Original Date: 01/26/1998
Revision Date: 01/18/2003
Best Practice : Wheat Starch Abrasive Media
Corpus Christi Army Depot’s (CCAD’s) primary mission is to overhaul, repair, and modernize military (Army, Navy, and Air Force) helicopters. Since May 1997, CCAD has successfully depainted helicopters’ composite material surfaces using wheat starch based abrasive as a blasting material. Before wheat starch based abrasive media was used, hand sanding was commonly used for composite material surface depainting. Plastic media blasting (PMB) was allowed with limitations for some composite material depainting operations. CCAD uses proprietary starch media, off-the-shelf wheat starch media blasting equipment, and recycling equipment.
There are no military specifications or criteria for the performance of wheat starch based abrasive media blasting on composite material surfaces. However, the Society of Automotive Engineers is in the process of developing Aerospace Standards for Starch Media Abrasives. Operators who use wheat starch based abrasive media should have knowledge about media (e.g., materials and geometry), maintenance requirements for equipment type and conditions of coatings, and receive training to perform equipment maintenance.
CCAD learned that wheat starch based abrasive media blasting works; however, the facility must be kept dry at all times; a metal mesh floor is used to keep paint peelings out of equipment; after blasting, resealing of the blasted surface is necessary; and special gages are needed to measure paint thickness on composite material. Wheat starch based abrasive media blasting is faster than hand sanding, and causes less damage to the composite material surface than PMB. Benefits of using wheat starch media include cost savings from efficient depainting compared with manual sanding; minimum damage to fibers; less paint adhesion failures; and reuse of media (several times).
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