Metal Finishing Guide Book


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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. especially the nickel-rich 300 series stainless steels. The electrolyte is typically a mixture of mineral acids. Parts are predominantly racked. The ranges in the operating parameters shown in Table VIII reflect the use of more than one type of electrolyte. 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 Table XII. Aluminum Alloy Designations Aluminum Alloy Type 99% minimum and greater Number Group 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. 146

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