Machining process specification

The process specification of mechanical processing, the technicians determine the process to be adopted according to the number of products, equipment conditions and workers' quality, and write the relevant contents into process documents, which are called process specifications.

In order to facilitate the preparation, execution and production organization and management of process specifications, it is necessary to divide the process into units of different levels. They are process, installation, station, work step and tool path. Among them, the process is the basic unit in the process.

The mechanical processing process of parts consists of several processes.

Process

The part of the process that a (or a group of) workers continuously completes on one (or several) workpieces at a work site (or a machine tool) is called a process. The basis for dividing the process is whether the work site changes and whether the work process is continuous.

For example: when processing a batch of shafts on a lathe, each shaft can be roughed and finished continuously, or the whole batch of shafts can be roughed first, and then they can be finished in sequence.

In the first case, the processing includes only one process; in the second case, due to the interruption of the continuity of the processing process, although the processing is carried out on the same machine tool, it becomes two processes.

The process is the basic unit of the process and the basic unit of the production plan.

Installation

In the machining process, the process of clamping the workpiece on the machine tool or in the fixture to occupy a correct position and be clamped is called clamping. Sometimes, the workpiece needs to be clamped multiple times on the machine tool to complete the work content of a process. Installation refers to the part of the process content completed after the workpiece is clamped once.

For example, when machining a shaft on a lathe, first machine part of the surface from one end, then turn around and machine the other end. At this time, the process content includes two installations.

Workstation

When using a transfer (or shift) fixture, a rotary table or a multi-axis machine tool for processing, after the workpiece is clamped on the machine tool once, it must be processed in several positions in sequence. The part of the process completed at each position occupied by the workpiece on the machine tool is called a workstation

In simple terms, the part of the process content completed by the workpiece relative to each processing position of the machine tool or tool is called a workstation.

Workstep

Under the condition that the processing surface, cutting tool, cutting speed and feed rate remain unchanged, the part of the process content completed continuously is called a workstep. It is also often called "feed" in production.

In order to improve productivity, the work steps of several processing surfaces are processed simultaneously with several tools, which are called compound worksteps, and can also be regarded as one workstep.

Tool pass

The part of the work step completed by the processing tool on the processing surface once is called a tool pass.

For example, if the metal layer to be cut off of shaft parts is very thick, it needs to be cut several times. At this time, each cutting is called a tool pass. Therefore, under the premise that the cutting speed and feed rate remain unchanged, the tool completes one feed movement which is called one cutting pass.