Tolerances for aluminium castings

As is generally known, all series products are subject to procedural and technical tolerances.
In the aluminium casting technique these tolerances result from the moulds, the alloys and the casting procedure.
Aluminium alloys to DIN 1725 are used by BOPLA for its enclosures.

Tolerances for Pressure Dia-Castings (DIN 1688, Page 4)

In pressure-die cast parts in light metal alloys the deviations in dimensions are mainly dependent on:

the exactitude of the dimensions and function of the mould, which in turn is characterised by the degree of exactitude of
the position of the mould division, characterised by the subdivision into shape-related and non-related dimensions (see DIN 1680, Page 1)
the shape or size of the casting, characterised by the spatial diagonals and
the nominal dimensions.

Determining the Spatial Diagonals
The spatial diagonal R is that between the extreme points of the casting.
It is calculated from the nominal dimensions of the prismatic body, which delimits the casting, whatever its shape.

Table 1

Tolerances of dimensions not related to the shape, linear dimensions (lengths, widths, heights, central distances, diameters, roundings)

Spatial diagonal area ¹)	Degree of exactitude	Shape depen dency	Nominal dimensions
up to 18	18 to 30	30 to 50	50 to 80	80 to 120	120 to 180	180 to 250	250 to 315	315 to 400	400 to 500	500 to 630	630 to 800	800 to 1000	1000 to 1250
Up to 50	GTA 13	shape- related	± 0,14	± 0,17	± 0,2
not shape- related	± 0,24	± 0,27	± 0,3
50 to 180	GTA 13/5	shape- related	± 0,17	± 0,2	± 0,25	± 0,3	± 0,35	± 0,4
not shape- related	± 0,32	± 0,35	± 0,4	± 0,45	± 0,5	± 0,55
180 to 500	GTA 14	shape- related	± 0,22	± 0,26	± 0,31	± 0,37	± 0,44	± 0,5	± 0,6	± 0,65	± 0,7	± 0,8
not shape- related	± 0,42	± 0,46	± 0,51	± 0,57	± 0,64	± 0,7	± 0,8	± 0,85	± 0,9	± 1
500	GTA 14/5	shape- related	± 0,25	± 0,35	± 0,4	± 0,45	± 0,55	± 0,65	± 0,75	± 0,8	± 0,85	± 0,95	± 1,1	± 1,2	± 1,4	± 1,6
not shape- related	± 0,55	± 0,65	± 0,7	± 0,75	± 0,85	± 0,95	± 1	± 1,1	± 1,1	± 1,2	± 1,4	± 1,5	± 1,7	± 1,9

Spatial
diagonal
area ¹)

Degree
of exactitude

Shape
depen
dency

Nominal dimensions

up to
18

18
to 30

30
to
50

50
to
80

80
to 120

120
to 180

180
to 250

250
to 315

315
to 400

400
to 500

500
to 630

630
to 800

800
to 1000

1000
to 1250

Up to 50

GTA 13

shape-
related

± 0,14

± 0,17

± 0,2

not
shape-
related

± 0,24

± 0,27

± 0,3

50
to 180

GTA 13/5

shape-
related

± 0,17

± 0,2

± 0,25

± 0,3

± 0,35

± 0,4

not
shape-
related

± 0,32

± 0,35

± 0,4

± 0,45

± 0,5

± 0,55

180
to 500

GTA 14

shape-
related

± 0,22

± 0,26

± 0,31

± 0,37

± 0,44

± 0,5

± 0,6

± 0,65

± 0,7

± 0,8

not
shape-
related

± 0,42

± 0,46

± 0,51

± 0,57

± 0,64

± 0,7

± 0,8

± 0,85

± 0,9

± 1

500

GTA 14/5

shape-
related

± 0,25

± 0,35

± 0,4

± 0,45

± 0,55

± 0,65

± 0,75

± 0,8

± 0,85

± 0,95

± 1,1

± 1,2

± 1,4

± 1,6

not
shape-
related

± 0,55

± 0,65

± 0,7

± 0,75

± 0,85

± 0,95

± 1

± 1,1

± 1,2

± 1,4

± 1,5

± 1,7

± 1,9

Table 2

Tolerances of Dimensions not related to the Shape for Thickness (wall thickness, ledges, ribs)

Spatial diagonal area ¹)	Degree of' exactitude	Shape dependency	Nominal dimensions
Spatial diagonal area ¹)	Degree of' exactitude	Shape dependency	to 3	3 to 6	6 to 10
Up to 50	GTA 13	shaperelated	± 0,15	± 0,2	± 0,2
Up to 50	GTA 13	not shaperelated	± 0,25	± 0,3	± 0,3
50 to 180	GTA 13/5	shaperelated	± 0,2	± 0,25	± 0,3
50 to 180	GTA 13/5	not shaperelated	± 0,35	± 0,4	± 0,45
180 to 500	GTA 14	shaperelated	± 0,25	± 0,3	± 0,35
180 to 500	GTA 14	not shaperelated	± 0,45	± 0,5	± 0,55
500	GTA 14/5	shaperelated	± 0,3	± 0,4	± 0,45
500	GTA 14/5	not shaperelated	± 0,55	± 0,65	± 0,7

Shape-related dimensions are those in the same part of the tool;
Not shape-related dimensions are those created by the interaction of mobile tool components, e.g. wall thicknesses and base thicknesses or dimensions affected by additives or extenders.

Tolerances for Chill Castings (DIN 1688 T.3)

In the case of raw castings made of light metal alloys in the chill casting process all deviations in dimensions are essentialy dependent on:

the exactitude of the dimensions of the mould, characterised by the degree of exactitude
the position of the mould division, cores, extenders, characterised by the subdivision into shape-related and not shape-related dimensions (see DIN 1680 Part 1)
the nominal dimensions.

Table 1

Deviations in lengthwise dimensions (lengths, widths, heights, central distances, diameters, roundings)

Degree of exactitude	Shape dependency	Nominal dimensions
up to 18	18 to 30	30 to 50	50 to 80	80 to 120	120 to 180	180 to 250	250 to 315	315 to 400	400 to 500	500 to 630	630 to 800	800 to 1000	1000 to 1250
GTA 15/5	shape- related	± 0,45	± 0,5	± 0,6	± 0,75	± 0,85	± 1	± 1,2	± 1,3	± 1,4	± 1,6	± 1,7	± 2	± 2,3	± 2,6
not shape- related	± 0,55	± 0,65	± 0,8	± 0,95	± 1,1	± 1,3	± 1,5	± 1,6	± 1,8	± 2	± 2,2	± 2,5	± 2,8	± 3,3

Degree of
exactitude

Shape
dependency

Nominal dimensions

up to
18

18
to
30

30
to
50

50
to
80

80
to 120

120
to 180

180
to 250

250
to 315

315
to 400

400
to 500

500
to 630

630
to 800

800
to 1000

1000
to 1250

GTA 15/5

shape-
related

± 0,45

± 0,5

± 0,6

± 0,75

± 0,85

± 1

± 1,2

± 1,3

± 1,4

± 1,6

± 1,7

± 2

± 2,3

± 2,6

not
shape-
related

± 0,55

± 0,65

± 0,8

± 0,95

± 1,1

± 1,3

± 1,5

± 1,6

± 1,8

± 2

± 2,2

± 2,5

± 2,8

± 3,3

Table 2

Deviations in Thicknesses (wall thicknesses, ledges, ribs)

Degree of exactitude	Shape dependency	Nominal dimensions
Degree of exactitude	Shape dependency	up to 6	6 to 10	10 to 18
GTA 15/5	shaperelated	± 0,6	± 1,2	± 1,8
GTA 15/5	not shaperelated	± 0,8	± 1,5	± 2,2

Shape-related dimensions are those in the same parts of the tool.

Not shape-related dimensions are those created by the interaction of mobile tool components, e.g. wall thicknesses and base thicknesses, or dimensions that are affected by additives or extenders.