INSERT SELECTION GUIDE
Insert Shape
Application Conditions (+)
Considerations (-)
• Very strong 90 o corner with excellent economy (8 edges on double-sided inserts). • Most often used for rough facing operations – especially on castings, forgings and rough- sawed blanks.
• Unable to turn or face up to a shoulder (must be used in a toolholder with minimum 5 o lead angle). • High radial forces push against the workpiece when used for turning. • Should always be used in a stable set-up.
90 o
S - Square
• The most popular insert shape due to high versatility. • Strong cutting edge with secure seating in the insert pocket. • 80 o corner can be used for both turning and facing operations. • Opposite 100 o corners can be used for general roughing applications (especially facing), providing maximum economy of 8 total cutting edges.
80 o
• With only 5 o of clearance between the trailing side of the insert and the workpiece, chip jamming can occur when boring.
C - 80 o Diamond
• Six-corner 80 o diamond shape that can increase economy compared to CNMG-style inserts. • Generally used on more moderate depths of cut and feedrates than CNMG-style inserts.
• Seating of insert in pocket is not as stable as CNMG-style inserts. • Cannot take as deep a depth of cut as similar sized CNMG-type inserts.
80 o
W - 80 o Corner Trigon
• Edge is measurably weaker than 80 o diamond shaped inserts. • Be sure not to use a triangle insert that is “too large” for the application, as the cost per edge can increase. For example, a 3/8” iC (Inscribed Circle) triangle insert (TNMG-33x) can manage up to .375” depth of cut in most situations with nearly the same insert strength – but a much lower cost - than a 1/2” iC triangle insert (TNMG-43x).
• Very versatile insert shape – can be used for turning, facing, boring, copy turning and basic profiling. • Good economy with up to 6 cutting edges. • Excellent choice for general boring due to very stable seating of the insert in the boring bar pocket, and extra side clearance between the insert and the workpiece bore (greatly reducing the risk of chip jamming). • Generally the first choice for profile / copy turning applications. • Able to ”In-Copy” (plunge turn into a smaller diameter) at an angle of 30 o . • Commonly used when machining close to the tailstock / live center.
60 o
T - Triangle
55 o
• Somewhat weaker edge strength than a triangle insert. • Cost per edge is higher than most other turning inserts (except 35 o diamond shape).
D - 55 o Diamond
• The weakest turning insert shape / corner – depths of cut and feedrates must be lighter. • Highest cost per edge. • Negative style (VNMG) should mainly be used for external applications. • Positive style (VCMT) can be used for external and internal applications, and in many cases improved performance outweighs the increased cost per edge (2 edges vs. the 4 edges of a negative 35 o diamond VNMG).
• First choice for intricate shape copy turning. • Can ”In-Copy” (plunge turn into a smaller diameter) at an angle up to 49 o . • Can work extremely close to the tailstock / live center.
35 o
V - 35 o Diamond
8
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