Here are the issues we are facing with the cooling tube:
Is it even needed? - We are extruding from flake and the viscosity is quite low once we have melted the PET. The cooling tube helps us to increase the viscosity of the melt before it leaves the nozzle. Could we achieve the same results with a better heating profile or easier strategy?
Alignment - Because of the bend, the cooling tube must be oriented properly. Because the extruder body is assembled with threaded couplings, the cooling tube must be bent after it is attached to the rest of the extruder body. A better design for coupling the cooling tube to the barrel could fix this.
Heaters Problematic - The cooling tube is heated with fiberglass insulated nichrome wire. The fiberglass is tightly woven and tends to become brittle and break off. We have had the heaters short out against the cooling tube. We have been wrapping the cooling tube in Kapton tape but it doesn't seem like a great solution. We are thinking of threading the nichrome through a different type of fiberglass insulation to solve the issue. What other types of heaters might we use?
Threads - The 3/8 in coarse threads cut most of the way through the tube. We need to switch to fine threads. A new coupling design between the cooling tube and the barrel could eliminate the need to cut threads in the tube on this end.
Here are the issues we are facing with the cooling tube:
Is it even needed? - We are extruding from flake and the viscosity is quite low once we have melted the PET. The cooling tube helps us to increase the viscosity of the melt before it leaves the nozzle. Could we achieve the same results with a better heating profile or easier strategy?
Alignment - Because of the bend, the cooling tube must be oriented properly. Because the extruder body is assembled with threaded couplings, the cooling tube must be bent after it is attached to the rest of the extruder body. A better design for coupling the cooling tube to the barrel could fix this.
Heaters Problematic - The cooling tube is heated with fiberglass insulated nichrome wire. The fiberglass is tightly woven and tends to become brittle and break off. We have had the heaters short out against the cooling tube. We have been wrapping the cooling tube in Kapton tape but it doesn't seem like a great solution. We are thinking of threading the nichrome through a different type of fiberglass insulation to solve the issue. What other types of heaters might we use?
Threads - The 3/8 in coarse threads cut most of the way through the tube. We need to switch to fine threads. A new coupling design between the cooling tube and the barrel could eliminate the need to cut threads in the tube on this end.