Attachment features — identifying protrusions Which term refers to a flat or rounded tab that protrudes from a surface, usually provided to allow attachment by bolts or other fasteners?

Introduction / Context:
Designers often add localized protrusions to enable mounting, lifting, or alignment. Using precise terminology on drawings prevents confusion during casting, machining, and assembly, and guides inspectors on acceptance criteria.

Given Data / Assumptions:

• The feature is a protruding tab intended for attachment.
• It may be flat or rounded in plan.
• Common alternatives include bosses and pads with different purposes.

Concept / Approach:
A lug is a protruding tab, frequently with holes or slots for fastening. A boss is a raised cylindrical feature, typically used to reinforce a hole, provide a bearing surface, or accept a fastener or insert. A chamfer is an edge modification, while a spotface is a shallow facing operation to create a flat seating surface around a hole. The description given matches “lug.”

Step-by-Step Solution:

Verification / Alternative check:
Inspect casting and forging drawings: lugs are common for lifting eyes, hinge points, and bracket attachments, while bosses are circular and often centered on holes to thicken material locally.

Why Other Options Are Wrong:

• Boss: typically cylindrical and centered on a hole for reinforcement rather than a tab.
• Chamfer: edge bevel, not a protrusion.
• Spotface: small machined flat around a hole, not a protruding tab.

Common Pitfalls:

• Using “boss” and “lug” interchangeably; shape and purpose differ and affect machining and tooling.
• Failing to specify thickness and hole details on the lug, leading to inadequate strength.

Final Answer:
Lug