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Technical Data

Tolerances


Surface Finish Concentricity
General Tolerances Roundness
Straightness Minium Section Thickness
Flatness Parallel Selections
Cast Holes Other Features

Surface Finish ^ top
As-cast finishes will vary with alloy specified but generally fall within the range quoted. For a ground finish an allowance of 0.010 in. (0.25mm) should be made.

Metal C.I.A. value
Micro-inches
As-cast Machined
Stainless Steels 90-126   60-125
Cobalt Chrome Alloys 80-100 50-100
Carbon Steels 90-125 60-125

General Tolerances ^ top
Shape and alloy selected will influence accuracies achieved but values given are normally accepted through out the investment casting industry.

Dimension Tolerance
Upto 25 mm ±0.25mm
Above 25 mm ±0.25mm/25mm

Straightness ^ top
There are practical limits to straightness which can be achieved but mechanical straightning can reduce variations.

Casting Length As-cost Corrected
25 mm ±0.50 mm ±0.25 mm
50-100 mm ±0.75 mm ±0.50 mm
100-150 mm ±1.00 mm ±0.50 mm
150 mm ±1.50 mm ±0.62 mm

Flatness ^ top
Flatness is also affected by dimensions of casting. Addition of ribs will minimize bowing, twisting and distortion and mechanical straightning will reduce variations where necessary.

Casting Length As-Cast Corrected
25 mm ±0.20 mm ±0.10 mm
50 mm ±0.37 mm ±0.15 mm
75 mm ±0.50 mm ±0.20 mm
100 mm ±0.62 mm ±0.25mm
Cast Holes ^ top
Depth (D) and Diameter(d) of hole must allow for adequate penetration of investment material.

Values given show usual limits for cast holes but pre-formed ceramic cores allow this restrictions to be exceeded, although usually at increased cost.

Through holes Blind Holes
Diameter (d) mm Maximum Depth (D) mm Diameter (d) mm Maximum Depth (D) mm
3.17-6.35 D upto 1.5 d 4.76-12.70 D upto 1.5d
6.35-12.70 D upto 3.0 d 12.70 D upto 2.0 d 
12.70 D upto 5.0 d  

Concentricity ^ top
The larger the outside diameter becomes, the closer to concentric an inside diameter can be cast.

Mechanical correction can normally be made where wall thickness is thin enough to allow plastic deformation.

O.D.(mm) I.D. (mm) Eccentricity (mm)
As-cast Corrected
18.75 6.25 ±0.100 ±0.100
25.00 12.50 ±0.125 ±0.125
37.50 18.45 ±0.200 ±0.200
50.00 25.00 ±0.250 ±0.200

Roundness ^ top
For solid bars roundness is affected by solidification stresses and tolerance required increases nearly in proportion to diameter, inline with usual 'Lost Wax' tolerances.

Values shown are for as-cost roundness on inside and outside diameters of tubes of varying sizes. Wall thickness is important and tighten tolerance can be obtained by mechanical correction if desired.

O.D. (mm) Tolerance (mm) I.D. (mm) Tolerance (mm)
12.50 ±0.25 upto 6.25 ±0.30
25.00 ±0.50 6.25-12.50 ±0.40
37.50 ±0.60 12.50-25.00 ±0.50
50.00 ±0.75 above 25.00 ±0.50 (per 25 mm)

Minium Section Thickness ^ top
Wall thickness will depend upon area of casting and alloy selected. The following values are of guide from general experience.

Material Minimum wall thickness obtainable
18/8 stainless steels 1.62 mm
25/12 stainless steels 1.50 mm
Carbon steels 2.25 mm

Cobalt-Chrome alloy

1.12 mm

Parallel Selections ^ top
Parallelism can be maintain by adding fire-bars to minimize distortions. Values shown are typical tolerances for various gap-widths between parallel sections per inch cost.

Gap (mm) Tolerance(mm)
As-cast
Corrected
6.25 ±0.075 ±0.075
12.50 ±0.125 ±0.100
18.65 ±0.150 ±0.100
25.00 ±0.175 ±0.125

Other Features ^ top
Angles : Angular tolerance to ±1/2° (Closer by mechanical corrections).
Symbols : Latters, Numbers, etc., can be reproduce in relief or inset.
Serrations, Splines and Gear Teeth may be cast in certain instances subject to prior agreement.
Technical Data
Introduction Process Advantages of IC Rapid Prototyping Alloy / Materials Used Tolerances
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