Its function is to act as a thermal barrier between the hot nozzle and the relatively cool sprue bushing
If the RTO is opposite the sprue bushing
, the hex also functions as the all-important cold well to catch and retain any semi-solidified material residing in the machine nozzle tip.
When switching from one injection unit to the other, the carriage is unlocked and manually moved to the side, aligning the desired injection unit with the sprue bushing
. The first machines of this design were built for a rubber molder using the same mold to produce parts from two different rubber compounds.
"For example, in the back of a zinc die casting die is a bushing called the sprue bushing
with a female radius on it.
RTOs are often located opposite a sprue bushing
, but they are also commonly located at the intersection of a runner branch.
The assembly permits perfect radius alignment between the sprue bushing
and nozzle tip while compensating for misalignment up to .040" overall travel in all directions.
PCS was working with NXCMFG on mold components that utilize 3D printing, and one of the first developments to come from that partnership was a sprue bushing
featuring a conformai cooling channel.
For example, does the nozzle tip mate properly with the sprue bushing
? Is a temperature zone overriding?
There are pressure drops as the material passes through the restrictive machine nozzle tip, the sprue bushing
, the runner, and the gates.
Checking the match between nozzle-tip radius and orifice to those of the mold's sprue bushing
This solidification is a result of heat being sucked out of the nozzle tip due to surface contact with the cold sprue bushing
* The condition of the sprue bushing
and the machine nozzle tip;