A free publication from Allan Heywood Enamels - all links will open in a separate browser window |
|
G'day folks - this little article contains an exercise in simple logic based on observation. Were the deficiencies in the casting/s pictured in these pages caused by flaws in the mould? The Managing Director of Chemgold Refinery Australia P/L, the company that did the casting, attributes the flaws in the castings directly (and exclusively) to faults in the mould. This was the company's second attempt to cast this design, the first having failed because the trial waxes I sent them were too thin. Following a lengthy but more or less amicable discussion with the M.D., Larry, about the reasons for the first castings being too thin I sent him the mould so that they could pull their own waxes. The results are laid out in the pictures and described in the letter below. * The round "bubbles" circled in red in some of the pictures are in the mould and were caused by partial delamination of the photopolymer from the steel backing during the mould making process. They were an annoying but minor problem and since they are raised on the casting could be removed with a spitstick graver - there were only half a dozen and I could have worked around them if they were the only faults. The series of pictures on the following pages shows: The casting, actual size: picture 1 The casting, enlargements: picture 2 The properly-filled 1.5mm thick (blue) wax pulled by the original mould-maker: picture 3 Detail of the casting superimposed on the good wax: picture 4 Chemgold's unfilled 3mm thick orange waxes: picture 5 Detail of the properly-pulled wax superimposed on the Chemgold wax: picture 6 The mould: picture 7 Detail of the mould: picture 8 Detail of the mould # 2: picture 9 Technical explanation of the observed casting anomalies by Chemgold's M.D.: picture 10 Letter of complaint: Letter |
|
|
|