Machining is the process by a mechanical device or performance of dimensions of the workpiece changes. There are many to understand its meaning: the generalized use mechanical means to refer to all product manufacturing process; narrowly refers lathe (Lathe Machine), milling (Milling Machine), drilling (Driling Machine), Grinder (Grinding Machine), punching machines, die casting machine and other process equipment manufacture parts on machinery specialized camp.
 When machining will be some errors, below, and we talk about the process and the initial state of the system itself, related to the original error is how:
① principle error that is present on the working principle of the method error.
 ② Process Systems geometric error
 Error of the relative position of the workpiece and tool in the static state already exists, such as tools and fixtures manufacturing error, installation error and error adjustment;
 Error relative position of the tool and the workpiece in the presence of the state of motion, such as machine tool spindle radial motion error, error guide rails, chain drive transmission errors.(2) the initial error associated with the cutting process
 ① force effect caused by the deformation process systems, such as stress and deformation process system error, workpiece stress generation and deformation caused by the disappearance caused.
 ② deformation process system caused by thermal effects, such as the error caused by the machine, tool, workpiece thermal deformation. In the machining process, between the tool and the workpiece surface reasonable position relationship, precision machined surface processing requirements can be achieved, otherwise it can not reach the processing requirements, precision analysis of various factors is analyzed and studied precision can not meet the requirements, namely the possibility of errors generated by a variety of original and take effective measures to overcome the process, thus improving accuracy.