Uniquecoat® G4™
Precision Gravimetric Powder Feeder
A versatile gravimetric powder feeder engineered for excellence in thermal spray processes such as HVOF, HVAF, Plasma, Cold Spray, Laser Cladding, and a broad spectrum of industrial applications. The G4 automatically maintains the feed rate, adjustable in standard or customary units. Its patented, seal-free feeding mechanism ensures smooth, pulseless powder flow that remains consistent over time.
G4 Powder Feeder
Key Features
Gravimetric G4 Powder Feeder
● Automatic Feed-Rate Control
Maintains the desired feed rate, configurable in grams per second, grams per minute, kilograms per hour, or pounds per hour.
● Gravimetric and Volumetric Modes of Operation
Allows flexible selection between gravimetric and volumetric feeding, depending on process requirements.
● Patented Powder Feed Design
Ensures smooth, pulseless powder flow and allows quick powder start and stop with no afterflow.
● High Feed Accuracy
Delivers precise powder delivery with most powders.
● Quick Start/Stop
Starts powder flow quickly and stops cleanly with no powder afterflow, providing controlled and efficient operation.
● Powder Calibration Function
Enables quick powder startup at the target feed rate, eliminating long stabilization periods.
● Built-In Load Cell Calibration
Enables quick recalibration and maintains precise measurement accuracy.
● Feed Rate Startup Ramp
Provides controlled increase or decrease of powder feed rate over a selected time period, enabling uniform coating thickness on tapered parts or discs.
● No Wearing Seals
Seal-free design eliminates consumable parts and reduces maintenance requirements.
● Large Recipe Storage Capacity
Stores and recalls multiple powder calibration profiles for fast process setup.
● Dump Powder Function
Allows quick, convenient hopper emptying at the touch of a button.
● Setpoint & Real-Time Feed-Rate Display
Provides clear visibility of both setpoint and live process feedback.
● Touchscreen Interface
Intuitive control panel for simple, user-friendly operation.
● Backpressure Insensitivity
Maintains stable, uniform powder flow regardless of backpressure variations.
● ASME Code Compliance
Designed and built in accordance with ASME pressure vessel standards.
● Optional Add-Ons
– Carrier-gas mass flow controllers
– Analog I/O or RS-232 interface for remote control and automation
Applications:
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HVAF
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HVOF
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Plasma
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CS
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Laser Cladding
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Additive Manufacturing
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Other Industrial Applications
Performance Demo
G4 Feeding Performance
This test was performed to evaluate powder flow stability and identify any fluctuations in feed rate. During the test, powder was collected in a bowl placed on a scale with 0.01 g resolution and direct strain-gauge output to a computer. The plotted curves are direct, unfiltered scale readings showing collected powder mass over time. Because the feeder is a gravimetric loss-in-weight feeder, the measured mass gain is presented as equivalent feeder weight loss.
Amperit 558.074, WC-10Co-4Cr, 15-45 µm
20 g/min
50 g/min
100 g/min
180 g/min
250 g/min
350 g/min
Amperit 658.067, WC-10Co-4Cr, 5-15 µm
20 g/min
50 g/min
100 g/min
180 g/min
250 g/min
350 g/min
Elemental Boron, 1-5 µm
Interpretation of the Feed-Rate Stability Test
The near-linear cumulative weight-loss curve demonstrates that the G4 feeder’s mechanical metering system delivers this fine WC-based powder at a highly stable average rate, within the resolution and sampling bandwidth of the measurement. This level of mechanical feed stability is essential for producing uniform coating thickness, since fluctuations in powder delivery can result in local variations in deposition rate. However, this test characterizes the powder discharge from the feeder only. It does not necessarily prove that the instantaneous powder flow exiting the spray gun is completely free of pulsation. Flow irregularities may be introduced downstream of the feeder as the powder is transported through the carrier-gas line. Possible causes of downstream powder pulsation include: - improper powder-hose diameter for the selected powder feed rate and carrier-gas flow; - excessive hose length, vertical lift, sagging sections, loops, sharp bends, or kinks; - abrupt changes in internal diameter at hose connections, reducers, unions, compression nuts, or other fittings; - internal steps, cavities, protrusions, or dead volumes inside adapters and connectors where powder can accumulate and then be released in batches; - powder accumulation in low points, elbows, fittings, or the gun injector, resulting in intermittent slugging; - insufficient, excessive, or unstable carrier-gas flow; carrier-gas pressure fluctuations caused by regulators, valves, mass-flow controllers, or the gas supply; - inadequate or varying pressure differential between the feeder and the gun; - changing backpressure from the gun, injector, combustion chamber, or nozzle; - leaks, loose fittings, or unintended gas ingress into the powder line; - partial restriction, contamination, wear, or improper geometry of the powder injector; - electrostatic charging of the powder or hose, particularly with very fine powders; - powder agglomeration caused by moisture, cohesion, or interaction with the hose wall; - incomplete feeder pressurization or unstable conditions during startup and shutdown. Therefore, the graph confirms the excellent mechanical performance of the G4 metering system, while the stability of the powder stream at the gun outlet also depends on the correct design and operating conditions of the entire powder-transport path—from the feeder outlet through the hose, fittings, and injector to the gun nozzle.
Examples of Powder Streams
Stream of ultra-fine WC-based powder (+2–15 µm) exiting a 2 mm powder injector connected to the G4 feeder at a feed rate of 180 g/min, demonstrating smooth and pulsation-free powder delivery.
Ultra-fine WC-based powder (2–15 µm) exiting the M2H gun nozzle, supplied by the G4 feeder at a feed rate of 180 g/min. Eliminating powder stream pulsation is essential for achieving Near-Net-Shape (NNS) coatings, as even minor fluctuations directly affect coating thickness uniformity.
Stream of WC-based powder (5–30 µm) exiting the nozzle of the internal-spray HVAF gun i7 at a feed rate of 15 g/min, demonstrating stable and pulse-free operation of the G4 gravimetric powder feeder at low feed rates.
Stream of WC-based powder (5–30 µm) exiting the nozzle of the internal-spray HVAF gun i7 at a feed rate of 120 g/min, demonstrating stable and pulse-free operation of the G4 gravimetric powder feeder at a feed rate typical for the i7 gun.
This 15-minute video demonstrates the stability and accuracy of the G4 feeder operation. You can compare the Setpoint with the actual powder feed rate. During the demonstration, the operator changes the Setpoint, and the feeder responds almost instantly. This performance is achieved thanks to the feeder’s powder calibration feature.
Our Similar Products
Model G10L™
The G10L gravimetric powder feeder is specifically engineered for Laser Cladding applications, where exceptionally high accuracy at very low feed rates is paramount. In laser cladding, the powder is delivered directly into the laser-induced melt pool. This process requires a stable, pulseless powder stream to ensure uniform track geometry, consistent layer thickness, and strong metallurgical bonding. Even minor fluctuations in powder delivery can cause variations in bead width, porosity, or dilution of the substrate.