Will Call wrote:I want to thorw in a question. If you pack them dry as molded and keep them dry doesn't the material become brittle? I've seen products molded and extruded in PA66 where the supplier poured a cup of water into the box. When I asked why he told me that it added moisture back to the material to keep them from breaking.
Yes and No.
Dry parts are more brittle and moisture solves that at the expense of dimensions.
If the issue is inspecting parts for dimensions prior to use and then rejecting them, and not one of functionality when assembled, ship dry should work.
If it is a question of the parts not assembling as they are too big when reaching equilibrium, dry should work, UNLESS there is stress placed on the parts during assembly.
If the parts assemble OK when dry, they will reach equilibrium in use.
But none of our posts have addressed the original posters question, stability of PA66 with and without master batch. I should think that it would not vary once molded as the key ingredient is PA66, so moisture will be absorbed and the size will change on both mixes. The issue might be that the tool runs differently with and without the master batch, causing different pack rates that results in a size as molded change.
That change may be small enough to allow the parts to pass dimensional specifications as molded, but large enough to allow them to swell out of tolerance with age.
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