Large components produce large chips
The machining of large components produces chips that are extraordinarily large, compared to similar shaped chips of a produced during general machining. Chips that weigh up to 400 grams (about as much as a can of soft drink) can be produced.
Components such as power-generation rotor shafts, main shafts, windmill shafts, marine crankshafts, metallurgical rolls and nuclear vessels can have a forging which weighs between 20 and 250 tonnes. A significant amount of this material is removed from such components during machining.
Jayakumar Naranath-Raghavan, Heavy Machining Manager at Seco in Sweden, says the machining of large components requires a material-removal rate (MRR) between 800 and 4,000 cm3/min. A depth of cut of up to 30–50 mm and a feed rate of 2.5 mm/rev is used for various steels and alloyed steels. For super alloys, a depth of cut of up to 15–20mm and feed rate of up to 1.5 mm/rev is used.
Naturally, these parameters produce large chips. Heavy machining involves higher power and torque requirements. So, bigger machines with strong spindles, stable holding systems and dedicated bigger insert solutions with suitable geometry-grade combination are required.