Line types and thicknesses

The standard ISO 128:1982 gives 10 line types that are defined A to K (excluding the letter I). The table in Figure 3.4 shows these lines.

Flame harden to 50HRC

Flame harden to 50HRC

Drawing Line Types

HARDENED INSERT. Part No 2.

Material: medium carbon steel. All dimensions in mm.

Not to scale.

Figure 3.3 Detailed engineering drawing of the 'hardened insert', part number 2

HARDENED INSERT. Part No 2.

Material: medium carbon steel. All dimensions in mm.

Not to scale.

Figure 3.3 Detailed engineering drawing of the 'hardened insert', part number 2

The line types are 'thick', 'thin', 'continuous', 'straight', 'curved', 'zigzag', 'discontinuous dotted' and 'discontinuous chain dotted'. Each line type has clear meanings on the drawing and mixing up one type with another type is the equivalent of spelling something incorrectly in an essay.

The line thickness categories 'thick' and 'thin' (sometimes called 'wide' and 'narrow') should be in the proportion 1:2. However, although the proportion needs to apply in all cases, the individual line thicknesses will vary depending upon the type, size and scale of the drawing used. The standard ISO 128:1982 states that the thickness of the 'thick' or 'wide' line should be chosen according to the size and type of the drawing from the following range: 0,18; 0,25; 0,35; 0,5; 0,7; 1; 1,4 and 2mm. However, in a direct contradiction of this the standard ISO 128-24:1999 states that the thicknesses should be 0,25; 0,35; 0,5; 0,7; 1; 1,4 and 2mm. Thus confusion reigns and the reader needs to beware! With reference to the table in Figure 3.4, the A-K line types are as follows.

The ISO type 'A' lines are thick, straight and continuous, as shown in Figure 3.5. They are used for visible edges, visible outlines, crests of screw threads, limit of length of full thread and section viewing lines. The examples of all these can be seen in the vice assembly detailed drawings. These are by far the most common of the lines types since they define the artefact.

The ISO type 'B' lines are thin, straight and continuous, as shown in Figure 3.6. They are used for dimension and extension lines,

ENGINEERING DRAWING LINES

Continuous Lines

Discontinuous Lines

Thick

Thin

Thick

Thin

Thick

Straight

Wavy

Straight

Non-straight

Dash

Chain

Dash

Chain

& thin

Curved

Zigzags

Single

Double

1

none

5

i

1 1 1

1 i

i j

i

! i i

IS0128 Classification of Line Types, 'A' to 'K'

A

none

B

c

D

E

J

F

G

K

H

Figure 3.4 Engineering drawing line types A to K (ISO 128:1982)

Figure 3.4 Engineering drawing line types A to K (ISO 128:1982)

leader lines, cross hatching, outlines of revolved sections, short centre lines, thread routes and symmetry ('equals') signs.

The ISO type 'C' lines are thin, wavy and continuous, as shown in Figure 3.7. They are only used for showing the limits of sections or the limits of interrupted views as would be produced by freehand drawings by a draughtsman on a paper-based drawing board. Examples of type 'C' lines are shown on the assembly drawing, part number six, jaw clamp screw.

The ISO type 'D' lines are thin, zigzag and continuous, as shown in Figure 3.8. These have exactly the same use as the type 'C' lines

ISO Type'A1 Line

Thick, Continuous

Outlines Edges Thread c

s>m -x rests Limit of Section full thread viewing line

Figure 3.5 ISO 128 engineering drawing line type A'

Figure 3.5 ISO 128 engineering drawing line type A'

ISO Type 'B' Line thin, straight, continuous

Dimensionand Leader Lines Cross Outline of extension lines hatching revolved sections

Short centre Thread roots Symmetry sign lines

Figure 3.6 ISO 128 engineering drawing line type 'B'

ISO Type 'C' Line

Thin, wavy, continuous

Limit of section. Limit of interrupted view. For freehand drawings.

Limit of section. Limit of interrupted view. For freehand drawings.

Figure 3.7 ISO 128 engineering drawing line type 'C'

ISO Type'D1 Line

Thin, zig-zag, continuous

Limit of section. Limit of interrupted view. For machine drawings.

Limit of section. Limit of interrupted view. For machine drawings.

Figure 3.8 ISO 128 engineering drawing line type 'D'

but they are used for machine-generated drawings. Again they apply to the limit of sections or the limit of interrupted views. Examples of the type 'D' line are shown in the vice assembly drawing.

The ISO type 'E' lines are thick, discontinuous and dashed, as shown in Figure 3.9. They are only used for an indication of permissible surface treatment. This could be, for example, heat treatment or machining. This type of line is shown on the hardened insert detailed drawing.

The ISO type 'F' lines are thin, discontinuous and dashed, as shown in Figure 3.10. They are used for displaying hidden detail, be that hidden detail edges or outlines. Hidden detail can be seen on the movable jaw and hardened insert detailed drawings in Figures 3.2 and 3.3 respectively.

The ISO type 'G' lines are thin, discontinuous and chain dotted, as shown in Figure 3.11. They are used to show centre lines of either

ISO Type 'E' Line

Thick, discontinuous, dash

' Indication of permissable surface

j — treatment, eg heat treatment

1 1

Figure 3.9 ISO 128 engineering drawing line type 'E'

Figure 3.9 ISO 128 engineering drawing line type 'E'

Hidden edges Hidden outlines

Figure 3.10 ISO 128 engineering drawing line type 'F'

individual features or parts. Centre lines can be seen on the vice assembly drawing as well as the movable jaw and hardened insert drawings.

The ISO type 'H' lines are a combination of thick and thin, discontinuous and chain dotted, as shown in Figure 3.12. They are used to show cutting planes. The thick part of the type lines are at the ends where the cutting section plain viewing direction arrows are shown as well as at the points of a change in direction. An example of a staggered type 'H' cutting plane is shown in the movable jaw detailed drawing.

Note that no line type T is defined in the ISO 128:1982 standard.

The ISO type 'J' lines are thick, discontinuous and chain dotted, as shown in Figure 3.13. They are used for the end parts of cutting planes as shown previously in the above type 'H' lines. They are also used to provide an indication of areas that are limited for some

ISOType'G' Line

-------

Thin, discontinuous, chain

^_____ Centre lines

-^ Lines of symmetry o j*—^

Figure 3.11 ISO 128 engineering drawing line type 'G'

Figure 3.11 ISO 128 engineering drawing line type 'G'

ISO Type'H' Line

Thick and thin, discontinuous, chain

-Extent of staggered cutting planes

Figure 3.12 ISO 128 engineering drawing line type 'H'

ISO Type 'J' Line

-------

Thick, discontinuous, chain

r

Indication of limited areas, /eg measuring — area or heat T treatment

Figure 3.13 ISO 128 engineering drawing line type 'J'

Figure 3.13 ISO 128 engineering drawing line type 'J'

reason, e.g. a measuring area or a limit of heat-treatment. Examples of this type of line can be seen in the movable jaw detailed drawing.

The ISO type 'K' lines are thin, discontinuous and chain dotted with a double dot, as shown in Figure 3.14. They are used to indicate the important features of other parts. This could be either the

ISO Type'K1 Line

Thin, discontinuous, double-chain

Outlines of / -r adjacent parts K

V*/

Extreme positions | ^ of movable parts —

d

"N

Figure 3.14 ISO 128 engineering drawing line type 'K'

Figure 3.14 ISO 128 engineering drawing line type 'K'

outline of adjacent parts to show where a particular part is situated, or, for movable parts, the extreme position of movable parts.

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  • lana
    How to draw limits of interrupted views?
    9 years ago
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    What are discontinuous lines of symmetry?
    8 years ago
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    What are the line types for engineering?
    7 years ago
  • christina
    What are the thicknesses of different types of lines?
    2 years ago
  • Rose
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    2 years ago
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