Perm Mold Problem Solvers
Address your permanent mold casting problems quickly with this guide to defects, their possible causes and suggested actions. AFS PERMANENT MOLD PRACTICES COMMITTEE (2E) AND TED SCHORN, ENKEI WHEEL CORP., COLUMBUS, INDIANA
sand mold. Instead, it is saddled with correcting defects related to metallurgical practices and the permanent mold process and equipment. Common defects encountered in permanent mold castings, such as dross and associated gas holes, blow
A ▼ ▼
Possible Cause Dirty metal results
from excess agitation in transferring from melting furnace to holding furnace.
Suggested Action Avoid fast pouring
rates. Pour at a steady rate with minimum metal fall. Flux to remove suspended dross.
Possible Cause Dross is picked up in
the pouring ladle when it’s dipped in the holding furnace.
Suggested Action Skim the metal
frequently. Push back the surface when dipping the ladle. Avoid splashing or pushing dross under the surface. Ladle only enough metal to fill the mold.
40 | MODERN CASTING February 2012
permanent mold casting facility typi- cally experiences little difficulty with dimensional errors or defects due to faulty mold creation, such as forming a
holes, pinhole porosity, misruns, cold shuts and cracks, are similar to those experienced in other processes, but the approach to eliminating these defects can be differ- ent. Common permanent mold defects can be observed by the mold operator, who can correct or adjust melting and operating practices at the casting station. Te next time you find a defect in your permanent
mold castings, consider the following possible causes and suggested actions.
Defect: Oxides and Inclusions ▼
Possible Cause Excessive metal
agitation occurs in the gating system and upon entering the mold cavity.
Suggested Action Alter your gating
practices. In vertical castings, increase the width of the web feeding the cavity from the side riser. For static pour permanent mold, the ideal gating system has a short drop from the top of the sprue to the bottom of the mold.
▼
Possible Cause Air is dragged into
the sprue with the metal during pouring.
Suggested Action
Use a tapered sprue and keep it full while pouring.
ONLINE RESOURCE
For permanent mold gating design tips, Visit
www.moderncasting.com.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68