Investment casting
investment casting

 

Producing steel components of complex shape through (lost wax process) and M.I.M. (Metal Injection Moulding) Technology.

 

Investment casting, also called lost-wax casting, is one of the oldest known metal-forming techniques. From 5,000 years ago, when beeswax formed the pattern, to today’s high-technology waxes, refractory materials and specialist alloys, the castings allow the production of components with accuracy, repeatability, versatility and integrity in a variety of metals and high-performance alloys.

The process is generally used for small castings, but has produced complete aircraft door frames, steel castings of up to 300 kg and aluminium castings of up to 30 kg. It is generally more expensive than die casting or sand casting, but can produce complicated shapes that require little rework or machining.

Investment casting offers high production rates, particularly for small or highly complex components, and extremely good surface finish (CT4-CT6 class accuracy and Ra1.6-6.3 surface roughness) with very little machining. The drawbacks include the specialized equipment, costly refractories and binders, many operations to make a mould, and occasional minute defects.

Is used in the aerospace and power generation industries to produce single-crystal turbine blades, which have more creep resistance than equiaxed castings. It is also widely used by Sturm, Ruger among other firearms manufacturers to fabricate firearm receivers, triggers, hammers, and other precision parts at low cost. Other industries that use standard investment-cast parts include military, medical, commercial and automotive.

investment casting mim

  • a skilled company producing steel components of complex shape through investment casting (lost wax process) and M.I.M. (Metal Injection Moulding) Technology.
    Altought parts produced with these two methods have similar properties process phases are quite different:
    in Fact.

    Investment casting (Lost wax casting) process phases are:
  • Mould construction to inject wax pattern
  • Injection of wax patterns trough hydraulic press
  • Assembly of wax patterns on wax cluster
  • Wax clusters dip in a binder
  • Cluster stuccoing with refractory to become a ceramic shell
  • Dewaxing trough autoclave
  • Ceramic shell firing
  • Molten metal pouring into shells
  • Ceramic shell knock-out
  • Parts cut from the steel shell and finishing

    INVESTMENT CASTING

    – DIMENSIONAL TOLERANCES
    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, 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.

    STEELS FOR INVESTMENT CASTING
     
    LOW CARBON steels
    C10 C15 12NiCr3 16CrNi4 16NiCr11 16NiCrMo2 16NiCrMo12
    16MnCr5 18CrMo4 18NiCrMo5 18NiCrMo7 20MnCr5 20CrNi4 20NiCrMo2
         
    HARDENING steels
    C20 C25 C30 C35 C40 C45 C55
    C50 C60 25CrMo4 C28Mn 30CrMo4 30NiCrMo8 30NiCrMo12
    32CrMo12 34NiCrMo16 34Cr4 35CrMo4 35NiCrMo15 36CrMn5 38Cr2
    39NiCrMo3 42CrMo4 40NiCrMo2 40NiCrMo7 41Cr4 50CrMo4 90Mn4
     
    SPRING steels
    48Si7 55Si7 60Si7 60SiCr8 52SiCrNi5 45SiCrMo6 55Cr3
    50CrV4 51CrMoV4
     
    BEARING steels
    100Cr6 100CrMo7 X45Cr13 X105CrMo17 X80MoCrV44 X82MoWMoV65 X75WCrV13
     
    TOOL steels
    X155CrVMo12.1 KU X205Cr12KU X37CrMoV5.1KU X40CrMoV51.1KU
    90MnVCr8KU 95MnWCr5KU HS 2-9-1-8 HS 6-5-2 45WCrV8KU
    HS 18-0-1
     
    STAINLESS steels
    AUSTENITIC (AISI)
    201 202 301 302 303 304 304LN
    304H 304L 305 309 310 314 316
    316L 316H 316LN 316N 316F 316Ti 316Cb
    317 317L 317LN 321 321H 347 347H
    310MoLN XM19 330
    DUPLEX (UNS)
    S32900 S31803 S32304 S32750 S32550 S32760
    FERRITIC (AISI)
    405 409 410S 430 430F 434 439
    XM-34 446
    MARTENSITIC (AISI)
    403 414 416 420 420F 422 431
    440A 440B 440C
    PRECIPITATION HARDENING (UNI)
    17-4PH 15-5PH PH 15-7 Mo 17-7PH 17-10P
     
    NICKEL BASE ALLOYS
     
    COBALT BASE ALLOYS

    INVESTMENT CASTING GENERAL TOLERANCES
     
    NOMINAL DIM. (mm) Lenght, Width, Height
    LINEAR PRECISION GRADES
    Up 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