Machining

HSS and HSS-Co are tough, shock-tolerant and economical, suiting older machines, low speeds and interrupted cuts. Carbide runs several times faster with longer tool life but is brittle and needs a rigid machine and low runout.

ISO 513 groups workpiece materials as P steel (blue), M stainless (yellow), K cast iron (red), N non-ferrous (green), S heat-resistant alloys and titanium (brown), H hardened steel (grey). Tool grades and coatings are specified against these groups, so this is the first thing to establish.

You need the workpiece material and hardness, the operation, dimensions and tolerances, the machine and spindle interface (for example BT40, HSK63A), and coolant conditions. You can send the drawing and these details to sales@kit.com.vn for KIT to check when quoting.

Cutting speed Vc is in m/min, and spindle speed n = Vc x 1000 / (3.14 x D), with D the diameter in mm. Table feed equals spindle speed times number of flutes times feed per tooth fz. Take Vc and fz from the tool maker's recommendations for each material group, then adjust to machine rigidity.

PVD or CVD coatings a few micrometres thick raise surface hardness, cut friction and insulate the edge from heat, so tool life increases or higher cutting speeds become possible. Each coating suits certain material groups, so choose by workpiece material rather than by color. Regrinding a coated tool removes the coating on the ground face.

Worsening surface finish, drifting dimensions, a change in cutting sound, discolored chips or rising spindle load are common signs. Flank wear of about 0.2 to 0.3 mm is often used as the change point for many finishing operations. Changing tools after a fixed part count helps avoid scrapped parts and broken tools.