Investment casting ( ‘ lost wax ' ) tolerances are specified by the international standard: DIN VDG P690. As a general rule normal linear tolerance on an investment casting can be + 0,75% of the nominal dimension, with a minimum of + 0,10 mm for dimensions lower than 15 mm in order to achieve closer tolerances, a machining allowance is required, you can refer to general tolerance on machined parts but never forget that an investment casting always permits to reach very complex geometries.
As a good rule severe tolerances are to be avoided if not necessary to allow the higher production yelds and lower piece costs.
Therefore, functional or closer dimensions must be pointed out in the drawings and dealed with the technical department. The cast tolerances in the tables below can be used as an indication, depending on the steel alloy used and the product geometry.
Linear Tolerance:
METRIC - Millimeters |
Tolerance class |
Range |
D1 |
D2 |
D3 |
0 to 6 |
±0,10 |
±0,08 |
±0,06
|
6 to 10 |
±0,12 |
±0,10 |
10 to 14 |
±0,15 |
±0,12 |
±0,09
|
14 to 18 |
±0,20 |
±0,14 |
18 to 24 |
±0,25 |
±0,17 |
±0,12 |
24 to 30 |
±0,30 |
±0,20 |
±0,14 |
30 to 40 |
±0,37 |
±0,25 |
±0,17 |
40 to 50 |
±0,44 |
±0,30 |
±0,20 |
50 to 65 |
±0,52 |
±0,38 |
±0,23 |
65 to 80 |
±0,60 |
±0,46 |
±0,27 |
80 to 100 |
±0,68 |
±0,53 |
±0,30 |
100 to 120 |
±0,76 |
±0,60 |
±0,33 |
120 to 140 |
±0,84 |
±0,65 |
±0,36 |
140 to 160 |
±0,92 |
±0.72 |
±0.38 |
160 to 180 |
±1,02 |
±0.80 |
±0.42 |
180 to 200 |
±1.12 |
±0.88 |
±0.43 |
200 to 225 |
±1.28 |
±0.95 |
±0.47 |
225 to 250 |
±1.44 |
±1.05 |
±0.51 |
250 to 280 |
±1.64 |
±1.15 |
±0.56 |
280 to 315 |
±1.84 |
±1.25 |
±0.63 |
315 to 355 |
±2.10 |
±1.40 |
±0.71 |
355 to 400 |
±2.40 |
±1.60 |
±0.80 |
400 to 450 |
±2.70 |
±1.80 |
±0.90 |
450 to 500 |
±3,10 |
±2.00 |
±1.00 |
Tolerance for straightness, flatness and parallelism
METRIC - Millimeters |
Tolerance class |
Lengths |
D1 |
D2 |
D3 |
to 25 mm |
0,15 mm |
0.10 mm |
0.10 mm |
25 to 50 mm |
0.25 mm |
0.20 mm |
0.15 mm |
above 50 mm |
0.60 % |
0.40 % |
0.30 % |
Dimensions for holes and channels
Dia. resp. □ |
Greatest length, depth repectively |
d (mm) |
continuous |
blind |
|
~ 1 x d |
~ 0.6 x d |
＞ 4 to 6 |
~ 2 x d |
~ 1.0 x d |
|
~ 3 x d |
~ 1.6 x d |
|
~ 4 x d |
~ 2.0 x d |
Geometrical tolerance
Properties |
METRIC - Millimeters |
Symbol |
|
±0.10 per 20mm |
|
|
±0.10 per 20mm |
|
|
±0.15 per 20mm |
|
|
±0.10 per 20mm |
|
|
±30' |
|
Position accuracy |
±0.10 per 20mm |
|
|
±0.10 per 20mm |
|
|
±0.15 per 20mm |
|
|
±0.10 per 20mm |
|
Surface quality
Degree
|
Roughness values |
Ra (μm) |
Rz (μm) |
CLA(μm) |
|
1.6 |
6 - 8 |
63 |
|
3.2 |
12 - 16 |
125 |
|
6.3 |
23 - 32 |
250 |
Machining allowances
|
Opertation |
METRIC - Millimeters |
| For grinding |
0.1 to 0.3 mm
|
|
0.1 to 0.3 mm |
Liner tolerance for Soluble glass process investment Casting avalible in optional
Degree
|
Roughness values |
CT-5 |
CT-6 |
CT-7 |
|
|
0.52 |
0.74 |
|
|
0.54 |
0.78 |
| 16-25 |
0.42 |
0.58 |
0.82 |
| 25-40 |
0.46 |
0.64 |
0.90 |
| 40-63 |
0.50 |
0.70 |
1.00 |
| 63-100 |
0.56 |
0.78 |
1.10 |
| 100-160 |
0.62 |
0.88 |
1.20 |
| 160-250 |
0.70 |
1.00 |
1.40 |
| 250-400 |
0.78 |
1.10 |
1.60 |
| 400-630 |
0.90 |
1.20 |
1.80 |
| 630-1000 |
1.00 |
1.40 |
2.00 |
| 1000-1600 |
|
1.60 |
2.20 |
| 1600-2500 |
|
|
2.60 |
Note: Hua Xing Manufacturing no rights can be obtained from above values.
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