An automatic transmission case is a complex casting that includes a sophisticated valve body with many channels and passages. These channels and passages must be precisely connected to ensure smooth, accurate shifting. However, it is not always possible to cast all the interconnections in place. Often, manufacturers must drill through the outer shell of the casting—and one or more internal channel walls—in a process called “cross-drilling.” Doing so leaves a hole in the outer shell, which must be sealed to prevent fluid loss.
For one leading transmission manufacturer, the process of sealing such holes was simple. The company had long been using an Electro-Mechanical Assembly Press (EMAP) from Promess Inc. to insert a steel ball into the hole and thereby seal the casting.