Rust in narrow pocketed surface of EN plated component

We are doing Electroless nickel plating on Fe based material which will be used in computer hard disc assembly. This is stamped part followed by machining and tumbling process before EN plating. High burr which will come stamping process becoming closed during the tumbling process and creating micro pockets along the edges and lot of tumbling powder stuck in side these macro gaps. Subsequent plating process can not able to clean these pocketed areas thoroughly and forming rusty spots/Yellow stains along the edges after plating. Your in puts very much appreciated to eliminate this problem.

First of two simultaneous responses --

How about choosing a different media for tumbling, the main goal here should be dealing with the root of the problem, burrs.

Second of two simultaneous responses --

Are you tumbling wet? If so, try not to. G. Marrufo-Mexico

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