Investment moulding process and apparatus

Abstract

An investment mould process for forming a cast member is described. The process comprises forming a precursor casting ( 12 ) from a master mould ( 10 ). The master mould ( 10 ) has an internal surface ( 16 ) defining a space ( 14 ) in which the precursor casting ( 12 ) can be formed. The surface ( 16 ) defines a location indentation ( 20 ) to provide a corresponding location projection ( 3 ) on the precursor casting ( 12 ). A holding member ( 22 ) can be inserted into the location projection ( 3 ) to hold an internal member ( 17 A, 17 B).

1 - 9 . (canceled)  
   
   
       10 . A precursor casting of a cast member to be formed during an investment moulding process, the precursor casting having the configuration of the cast member the precursor casting comprising a main body ( 29 A,  24 B) and an internal member within said main body, the main body having an external surface characterised in that a location projection is provided on the external surface into which a holding member can be located to engage the internal member in the precursor casting, wherein the location projection has a first dimension transverse to said surface and a second dimension generally parallel to said surface, the first dimension being less than the second dimension.  
   
   
       11 . A precursor casting according to  claim 10  characterised in that the ratio of the first dimension to the second dimension is in the range of 1:5 to 1:10.  
   
   
       12 . A precursor casting according to  claim 11  characterised in that the ratio of the first dimension to the second dimension is in the range of 1:6 to 1:10.  
   
   
       13 . A precursor casting according to  claim 12  characterised in that the ratio of the first dimension to the second dimension is in substantially 1:7.5.  
   
   
       14 . A precursor casting according to  claim 10  characterised by being formed of a suitable first removable material.  
   
   
       15 . A precursor casting according to  claim 10  characterised in that the internal member is formed of a second removable material.  
   
   
       16 . A precursor casting according to  claim 10  characterised in that the location projection is generally circular.  
   
   
       17 . A precursor casting according to  claim 10  characterised in that the location projection is generally of an aerodynamic configuration.  
   
   
       18 . A precursor casting according to  claim 10  characterised in that the precursor casting includes a plurality of said location projections arranged in pairs, generally opposite each other.  
   
   
       19 . An investment moulding process for forming a cast member, the investment moulding process comprising providing a master mould using the master mould to form a precursor casting from a first removable material, the master mould having an internal surface defining a space in which said precursor casting can be formed, characterised in that said surface defines a location indentation to provide a corresponding location projection on the precursor casting, into which a holding member can be located to engage an internal member in the precursor casting.  
   
   
       20 . An investment moulding process according to  claim 19  characterised in that the location indentation has a first dimension transverse to said surface, and has a second dimension generally parallel to said surface, the first dimension being less than the second dimension.  
   
   
       21 . An investment moulding process according to  claim 19  characterised in that the location projection has a first dimension transverse to said surface of the precursor casting and a second dimension generally parallel to said surface of the precursor casting, the first dimension being less than the first dimension.  
   
   
       22 . An investment moulding process according to  claim 19  characterised in that the method further includes locating a holding member on the location projection, and thereafter inserting the holding member into the precursor casting to engage the internal member.  
   
   
       23 . An investment moulding process according to  claim 19  characterised in that the precursor casting is provided with a plurality of location projections, and the method further includes locating a respective holding member on each location projection and inserting each holding member into the precursor casting to engage the internal member.  
   
   
       24 . An investment moulding process according to  claim 23  characterised in that the method includes encasing the precursor casting in a second removable material to form an investment mould, wherein the step of inserting the or each holding member includes arranging the or each holding member to project outwardly from the precursor casting held in place by the second removable materials.