Tin bronze The copper-based alloy with tin as the main alloying element is called tin bronze. Most of the tin bronze used in industry has a tin content between 3% and 14%. Tin bronze with a tin content of less than 5% is suitable for cold working; tin bronze with a tin content of 5% to 7% is suitable for hot working; tin bronze with a tin content of more than 10% is suitable for casting. It is widely used in shipbuilding, chemical industry, machinery, instrumentation and other industries, mainly used to manufacture wear-resistant parts such as bearings and bushings, elastic components such as springs, and anti-corrosion and anti-magnetic parts.
Aluminum bronze A copper-based alloy with aluminum as the main alloying element is called aluminum bronze. The mechanical properties of aluminum bronze are higher than those of brass and tin bronze. The aluminum content of the practical aluminum bronze is between 5% and 12%, and the aluminum bronze with aluminum content of 5% to 7% has the best plasticity and is suitable for cold working. When the aluminum content is greater than 7% to 8%, the strength increases, but the plasticity decreases sharply, so it is mostly used in the as-cast state or after hot working.
The abrasion resistance and corrosion resistance of aluminum bronze in the atmosphere, seawater, seawater carbonic acid and most organic acids are higher than those of brass and tin bronze. Aluminum bronze can manufacture gears, bushings, worm gears and other high-strength wear-resistant parts and elastic components with high corrosion resistance. For high-precision machining of tin bronze parts, PCD (diamond) tools can generally be used. In practice, tin bronze is rarely used for shafts, and more used for sleeves and bearings.
When tin bronze material is processed with high precision, the tool should use single crystal diamond as much as possible, and effectively obtain the lattice position. When sharpening the geometric angle of the ultra-finishing tool, a wide blade and a large rake angle can be used. The accuracy of all moving parts and transmissions of the machine tool must be higher than the machining accuracy. The machine tool must be rigid enough to avoid vibration during machining. At the same time, the influence of environmental vibration must be avoided. The machine tool spindle must have long-term high-speed running accuracy, and must have a lubrication and cooling system.
Because PCD is used for high-precision machining of tin bronze materials, it must be rotated at high speed, and the accuracy of the spindle will directly affect the machining accuracy. The superfinishing allowance should be small, generally less than 0.1 mm. After semi-finishing, the workpiece must be fully cooled to the machine temperature before super-finishing. Too low or too high will affect the accuracy. There must be sufficient and effective cooling during processing to avoid the temperature of the workpiece rising due to the processing heat, resulting in thermal deformation and affecting the accuracy.
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