What is the Value of a Part Recognition System?


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Q. We are going to install a new powder booth and switch from manual spray guns to automatic spray guns. The suppliers of the application equipment are recommending we buy a part recognition system to trigger the guns on and off based on the part sizes that enter the booth. Is it really worth the money to install this system? It is not cheap!

A. The part recognition system uses photo eyes to identify the presence of a part and the size of the part. An encoder mounted on the conveyor will control what gun or guns come on and turn off and when they are triggered. There is a short lead time and lag time to avoid triggering the gun when the part is directly in front of the gun tip. The triggering function reduces over-sprayed powder because the guns are off when there is not part present.

The alternative to automated gun triggering is relying on a person to turn the guns on at just the right time and turn them off when parts have passed. This is not as effective and certainly not as reliable. As a result, manual triggering invariably causes a higher amount of oversprayed powder and raises the coating cost. The answer to your question of whether or not it is worth it to install the system is not absolutely clear, but you will likely save enough money to pay for the system rather quickly. The payback is longer if you reclaim powder, because there is less powder loss, but even if you reclaim, you should work hard to reduce overspray. Powder particle size distribution is altered in a reclaim system, and the initial efficiency experienced with fresh material will likely decline when reclaim is introduced. First pass transfer efficiency is important to quality and cost. It becomes very critical if the system is not designed for recovery of oversprayed powder because the overspray is thrown away. Either way, recovery or no recovery, gun triggering of automatics saves money and does pay for itself in a reasonable time frame.  

Originally published in the August 2015 issue.

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