For the technical specification of mechanical processing, the technicians determine the technical process to be adopted according to the quantity of products, equipment conditions and the quality of workers, and write the relevant content into a technical document, which is called a technical specification.

In order to facilitate the preparation, execution and production organization management of process regulations, it is necessary to divide the process into different levels of units. They are operations, installations, stations, steps and passes. The process is the basic unit in the process.

The machining process of parts consists of several processes.

process

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

For example: Machining a batch of shafts on a lathe can either rough and finish each shaft continuously, or rough the entire batch and then finish them in sequence.

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

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

Install

In the machining process, the process of making the workpiece occupy a correct position on the machine tool or in the fixture and clamp it is called clamping. Sometimes, the workpiece needs to go through several clampings on the machine tool to complete - the work content of one operation. Installation refers to the part of the process completed after the workpiece is clamped once

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

Station

When using an indexing (or shifting) fixture, a rotary table or processing on a multi-axis machine tool, after the workpiece is clamped once on the machine tool, it must be processed in sequence through thousands of positions. The part of the process that is completed at the location is called the station

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

work step

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

In order to improve productivity, several tools are used for simultaneous machining, and several steps for machining surfaces, called compound steps, can also be regarded as one step.

take a knife

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

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