The Actual Breakout

When breaking out a flask, we rely on vibration to fracture the investment surrounding the casting.  There are a variety of processes used to begin the breakout, from hammering against the side of the flask, to pushing the investment from the flask with a hydraulic or air ram.  After the investment is revealed, it’s hammered to begin to fracture it from around the button.  Once exposed, the button is gently hammered to send vibrations throughout the casting, which fractures the investment surrounding them.  This will eliminate about 80% to 90% of the investment surrounding the castings.

So, how does one create the proper amount of vibration? By using a metallic hammer, with steel being the most popular choice.  Resinous and non-marring hammers and mallets are not as efficient, because they don’t transfer vibration to the castings effectively.  NOTE: Be careful not to damage the casting when hammering. For instance, high volume casters often use pneumatic hammers to speed up the breakout process.  But, the sufficient force they generate can distort the castings.

Breakage During Breakout

During the breakout, it’s not uncommon to find that a casting has broken off from the tree or base. That’s why it’s a good idea to breakout the casting in a contained area. This allows you to sieve through the investment and recover these separated castings.  Small bits and pieces of metal surrounding the button during casting also separate and fall into the investment pile as well.

Clean Up

At this stage, most of the investment has been broken from the casting, so the remainder can be removed through a washing operation.  It can be as simple as a brush and bucket of water, to state-of-the-art water blasting cabinets.  The objective here is to remove as much of the residual investment as possible.  However, even after washing, there may still be minute traces of investment left behind.  A good final step to remove the last traces of investment is to soak the castings in a pickle solution.  Not only does the pickle help to breakdown the remaining investment, but it also helps to remove oxides from the surface of the castings.

At this point in the process, all that is left is rinsing the castings to remove the pickle; cleaning them in an ultrasonic cleaner; and rinsing to remove any detergents.  Dry your castings and get ready to remove them from the button.

If you enjoyed this article series, we invite you to read more in our library. Also, if you have expertise in casting and additional thoughts to share, contact us about contributing and article. Or, start a conversation in our forums. See you at the bench!