Generally speaking, factors affecting the surface roughness of machining include machine tools, workpieces, fixtures, tools and other factors.
1. The machine tool "CNC machining center" is actually a rather general concept, which has different requirements for different machine tools:
(1) to boring, it requires that the spindle has a larger Z direction of motion size and better precision.
(2) to mill the main, it requires the spindle has greater rigidity and greater power. In particular, to mill the main plane, the main (Z) axis should be relative to XY plane can trace swing, adjust the Angle.
(3) precision machine tools have corresponding requirements for the detection, feedback and execution of all transmission components. Some machine tools also have higher requirements for the indexing accuracy of rotary table.
(4) high-speed machine tools on the spindle and moving parts of the accuracy, lubrication, heat dissipation has special requirements.
(5) nothing can meet the requirements of the machine tool is not. What can not meet the requirements of the general precision machine tool, plus a numerical control system, plus a tool library module, or more plus a work table.
2. The workpiece
(1) the amount of silicon in the aluminum workpiece, will directly affect the cutting speed of the choice of general said silicon content below 6% for low silicon aluminum, silicon content 6%~12% compared to medium silicon aluminum, 12%~22% of the higher silicon aluminum. Aluminum alloys containing more than 23% silicon are rare in civil use.
(2) the use of performance to go to the higher aluminum alloy, in addition to the silicon accident, there will be other elements, will also affect the processing.
(3) the manufacturing process of workpiece blank (such as die casting or forging) causes different density, which will also directly affect the quality of the processed surface.
(4) due to the structural requirements of the workpiece, its rigidity is poor, easy to cause vibration, it is difficult to improve the surface roughness.
3. The jig
Will directly affect the rigidity of the workpiece clamping, will also affect the machining surface.
4. The cutting tool
(1) precision machining of aluminum parts, tool materials can be selected from high-speed steel, carbide, diamond.
(2) the diameter of 10 mm end milling cutter, the processing of aluminum and silicon as an example,
Spindle speed:
High speed steel tool n = 6000~10000 RPM
Carbide cutting tools n = 18,000 ~ 25,000 RPM
Diamond tool n = 25,000 ~ 35,000 RPM
Feed: 0.01~0.1 mm/blade
Finish cutting depth:
The radial cutting depth of the end mill is about 0.1~0.3 mm, and the axial cutting depth is 1D.
The axial cutting depth of the face milling cutter is about 0.15~ 0.3mm, the cutting width is 0.8d, and the axial height of the polished blade is 0.05mm.
(3) the cutter should be large spiral, large chip slot, generally 3 or 2 blade.
(4) the blade length and the tool overhang should be as short as possible, and the blade tip should have a certain rounded Angle.
(5) if conditions permit, the spindle is inclined 0.5~1/1000 along the direction of entry.
(6) large diameter surface milling cutter milling plane must be with polished blade.
(7) check the dynamic balance of the cutting tool.
5. The cutting fluid for finishing should be oily.