Troubleshooting in turning

	Cause	Solution

Chip control Long, unbroken snarls winding around the tool or workpieces. Caused normally by low feed, low and/or shallow depth of cut.	Feed is too low for the chosen geometry	Increase feed Select an insert geometry with better chip breaking capabilities Use a tool with precision coolant
	Depth of cut is too shallow for the chosen geometry	Increase depth of cut or select a geometry with better chip breaking capability
	Too big nose radius	Select a smaller nose radius
	Unsuitable entering angle	Select a holder with as large entering angle (lead angle) as possible. KAPR= 90° (PSIR =0°)

Chip control Very short chips, often sticking together, caused by chip breaking that is too hard. Hard chip breaking often causes reduced tool life or even insert breakages, due to high chip load on the cutting edge.	Feed is too high for the chosen geometry	Choose a geometry designed for higher feeds, preferably a single-sided insert Reduce feed
	Unsuitable entering angle	Select a holder with as small entering angle (lead angle) as possible. KAPR= 45°–75° (PSIR 45–15°)
	Too small nose radius	Select a larger nose radius

Surface finish The surface looks and feels “hairy” and does not meet the tolerance requirements.	The chips are breaking against the component and marking the finished surface	Select a geometry which guides the chips away from the component Change entering angle Reduce depth of cut Select a positive tool system with a neutral angle of inclination
	Hairy surface is caused by excessive notch wear on the cutting edge	Select a grade with better resistance to oxidation wear, for example a cermet grade. Reduce the cutting speed
	Feed is too high, in combination with a nose radius that is too small, a rough surface is generated	Select a wiper insert or a larger nose radius Reduce feed

Burr formation Burr formation on the workpiece when entering or exit of the workpiece.	The cutting edge is not sharp enough The feed is too low for the edge roundness	Use insert with sharp edges, PVD coated inserts or ground inserts at small feed rates, < 0.1 mm/rev (0.004 in/rev)
	Notch wear at depth of cut, or chipping	Use a holder with a small entering angle
	Burr formation at the end or start of cut	End or start the cut with a chamfer or a radius when exiting/entering the workpiece

Vibration High radial cutting forces due to vibrations or chatter marks which are caused by the tooling or the tool mounting. Typical for internal machining with boring bars.	Unsuitable entering angle	Select a larger entering angle (lead angle). KAPR = 90° (PSIR = 0°)
	Nose radius is too large	Select a smaller nose radius
	Unsuitable edge rounding, or negative chamfer	Select a grade with a thin coating, or an uncoated grade
	Excessive flank wear on the cutting edge	Select a more wear resistant grade or reduce speed

Vibration High tangential cutting forces.	Insert geometry creating high cutting forces Chip breaking is too hard, producing high cutting forces	Select a positive insert geometry Reduce the feed or select a geometry for higher feeds
	Cutting forces vary or are too low due to small depth of cut	Increase the depth of cut to make the insert cut
	Tool is incorrectly positioned	Check the centre height
	Instability in the tool due to long overhang	Reduce the overhang Use the largest possible bar diameter Use a Silent Tools™ or a carbide bar
	Unstable clamping leads to insufficient rigidity	Extend the clamping length of the boring bar Use EasyFix™ for cylindrical bars

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Insert wear

To achieve optimized cutting data, best possible component quality and tool life, always remember to check the insert/cutting edge after machining. Use this list of causes and solutions to different forms of insert wear as a reference for successful turning.

	Cause	Solution

Flank wear Preferable wear type in every application. Offers predictable and stable tool life.	Cutting speed too high Too tough grade Insufficient wear resistance Hard inclusions in workpiece material	Reduce cutting speed Select a more suitable grade depending on toughness demand or wear resistance

Notch wear	Sticky and/or work-hardening materials Use a ~90° entering angle (~0° lead angle) Geometry is too negative	Select a sharper edge Decrease entering angle Vary depth of cut

Crater wear	Too high cutting speed and/or feed Chip breaker too narrow Chemical dissolution or abrasive wear Wear resistance too low	Reduce cutting speed or feed Select a more wear resistant grade Select a more open/positive geometry

Plastic deformation Depression Impression	High heat load and pressure, cutting temperature too high Grade too tough/soft Lack of coolant supply	Reduce heat and pressure load by reducing cutting speed and/or feed If edge depression, reduce feed first If flank depression, reduce speed first Select a more wear/heat resistant grade Select a more open/positive geometry Improve coolant supply

Built-up edge (B.U.E)	Too low cutting temperature Sticky/smeary material Geometry too negative Coating too thick	Increase cutting temperature by increasing speed Select a PVD-coated grade (less BUE on PVD-coatings) Select a more positive geometry

Flaking	Smeary material Cutting speed too low Intermittent machining with coolant Coating too thick	Increase cutting speed Turn off coolant Select a grade with thinner coating and better edge line security (PVD)

Chipping on edge	Unstable conditions Grade too hard/brittle Coating too thick (CVD, leading to edge line flaking)	Make the machine conditions more stable Select a tougher grade Select a stronger geometry Select grade with thinner coating (PVD)

Thermal cracks	Varying cutting edge temperatures Intermittent cuts and coolant Grade is sensitive to heat shock variations Use of grade with thicker coating (CVD)	Switch off coolant or apply coolant copiously to obtain an even temperature level Decrease cutting speed Select grade with thinner coating (PVD)

Breakage	Excessive wear Wrong choice of grade (too tough/hard) Wrong cutting data	Run shorter (time in cut) operations: check how wear begins and the dominant wear type Change cutting data Select a more suitable insert grade/geometry

Slice fracture - ceramics	Excessive tool pressure	Reduce feed Select a tougher grade Select an insert with a smaller chamfer, or use another geometry to change cutting force direction

Chipping outside cutting zone	Chip jamming because of facing towards shoulder The chips are deflected against the cutting edge Not optimized feed or feed direction	Change operation path (to avoid facing towards shoulder) Change feed Select a PVD-coated grade Select an insert geometry that alters the chip flow