Topic: Die Swell Ratio, Drawdown control and other musings.
Basically molten polymers tend to expand or swell on leaving a die. This a well known phenomenon in industry. Most diemakers have charts of swell rations they've worked out for various polymers and die shapes over the years, and we are making progress in regards to computer-simulating it at the design stage. This eliminates the trial-and-error and wasted effort.
Has anyone compiled a "master list" die sizes for various materials needed to get 1.75mm filament in the various materials we are experimenting with? I am going to begin drilling out my own dies very soon, and would like to avoid some of the "error" state of testing.
Second: One of the keys to successful industrial extrusion is the "haul-off" stage of the process. This consists of caterpillar-belts, S-wrap rollers and other means. This allows the process to be controlled independently of the winder tension. In our application can use an independent pull roller to adjust the amount of "pull" in relation to the "push" from the die. By adjusting this we should be able to realize a marked improvement in material quality, especially for challenging materials.
Third, I am pondering die materials. Currently my dies are machined brass. Most extrusion dies I've seen are tool-steel or related. Has anyone experimented with steel dies or other materials? If so what were your experiences?
Filistruder (Operational) (Scanners RMA'd Due To Missing Components)
Benchtop Molding Press, Arburg All-Arounder IMM, Bridgeport ProTrac, Monarch 10EE Lathe, Light Machine CNC Mill & Lathe
(THIS IS JUST MY HALF OF THE WORKSHOP MUAHAHAHAHA)