Start at a low feed to ensure insert security and surface finish, increase feed to improve chip breaking Run at a cutting depth larger than the nose radius. This will minimize the radial deflection of the insert, which is important in internal machining Setting the cutting speed too low will result in inadequate tool life. Always run at the highest possible cutting speed, vc mmin (ftmin)

• types of cast ironGrey Cast Iron (GCI) Nodular Cast Iron (NCI) Malleable Cast Iron (MCI) Compacted Graphite Iron (CGI)

The first choice should be the GC3200 grade series and -WMX geometry for finishing and medium operations. For roughing, -KR is the strongest and first choice geometry. CC620: For high speed finishing of grey cast irons in stable and dry conditions. Grade CC650 (mixed ceramic) is recommended for finishing under stable conditions, and CC6190 (SiN-ceramic) for medium and rough machining. If possible, use coolant in continuous machining, and use dry machining on interrupted cuts. The grade CC650 is the exception, it should be machined dry at all times.

The machinability of steel differs depending on alloying elements, heat treatments and manufacturing processes (forged, cast etc.). Steels can be categorized as unalloyed, low alloyed and high alloyed, all of which affect the machining recommendations for turning.

Machinability for low alloyed steels is dependent on alloy content and the heat treatment (hardness). For all materials in this group, the most common wear mechanisms are crater and flank wear. Because hardened materials produce higher heat in the cutting zone, plastic deformation is also a common wear mechanism.

High alloy steels include carbon steels with a total alloy content over 5%. The group includes both soft and hardened materials (below 50 HRc). Machinability decreases at higher alloy contents and hardnesses. As for the low alloyed steels, the first choice are the steel grades (4200 and 4300 series) of grades and the steel geometries (-PF, -PM, -PR). For good surface finish needs, use the wiper geometries -WF and -WMX.

• BenefitsIncreased productivity. Lower costs per part. Complex component shapes machined in one set-up.

Turning steel with a hardness over 45 HRc (typically within the range of 55-68 HRc) is defined as hard part turning and is a cost efficient alternative to grinding. Hard part turning has been proven to reduce machining time and costs by 70% or more, and also offers improved flexibility, better lead times and higher quality.