Recommended cutting speed for HSS on mild steel For machining a mild steel workpiece using a high-speed steel (HSS) tool under typical shop conditions, which average cutting speed is most appropriate?

Introduction / Context:
Cutting speed selection is central to tool life and productivity. For HSS tools cutting mild steel, shop handbooks provide ranges that balance wear, heat, and finish. Too low wastes time; too high burns the edge.

Given Data / Assumptions:

• Tool: HSS (uncoated), standard geometry.
• Material: mild steel (~0.15–0.25% C).
• Conventional coolant and feeds; average conditions.

Concept / Approach:
Typical speeds for HSS on mild steel are around 25–35 m/min for turning, depending on rigidity, coolant, and depth of cut. Values like 5–15 m/min are excessively conservative and uneconomical; 60 m/min is more suited to coated carbides.

Step-by-Step Solution:

Verification / Alternative check:
Machining handbooks and shop experience confirm acceptable tool life and finish near 30 m/min with HSS on mild steel.

Why Other Options Are Wrong:
5, 10, 15 m/min: needlessly slow, poor productivity unless under severe constraints.60 m/min: typically too fast for HSS on mild steel; risk of rapid wear.

Common Pitfalls:
Ignoring feed and DOC interactions; failing to adjust speed for interrupted cuts or poor coolant delivery.

Final Answer:

30 m/min