1. Three basic requirements for selecting a reference: (1) The selection of a reference should ensure accurate workpiece positioning, convenient and reliable loading and unloading. (2) The selection of benchmarks and the calculation of dimensions for each processing part are simple. (3) Ensure machining accuracy. CNC machining center machine tool

2. Six principles for selecting positioning benchmarks: (1) Try to choose the design benchmark as the positioning benchmark as much as possible; (2) When the positioning reference and design reference cannot be unified, the positioning error should be strictly controlled to ensure machining accuracy; (3) When the workpiece requires more than two clamping processes, the selected benchmark can complete the processing of all key precision parts in one clamping positioning; (4) The selected benchmark should ensure the completion of as much processing content as possible; (5) During batch processing, the positioning reference of the parts should be as close as possible to the tool alignment reference used to establish the workpiece coordinate system; (6) When multiple clamps are required, the reference should be consistent before and after. Determination of the fixture for the machining center: 1. Basic requirements for the fixture: (1) The clamping mechanism shall not affect the feed, and the processing part shall be open; (2) The fixture can achieve directional installation on the machine tool; (3) The fixture has good rigidity and stability. 2. Common fixture types: (1) Universal fixtures: such as vises, indexing heads, chucks, etc; (2) Combination fixture: The combination fixture is composed of a set of universal component combination components with standardized structure and size; (3) Special fixture: a fixture designed and manufactured specifically for a certain or similar processing; (4) Adjustable fixture: The combination of modular fixtures and specialized fixtures ensures machining accuracy and provides greater flexibility in clamping; (5) Multi station fixture: a fixture that can simultaneously hold multiple workpieces; (6) Group fixture: Specially used for clamping workpieces with similar shapes, sizes, positioning, clamping, and processing methods. CNC machining center machine tool

3. The selection principle of machining center fixtures: (1) On the premise of ensuring machining accuracy and production efficiency, priority should be given to using universal fixtures; (2) Batch processing can consider using simple specialized fixtures; (3) Multi station fixtures and efficient pneumatic, hydraulic and other specialized fixtures can be considered for large-scale processing; (4) When using group technology, group fixtures should be used; 4. The optimal clamping position of the workpiece on the machine tool workbench: The clamping position of the workpiece should ensure that the workpiece is within the machining stroke range of each axis of the machine tool, and make the length of the tool as short as possible to improve the machining rigidity of the tool. CNC machining center machine tool