Hot Tears in Castings
Figure 10.12 Examples of hot tears in castings. These defects occur because the casting
cannot shrink freely during cooling, owing to constraints in various portions of the molds and
cores. Exothermic (heat-producing) compounds may be used (as exothermic padding) to control
cooling at critical sections to avoid hot tearing
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Common Casting Defects
Figure 10.13 Examples of common defects in castings. These defects can be
minimized or eliminated by proper design and preparation of molds and control of
pouring procedures. Source: After J. Datsko.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Types of Internal and External Chills used in Casting
Figure 10.14 Various types of (a) internal and (b) external chills (dark areas at corners)
used in castings to eliminate porosity caused by shrinkage. Chills are placed in regions
where there is a larger volume of metal, as shown in (c).
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Solubility of Hydrogen in Aluminum
Figure 10.15 Solubility of
hydrogen in aluminum. Note the
sharp decrease in solubility as
the molten metal begins to
solidify.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Casting of an Aluminum Piston
Figure 10.16 Aluminum piston for an Figure 10.17 Simulation of mold filling
internal combustion engine: (a) as- and solidification. (a) 3.7 seconds after
cast and (b) after machining. start of pour. Note that the mushy zone
has been established before the mold is
filled completely. (b) Using a vent in the
mold for removal of entrapped air, 5
seconds after pour.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
