Manufacturing process

Area	terminology
title	Manufacturing processes - terms, classification
Latest edition	2003-09
ISO

In manufacturing technology, all processes for the production of geometrically determined solid bodies ( workpieces ) are referred to as production processes , i.e. bodies with certain dimensions and shapes, including surface roughness. The most important manufacturing processes include casting , forging , milling , drilling , welding and soldering . In addition, the manufacturing processes include changing material properties, such as hardening or soft annealing. The production of bodies without a specific shape, on the other hand, is a matter of process engineering .

The workpieces can be semi-finished products that have to be processed further (sheets, bars, rods) or finished products. As a rule, several manufacturing processes have to be combined in order to manufacture finished products from raw parts to semi- finished parts. The starting point is the data of the design , such as technical drawings or three-dimensional CAD models. This includes the dimensions of the workpieces, their material and the permissible deviations ( tolerances ).

The numerous different manufacturing processes are divided into six main groups in DIN 8580 according to common process principles, each of which is divided into several groups, subgroups, processes and process variants.

Main groups according to DIN 8580

According to DIN 8580, the manufacturing processes are divided into six main groups, the focus of which is on metal processing. The characteristic of the classification is the cohesion in the sense of the cohesion of particles of a solid body. The cohesion is either created (archetype), maintained (reshaping, rearrangement of material particles), reduced (separating, separating out material particles) or increased (joining, coating, introduction of material particles).

Archetypes (creating cohesion): All manufacturing processes in which a workpiece is made from shapeless material are referred to as primary molding processes. In this process the cohesion of the material particles is created. Any source material whose shape is not defined, such as a liquid that adapts to the inner walls of the container, counts as shapeless material. The group’s most important process is pouring from molten starting material. Otherwise, powders and granulates are used for sintering, or pastes. The various generative manufacturing processes , some of which are also known as 3D printing or rapid prototyping, are not yet categorized as relatively new processes in the DIN standards; in the specialist literature, however, they are mostly assigned to the archetype.
Reshaping (maintaining cohesion): All manufacturing processes in which workpieces are created from solid raw parts by permanent change in shape are called forming processes, provided that neither material is added nor removed. The mass of the blank is equal to the mass of the finished part . The most important processes of the group are rolling , die forging , extrusion , extrusion , deep drawing and bending .
To separate (reduce cohesion): All processes in which the shape of a workpiece is changed by breaking the material cohesion at the processing point and thus reducing the material cohesion as a whole are called cutting processes. The most important group is machining , in which material is removed in the form of chips ( sawing , planing , milling , drilling , ...). Other important separating processes are shear cutting (punching), flame cutting or spark erosion . Disassembling for dismantling is also part of separating .
Joining (increasing cohesion): Joining is the long-term connection of several workpieces. This includes in particular welding , soldering and gluing, but also riveting , screwing or assembling .
Coating (increasing cohesion): Coating is manufacturing by applying a firmly adhering layer of shapeless material to a workpiece. Example: painting , electroplating , powder coating , hot-dip galvanizing .
Change substance properties: is manufacturing by changing the properties of the material from which a workpiece is made. This includes hardening and annealing (e.g. softening to facilitate processing).

Properties and selection criteria of manufacturing processes

Many workpieces can be manufactured using various manufacturing processes. Gears for example, can be produced by forging, hobbing , Wälzhobeln manufacture or many other manufacturing processes. However, these methods differ in the achievable accuracy, surface quality (roughness), the necessary processing time, the required machines and tools as well as the flexibility. The flexibility can relate to the number of workpieces as well as the range of shapes that can be manufactured and the materials to be processed.

Casting and forging are relatively imprecise manufacturing processes, but they are also suitable for large quantities and are then associated with low unit costs. With casting, however, molds or models must first be made, with drop forging the dies. Since they are quite expensive, both methods are only suitable for larger quantities. In addition, both are essentially limited to metals as a material. Wood or ceramic, on the other hand, can also be processed by milling, grinding or drilling. Milling and grinding in particular are suitable for many different shapes and quantities. Both can also be used to achieve very good accuracies and surface qualities.

Often there are combinations of manufacturing processes to combine the various advantages. So-called semi - finished products such as sheet metal, bars or rods are mostly manufactured using processes suitable for mass production such as forging or casting. Then they are further processed into the end products using more precise and flexible methods. Body parts can be produced from sheet metal, for example, by punching and then bending and deep drawing. The workpieces often go through the processes in the order in which they are summarized in the main groups in DIN 8580. So they are first made by primary forming, then further processed by forming and finally finished by cutting and joining.

Developments and trends

Lightweight construction

One of the most enduring trends in manufacturing technology is lightweight construction. Almost every product benefits if unnecessary weight can be saved in the right place. Plastics or light metals are often used here. But steel also offers lightweight construction advantages, because high-performance steel alloys enable a significantly more compact construction due to their high strength.

Additive manufacturing processes

With the help of additive manufacturing processes - also known as generative manufacturing processes or 3D printing - both plastics and metals can be precisely shaped into the final component.

literature

Karl-Heinrich Grote, Jörg Feldhusen (Hrsg.): Dubbel - paperback for mechanical engineering . 22nd edition. Springer, Berlin 2007. ISBN 3-540-68186-8
Günter Spur, Theodor Stöferle (Ed.): Handbook of manufacturing technology . Karl Hanser / Hanser Fachbuch, Munich / Vienna 1981, ISBN 978-3-446-12538-4 (6 volumes).
Alfred Herbert Fritz, Günter Schulze (ed.): Manufacturing technology . 10th revised edition. Springer, Berlin 2012. ISBN 978-3-642-29785-4

Web links

Wikibooks: Overview of manufacturing techniques - learning and teaching materials

Individual evidence

↑ DIN 8580: 2003-09, p. 4
↑ Overview of manufacturing processes: description, advantages, trends. Retrieved February 19, 2018 .
↑ Overview of manufacturing processes: description, advantages, trends. Retrieved February 19, 2018 .

[1] DIN 8580: 2003-09, p. 4

[2] Overview of manufacturing processes: description, advantages, trends. Retrieved February 19, 2018 .

[3] Overview of manufacturing processes: description, advantages, trends. Retrieved February 19, 2018 .