The spindle of a horizontal machining center is horizontal, usually with a square table for indexing rotary motion. Generally, there are 3 to 5 motion coordinates. The common one is three linear motion coordinates plus one rotary motion coordinate. It can make the workpiece complete the processing of the remaining four surfaces except the mounting surface and the top surface after one clamping. Machining box parts. Generally, it has an indexing worktable or a numerical control conversion worktable, which can process all sides of the workpiece; it can also make joint movements of multiple coordinates to process complex spatial surfaces. Some horizontal machining centers are equipped with an automatic exchange table, which can be loaded and unloaded on the workbench at the loading and unloading position while processing the workpiece on the workbench at the working position, thereby greatly shortening the auxiliary time and improving processing efficiency.