When cutting flexible workpieces compared with rigid workpieces, which of the following cutting speeds should you generally use?

• A. Higher cutting speeds
• B. Lower cutting speeds
• C. Moderate cutting speeds
• D. No change in speed

Answer: (B)

When a workpiece is flexible, its low stiffness makes it easy to deflect or vibrate under cutting forces. Higher cutting speeds increase heat and cutting power, which exaggerates deflection and can trigger chatter, leading to poor surface finish and dimensional inaccuracies. Using a lower cutting speed helps keep the cut stable by reducing both the forces acting on the part and the heat generated, allowing better control over the geometry and surface quality. This stability is especially important for thin-walled or long slender pieces that can flex easily. In practice, you throttle speed for flexibility, and only afterward consider adjusting other factors like feed or depth of cut to maintain productivity without sacrificing stability.