Appendix I
ZCast Design Guide - 25
11.1 Sand Casting Glossary
11.1.1 Cope and Drag
Molds are typically made up of two halves
encapsulating the outer surfaces of the casting.
The two parts are called the cope and drag; the
cope being the “top” section and the drag being
the “bottom.” These components are traditionally
formed by packing sand (typically with a chemical
binder) around a machined pattern. There is
often a separate machined pattern for each the
cope and the drag.
11.1.2 Cores
Cores form the internal surfaces of a casting. In
traditional sand casting, cores are also used to form
features that are undercuts with respect to the parting
line. The limitation in traditional casting is the pattern
must be pulled out of the packed sand, and therefore
must not contain undercuts in the pull direction.
Some castings will not have any cores; others will
need several as shown in figure 16. The mold in figure
15 has three separate cores.
In traditional casting, for every core a tool called a core
box must be made. A core box is essentially a
machined mold used to form sand cores on a
large scale basis. Complexity varies from
simple to complex with separate cores and
multiple components (figure 17).
11.1.3 Core Prints
Core prints are simply the locations at which the
cores lock into the cope or drag (typically the
drag). These are designed to minimize the
amount of flash (metal leaking between mating
surfaces) between the cores and the cope and
drag. They also key into the drag, typically
utilizing drafted walls, to help maintain accuracy
and positioning of the core in the proper
location.
Drag
Cope
Figure 15: Cope and drag – manifold
Figure 16: Cores for manifold casting
Figure 17: Multi-piece core