The SPMT120408 is a standardized ISO code for a common style of indexable turning insert. This "T-style" insert is known for its sharp, positive rake geometry, making it ideal for light cutting, finishing, and general turning applications on a wide range of materials.
Understanding the code defines the insert's geometry and size:
S: Shape = Square (80° corner angle)
P: Clearance Angle = 11° (Positive rake insert)
M: Tolerance Class = Medium precision (Defines dimensional tolerances like ±0.005" on thickness, ±0.002" on inscribed circle)
T: Insert Type = This indicates a specific chipbreaker and hole style, often with a built-in clamp hole.
12: Cutting Edge Length (I.C.) = 12.70 mm (1/2 inch)
04: Insert Thickness (S) = 4.76 mm (3/16 inch)
08: Corner Radius (R) = 0.8 mm (A small radius for fine finishing and light roughing)
Geometry: Positive rake design provides sharp cutting action, lower cutting forces, and good surface finish. It has three usable cutting edges.
Chipbreaker: The "T" type typically includes an integrated chipbreaker for effective chip control and evacuation.
Primary Use: Excellent for finishing operations, light roughing, contouring, and general purpose turning on:
Carbon Steel
Stainless Steel
Ductile Cast Iron
Alloy Steel
Machining Type: Primarily used on CNC lathes for external turning, facing, and boring operations.
Low Cutting Forces: The positive geometry reduces power consumption and is ideal for less rigid setups.
Excellent Finish: Produces superior surface quality compared to negative rake inserts.
Good Chip Control: The integrated chipbreaker helps break chips into manageable pieces for safer machining.
Versatility: A very common insert size and style, available from numerous manufacturers in various carbide grades and coatings (like TiAlN, TiCN).
