Foundry cores and parting: When a hole or internal cavity to be formed by a core is not aligned with (i.e., does not lie on) the mould’s parting surface, which specific type of core arrangement is used to place and support the core accurately?

Introduction / Context:

In sand casting, cores create internal cavities. When these cavities are located away from the parting plane, special core seating and support methods are required to position the core correctly without damaging the mould or causing misalignment during assembly and pouring.

Given Data / Assumptions:

• The cavity axis does not coincide with the parting surface.
• Core must be placed after the cope and drag are separated and reassembled.
• Goal is accurate, repeatable location of the core.

Concept / Approach:

A drop core is used when the core cannot be supported by the natural parting. It employs special seats, core prints, and possibly chaplets, allowing the core to be lowered (‘‘dropped’’) into place within the mould cavity and properly located away from the parting plane. By contrast, horizontal/vertical core terms describe orientation rather than the off-parting placement method; a balanced core refers to weight distribution, not location strategy.

Step-by-Step Solution:

Verification / Alternative check:

Foundry practice texts list drop cores for off-parting cavities, using core prints and sometimes loose pieces to enable assembly.

Why Other Options Are Wrong:

• Horizontal/Vertical core: describe orientation, not the off-parting placement solution.
• Balanced core: addresses stability/weight; not the placement challenge.
• Rocker core: a special mechanism for complex withdrawals; not the standard answer for off-parting cavities.

Common Pitfalls:

• Confusing core orientation terms with assembly/placement methods.
• Overusing chaplets instead of proper core-print design for location.

Final Answer:

drop core