The KM process flow entails the conversion of potential energy, in the form of a compressed carrier gas, and thermal energy, from the thermal conditioning unit (TCU), into kinetic energy of powder particulate. The carrier gas (helium) is split into two paths after leaving the storage tanks: a cold leg, and a hot leg. The cold leg gas is routed through the powder fluidizing unit (PFU) where it entrains powder particles and carries them to the KM Gun assembly. The hot leg gas is routed through the TCU where it is heated to a temperature that depends upon powder composition and particle size. The two legs recombine in the mixing chamber where particle heating/softening occurs. The merged gases are then accelerated through a friction compensated deposition nozzle (DN). As the gas is accelerated to near sonic velocity momentum is transferred to the entrained particles. Particle energy is converted, upon particle collision with the substrate, into plastic deformation of the particles and intimate contact between particles and the substrate. The result of these two manifestations of energy conversion is metallic bonding.
Process parameters include carrier gas pressure and flow rate, temperature, and powder feed rate. In addition, the deposition parameters include sweep velocity, step size, working distance, and consecutive layering. Together, the parameter space that obtains is capable of a wide range of material systems.
The components required to control the process flow consist of pressure regulators, valves and actuators, sensors, and basic high pressure fittings. The TCU is a customized device with very low thermal inertia to allow for rapid heating and cooling. The PFU is a patented brush-vibratory feeder capable of dispensing fine powders at constant rates. All major process flow components are controlled through a proprietary graphical user interface that lends itself to both novice and experienced users.
