CNC Lathe Machining — Common Tool Classifications Complete Guide

OD Turning Tools

Boring Bars (ID Turning Tools)

Boring bars are used to enlarge hole diameters or finish the internal profile. The enclosed machining space makes chip evacuation difficult, requiring far greater tool rigidity than OD machining.

Shank Characteristics

Shanks are typically round, with diameters ranging from approximately 10–50mm. The tool must extend into the hole; the longer the overhang, the higher the vibration risk, making shank material selection critical.

Chip Evacuation Design

The enclosed machining space easily accumulates chips. It is recommended to use the Internal Coolant function, where high-pressure coolant flushes chips outward from the bore, preventing chips from scratching the bore wall or damaging the tool.

Drilling Tools

Drilling is typically the first operation in metal machining. The hole center accuracy directly affects the datum for all subsequent operations — tool selection cannot be taken lightly.

Rotation Direction

Common Drilling Tool Types

Tapping Tools

Tapping tools are used to cut internal threads in pre-drilled holes. The CNC lathe must have Rigid Tapping (Synchronous Tapping) capability, which precisely synchronizes spindle speed with Z-axis feed (feed rate = spindle speed × pitch), ensuring thread accuracy and tool safety.

Grooving Tools

Grooving tools cut grooves of a specific width on the OD or face of a workpiece. Common applications include O-ring grooves, undercuts, and snap ring grooves.

Insert Width vs. Groove Width

Grooving insert widths range from 1.5mm to 6mm. In general, insert width equals groove width. Confirm the groove width from the design drawing before selecting a tool — inserts of different widths cannot be interchanged. For high-precision groove width requirements, use an insert narrower than the target width and finish to dimension with side turning.

Groove Depth Limits

Limited by insert overhang strength, the general rule of thumb is groove depth approximately 2–3 times the insert width. The actual limit varies by brand specifications — confirm the manufacturer's spec sheet before selecting. For deeper grooves, use multiple passes or select a dedicated deep-groove tool.

Face Grooving

Some grooving tools support face grooving. The shank design differs from OD grooving tools — be careful to distinguish them during purchase, as they cannot be used interchangeably.

• Confirm groove width before tool selection; insert width must match drawing specification
  Grooving inserts cannot profile like OD tools — the wrong width means changing the tool and redoing the operation.
• When groove depth exceeds 3× the insert width, use multiple passes or switch to a deep-groove tool
  Prevents chatter or insert fracture caused by excessive overhang.
• Face grooving and OD grooving tools have different shank designs and cannot be interchanged
  Their feed directions differ; forced substitution will cause dimensional errors or tool damage.

Threading Tools

Threading tools are used to cut external threads on the OD of a workpiece through progressive multi-pass cutting to gradually reach the design thread depth. An essential tool for producing parts with external threads.

Difference from Tapping Tools

Insert Thread Form Selection

Thread inserts come in specifications matching thread standards: M (metric), UN (unified inch), G (pipe thread), etc. The insert tooth angle must exactly correspond to the thread standard; otherwise the thread will not mate correctly.

Cutting Method

A CNC lathe uses thread cutting cycle commands to control the depth of cut per pass, progressively deepening to the final thread depth. The number of passes and cut-per-pass depth directly affect thread surface quality and tool life. Refer to the controller's operation manual for detailed programming syntax.