Uniform sand packing in large moulds — which machine is used? To achieve uniform and consistent ramming of moulding sand throughout large mould cavities and around cores, which equipment is preferred?

Introduction / Context:
Quality sand moulds require uniform density to minimize defects like erosion, blows, and misruns. Manual ramming can be inconsistent, especially in deep pockets or around cores. Specialized machines are used to pack sand uniformly.

Given Data / Assumptions:

• Large moulds with complex geometry.
• Need for consistent sand compaction at all locations.
• Industrial foundry setting.

Concept / Approach:
A sand slinger pneumatically propels sand at high velocity through a nozzle, compacting it in successive layers and ensuring uniform packing even in remote regions of the flask. In contrast, jolt and squeeze machines compact sand primarily by vertical impacts or top compression and are better suited for smaller moulds; they can leave density gradients in large or intricate moulds. Stripper plate machines relate to pattern withdrawal, not compaction.

Step-by-Step Solution:

Verification / Alternative check:
Process audits show improved consistency of green strength and permeability indices when sand slingers are used for big boxes.

Why Other Options Are Wrong:

• Squeezing/jolt machines: effective but may not reach recesses uniformly in large cavities.
• Stripper plate machine: assists mould stripping; not a compaction tool.
• Vibratory table: aids settling but not targeted compaction.

Common Pitfalls:
Over-compaction causing low permeability; misdirected slinger stream eroding cores or prints.

Final Answer: