For milling a workpiece which one of the following properties is most important for selection of cutting speed ?

Softness of material to be machined

Hardness of material to be machined

Toughness of material to be machined

Brittleness of material to be machined

Wide surfaces

Narrow surfaces

'T' slots

'V' grooves

Brazed tipped cutters are costly

Brazed tipped cutters cannot be reconditioned

Brazed tipped cutters are used only for machining high tensile strength steel job

Brazed tipped cutters are used only for machining low tensile strength steel job

0.1 mm

0.2 mm

0.5 mm

0.8 mm

Quality of surface finish

Rigidity of machine

Depth of cut

Rigidity of workpiece