How To Choose The Feeding Method on The Tablet Press

Standard (gravity) feeding is suitable in the following cases:

✅ Good Material Flowability

• Carr Index ≥60, or angle of repose ≤30°

• No significant adhesion, agglomeration, or bridging

✅ Production of Standard Single-Layer Tablets

• No layered filling required; single-component or pre-mixed uniform materials

✅ Low to Medium Speed Compression (≤50 rpm)

• Sufficient die filling time without mechanical assistance

✅ Standard Round or Shallow Concave Dies

• Simple die shapes without deep cavities or complex structures

✅ Moderate Weight Variation Tolerance (±3%~5%)

• Suitable for conventional tablets (e.g., standard oral solid dosage forms)

✅ No Special Dust Containment Requirements

• Non-toxic, non-potent materials where open feeding is acceptable

Advantages: Simple structure, easy maintenance, low cost
Disadvantages: Unsuitable for poor-flowing or special-shaped tablets

Enclosed (sealed) forced feeding is required for:

✅ Potent, Toxic, or Highly Sensitive APIs

• E.g., hormones, cytotoxics – prevents cross-contamination

✅ Dust-Generating Materials

• High fine powder content; complies with GMP containment

✅ High-Precision Tablets (Weight Variation ≤±1.5%)

• Controlled-release tablets requiring strict fill uniformity

✅ High-Speed Compression (>100 rpm)

• Ensures uniform filling in very short time

✅ Extremely Poor-Flowing Single-Layer Formulations

• Highly cohesive, hygroscopic, or electrostatic materials

✅ Continuous Large-Scale Production

• Minimizes downtime for cleaning

Advantages: Dust-free, contamination-proof, ideal for high-end production
Disadvantages: Complex design, higher cost, unsuitable for multi-layer tablets

3. When to Use Open-Type Forced Feeding?

Open-type forced feeding (with agitators) is suitable for:

✅ Multi-Layer Tablets (Bi-Layer, Triple-Layer, etc.)

• Requires layered filling of differently colored materials

• Allows visual monitoring and control of layer distribution

✅ Materials with Poor Flowability

• High fine powder content (>20%), slightly cohesive

• But does not require full containment

✅ Non-Standard or Deep-Cavity Dies

• Shapes like heart, triangle, oval, etc.

• Deep dies where gravity feeding is insufficient

✅ Medium to High Speed Compression (50~100 rpm)

• Mechanical assistance ensures fast and uniform filling

✅ R&D or Small-Batch Production

• Easy parameter adjustment and process observation

Advantages: High flexibility, suitable for multi-layer tablets, easy cleaning
Disadvantages: Poor dust containment; unsuitable for potent/toxic compounds