What is technical communication

Technical communication

Technical communication

Concept and purpose
The word communication is derived from the Latin verb "communicare" and means "exchange".
We speak of technical communication when it comes to the exchange of information in the area of ​​manufacturing or modifying a product.
The purpose of technical communication is to provide all persons involved in the manufacture or modification of a product - in the broader sense also departments of a company - with all the information they need in order to make production run as quickly and smoothly as possible. To do this, it is essential that the information reaches the right place at the right time and that it is free from errors.
Technical communication takes place both within the company and between the company and the customer, e.g. when a person ordering a system informs the manufacturer of his wishes and ideas, or when the buyer of a device is supplied with an operating manual.
Means of communication
The number and type of means of communication used depends on the type of production and the structure of the company. Stand in the foreground drawings and parts lists. Electronic data carriers enable, among other things. the storage of the information so that it is available in the shortest possible time for a later identical or similar production. Other means of communication are work plans, function plans, production programs, spare parts lists, operating instructions, diagrams and others.

Out: Hans Schindler Technical Communication Basic Level Verlag Gehlen ISBN 3-441-08013-0


Why is a technical drawing needed?

If a workpiece is to be manufactured, it makes sense to make a drawing beforehand. The production of the workpiece is preceded by the construction by drawing. This has the advantage that possible errors are recognized and eliminated during the planning phase, so that no expensive material is wasted during production. In a society based on the division of labor, design and production are separated from each other. The technical drawing serves as a means of communication between planning and production. The planner (engineer) must be able to bring ideas into the form of a technical drawing. The worker in production must be able to read the technical drawing correctly and work precisely according to the specifications.

The standardization

A technical drawing consists of lines, numbers, auxiliary lines and symbols. For reasons of clarity and so that technical drawings can be understood by everyone involved in the production process, there are binding rules, the standards. The shapes and dimensions of objects are shown uniformly. Terms have the same meaning. In Germany, DIN (Deutsches Institut für Normung e.V.) is responsible for standardization work. The result of the standardization work is reflected in the DIN standard sheets.

Drawing devices

For making drawings one uses:

  • Medium hardness pencils (HB) or fine lead holders
  • A ruler 300 mm long
  • A triangle with angles 90, 45, 45 degrees (l about 160 mm)
  • A triangle with angles 90, 60, 30 degrees (l about 160 mm)
  • A circle template and a pair of compasses

Sheet sizes

According to DIN 823, the drawing sheets have the following names and sizes:

A0: 841 mm x 1189 mm
A1: 594 mm x 841 mm
A2: 420mm x 594mm
A3: 297 mm x 420 mm
A4: 210 mm x 297 mm
A5: 148 mm x 210 mm

For the drawing area, a 5 mm wide border is cut off on all sides. In many cases, A4 paper is sufficient.

The scale

Drawings of workpieces in natural size are on a scale of 1: 1. For larger workpieces, the drawings must be made smaller. For this, depending on the size of the workpieces, the following standards according to DIN 823 are selected.

Reductions: M 1: 2; M 1: 5; M 1:10; M 1:20; M 1:50 ...

The scale M 1:10 says that 1 mm in the drawing corresponds to a natural length of 10 mm.

If the workpieces are very small, they are shown enlarged in the drawing, in the following scales:

Enlargements: M 2: 1; M 5: 1; M 10: 1; M 20: 1; M 50: 1 ...

The scale M 10: 1 says that 10 mm in the drawing corresponds to a natural length of 1 mm.

The scale used must always be indicated in the drawing.


The drawing of a house: 1:50 or 1: 100
The drawing of a microchip: M 10: 1 or M 20: 1

Lines according to DIN 15

The line group DIN 15 - 0.5 should preferably be used for the drawing formats A4 to A2.

  • 0.5 mm for all wide lines.
  • 0.35 mm for dimensions and words and for symbols.
  • 0.25 mm for all narrow lines.
Line group DIN 15 - 05

Line style

Line width





0.5 mm

Full line

For visible edges and outlines.


0.35 mm

Dashed line

For hidden edges and outlines.


0.35 mm



Font for dimensions and lettering.


0.25 mm

Full line

Dimension lines, extension lines, hatching lines, surface symbols, diagonal crosses, reference lines.


0.25 mm

Dotted line

Center lines, pitch circles, bolt circles.


0.25 mm

Freehand line

Fault lines.

Lettering of drawings

Reading and writing direction.

The representation and the lettering of a drawing must always be legible in the same direction as the reading direction of the text field. The direction of writing for the dimension entry is determined by the course of the dimension line.

Written form.

For the line width d = 0.35 mm, the following values ​​apply to the characters:

  • Height of the capital letters and digits: h = 3.5 mm
  • Height of the lower case letters without ascending or descending length: c = 2.5 mm
  • with upper and lower length: h = 3.5 mm
  • Minimum distance between characters: a = 0.7 mm
  • Minimum space between words: e = 2.1 mm
  • Minimum distance between baselines: b = 5 mm

Font templates take all dimensions into account, but are expensive.

Font size.

According to DIN 6774, three font sizes are provided for you to label drawings:

0.5 mm for scale and marking of sections.
0.35 mm for dimensions and words.
0.25 mm for indices and exponents.

The title block

Technical drawings are provided with a title block in which all information required for the user of the drawing is entered.

The writing field according to DIN 6771.


Size of the title block: 54.99 mm x 182.88 mm

Line widths:

Boundary lines of the text field: 0.7 mm
Boundary lines of the main fields: 0.35 mm
All other lines: 0.18 mm

The individual fields should contain the following entries:

Box 1: Area of ​​use
Field 2: Permissible deviation for dimensions without specification of tolerances
Field 3: Rules for the surface of the depicted
Field 4: scale
Box 5: Weight
Field 6: Model number, raw part number, information on the material, etc.
Field 7: Information on the change status of the drawing
Field 8 and 9: Special notes from the manufacturer of the drawings
Field 8a / 9a: Name of the creator and the examiner of the drawing
Box 10: Name of the person depicted
Field 11: Company of the author of the drawing
Field 12: Drawing number of the creator
Field 13: Sheet number and number of sheets if several sheets of the same drawing number are required
Box 14: Number of the original drawing if the drawing was created from another
Field 15a: If a drawing becomes invalid as a result of this drawing, its number can be entered here
Field 15b: If the present drawing is replaced by another, its number can be entered here

The standard-compliant writing field is usually too extensive for school use. The trade offers drawing paper with simplified text fields that are adapted to school use. When using neutral drawing paper, the simplified title block shown below can be used. It coincides with the standardized writing field in essential individual dimensions.

Representation and dimensioning of the workpieces

Basics of dimensioning

The dimensions determine how large the individual shapes of the workpieces to be drawn are. The size is indicated with the help of dimension lines and symbols to limit them, with dimension lines and with dimension numbers.

Line widths
Visible edges: 0.5 mm
Dimensional numbers: 0.35 mm
Dimension lines: 0.25 mm
Extension lines: 0.25 mm
Drawing rules for dimension lines
The dimension lines are as long as the edges whose length they determine.
Dimension lines are drawn in narrow solid lines (0.25 mm).
Dimension lines are parallel to the workpiece edges that are being dimensioned.
The distance between the edge of the workpiece and the dimension line should be around 10 mm. If there are several dimension lines in parallel next to or below one another, their distance from one another should be uniform and at least 7 mm.
Body edges must not be used as dimension lines.

Dimension line limit

Closed dimension arrows are isosceles triangles with a vertex angle of 15 °. The length of the dimension arrows is 2.5 mm.
Variants for dimension line limits
Oblique lines:
In addition to dimension arrows, oblique lines are often used in metal construction. They run at an angle of 45 ° to the dimension line from bottom left to top right. Their length is 3 mm.
If there is not enough space, dimension lines can be limited by points. They are filled in black and have a diameter of 0.75 mm.
Drawing rule:
Only one type of dimension line boundary is to be used within one and the same drawing.
Combinations as in the adjacent drawing.

Extension lines

If the dimensions are not carried out within the workpiece edges, then the workpiece edges must be extended using extension lines. The extension lines are drawn as narrow solid lines (0.25 mm). They are perpendicular to the dimension lines and protrude about 2 mm above them.

Drawing rules for dimensions

Dimensional figures should preferably be written in vertical middle script, the standard script. The font size is 3.5 mm, the line width 0.35 mm.
ABCD ...
abcde ...
Dimension numbers are written over the solid dimension line. If there is insufficient space, it is permitted to interrupt the dimension line and write the dimension number in the gap that has been created.

The unit of measurement is only written after the dimension number if the unit of measurement is not mm.

The dimensions 6, 9, 66, 68, 86 and the like. receive a point after the number if they can be mixed up due to their position (6th, 9th, 66th, 68th, 86th).

In the case of vertical dimension lines, the dimension numbers must be written so that they can be read from the right. If dimension lines are at an angle, then the dimension numbers must be inserted as shown in the adjacent figure.

Position of the dimensions for angles.
If several parallel dimension lines are close together, the dimension numbers must be offset from one another.

General dimensioning rules

The dimensions are extracted from the workpiece with the help of extension lines (Figure 1). If the edges to be dimensioned are very short, then a dimension distribution according to Figure 2 should be selected. Each dimension may only be entered once.
Dimension lines should not intersect extension lines and other dimension lines. Cutting with wide solid lines (workpiece edges) should also be avoided if possible.

Dimension arrows must not hit corners. If necessary, the distance between the edge of the workpiece and the dimension line must be increased (Figure 3).

If dimensions are strung together, this should not be done in stages if possible.

Closed dimensional chains are to be avoided. A closed dimensional chain exists when the total length of a workpiece is made up of lined up, dimensioned individual lengths. With this dimensioning, the errors add up during production.

Dimensioning flat workpieces

Flat workpieces have a uniform thickness. You put them there in just one view and specify the workpiece thickness. The thickness is determined using the designation t = thickness (t from the English thik (thick)). The thickness information is to be written in a clearly arranged place on the workpiece. If there is not enough space, it can also be placed next to the workpiece.

Dimensioning with reference planes

Dimensioning is easiest when working with reference planes. Dimension reference planes are those workpiece shapes to which the individual dimensions refer. The dimensions are based on these reference elements. The system of this dimension entry becomes even clearer if one ignores the workpiece edges and only draws the 8 dimensions and the two reference planes.

Drawing rules:

As a rule, two dimension reference levels have to be determined:

One horizontal reference plane for all vertical dimensions and one vertical plane for all horizontal dimensions.

Unless the task stipulates otherwise, the longest workpiece edges are selected as the dimension reference planes.

Not only the workpiece edge itself is used as the reference plane, but also its extension by extension lines.

Symmetrical workpieces

A body is symmetrical if it can be divided into two halves by an axis of symmetry in such a way that these two halves coincide when folded around the axis of symmetry.

Symmetrical workpieces are given a center line. It is drawn as a narrow dash-dotted line (0.25 mm).

Drawing rules:

The length of the lines is approx. 10 mm, those of the dots and spaces approx. 1 mm.
With small body shapes, e.g. small circles, only the lines are drawn.
Dash-dotted lines start and end with a dash.
The center line extends beyond the workpiece edges by a few millimeters.
If two center lines intersect, the point of intersection must lie in the area of ​​the lines.
The dimensions running across the center line are given as total dimensions.
If a dimension line intersects a center line, the center line must be interrupted for the dimension number. If there is enough space, the dimension can also be written next to the center line.
A center line must not be used as a dimension line.
Draw the sheet metal shown opposite on a scale of 1: 1 and measure it. A box is 0.5 mm x 0.5 mm. The thickness of the sheet is 7 mm.
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