Metal finishing Q&As since 1989

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Drying after corncob tumbling

Hi, we are manufacturing steel pins ( 5 mm dia.) which we are polishing in tumbling open barrels. After polishing we wash the pins with regular water and then dry the pins in corn cob, size of corn cob is approx. 2mm. After drying in corn cob we separate the pins from the corn cob by using stainless steel mesh having drilled holes so that the corn cob falls down thru the holes and the pins remain on top. However when we check the pins under microscope we observe that minute corn cob dust is still stuck on the pins. Can you kindly suggest a method of drying so that this dust does not remain.

John Craig
- Praha, Czech
2003

Try heating the ground corn cobs and keeping them warm during the drying process. A double boiler or small steam table with stainless steel pans (available from restaurant suppliers)will work well. Moisture is causing the corn cob particles to stick.

Jim Sivertsen
- Alden, New York U.S.A
2003

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I'm not sure you can totally eliminate the particles if you use corncob for drying purposes.It's just got to happen unless you can figure a way to use static electricity during separation. You might want to consider using hot DI water as the final operation and either blow dry through screen or create a vacuum through the screen. The heat will speed up drying and hopefully minimize oxidation.

AF Kenton
retired business owner - Hatboro, Pennsylvania
2003

You may want to try to pre dry (spin dry, blow dry after a hot rinse). Corn cob is a very good fine polishing media for fine polishing and would help keep corn cob dryer

Chris Snyder
plater - Charlotte, North Carolina
2003