Purpose-designed blast media for aerospace paint stripping applications

Purpose-designed blast media for aerospace paint stripping applications

Purpose-designed blast media for aerospace paint stripping applications

Keywords: Vacu-Blast, Paint stripper

PML (Polymedia Lite) dry paint stripping media, available exclusively in the UK from Vacu-Blast (part of the USF Surface Preparation Group), is said to be the first material of its kind to be specifically designed from the molecular level to meet the specific and technically demanding stripping and substrate criteria of the aerospace industry.

According to Vacu-Blast, a polymer-based media, PML has been demonstrated to provide the high paint removal rates of acrylic materials, together with the stripping precision and consistent surface finish associated with wheat starch media - yet is described by operators to be "more forgiving" than either. Because PML strips quickly at low pressures while using a fine working mix, greater control and sensitivity can be achieved. The media are also less sensitive to moisture than wheat starch and can be used in existing abrasive blasting equipment with only minimal adjustments to media delivery and recovery systems.

Another important benefit claimed of PML, which has been tested thoroughly in the US aerospace industry, is its ability to remove paint from thin-skinned and delicate aluminium and composite airframe components without adversely affecting their inherent material properties.

Controlled paint stripping using plastic or wheat starch dry abrasive blast media (often referred to as PMS) is now widely accepted as a less hazardous and more environmentally friendly alternative to traditional chemical strippers in aerospace applications. However, concerns have been raised about the effects of the blasting process on thin-skinned aluminium structures, in particular, using some existing types of dry blasting media produced either from wheat starch or from acrylic materials.

It is reported that in comparative tests, carried out under the auspices of the US Air Force Coating Technology Integration Office (CTIO), PML was found to have had no effect on the tensile properties of a 0.032-inch thick aluminium panel, whilst "conventional" plastic blast media did have an effect. Also, there was no degradation of the panel and the resultant surface finish was in line with the best available using current media types. The tests were carried out in accordance with stringent ASTM (American Society for Testing Materials) specifications.

Field trials stripping paint from a composite radome section of an F15 fighter aircraft are said to have proved similarly successful.

PML is available in a screen size of 20-50 (850 -298 ), and is an inert virgin material formulated to meet the Mil-Spec Type 7 specification and conform to Mil P-85891A.

Details from Vacu-Blast Ltd. Tel: +44 (0)1753 526511; Fax: +44 (0)1753 538093; E-mail: info@vacu-blast.co.uk; Web site: http://www.vacu-blast.co.uk