The factors that affect the surface finish of the machined are machine tools, workpieces, fixtures, tools, etc.
Machine Tools
(1) For boring, which requires the spindle to have a larger Z-direction movement size and better accuracy.
(2) For milling, the spindle is required to have greater rigidity and greater power. Especially when milling large planes is the main method, the main (Z) axis should be able to slightly swing relative to the XY plane to adjust the angle.
(3) For precision machine tools, there are corresponding requirements for the detection, feedback, and execution of all transmission components. Some machine tools also have higher requirements for the indexing accuracy of the rotary table.
(4) High-speed machine tools have special requirements for the accuracy, lubrication and heat dissipation of the spindle and moving parts.
(5) There is no machine tool that can meet the requirements. Generally, it is composed of ordinary precision machine tools that can not meet the requirements of anything, plus a numerical control system, plus a tool magazine module, or plus a workbench.
Workpiece
(1) The silicon content of aluminum workpieces will directly affect the choice of cutting speed. Generally speaking, the silicon content of less than 6% is low silicon aluminum, and the silicon content of 6%-12% is higher than that of medium silicon aluminum, 12%-22 % Higher silicon aluminum. There are few civil aluminum alloys with silicon content greater than 23%.
(2) For aluminum alloys with higher service performance, in addition to the accidental silicon content, there will be other elements that will also affect the processing.
(3) The manufacturing process of the workpiece blank (such as die-casting or forging) causes different densities, which will also directly affect the quality of the processed surface.
(4) Due to the structural requirements of the workpiece, the rigidity of the workpiece itself is poor, and it is easy to cause vibration, and it is difficult to improve the surface roughness.
Fixture
It will directly affect the rigidity of the workpiece after clamping, and it will also affect the machined surface.
Tool
(1) For the finishing of aluminum parts, the tool materials can be high-speed steel, cemented carbide, and diamond.
(2) Take an end mill with a diameter of 10 mm to process silicon and aluminum as an example.
Spindle speed:
High-speed steel cutter n = 6000~10000 revolutions per minute
Carbide tool n = 18000~25000 revolutions per minute
Diamond tool n = 25000~35000 rpm
Feed rate: 0.01~0.1mm/edge
Depth of cut for finishing:
End mills The radial depth of cut is about 0.1~0.3 mm, and the axial depth of cut is 1D.
Face milling cutter The axial cutting depth is about 0.15~0.3 mm, the cutting width is 0.8D, and the axial height of the wiper blade is 0.05 mm.
(3) The tool should be large spiral and large chip flute, generally 3 or 2 flutes.
(4) The blade length and tool overhang should be as short as possible, and the blade tip should be rounded.
(5) If possible, the spindle is inclined by 0.5 to 1/1000 along the advancing direction.
(6) The milling plane of the large-diameter face milling cutter must have a wiper blade.
(7) Check the dynamic balance of the tool.
Cutting fluid
Oily cutting fluid is the best for finishing