Metal Finishing Guide Book

2012-2013

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Table XI. Mass Finishing Media Shapes and Applications Media Application Triangles Reach slotted areas and reach into corners Cones More effective on concave and convex surfaces Pyramids Large, flat surface contact; works holes, doesn���t pass through Stars Deburrs inside diameters, blind holes, reduces lodging Tetrahedrons Sharper points provide better penetration into remote areas Wedges Reduces lodging. Large, flat surface maximizes contact Angle-cut cylinders Best on concave surfaces, round areas, and holes Tri-Cylinders Excellent for concave and convex; corners, slots, angles Spheres Smooth rolling. Good for concave. Rolls around and through Angle-cut triangle Better penetration into remote areas Ellipses 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 combinations 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 procedure. 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 (approximately 8) to high pH (14). This accommodates cleaning many metals (aluminum, 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 Number Group 99% minimum and greater 1XXX Copper 2XXX Manganese 3XXX Silicon 4XXX Magnesium 5XXX Magnesium and silicon 6XXX Zinc 7XXX Other elements 8XXX Unused series 9XXX First digit: alloy type. Second digit: alloy modification. Third and fourth digits: aluminum purity of alloy. 159

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