Interesting.
Run the meat with seasoning mixed through the Champion, then run the fat through separate then mix the two together in your stand mixer with ice water. The cold is absolutely key.
As far as the trouble to ice pack or freeze the grinder head,,,, I gave that up years ago, it’s to much work and doesn’t solve anything other than make you feel like you are doing it right.
If you will chill the meat to around 32* before processing that’s all the cold you need, but do this at each step and keep the meat cold all the way through. As far as heat generation, most of that is generated by the auger itself. You need to lube the back end of the auger shaft where it’s driven from, specifically the contact points of the nylon bushing at the back of the grinder. Lube the smooth part of the shaft and the thrust washer with food grade lube or I just use plain crisco type shortening, no oils. This will stop heat generation and the grinder head will stay the same temperature as the meat going through it. No ice packers required, which don’t and cannot cool the auger itself if warm to hot.
Thank you for your reply again, especially so soon after I posted.
Actually, I've had positive outcomes myself using those gel freeze packs held on with velcro tape, quick and easy. In my testing done without and with, I can go a LOT longer before the meat temperature exiting gets above 40°.
While the auger has friction heat there is also friction heat between auger and meat and meat and housing as well.
Any heat from auger is tempered by the cool transferred quickly through the aluminum housing to the meat, negating some of that friction heat whatever is causing it.
I can actually do almost twice as much emulsifying before having to stop for elevating meat temperature.
I didn't have the same luck with the gel packs on the food processor, probably because outer case was plastic and the distance for cold to travel is many inches more because of the diameter of the bowl.
Fortunately one of my freezers is an 18 cu ft one and I have NO problem getting my meat down BELOW water freezing temperature where the meat is still not fully frozen.
All this is a moot point however as if I use the Champion I can't do external cooling but will test the output to be sure it doesn't get higher than about 40°. I'll still start with meat temps cold but not frozen in any way due to the damage that partially frozen may cause to the auger pins if I do get below 32°.
Anyway, I WILL add the seasonings along with the salt as you suggest and mix the fat in after running through the Champion but after mixing I'll have to run it through the Champion again as even if I use my 3mm grind for the fat it will still be too large for me. I don't want a mortadella effect even in the slightest.
The stand mixer is actually a big heat pain and I have to stop frequently to cool the mix.