Double Wheel Powder Filling Machine

The Double Wheel Powder Filling Machine (also known as Double Wheel / Double Head Injectable Dry Powder Filling Machine) is a high-speed, volumetric dosing system designed for sterile filling of dry powders into glass vials. It is commonly used in pharmaceutical injectable production lines and is often integrated with rubber stoppering in a monobloc design. It operates on the vacuum-pressure (or vacuum-air) volumetric principle using two rotating powder wheels for higher output (typically 150–250+ vials per minute depending on the model).

Step-by-Step Working Principle

• Powder Feeding & Agitation Sterilized powder is loaded into one or two powder hoppers. Mechanical agitators (usually a pair) continuously stir the powder to maintain uniform bulk density, prevent bridging/clumping, and ensure consistent flow. This is critical for achieving repeatable fill weights, especially under low-humidity conditions (ideally <28–30% RH).

• Powder Wheel Rotation & Dosing Each powder wheel (typically with 8–12 ports) rotates at a pre-determined speed below the hopper with minimal clearance.
  • Inside each port is an adjustable piston that determines the fill volume.
  • A vacuum plate is positioned behind the wheel (held by spring pressure for zero clearance).
  • As the port aligns under the hopper, vacuum suction draws powder into the port. The piston controls the exact volume.
  • A doctor blade (wiper) scrapes off excess powder from the top of the wheel for precision.

• Vial Indexing & Transfer Sterilized vials are fed via an infeed turntable onto a slat conveyor or rotary indexing system. Vials move intermittently or continuously in synchronization with the wheels. Sensors detect vial presence (“No Vial – No Fill” system) to prevent wastage.

• Powder Discharge When a filled port reaches the position directly above a vial:
  • Vacuum is released.
  • A pulse of compressed air or nitrogen pushes the precise dose of powder from the port into the vial.
  • Diving nozzles or funnels often lower close to the vial neck for dust-free, accurate transfer. The double-wheel setup allows two dosing stations, significantly boosting speed and enabling multiple doses per vial if needed.

• Rubber Stoppering (if monobloc) Filled vials immediately proceed to the stoppering station. Stoppers from a vibratory bowl are picked up and pressed (half or full bunging) onto the vials under laminar airflow to maintain sterility.

• Output & Controls Filled and stoppered vials exit via outfeed turntable or conveyor. The entire process is controlled via PLC with HMI, servo motors for precise indexing, and safety interlocks (low vacuum/air pressure stop, overload protection, etc.).