Method for powder flow control

A method for controlling powder mixing and feeding, comprising:

• feeding a first powder from a first hopper into a powder feeding system,
• feeding a second powder from a second hopper into the powder feeding system,
• mixing the first and second powders with a multi-disc powder feeding apparatus that includes:
• a first wheel that is donut-ring-shaped and has a first groove recessed below a top surface of the first wheel;
• a first hopper positioned above the first wheel and configured to receive the first powder;
• a first conduit connecting a bottom of the first hopper to the first groove and defining a first feeding path for a first material;
• a mixer unit;
• a first suction head having a first end connected to the first groove and a second end connected to the mixer unit;
• a first motor configured to rotate the first wheel so that the first material is transferred from the first hopper to the first groove via the first conduit and then to the mixer unit via the first suction head;
• a second wheel that is donut-ring-shaped and has a second groove recessed below a top surface of the second wheel;
• a second hopper positioned above the second wheel and configured to receive the second powder;
• a second conduit connecting a bottom of the second hopper to the second groove and defining a second feeding path for a second material;
• a second suction head having a first end connected to the second groove and a second end connected to the mixer unit;
• and
• a second motor configured to rotate the second wheel so that the second material is transferred from the second hopper to the second groove via the second conduit and then to the mixer unit via the second suction head, wherein
• the mixer unit is configured to mix the first material and the second material.