Insufficient → Ejection issues.

· Excessive → Reduced hardness or hydrophobic coating.

‌5. Additional Parameters‌

· ‌Environmental Conditions‌:

· Temperature: 18-26°C

· Humidity: 40-60% (critical for hygroscopic materials like herbal extracts).

· ‌Tooling Condition‌:

· Die wear affects tablet appearance and ejection efficiency.

Note: Parameters are interdependent; optimization requires orthogonal testing or process validation.