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 PRODUCTION 		PRECISION AND FLEXIBILITY ON TOLERANCES

TOLERANCES ON INVESTMENT CASTING
NOMINAL
DIMENSION (mm)		 Length, Wideness, Height
PRECISION LEVEL
From to D1 D2 D3
  6 ±0,10 ±0,08 ±0,06
6 10 ±0,12 ±0,10  
10 14 ±0,15 ±0,12 ±0,09
14 18 ±0,20 ±0,14  
18 24 ±0,25 ±0,17 ±0,12
24 30 ±0,30 ±0,20 ±0,14
30 40 ±0,37 ±0,25 ±0,17
40 50 ±0,44 ±0,30 ±0,20
50 65 ±0,52 ±0,38 ±0,23
65 80 ±0,60 ±0,46 ±0,27
80 100 ±0,68 ±0,53 ±0,30
100 120 ±0,76 ±0,60 ±0,33
120 140 ±0,84 ±0,65 ±0,36
140 160 ±0,92 ±0,72 ±0,38
160 180 ±1,02 ±0,80 ±0,42
180 200 ±1,12 ±0,88 ±0,43
200 225 ±1,28 ±0,95 ±0,47
225 250 ±1,44 ±1,05 ±0,51
250 280 ±1,64 ±1,15 ±0,56
280 315 ±1,84 ±1,25 ±0,63
315 355 ±2,10 ±1,40 ±0,71
355 400 ±2,40 ±1,60 ±0,80
400 450 ±2,70 ±1,80 ±0,90
450 500 ±3,00 ±2,00 ±1,00
D1: Non functional dimensions without tolerances
D2: Functional dimensions requiring well defined tolerances
D3: Dimensions with strict tolerances and agreed with customer

M.I.M. GENERAL TOLERANCES
Dimension (mm)
1÷3
3÷6
6÷10
10÷18
18÷25
25÷35
30÷50
50÷80
80÷120
 Tolerance field
±0,03
±0,04
±0,05
±0,07
±0,11
±0,15
±0,20
±0,35
±0,50

In case special tolerances are needed please contact our technical department.

TOLERANCES
In the investment casting process it' s convenient, on an economical point of view, to avoid fixing limits of tolerances superior to the functional necessity of the part to be manufactured.
Generally speaking the better tolerance range on precision casting it' s + / -0,7% of the nominal dimension, to a minimum of + / - 0,10 mm for dimensions beneath 15 mm. It is to be considered that the more the melting point of metal it's low, the more have to be restricted margins of tolerances.
The choice of the tolerance level l always has to be agreed with the customer.
It is available a scale tolerances accuracy:
DEGREE 01: suitable to all processing that do not require particular limits of complexity.
DEGREE 02: suitable to all processing that require precise functional constrains on the entire realized piece.
DEGREE 03: suitable only on single areas of a piece that require absolute high precisions level.
Ranges of variation of each of the three degrees changes according to the kind of processing, if it concerning distance between centers, thickness of walls, linearity factors, planarity, parallelism, perpendicularity or angular dimensions.

MACHINING ALLOWANCE
nominal dimensions
from to
  18
18 50
50 80
80 120
machining allowance
   
0,5 0,3
0,8
1,0
Making use of machining allowance it is necessary
when stringent tolerances, superior to the standards
are required. In these cases machining allowance,
studied according to alloy and necessary processing,
allow a precise finishing operation.
On chart m. two are indicated the general
values normally used.


HOLES AND HOLLOWS
HOLES HOLLOWS
DIAMETER "D"
FROM TO
2 4
4 6
6 10
10  
MAX DEPTH
TROUGH
HOLE		 BUNO
HOLE
1 x D 0,5 x D
2 x D 1 x D
3 x D 1,5 x D
>3 x D <2 x D
BREADTH
FROM TO
2 4
4 6
6 10
10  
MAX DEPTH
   
1 x L 1 x L
2 x L
3 x L 1,5 x L
4 x L <2 x L
The attention to holes and hollows tolerances has to be careful, because in this range deviations engrave substantially, mostly on distances between centers. Chart m. three shows normal permitted values.

MIM VS INVESTMENT CASTING
ATTRIBUTE INVESTMENT CASTING MIM
Precision ± 0,7% of
nominal dimension		 ± 0,4% of
nominal dimension
Mould cost Low Medium-high
Surface Roughness (Ra) 3,2 1,6
Steel choice Unlimited Limited
Geometrical complexity
achievable		 Medium-high High
Component weight Max 5 Kg Max 0,06 Kg
Detail level Medium-high High
Batch dimension Small Medium-high
Mechanical properties Equal

MICROFOND BRESCIANA Viale Europa, 8
25040 MONTICELLI BRUSATI (BS) Italia
P.IVA 03268220179