CNC G-Code Generator | Turning Program Builder

Lathe Operations Overview

Understanding each operation helps you select the right tool geometry, insert grade, and cutting parameters.

Operation	Description	Common Tools	Key Considerations
Facing	Machining the end face perpendicular to axis	PCLNR, MCLNR, DCLNR	Use 80° or 55° inserts; ensure clearance at center
OD Turning	Reducing the outside diameter along length	PCLNR, MCLNR, DWLNR	Match insert angle to approach; consider chip flow
Roughing	High material removal rate with larger DOC	PCLNR, MWLNR	Use strong insert shapes (C, W, S); heavy chipbreakers
Finishing	Final pass for surface finish and accuracy	SVJBR, SDJCR	Small nose radius; light chipbreakers; higher speeds
Taper Turning	Creating a conical surface with varying diameter	PCLNR, MCLNR	Consider effective cutting angle; use appropriate clearance
Profiling	Complex contours combining radii, tapers, steps	SVJBR, SDJCR, DVJNR	35° or 55° inserts for accessibility; check interference
Boring	Enlarging an existing hole from inside	S-SCLCR, A-SDUCR	Minimize overhang; use anti-vibration bars for deep bores
Drilling	Creating a hole in the center of workpiece	Center drills, indexable drills	Start with center drill; peck for deep holes
OD Threading	Cutting external threads on workpiece	SER, SEL, Laydown	Match thread form (60° metric, 55° BSP); use thread relief
ID Threading	Cutting internal threads inside a bore	SIR, SNR	Ensure bore diameter allows tool entry; check clearance
Grooving	Cutting a narrow channel or recess	GFVR, DGFHR	Match insert width to groove; consider chip evacuation
Parting	Cutting off the workpiece from bar stock	QD, GY, Cut-off blades	Use narrow inserts; reduce speed near center; support part

Tool Holder Nomenclature

Tool holders follow standardized naming conventions that describe their clamping method, insert compatibility, and dimensions.

ISO Standard (Metric)

Example: PCLNR2525M12

P C L N R 25 25 M 12

PClamping System

CInsert Shape

LInsert Clearance

NTool Style

RHand

25Shank Height

25Shank Width

MTool Length

12Insert IC

Position 1: Clamping System

Code	System	Description
`P`	Lever Lock	Most common; uses a lever to pull insert into pocket
`C`	Top Clamp	Clamp presses on top of insert; good for negative inserts
`S`	Screw	Center screw through insert; compact design
`M`	Multi-Lock	Combination of clamp and pin; very secure
`D`	Lever + Clamp	Dual locking for heavy machining

Position 2: Insert Shape

Code	Shape	Angle	Strength	Best For
`C`	Rhombus	80°	High	General turning, versatile
`D`	Rhombus	55°	Medium	Profiling, copy turning
`V`	Rhombus	35°	Low	Fine profiling, tight corners
`T`	Triangle	60°	Medium	General turning, 3 edges
`S`	Square	90°	High	Heavy roughing, 4/8 edges
`R`	Round	-	Highest	Heavy roughing, scaling
`W`	Trigon	80°	High	Heavy cuts, 6 edges

Position 3: Insert Clearance Angle

Code	Angle	Application
`N`	0°	Negative insert - double-sided, strong
`C`	7°	Standard positive clearance
`P`	11°	More positive - light cuts, profiling
`B`	5°	Slight clearance

Position 4: Tool Style (Approach Angle)

Code	Lead Angle	Application
`A`	90°	Square shoulder, facing
`B`	75°	General turning
`D`	45°	Heavy roughing
`F`	90°	End cutting, facing
`J`	93°	General with slight lead
`K`	75°	Standard OD turning
`L`	95°	Back-facing capable
`S`	45°	Maximum chip thinning

Position 5: Hand of Tool

Code	Hand	Description
`R`	Right-hand	Cuts from right to left (toward chuck) - most common
`L`	Left-hand	Cuts from left to right (away from chuck)
`N`	Neutral	Can cut in both directions

ANSI Standard (Inch)

Example: MCLNR-164D

M C L N R - 16 4 D

MClamp Type

CInsert Shape

LClearance

NStyle

RHand

16Shank (1/16")

4Insert IC

DLength

Tip: ANSI shank size is in 1/16" increments. So "16" = 16/16" = 1" square shank. The insert IC is in 1/8" increments, so "4" = 4/8" = 1/2" IC.

Insert Nomenclature

Carbide inserts use a standardized code that defines shape, size, tolerance, and features.

ISO Standard

Example: CNMG120408-PM

C N M G 12 04 08 - PM

CShape

NClearance

MTolerance

GFeatures

12Size (IC)

04Thickness

08Corner R

PMChipbreaker

Position 1: Insert Shape

Code	Shape	Included Angle	Edges	Strength
`C`	Rhombus	80°	2/4	Good balance of strength and accessibility
`D`	Rhombus	55°	2/4	Better accessibility, less strength
`V`	Rhombus	35°	2/4	Best accessibility, weakest
`T`	Triangle	60°	3/6	Good economy, medium strength
`S`	Square	90°	4/8	Strong, good for roughing
`R`	Round	-	Infinite	Strongest, for heavy roughing
`W`	Trigon	80°	3/6	Good economy and strength

Position 2: Clearance Angle

Code	Angle	Type	Application
`N`	0°	Negative	Double-sided, strongest, most economical
`A`	3°	Positive	Light cutting
`B`	5°	Positive	General positive
`C`	7°	Positive	Standard positive
`P`	11°	Positive	Heavy positive for aluminum/soft materials

Negative vs Positive: Negative inserts (N) are double-sided (twice the edges) and stronger but require more power. Positive inserts (C, P) cut more freely with lower forces but are single-sided.

Positions 5-6: Insert Size (IC)

Code	IC Diameter	Common Uses
`06`	6.35mm (1/4")	Small parts, finishing
`09`	9.525mm (3/8")	Light to medium machining
`12`	12.7mm (1/2")	General purpose - most common
`16`	15.875mm (5/8")	Heavy machining
`19`	19.05mm (3/4")	Heavy roughing

Positions 9-10: Corner Radius

Code	Radius (mm)	Radius (inch)	Application
`02`	0.2mm	0.008"	Fine finishing, weak edge
`04`	0.4mm	0.016"	Finishing
`08`	0.8mm	0.031"	General purpose
`12`	1.2mm	0.047"	Medium roughing
`16`	1.6mm	0.063"	Heavy roughing

Surface Finish Formula: Ra (μm) ≈ (feed² × 1000) / (8 × nose radius). Larger nose radius = better finish at same feed rate.

ANSI Standard

Example: CNMG-432

C N M G - 4 3 2

CShape

NClearance

MTolerance

GFeatures

4IC (1/8")

3Thick (1/16")

2Corner R

Tool Types by Operation

Select the right tool holder style for your specific machining operation.

OD Turning - General

PCLNR - 80° insert, lever lock, versatile
MCLNR - 80° insert, top clamp
DCLNR - 55° insert, more access
DWLNR - 80° trigon, heavy cuts

OD Turning - Finishing

SVJBR - 35° insert, tight profiles
SDJCR - 55° insert, profiling
SVVCN - 35° insert, very accessible
SDUCR - 55° positive, light cuts

Facing

PCLNR/PCLNL - Standard facing
MWLNR - Heavy facing
SCLCR - Light facing

Boring Bars

S-SCLCR - Standard steel shank
S-SDUCR - 55° for profiles
A-SCLCR - Anti-vibration
E-SCLCR - Carbide shank
C-SCLCR - Coolant-through

Threading - External

SER - 60° external right-hand
SEL - 60° external left-hand
SER-NF - UN threads (55°)
Laydown style for rigidity

Threading - Internal

SIR - Internal right-hand
SNR - Internal neutral
Match bar diameter to bore
Consider chip evacuation

Grooving

GFVR - Face grooving
DGFHR - OD grooving
GY - Deep grooving
Match insert width to groove

Parting / Cut-off

QD - Quick disconnect blades
GY - Deep parting
Narrow inserts (2-3mm)
Reduce speed near center

Boring Bar Selection Guide

Bore Diameter	Bar Diameter	Max Overhang	Type
10-15mm	6-8mm	3×D	Steel
15-25mm	10-16mm	4×D	Steel
25-40mm	16-25mm	4×D	Steel or Carbide
40-60mm	25-40mm	5-6×D	Carbide or Anti-vib
>60mm	>40mm	6-10×D	Anti-vibration

Rule of Thumb: Use the largest possible boring bar diameter. Maximum overhang for steel is 4×D, carbide 6×D, anti-vibration 10×D.

Insert Grades & Coatings

Selecting the correct grade and coating is critical for tool life and productivity.

ISO Material Classification

ISO Code	Color	Material Group	Characteristics	Grade Range
P	Blue	Steel	Long chips, good machinability, adhesive wear	P10 - P40
M	Yellow	Stainless Steel	Work hardening, built-up edge, abrasive	M10 - M40
K	Red	Cast Iron	Short chips, abrasive, easy to machine	K10 - K40
N	Green	Non-ferrous	Soft, gummy, long chips, low forces	N10 - N30
S	Purple	Superalloys	High strength at temperature, work hardening	S10 - S30
H	Gray	Hardened Steel	>45 HRC, abrasive, high cutting forces	H10 - H30

Grade Number Guide: Lower numbers (P10, M10) = harder, more wear resistant, for finishing. Higher numbers (P40, M40) = tougher, for roughing and interrupted cuts.

Coating Types

Coating	Process	Max Temp	Best Applications
TiN	PVD	600°C	General purpose, easy wear detection, low-alloy steel
TiCN	PVD/CVD	400°C	Abrasive materials, cast iron, medium-carbon steel
TiAlN	PVD	800°C	High-speed machining, dry cutting, stainless, alloy steel
AlTiN	PVD	900°C	Extreme heat, hardened steel, superalloys, dry machining
Al₂O₃	CVD	1200°C	High-speed steel finishing, excellent chemical resistance
CVD Diamond	CVD	700°C	Aluminum, graphite, composites, non-ferrous
CBN	Sintered	1000°C	Hardened steel >45 HRC, cast iron, powder metal
PCD	Sintered	700°C	Aluminum-silicon, composites, non-ferrous, graphite

Material-Specific Recommendations

Material	ISO Grade	Coating	Speed Range	Notes
Low Carbon Steel	P15-P25	TiCN + Al₂O₃	150-300 m/min	Watch for built-up edge
Alloy Steel (4140)	P20-P35	TiAlN	100-200 m/min	Higher toughness needed
Stainless 304/316	M15-M25	TiAlN or AlTiN	100-180 m/min	Sharp edge, positive rake
Gray Cast Iron	K10-K20	TiN + Al₂O₃	150-300 m/min	Abrasive, dry cutting OK
Aluminum 6061	N10-N20	Uncoated/PCD	300-1000 m/min	Sharp edge, positive rake
Titanium Ti-6Al-4V	S15-S25	TiAlN/Uncoated	30-60 m/min	Low speed, high feed, coolant
Inconel 718	S20-S30	AlTiN/Ceramic	20-40 m/min	Very tough, work hardens
Hardened Steel 50 HRC	H10-H15	CBN	80-180 m/min	Rigid setup essential

Chipbreaker Selection

Chipbreakers control chip formation, breaking, and evacuation. Choose based on depth of cut and feed rate.

Chipbreaker	Type	DOC Range	Feed Range	Application
`-PF`	Light Finishing	0.3 - 1.5 mm	0.05 - 0.15 mm/rev	Fine finishing, tight tolerances
`-MF`	Medium Finishing	0.5 - 2.0 mm	0.10 - 0.25 mm/rev	General finishing, profiling
`-PM`	Medium	0.5 - 3.0 mm	0.15 - 0.35 mm/rev	General purpose, most common
`-MM`	Medium-Heavy	1.0 - 4.0 mm	0.20 - 0.40 mm/rev	Heavier roughing, good chip control
`-PR`	Heavy Roughing	1.0 - 6.0 mm	0.25 - 0.50 mm/rev	Maximum material removal
`-MR`	Roughing	2.0 - 8.0 mm	0.30 - 0.60 mm/rev	Heavy duty, interrupted cuts
`-GS`	Stainless	0.5 - 2.5 mm	0.10 - 0.30 mm/rev	Stainless steel specific
`-SM`	Superalloy	0.3 - 2.0 mm	0.08 - 0.20 mm/rev	Inconel, titanium, nickel alloys

Chip Control Tips:

If chips are too long: Increase feed or use a tighter chipbreaker
If chips are burning/blue: Increase coolant or reduce speed
If chips are nested: Wrong chipbreaker for the DOC/feed combination
If insert is chipping: Chipbreaker is too aggressive for the conditions

Quick Reference Charts

Nose Radius Selection

Surface Finish Required	Feed Rate	Recommended Nose Radius
Ra 0.8 μm (Fine)	0.05-0.10 mm/rev	0.4-0.8 mm
Ra 1.6 μm (Good)	0.10-0.20 mm/rev	0.8-1.2 mm
Ra 3.2 μm (Medium)	0.20-0.35 mm/rev	0.8-1.6 mm
Ra 6.3 μm (Rough)	0.30-0.50 mm/rev	1.2-2.4 mm

Recommended Tool Holder Sizes

Shank Size (mm)	Insert IC	Max DOC	Machine Size
12×12	6-9 mm	2 mm	Small lathes
16×16	9-12 mm	3 mm	Light duty
20×20	12 mm	4 mm	Medium duty
25×25	12-16 mm	6 mm	General purpose
32×32	16-19 mm	8 mm	Heavy duty

Threading Insert Selection

Thread Type	Profile Angle	Insert Code	Pitch Range
ISO Metric (M)	60°	16ER/IR AG60	0.5 - 6.0 mm
UN (UNC, UNF)	60°	16ER/IR UN60	4 - 28 TPI
Whitworth (BSW)	55°	16ER/IR W55	4 - 20 TPI
BSP/BSPP (G)	55°	16ER/IR W55	8 - 28 TPI
NPT/NPTF	60°	16ER/IR NPT	8 - 27 TPI
Acme	29°	16ER/IR ACME	2 - 16 TPI
Trapezoidal (Tr)	30°	16ER/IR TR30	1.5 - 12 mm

Thread Insert Sizing: The number before ER/IR indicates the insert size. 16ER = 16mm IC, 11ER = 11mm IC. Use full-profile inserts for best thread quality, or partial profile for multiple pitches.

Face + OD Turn

Face + Bore

Face + Drill

Full OD

Full ID

Custom