Need advice dear all polishing expert
Hi everyone, I would like to ask the polishing experts in this forum for some advice.
I have a project to build a coating pan unit used for coating tablets prior to packaging. The unit's design is quite simple—it resembles a washing machine's cylindrical drum with a front opening, and it rotates slowly at around 2-4 RPM during operation. The unit's shell features a perforated design with 2mm diameter holes. During fabrication, the client requested that the interior be mirror-polished, so we used a polishing compound.
However, after finishing everything and cleaning it using our standard procedure (with alcohol and a clean white cloth), a black residue appeared when we swabbed the surface using a white tablet product.
We have tried cleaning the unit several times:
First, using a special penetrant cleaner that is essentially contaminant-free.
Next, using various types of food-grade detergent mixed with hot water.None of these worked. We even tried performing a passivation process twice (before and after the unit was installed), hoping that the degreasing stage during passivation would lift the dirt off the unit.
Yet, after every cleaning attempt, wiping it with a clean white cloth shows no visible dirt, but swabbing it with a white tablet still leaves black smudges. We strongly suspect that the laser-cut perforated holes are trapping leftover polishing compound (Langsol) that has now encrusted and hardened, making it incredibly difficult to remove.
Does anyone have any suggestions on how to get this unit completely clean? We are completely out of ideas. Do we really need to poke and clean the holes one by one? Also, are there any specific cleaners or methods we can use to effectively clean this unit?