Abrasive grit blasting with www.ftguk.co.uk, or sand blast cleaning, is a surface treatment process widely used in a variety of different industries with many diverse purposes. Abrasive blasting is the process by which an abrasive media is accelerated through a blasting nozzle by means of compressed air. The abrasive used varies based on the surface treatment required. Common abrasives used include:
- steel shot
- steel grit
- glass bead
- crushed glass
- aluminum oxide
- silicon carbide
- walnut shell
- corn cob
- baking soda
- ceramic grit
- copper slag
Media selection is a crucial decision in the engineering of abrasive blasting processes. The different media types have different hardness, shape, and density, and each is available in a wide range of particle sizes. Many times it is necessary for sample processing to take place to lock in the final media type and size. The equipment used to perform the sand blasting process varies through industry; there are hand cabinets, dedicated automatic high production models, and completely robotic systems with closed loop process controls. The type of machine utilized depends on the surface treatment applied as well as the end use of the component.
Traditionally abrasive grit blasting with www.ftguk.co.uk has been considered a “low tech” process, generically called sand blasting. Today, however, abrasive blast cleaning is a vital process used not only to remove rust, but to prepare surfaces for high performance coatings or to treat final products to give them the luster and surface texture desired by the retail consumer
The range of uses for abrasive grit blasting are very broad and include:
- surface preparation prior to painting, bonding or other coating operations
- removal of rust, scale, sand, or paint from fabricated components
- roughening of industrial gas turbine engine component surfaces in preparation for thermal spray coating
- removal of burrs or edge profiling machined components
- providing a matte cosmetic surface finish on consumer products
- removal of mold flash from plastic components
- surface texturing of tooling, and molds to alter the appearance of molded or stamped products
Shot peening is a metal working process which enhances the surfaces of a variety of different materials.
Various manufacturing processes used throughout the aerospace, aircraft, automotive, energy, and heavy equipment industries can produce tensile stresses on the surface of components. These processes include milling, turning, drilling, welding, severe grinding, heat treating, bending, and forming. The tensile stress left behind on the surface provides a perfect environment for a cracking or stress corrosion to start forming, reducing the life of these components.
Shot peening is performed by accelerating spherical media toward the surface of a part. When the media hits the part, a small dent is formed, stretching the surface of the part. The material surrounding that dent resists this, and creates an area of compressive stress. When the surface of the part has these small dents all over the surface, there is a continuous layer of compressive stress on the surface of the part. This replaces the tensile stress on the surface with a compressive layer. The compressive layer stops the fatigue cracks and stress corrosion that typically start at the surface of the part.
Shot peening has been used successfully for many years. Although skill trades realized the benefits of this coldworking process long ago, modern shot peening has only had widespread use since the 1930’s. In 1945 a patent was issued to John Almen for a method to measure the intensity of shot peening. Mr. Almen is considered by many to be the father of modern shot peening. His patent uses a thin metal strip, now called an Almen Strip, and an arc measurement device, now called an Almen Gage, to assign a value to the intensity of the shot hitting the part. An Almen Strip is held down on a flat block with 4 screws. When the strip is shot peened, a compressive stress is placed into the surface of the strip. When the strip is removed from the block, the strip arcs because the thin cross-section cannot resist the stress placed into the surface of the strip. This arc is measured with an Almen Gage.