Improve Quality By Design
The best test of any manufacturing process is that you get the same quality after the thousandth part as you got on the first. That your design holds its dimensions and tolerances to multiple decimal points through every unit produced.
Other manufacturers call it exceptional repeatability. At Super Quali Cast, we call it business as usual.
Investment casting is already capable of excellent repeatability, but with early involvement and input by our technical staff, we take it even further.
Using our expert knowledge and world-leading technology, we can quickly identify and virtually eliminate sources of tolerance variation. And we don’t restrict ourselves to any single factor. We’ll create value right across part design, tooling, position, and production.
All you need to remember? Get Super Quali Cast involved in design early.
Make precision possible. Every time.
Tolerance & Dimensions
SURFACE FINISH
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
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 |
Closer tolerance may be held on selected dimensions following design evaluation.
StrAIGHTNESS
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
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-cost | 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
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 tobe exceeded, although usually at increased cost.
| Through holes | |
|---|---|
| Diameter (d) mm | Maximum Depth (D) mm |
| 3.17-6.35 | D upto 1.5 d |
| 6.35-12.70 | D upto 3.0 d |
| 12.70 | D upto 5.0 d |
| Blind Holes | |
| Diameter (d) mm | Maximum Depth (D) mm |
| 4.76-12.70 | D upto 1.5d |
| 12.70 | D upto 2.0 d |
CONCENtrICITY
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
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) |
MINIMUM SECTION THICKNESS
Wall thickness will depend upon area of casting and alloy selected. The following values are of guide from general experience.
| Material | Minimun 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 SECTIONS
Parallelism can be maintain by adding fire-bars to minimize distorsions. 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 :
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.