Key points of CNC tool selection
The characteristics and requirements of CNC tools (divided into two major systems: turning system and milling and boring system).
CNC tools require high precision, good rigidity, convenient clamping and adjustment, strong cutting performance and high durability. Reasonable selection can improve processing efficiency and product quality.
The main factors that should be considered in tool selection
1. The material and properties of the workpiece to be processed: metal, non-metal, its hardness, rigidity, plasticity, toughness and wear resistance, etc.
2. Processing technology category; turning, drilling, milling, boring or roughing, semi-finishing, finishing and super finishing, etc.
3. The geometric shape of the workpiece, the machining allowance, and the technical and economic indicators of the parts.
4. Cutting amount that the tool can withstand.
5. Auxiliary factors: How much is a CNC lathe for operating interruption time, vibration, power fluctuation or sudden interruption, etc.?
Turning system (integral tool system)
1. Composition: consists of blade (tool), cutter body, shank (or shank body), cutter head, etc.
2. Code and parameters of indexable inserts
3. Chipbreaker groove pattern of indexable inserts: free chip breaking and smooth chip removal
4. Clamping methods of indexable inserts: wedge-up pressing, lever-up, screw up-pressing requirements: reliable clamping, accurate positioning, smooth chip removal, simple structure, and convenient operation
5. Choice of indexable inserts
1). Blade material selection: high-speed steel, cemented carbide, coated cemented carbide, ceramic, cubic boron carbide or diamond
2). Blade size selection: effective cutting toughness length, amount of tool to be eaten, entering angle, etc.
3). Blade shape selection: according to surface shape, cutting method, tool life, indexing times, etc.
4) Selection of the nose radius of the blade:
A. For rough machining, large workpiece diameter, high blade strength, and large machine tool rigidity, choose a large tool point arc
B. Fine machining, small depth of cut, slender shaft machining, small machine tool rigidity, small tool point arc
Tool system (modular tool system)
1. Composition; blade (tool), tool holder (or handle body), spindle or blade (tool), working head, connecting rod, main handle, spindle
2. Selection of CNC milling tools
1) Selection of milling cutter type:
A. Choose a face milling cutter for processing larger planes,
B. Machining bosses, grooves, facet end mills,
C. Choose cemented carbide corn milling cutter for machining rough surface and rough machining hole,
D. Choose a ball-end milling cutter for surface processing,
E. Machining space curved surface mold cavity and punch surface select mold milling cutter,
F. Machining closed keyway and selecting keyway milling cutter, etc.
2) Selection of milling cutter parameters
A. Main parameter selection of face milling cutter
a). The diameter of the standard indexable face milling cutter is Φ16－Φ630): Choose the smaller diameter for rough milling, and choose the larger diameter for fine milling.
b) Determine the geometric parameters according to the workpiece material, tool material and processing properties: milling is usually selected for milling cutters with small rake angles, negative rake angles for materials with high strength and hardness, and large rear angles and hard ones for workpieces with low hardness. Small clearance angle, coarse-tooth milling cutter chooses a small relief angle, fine-tooth milling cutter takes a large relief angle, the blade inclination angle of the milling cutter is usually -5-15 degrees, and the entering angle is 45-90 degrees
B. Main parameter selection of end mills
a), the tool radius r should be less than the minimum curvature radius of the inner contour of the part ρ
b), the processing height of the parts
c), selection of non-through holes or deep grooves
d), select when processing shape and through groove
e), the tool diameter when processing the rib is
f) When rough machining the inner contour surface, the maximum diameter of the milling cutter
3. Selection of machining center tools
Machining center tools are usually composed of cutting tools and tool holders. The cutting edge has various milling cutters for surface processing and various drills for hole processing, reaming drills, boring cutters, reamers and taps, etc. The tool holder must meet the requirements of the machine tool. The spindle automatically loosens and clamps and locates, and can accurately install various cutting tools and adapt to the clamping requirements of the tool change manipulator.
1) Basic requirements for machining center tools
A. The tool should have higher rigidity
B. High repeat positioning accuracy