Pharmaceutical Oscillating Mill
Gentle Calibration with Variable Rotor Motion. Frewitt OW Series.
Overview
Frewitt’s oscillating mill uses a variable rotor that transitions between oscillatory and rotary motion with a 2-degree offset per oscillation. This produces a more uniform particle distribution than pure oscillating or pure rotary mills, with significantly lower fines generation. The result is gentle, consistent calibration of pharmaceutical granulates where particle integrity matters.
The mill head and motor are built as separate units, enabling true through-wall cleanroom installation. The head sits inside the classified space while the motor stays outside, simplifying GMP facility layouts. OEB 5 containment is achievable without a dedicated isolator when paired with a containment enclosure on the discharge side.
Two production models are available. The OW-3 handles throughput up to 600 kg/h, the OW-6 up to 1,000 kg/h. Both process input material up to 5 cm down to 250 microns. A lab-scale OW-1 head is also available on the FlexMill Lab platform for process development before scaling up.
The oscillating mill head is part of Frewitt’s modular platform architecture. It mounts on the same base unit as conical sieve, hammer mill, and rotary sifter heads, sharing a single Tri-Clamp flange interface. Facilities that already run other Frewitt milling heads can add oscillating capability without purchasing a separate machine.
Key Specifications
| Input Size | Up to 5 cm |
| Output Size | Down to 250 µm |
| Throughput (OW-3) | Up to 600 kg/h |
| Throughput (OW-6) | Up to 1,000 kg/h |
| Temperature Range | -20 °C to +60 °C |
| Containment | OEB 5 capable (< 1 µg/m³) |
| ATEX Classification | Internal: Zone 0/20, External: Zone 1/21 |
| Rotor Motion | Variable oscillatory/rotary with 2-degree offset |
| Construction | AISI 316/316L interior, AISI 304/304L exterior |
| Seals | FDA-compliant |
Key Features
Variable Rotor Motion
The rotor transitions between oscillating and rotating modes with a 2-degree offset per oscillation. This produces uniform particle calibration with minimal fines, preserving product quality for sensitive granulates.
Through-Wall Installation
Mill head and motor are separate units. The head mounts inside the cleanroom, the motor stays outside. Simplifies GMP facility layout and reduces classified space requirements.
OEB 5 Containment
Achieves operator exposure levels below 1 µg/m³ without a dedicated isolator. Compatible with containment enclosures for fully enclosed powder handling at the discharge.
Platform Compatibility
Mounts on the same base unit as conical sieve, hammer mill, and rotary sifter heads via Tri-Clamp flange. Add oscillating capability to an existing Frewitt line without a separate machine.
Low Fines Generation
The 2-degree offset rotor design minimizes over-milling. Critical for pharma granulates where excess fines affect tablet compression, flowability, and content uniformity.
ATEX Rated
Internal Zone 0/20 and external Zone 1/21 classification. Suitable for processing powders with explosion potential without additional inerting when MIE is above 1 mJ.
Models
| OW-3 | Up to 600 kg/h. Dimensions: 1,299 x 860 x 1,417 mm. |
| OW-6 | Up to 1,000 kg/h. Dimensions: 1,343 x 860 x 1,417 mm. |
| OW-1 (Lab) | Lab-scale head available on the FlexMill Lab platform for process development and scale-up studies. |
Applications
- Gentle calibration of pharma granulates where low fines are critical
- High-containment milling of potent APIs (OEB 5)
- IBC-to-IBC powder screening workflows
- Pre-sizing with a crusher upstream feeding into the oscillating mill for final calibration
- Mobile milling on a lifting column for flexible production layouts
Options
- CIP, WIP, and SIP cleaning systems
- Inerting system for powders with low MIE
- Containment enclosure for OEB 5 discharge handling
- FreLift mobile lifting column (up to 3 m stroke, ATEX zones 1 and 21)
- IBC-to-IBC screening configuration
- Upstream crusher integration for two-stage size reduction
MHS Pharma. Northeast US Representative for Frewitt.
MHS Pharma provides direct technical representation for Frewitt across the Northeast United States. Contact us to discuss the oscillating mill for your application.
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