Extra metal dots in extrusion of letters on casting in investment casting (lost wax casting) process 2

[Bharti__]

Hello!

For a casting using investment casting process in CF3 (SS 304) material, There is extra metal dots coming in letters of company symbol of customer.

For example, If letter is 'B' then holes of extruded 'B' on castings gets filled with extra metal. I have tried to avoid this extra metal by doing some experiments like decreasing extrude height of letters from 0.5mm to 0.3mm but there are no successful results acheived.

It would be great, If anyone can help me to avoid this thing by suggesting any remedies for that.

for info. only: This may occur in shelling process of wax patterns as it can not fill whole cavity of extruded letters on wax pattern.

aiming towards industry 4.0

 

[racookpe1978]

Provide a photo of the letter(s) involved. The font may be important, or may not.

Did you check cleanliness of the imprinted letter die?
Are all letters (all B, or all P, or all B but no D), behaving the same way, or only a few B, a few P, and a few D's?

 

[3DDave]

Is the extrusion straight wall or tapered? I'm guessing it is straight walled and is trapping air in the inside corners so the shell is not conforming to the letter.

 

[Bharti__]

@racookpe1978
yes all letters are behaving in same way, and die is cleaned properly.

@3DDave
Yes, we had provided tapper but we tried rounding top faces of the symbol (as it was little bit flat before) and we got success.

Thank you.

Aiming towards Industry 4.0