A single screw volumetric micro feeder meters powder by rotating a precisely machined screw inside a close-fitting tube, discharging a fixed volume per revolution. Feed rate is set by screw speed alone, making it the simplest and most economical micro dosing device for free-flowing powders from 0.05 to 450 litres per hour in SS 316L contact execution.
Challenges
Rate Drift with Bulk Density Variation
Volumetric metering assumes constant bulk density; lot-to-lot and fill-level density changes shift the true mass rate without any alarm.
Pulsating Discharge at Low Speed
At the low end of the turndown range, individual flight discharges appear as visible pulses rather than a smooth stream.
Flushing of Aerated Fine Powders
Freshly filled fine powders flow uncontrolled through the rotating screw clearance like a liquid.
Screw Wear Changing Displacement
Abrasive powders wear the screw and tube, gradually increasing clearance and altering the calibrated volume per revolution.
Incomplete Emptying at Product Change
Powder held in the screw flights and hopper throat resists complete discharge, extending cleaning at changeover.
Solutions
- Scheduled Catch-Sample Recalibration: Timed catch-weight checks with automatic speed correction in the controller compensate density drift between full gravimetric upgrades.
- Spiral or Double-Flight Screw at Low Rates: Open spiral and double-start screws overlap flight discharges, smoothing the stream across the low end of the range.
- Deaeration Hold and Discharge Valve: A settling residence in the hopper and a pinch or slide valve at the outlet block flushing until the powder deaerates.
- Hardened or Coated Screw Sets: Through-hardened or tungsten-coated screw and tube sets hold displacement calibration against abrasive duty.
- Tool-Free Quick-Strip Screw Assembly: Clamp-connected tube and slide-out screw allow full strip-down and cleaning in minutes without tools.
Applications
- Minor Ingredient Addition to Mixers: Continuous or dose addition of colours, flavours, and functional additives into blending lines.
- Tablet Coating Powder Dosing: Metered powder feed into coating suspension preparation vessels.
- Food Fortification Micro Dosing: Vitamin and mineral premix dosing into flour and staple food fortification lines.
- Filling Machine Rate Trials: Laboratory and pilot dosing during product and pack development.
- Catalyst and Additive Feed to Reactors: Small controlled powder streams into batch chemical reactions.
Model Range and Capacity: JBM-MF-S Series
Basis: Rates at 2 to 100 percent screw speed, kg/h quoted at 0.6 t/m3, SS 316L contact parts.
| Model | Screw Dia (mm) | Feed Rate (L/h) | Rate (kg/h) @ 0.6 t/m3 | Hopper (L) | Drive (kW) | Contact Material |
|---|---|---|---|---|---|---|
| JBM-MF-S12 | 12 | 0.05 – 4 | 0.03 – 2.4 | 5 | 0.18 | SS 316L |
| JBM-MF-S20 | 20 | 0.5 – 25 | 0.3 – 15 | 10 | 0.25 | SS 316L |
| JBM-MF-S30 | 30 | 2 – 90 | 1.2 – 54 | 25 | 0.37 | SS 316L |
| JBM-MF-S40 | 40 | 5 – 220 | 3 – 132 | 50 | 0.55 | SS 316L |
| JBM-MF-S50 | 50 | 10 – 450 | 6 – 270 | 75 | 0.75 | SS 316L |