Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 126 of 707

Table XI. Mass Finishing Media Shapes and Applications Media Application Triangles Cones Pyramids Stars Tetrahedrons Wedges Angle-cut cylinders Tri-Cylinders Spheres Angle-cut triangle Ellipses Reach slotted areas and reach into corners More effective on concave and convex surfaces Large, flat surface contact; works holes, doesn't pass through Deburrs inside diameters, blind holes, reduces lodging Sharper points provide better penetration into remote areas Reduces lodging. Large, flat surface maximizes contact Best on concave surfaces, round areas, and holes Excellent for concave and convex; corners, slots, angles Smooth rolling. Good for concave. Rolls around and through Better penetration into remote areas Good on concave surfaces Deburring and rough cuts require ratios from 6:1 down to 1:1. Burnishing and high luster require 10-12:1 or up to 20:1. The solutions are acidic, typically composed of the following inorganic acids: chromic, fluoboric, hydrochloric, phosphoric, and sulfuric, in varying combi- nations and strengths. Organic additives, such as glycols, help to condition the surface during electropolishing. Spray Cleaning A wide variety of ferrous and nonferrous metals are cleaned in this optional pro- cedure. Spray cleaning can be accomplished off line, as a precleaning step, or in the process line operation. It provides the following benefits: • Low foaming cleaning action with displacement of soils • Mechanical action facilitates cleaning • Lower temperature ranges for energy savings The alkalinity level of the spray cleaner may range from near neutral (approx- imately 8) to high pH (14). This accommodates cleaning many metals (alu- minum, brass, copper alloys, steel, stainless steel, and zinc). A desired or effective chemistry lifts soils. The concentration of surfactants and wetting agents can be low since mechanical action of spraying helps to dislodge soils. Displacement of Table XII. Aluminum Alloy Designations Aluminum Alloy Type 99% minimum and greater Copper Manganese Silicon Magnesium Magnesium and silicon Zinc Other elements Unused series Number Group 1XXX 2XXX 3XXX 4XXX 5XXX 6XXX 7XXX 8XXX 9XXX First digit: alloy type. Second digit: alloy modification. Third and fourth digits: aluminum purity of alloy. 125

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