Abstract: A pneumatic sanding machine for cleaning and scraping replaces a sanding disc with a high pressure compressed air disc swirling powder abrasive. Acceleration and ejection functions of the sanding nozzle are dissociated in two portions, allowing very thin ejection ports, even smaller than 400 micrometres in diameter, without clogging. The nozzle acceleration channel common to all ejection ports emerges on an anti-splash cone that bursts the jet of compressed air/abrasives exiting the nozzle, directing the air-abrasive flux towards tungsten carbide ejection members. Thus, the ejection ports are holes/slots drilled in tungsten carbide boards inserted in a disc/platen. The disc/platen may be driven to rotary speeds (RPM) obtained using a mini-turbine of 1,000-20,000, possibly exceeding 30,000, but generally 4,000-12,000, enabling high pressure work.

Abstract: In performing micro-cleaning and micro-blasting, a dry micro-cleaning abrasive powder is sprayed having a very small grain size. This enables high cleaning speeds to be reconciled with exceptionally fine blasting in order to remove dirty stains and encrusted deposits from valuable, delicate, or fragile medium as is the case when having to blast off pollutants and pollution that become stuck to the surfaces of monuments and buildings. Jets of compressed air charged with fine abrasive particles having grain sizes of less than 200 micrometers can also be sprayed towards the surface. The jets are emitted from nozzles at high speeds so that they sweep the surface with at least ten jets, each of which has a cross section lying in the range of 400 micrometers to 4 millimeters, so that very low kinetic energy is imparted to the surface.