The following article presents the basics of technological processes necessary for considering production technologies. The production process includes technological and auxiliary processes (basics) – all necessary steps to produce a given product, i.e:
- development and production of workpiece,
- machining of workpiece,
- quality control,
The development and manufacture of workpiece and assembly are processes closely related to production. Due to design principles and used manufacturing techniques, they are treated as separate issues. The technological process mainly concerns shaping the workpiece into the final product (decrement and additive techniques).
Quality control is integral with the production process, especially the technological process. The machining control is carried out at a processing station or in specially built and equipped measuring rooms.
The technological process includes machining of components (parts, objects) consisting in changing the shape, geometrical dimensions, surface quality (surface layer), physicochemical properties of the workpiece and combining the manufactured elements into assemblies (machines, mechanical devices, electromechanical devices).
The technological process of the part and the technological process of assembly are distinguished. The assembly process involves combining the manufactured parts into sets (machine, mechanical, electromechanical device).
Technological preparation of production uses technological processes defined for particular classes of parts (shafts, sleeves and disks, levers, bodies, flat elements, gears). The division into parts classes and related technological processes is an important support in the work of technologists.
Types of production
The division of the technological process depends on many factors. An important factor is the quantitative type of production. The technologist is interested in the volume of production, the number of production series. Mostly, production is divided into production series. The technological process is developed for production series. Figure 1 shows the types of production with the quantitative criterion.
Individual items or their small numbers are produced. Such production is not repetitive. Components are made at one time or very irregularly. The technological process should be developed in such a way that it would not be necessary to use machine tools, tools and specialized or special technological equipment. In this case, the cost is the key criterion. Only universal tools and equipment (commercially available) should be used. Setup and breaking-down time will be longer. It is also possible to extend the main machine time (time when machining is in progress). However, extending these times is a more economical solution than developing and manufacturing, for example, specialized technological equipment. However, it is not always possible to avoid using specialist or special tools. The machining of an internal cone with an unusual angle requires the use of a specialized tool.
Repeatable production series, within which certain number of components are made. The technological process is already significantly different from the piece production. The use of specialist and special technology tools and equipment is fully acceptable and desirable. Specialized and special technological equipment depending on the size of the production series can be more or less complicated. Specialized machine tools are used.
A very large number of manufactured items, almost continuously, at least for a very long period. Each technological operation is a specific machining station. First of all, machine tools and special tools are used. In many cases, the technological equipment will be used only within one technological process of a given part, without the possibility of using it in other technological tasks. What in the technological process for serial production was a technological operation in one operation, in mass production is a separate operation. Application of the so-called a special machine tool allows several serial production operations to be included in one for mass production.
The above information needs to be supplemented. Nowadays, the use of CNC machining centers and the automation of both transport subsystems and the machining stations themselves allows the implementation of structural optimization (reduction of preparatory and finaling time). The character of modern production closer to piece and small-lot production additionally justifies the use of CNC machines due to the greater flexibility from the point of view of the technological preparation of production. Undoubtedly, there are still technological tasks where the use of special machine tools, teamwork is fully justified, however the general character of production in the last 20 years has undergone significant changes. This process is clearly observable already in the 1990s.
Division of the technological process
Criteria for divisions: organizational (structure), qualitative, quantitative.
Figure 2 shows the division of the technological process with the criterion of structure. The technological process consists of individual technological operations. Technological operation consists of treatment (cut) – one or many. In a situation where a technological operation includes one treatment, technological treatment is a technological operation.
The technological operation is performed on one machine in one or several mountings. The necessary condition is the lack of any retooling of the machine tool between individual workpiece attachments (change in the technological equipment, change of tools, any other interference of the operator in the machining space). The technological operation can be carried out in one or several positions of the workpiece (e.g. five-axis machining – fig.2 – technological operation #20).
The technological operation on a conventional machine tool (not CNC) consists of one or many treatments – figure 2 – technological operation #10 – treatment #2. Each technological treatment has its own individually selected machining parameters.
- Feld M., Podstawy projektowania procesów technologicznych typowych części maszyn, WNT 2000
- Kapiński S., Skawiński P., Sobieszczański, Sobolewski J.Z., Projektowanie technologii maszyn, OWPW 2002
- Puff T., Technologia budowy maszyn, PWN 1985