Concentrate Questions

[joeprocess]

Looking for some info. on what other companies or stance is on the following questions.

-- Do pellet concentrates have a shelf life or is this something the suppliers say to create more sales?

-- Dry concentrates? Yes, No or Sometimes? We use a gravimetric color dosing system at the feed throat. (I was lead to believe that at our standard dosing rate of 4%, for just about all of our colors, it would not add enough moisture to the material to go over the max. recommended moisture content.)

[rickbatey]

As far as shelf life I’ve never worked in a shop that let them sit that long. But I could see certain additives either leaching out or their performance degrading when stored in the typical heat of a warehouse.
Color feeders are the easiest and cleanest method. As far as coloring engineered resins the added moisture usually isn’t an issue BUT you can request that the supplier use a carrier resin that does NOT require drying. Usually not an issue but on some resins or colors you may have to dry it in a smaller drying hopper.
Rick.

[Suhas]

Yes, some of the colors may have a shelf life.

Dry concentrates are easy to use but on small shots can be difficult to maintain consistencies. Liquids are best to get consitency from shot to shot and run to run but are a pain to feed and to measure.

Suhas

[Joel JS]

FYI - We run lots of pellet concentrates and don't dry any of them......

Joel

[rickbatey]

Joel what resins do you run?

[joeprocess]

The way I think about it, but not sure it is correct, hence the question is: At 4% dosing and a normal moisture content of lets say 1.5% for nylon. (Which is pretty high given we are a conditioned facility.) Would mean that the concentrate would add only 0.06% moisture to the blend. As long as the base resin is dried properly, this 0.06% would not effect the process. But, we know that water breaks the molecular chains so I'm not sure. The largest concern in whether this un-dried concentrate is likely causing higher splay rejects.

I could see possibly with a PC or PET whereas the carrier resin of the conc. is the base material. I can't see purchasing a bunch of small driers for concentrate and adding the additional resources needed to manage this if it isn't a standard injection molding practice. I have not heard this to be a standard practice unless the parts are super-critical.

[Joel JS]

Hi Rick, et al,

We run different nylons, and ABS(s), and PC/ABS(s) that are colored.

(If you are concerned, and you are drying beside the press, I have heard of another solution to take the drying hose, splitting it in two, one large, one small, and hooking the small hose to the color feeder, the large one of course back to the dryer.)

Joel

[Suhas]

I worked on a project with an irrigation company. The product was made in 5 colors. We had to dry two of them since they showed splay if they were not dried.
So it would depend on the carrier.
Suhas