Casting practice — purpose of a pattern in mould making In foundry work, is a pattern used to create the mould cavity that will later receive molten metal during casting?

Introduction / Context:
Patterns are replicas (with allowances) of the finished component used to prepare sand moulds. Correct understanding of patterns is fundamental to gating design, allowance planning, and dimensional control in cast products.

Given Data / Assumptions:

• Moulding method: sand moulding with removable patterns.
• Pattern includes allowances for shrinkage, machining, draft, and distortion.
• Cores may be added to form internal features.

Concept / Approach:
The pattern is placed in the moulding sand and rammed. After withdrawal, it leaves a cavity that mirrors the external shape (plus allowances) of the desired casting. Core prints on the pattern help support cores that create internal cavities. While processes like permanent-mould or investment casting use different tooling (dies, wax patterns), the core idea remains: tooling forms the cavity prior to pouring.

Step-by-Step Solution:

Verification / Alternative check:
Trial moulds and sectioned castings clearly show that the cavity corresponds to the pattern shape and allowances.

Why Other Options Are Wrong:

• “No” or restricted uses: patterns are standard across sand casting, not limited to specific methods.
• “Only to locate cores”: core prints are part of patterns, but the primary role is cavity formation.

Common Pitfalls:
Forgetting draft angles causing pattern damage; omitting machining allowance leading to undersize parts.

Final Answer: