Injection nozzles and static mixers for LSR - How do i prevent an uncleanable blockage between runs?

Question

I'm trying to implement a new material in our processes, and that's a 2 part, highly viscous (500-1000 Pa s) liquid silicone rubber. I will also be adding a pigment, so that's 3 components that need to be mixed before entering the mold.

I have very little experience with injection molding, and this part has me stuck in my thought process.

These will be low volume production. Maybe 5-10 runs per shot. Sometimes even 1 shot. Each shot in the range of 10-20cc

Once the three parts enter the static mixer, the ticker starts. at room temperature this has a pot life for about a day, but at temperatures around 100C, the cure time is in the range of 5 minutes.

How do I go about clearing out the injection nozzle and static mixer of the messy, thick, sticky, virtually insoluble in anything LSR so that the parts are not jammed unusable for my next use (which could be in a week)

The entire process and set up is still in the concept stage, I'm open for a radical rethinking, but the material choice remains fixed.

Answer 1

Consider a "one use" plastic syringe / mixer nozzle with a fixed volume of material ie enough for 5 shots or 10...

Then at the end of the run the plastic unit can be removed and replaced with a fresh unit of whatever mix is needed - either the same or a new mix.