Certainly the first step is to study how all items are handled during assembly and packaging. You need to determine at what point(s) most of the coating damage is being inflicted. Make sure that workers are aware that paint damage is a problem, and enlist their help in combating it. (Rewards such as a free pizza lunch at month's end if minimal paint scratching is achieved can work wonders.) Redesign fixtures and transfer equipment if needed to lessen damage to the finish during handling.
Since you do not indicate if the liquid paint sustains more damage than the powder paint, I can only suspect this is indeed factual. Let me suggest that a properly selected black epoxy powder coating should be quite economical. If you pick one with a hardness of 3H to 5H, it will be highly scratch resistant. Talk about this with the powder coating supplier or the company that does the powder coating for you.