Technical Data

Technical Data

Introduction

Investment Casting has been used as early as 1,800 B.C. to produce beautiful bronze works of art. Yet this method of casting fine ferrous and non-ferrous components is even more useful today than in the ancient times. It can still do so many things so much better than many alternatives.

The process involves a number of intricate steps resulting in components which feature considerable design flexibility and economy. The method competes to some degree with machining, forging, die casting and other processes, but is the only means which combines many of the benefits into one. It is the Most Preferable method when there is 100% emphasis on the Quality of the end product with great precision in geometric dimensions.

Our Process

Tooling

A tool maker build a precision die to make wax replicas of the part called patterns. Before start the casting process, injection die is constructed to produce wax patterns. This tool is constructed from Aluminum or hot die steel material, for most applications, single/multi cavity dies are used for high production quantities.

Pattern Injection

Molten wax is injected in to the die cavity. The resulting pattern is removed after it solidifies. This pattern is an exact replica of the metal part to be produced, with the allowances added to compensate for volumetric Shrinkage during the process. This wax pattern are inspected, cleaned before set-up on wax-Spares.

Pattern Assembly

The individual wax patterns are assembled on to a wax Spare to form a mold or tree/cluster. The number of patterns are assembled per tree varies, dependent upon the size, weight and configuration of a given part.

Shell Building

The Cluster or tree is dipped repeatedly in liquid binder and Ceramic powder to build up a shell mold. This process is repeated several times until a specified shell thickness results. The ceramic shell range in thickness from 5mm to 12mm depending on the size of the part being produced. Now, the molds are moved to a controlled drying area for completely dry before de-waxing.

De-Waxing & Pre-Firing

The wax is melted out, leaving a hollow ceramic shell. The moulds are pre-fire to fuse the ceramic particles together, so that the mold can withstand the pressure & temperature of the molten metal being cast.

Casting

The Molten metal is poured in to the preheated molds and solidifies to form a cluster of castings.

Cleaning & Casting Removal

The Ceramic Shell is removed form the metal mold with the help of pneumatic hammer or high pressure sand blast machine. The individual parts are then cut-off from the runner with the help of welding machine or cut-off machine. The gates are ground to the desired dimension utilizing fixturing. The parts are than deburred & sent for secondary operations such as heat treating and then finally will goes in sand/shots Blasting. After the final surface preparation each part is inspected to guarantee is meets as per the specification and customer requirement.

Advantages of IC

There are many reasons engineers and purchasing agents specify investment castings for their projects. Here are just a few:

  • Greater Design freedom.
  • Feasibility of replacing two or more fabricated sub-assembling by a single piece casting.
  • Lighter, Stronger components may be designed, without a mismatch, giving an improved aesthetic appearance.
  • The process permits a high level of consistency, batch to batch.
  • Compared to other conventional way of manufacturing castings, with lost wax process close dimensional tolerance of ±0.13mm per 25mm and a fine smooth grain finished from 80 to 120 micron inches, 2.0µ to 3.2µ , are normally achieved.
  • With the ability to produce special alloys to customers' requirements, the choice of metallurgical specifications is virtually unlimited.
  • The light stressed wax impression dies have a very long life and are not costly considering design complexity.
  • If required, minor design modification may be made economically without going for few tooling.
  • Increased productivity can result from reduction or elimination of machining and the consequent deployment of shop floor.
  • Delivery period for repeat orders in large or small quantities can be 3- 4 weeks.
  • Comparatively small orders can be produced at economical prices.
  • A high level of metallurgical integrity and Strength can be achieved in the lost wax process.

Rapid Prototyping

A system of Computer Aided Design and Manufacturing (CAD/CAM), identical on all sites, enables Manoir industriess to model complex surface or solid forms and subsequently to carry out the machining of its forging tools and casting patterns using N.C. machines. Various applications are installed such as calculation of resistance of materials and the simulation of the solidification.

The unicity of software enables all the sites to communicate and thanks to the IGES, SET, DXF, STP interfaces or in DOS format, exchanges are operated with the customers for the transmission of surface and solid 3D files and drawings.

Alloy / Materials Used

Material description ASTM Specification Grades
Low-carbon austenitic stain­less steel (carbon equal to or less than 0.03%) A 351/A 351M CF-3,CF-3A,
  CF-3M,CF-3MA,
A 743/A 743M CF-3,CF-3M,
  CF-3MN,CN-3M,
A 744/A 744M CF-3,CF-3M
Low-alloy steel (quenched and  tempered) A 148/A 148M 105-85,115-95,
  135-125,150-135,
  160-145,165-150,
  165-150L,210-180,
  210-180L,
  260-210,260-210L
A 352/A 352M LC2-1,LC1,LC2,
  LC3,LC4,LC9,
A 732/A 732M    7Q,8Q,9Q,10Q,11Q,
   12Q,13Q,14Q.
Carbon Steel (carbon less than 0.35% tensile strength less than or equal to 70 ksi (480 Mpa)) A 27/A 27M      All Grades
A 216/A 216M WCA,WCB
A 352/A 352M LCB,LCA
A 356/A 356M 1
A 732/A 732M 1A,2A
Low-alloy steel (annealed,normalised or normalised and tempered. Tensile strength less than 85 ksi (585 Mpa)) A 148/A 148M 80-50
A 217/A 217M WC1,WC4,WC5,WC6,
  WC9
A 352/A 352M LC1,LC2LC3,LC4
A 356/A 356M 2,5,6,8
A 389/A 389M C23,C24
Carbon steel (tensile strength greater than 70 ksi (480 Mpa)). Carbon-manganese  steel (tensile strength equal to or greater than 70 ksi but less than 90 ksi (620 Mpa))  A 148/A 148M 80-40
A 216/A 216M WCC
A 352/A 352M LCC
A 732/A 732M 2Q,3A
A 757/A 757M A2Q
Carbon and carbon-manganese steel (tensile strength equal to or greater than 90 ksi (620 Mpa)) A 732/A 732M 3Q,4A,4Q,5N
Low-alloy steel (annealed, normalised or normalised and tempered. Tensile strength equal to or greater than 85ksi (585 Mpa)). A 148/A 148M 90-60,105-85
A 217/A 217M C5,C12,WC11
A 356/A 356M 9,10
Ferritic Stainless steel A 743/A 743M  CB-30,CC-50
Martensitic Stainless steel  A 217/A 217M  CA-15
A 352/A 352M CA6NM
A 356/A 356M CA6NM
A 487/A 487M CA15-A,CA15-B,
  CA15-C,CA15-D,
  CA15M-A,CA6NM-A,
  CA6NM-B
A 743/A 743M  CA-15,CA-15M,
  CA6NM,CA-40,
  CA6N
Unstabilised austenitic Stainless Steel (Carbon greater than 0.03%)   A 351/A 351M  CF-8,CF-8A,
  CF-8M,CF-10,
  CF-10M,CG-8M,
  CH-8,CH-10,
  CH-20
A 447/A 447M Type 1
A 743/A 743M CF-8,CG-12,
  CF-20,CF-8M,
  CF-16F,CH-20,
  CG-8M,CE-30
 A 744/A 744M CF-8,CF-8M
  CG-8M
Stabilised austenitic stainless steel A 351/A 351M CF-8C,CF-10MC,
  CK-20,HK-30
  HK-40,HT-30,
  CN-7M,CT-15C
A 447/A 447M Type II
A 743/A 743M CF-8C,CN-7M,
  CN-7MS,CK-20
 A 744/A 744M CF-8C,CN-7M,
  CN-7MS
Austenitic-ferritic  stainless steel A 351/A 351M CD-4MCU
A 743/A 743M CD-4MCU
A 744/A 744M   CD-4MCU
Precipitation-hardened austenitic stainless steel A 747/A 747M CB7CU-1,CB7CU-2

Nickel-base alloys

A 494/A 494M

CW-12MW,CY-40,

CZ-100,M-35-1,

M-35-2,M-30C,

N-12MV,N-7M,

CW-6M,CW-6MC,

CW-2M,CX-2MW

Tolerances

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

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-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

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

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)

Minium Section Thickness

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

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

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

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.