What is the best way to clean parts with complex geometries such blind holes so that optimal cleaning is achieved?
When cleaning parts with complex geometries, you should pay particular attention to any blind hole that can trap air, particles or cleaning solution during the cleaning and rinsing process. Air trapped in a blind hole interferes with cleaning and rinsing. Blind holes that face up and trap solution can potentially trap particles and cleaning solution that would otherwise rinse away if the hole was able to drain. To clean a blind hole, you need to make sure that cleaning and rinsing fluid gets in to the hole and back out. If blind holes are all on one axis of a part, and you are cleaning under immersion such as with ultrasonics, then one way to assure this is to put the parts in with the blind holes horizontal so that they fill up with solution and release any trapped air, then under immersion, rotate the part so that the blind holes face down, which allows gravity assisted release of any particles or residues that are removed during the process. Reverse the process to remove the part from the tank to allow the cleaning solution to pour out from the blind holes in a horizontal position. Repeat for immersion rinsing, or better yet, rinse with running water being sure to flush the blind holes. If a part has blind holes on multiple axis, then for immersion cleaning, you would want to rotate the part under immersion in order to release all trapped air and fill the holes with cleaning solution. If practical, it is desirable to further rotate the part during cleaning to pause for a period of time so that each axis of blind hole faces downwards for part of the cleaning cycle. In some cases it can even be worth creating a basket or bracket system that continually rotates the parts during cleaning and rinsing if rinsing is done under immersion. For spray cleaning of parts with blind holes, you want to pay attention to the orientation of the spray to make sure it penetrates and flushes the blind hole during cleaning and rinsing.
Alconox, Inc manufacture’s a range of aqueous critical cleaners from acid to alkaline, powder to liquid, highly emulsifying to low foaming. Brands are available globally with consistent formulations and are GMP compliant. Downloadable certificates of analysis, technical bulletins, MSDS, trace analysis, and inhibitory residue testing are available from the Alconox website at Alconox.com.