A standard cone mill uses a rotating impeller (300–1,500 RPM) to force material through a conical stainless steel screen (0.5–25 mm aperture) by centrifugal action — providing gentle deagglomeration and controlled particle sizing of dry granules, slugs, and soft solids at 5–500 kg/h. Low tip speed (1–5 m/s) generates minimal fines and heat, preserving granule integrity for tablet compression and capsule filling — the GMP standard for pharmaceutical intermediate milling.
Material is fed into the top of the conical screen; the rotating impeller (300–1,500 RPM) sweeps material across the screen inner surface, applying centrifugal force and impact. Particles smaller than the screen aperture pass through; oversize particles are recirculated until reduced. Screen angle (45° or 60°) and impeller geometry (round bar, knife, or square bar) are selected per material type: round bar for fragile granules; knife impeller for agglomerates. Output particle size is primarily controlled by screen aperture, secondarily by impeller speed.
Challenges
Screen Blinding with Sticky Granules
Adhesive or high-moisture granules block screen apertures, reducing throughput progressively.
Granule Attrition at High Speed
Impeller tip speed above 5 m/s generates excessive fines, reducing tablet yield.
Screen Deformation Under High Load
Heavy feed loads at small apertures (0.5–1 mm) deflect screen and alter aperture geometry.
Containment for HPAPI Dry Milling
Open feed and discharge connections expose operators to potent API dust.
Scale-Up PSD Consistency
Impeller-to-screen clearance and residence time change with vessel diameter at scale-up.
Solutions
- Grater-Type or Rasping Screen Surface: Raised screen surface texture prevents adhesive granule blinding — extends run time 3–5×.
- VFD Impeller Speed Control (300–1,500 RPM): Programmed speed ramp prevents fines generation at start-up; matches speed to granule friability.
- SS 316L Screen with Reinforcement Ribs: Rib-reinforced screen maintains aperture geometry under maximum feed load.
- Contained Inlet Adapter (Split Butterfly / RTP): OEB 4–5 contained connection; no product exposure during charging and discharge.
- Impeller-to-Screen Clearance Validation at Each Scale: Mechanical similarity maintained by matching tip clearance ratio D/T across scales.
Applications
- Pharmaceutical: Dry granule sizing after roller compaction, wet granule sizing after FBP discharge, tablet blend milling.
- Nutraceuticals: Supplement granule sizing, herbal extract granule milling before capsule filling.
- Food & Beverage: Soft sugar deagglomeration, dried food particle sizing, spice granule reduction.
- Chemical: Catalyst granule sizing, fertiliser granule grading, specialty chemical agglomerate reduction.
- Cosmetics: Pressed powder granule sizing, dry cosmetic intermediate particle size control.
Models & Capacities
| Type 1 — Standard Under-Driven Cone Mill: Models & Capacities (Lab to Large Production) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Model | Scale | Throughput [kg/h] | Screen Aperture [mm] | Screen Area [cm²] | Impeller Speed [RPM] | Tip Speed [m/s] | Fines Generation [%] | Motor [kW] | Cone Ø [mm] | Inlet Ø [mm] | Overall L [mm] | Overall W [mm] | Overall H [mm] | Weight [kg] | |
| CM-UD-LAB | Lab | 1–20 | 0.5–10 | 55 | 300–3,000 VFD | 4–12 | <2 | 0.37 | Ø100 | Ø80 | 420 | 320 | 680 | 22 | |
| CM-UD-S4 | Lab | 5–50 | 0.5–10 | 120 | 300–3,000 VFD | 5–14 | <2 | 0.55 | Ø157 | Ø100 | 520 | 380 | 780 | 38 | |
| CM-UD-S7 | Pilot | 20–150 | 0.5–10 | 220 | 200–2,000 VFD | 5–14 | <2 | 1.1 | Ø220 | Ø140 | 680 | 480 | 980 | 75 | |
| CM-UD-U5 | Pilot | 50–300 | 0.5–10 | 450 | 150–1,500 VFD | 5–12 | <2 | 2.2 | Ø320 | Ø200 | 850 | 580 | 1,200 | 145 | |
| CM-UD-U10 | Production | 100–600 | 0.5–10 | 850 | 100–1,200 VFD | 5–12 | <2 | 4.0 | Ø450 | Ø280 | 1,100 | 750 | 1,550 | 280 | |
| CM-UD-U20 | Production | 200–1,200 | 0.5–10 | 1,650 | 80–1,000 VFD | 5–12 | <2 | 7.5 | Ø600 | Ø380 | 1,380 | 950 | 1,900 | 480 | |
| CM-UD-U30 | Production | 400–2,000 | 0.5–10 | 2,600 | 60–800 VFD | 5–11 | <2 | 11 | Ø750 | Ø480 | 1,650 | 1,100 | 2,200 | 750 | |
| CM-UD-U50 | Production | 600–3,500 | 0.5–10 | 4,000 | 50–600 VFD | 4–10 | <2 | 15 | Ø950 | Ø600 | 1,950 | 1,350 | 2,600 | 1,150 | |
| CM-UD-U75 | Large Prod | 1,000–5,000 | 0.5–10 | 6,200 | 40–500 VFD | 4–9 | <2 | 22 | Ø1,150 | Ø730 | 2,350 | 1,600 | 3,100 | 1,800 | |
| CM-UD-U100 | Large Prod | 1,500–7,500 | 0.5–10 | 8,500 | 35–420 VFD | 4–9 | <2 | 30 | Ø1,350 | Ø850 | 2,700 | 1,850 | 3,550 | 2,600 | |
| CM-UD-U150 | Large Prod | 2,500–12,000 | 0.5–10 | 12,500 | 30–360 VFD | 4–8 | <2 | 45 | Ø1,600 | Ø1,000 | 3,200 | 2,200 | 4,200 | 4,000 | |
| CM-UD-U200 | Large Prod | 4,000–20,000 | 0.5–10 | 18,000 | 25–300 VFD | 4–8 | <2 | 75 | Ø1,950 | Ø1,250 | 3,900 | 2,700 | 5,100 | 6,500 | |