The fixture must adapt to the geometric elements of the workpiece in shape.
The fixture must allow access to the machining characteristics of the workpiece.
The positioning tolerance of the fixture should fully meet the design tolerance of the workpiece.
The fixture should ensure the stability of the workpiece during machining.
The fixture should ensure sufficient rigidity of itself and the workpiece to prevent deformation during machining.
The cost of the fixture should not exceed the expected value.
The assembly and disassembly time of the fixture should not exceed the expected time.
The operation time of the fixture should not exceed the expected level.
The fixture must not interfere or collide with the tool (cutter) path.
The fixture must not interfere with other tooling equipment.
The fixture must not interfere with itself or the workpiece.
The mass of the fixture should not exceed the expected value.
The fixture should not damage the surface of itself and the workpiece.
The fixture should be able to guide the tool (cutter) according to the design characteristics of the workpiece.
The fixture should have mistake-proofing technology.
The fixture should facilitate chip removal.
CNC machine tools generally adopt high-speed cutting or powerful cutting, and the machining process is automated, which raises new functional requirements for CNC machining fixture design: the clamping force must be large, reliable clamping must be ensured, and high flexibility must be achieved to adapt to automatic control.
CNC fixtures usually adopt pneumatic, hydraulic, and electric automatic control fixtures. These fixtures have precise positioning, reliable clamping, and the guidance of fixtures is ensured by the CNC machine tools and CNC devices. Tool setting of fixtures is achieved through pre-setting operations or using external tool setting instruments to detect and input into the CNC system.
CNC machining center fixtures do not set up tool-setting devices. The relationship between the origin of the workpiece coordinate system and the machine coordinate system is established through pre-setting operations or using external tool-setting instruments to ensure the correct position of the workpiece and the tool. The position accuracy is guaranteed by the machine's motion accuracy.
In CNC machining fixture design, the coordinate direction of the fixture must be relatively fixed with the coordinate direction of the CNC machine tool, and the size relationship between the part and the machine coordinate system must be coordinated. This is a significant difference compared to conventional machine tool machining. Under traditional machining methods, due to the limitations of machine tool processing capabilities, multiple clamping operations are typically required to complete machining. CNC machine tools can machine multiple surfaces in a single clamping state, significantly reducing errors caused by frequent clamping.
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