CNC Programming Techniques : An Insider's Guide to Effective Methods and Applications

by Peter Smid

• ISBN13: 9780831131852
• ISBN10: 0831131853
• Edition: 1st
• Format: Hardcover
• Copyright: 2005-09-12
• Publisher: INDUSTRIAL PRESS

Summary

Written by the author of the bestselling CNC Programming Handbook and the recent release Fanuc CNC Custom Macros, this practical and very useful resource covers dozens of special CNC programming techniques that can be applied to machining parts in an efficient way.

Table of Contents

Part Program Development	1	(22)
Program Development Drawing	1	(2)
Drawing Evaluation	2	(1)
Material and Stock	3	(1)
Part Setup	3	(1)
Part Reference Point	3	(1)
Part Orientation	3	(1)
Selecting Part Zero	4	(1)
Tooling Selection	4	(6)
Identifying Machining Operations	4	(1)
Face Milling	5	(1)
Contour Milling	6	(1)
Circular Pocket Milling	6	(1)
Slot Milling	7	(1)
Spot Drilling	8	(1)
Drilling	9	(1)
Tapping	9	(1)
Summary of Tools Used	9	(1)
Machining Data	10	(1)
Spindle Speed	10	(1)
Cutting Feedrate	11	(1)
Tooling Data	11	(1)
Details of Operations	11	(12)
Tool 1 - Face Milling	12	(1)
Tool 2 - Outside Contour	13	(2)
Tool 2 - Circular Pocket	15	(1)
Tool 3 - Slot Milling	16	(1)
Tool 4 - Spot Drilling	17	(1)
Tool 5 - Drilling	18	(1)
Tool 6 - Tapping	19	(1)
Complete Program	20	(3)
Calculating Contour Points	23	(10)
Tools and Knowledge	23	(2)
Mathematical Knowledge	23	(2)
Organized Approach	25	(1)
Process of Calculating XY Coordinates	25	(8)
Step 1 - Establish the Main Contour Points	26	(1)
Step 2 - Fill-in the Coordinate Sheet	26	(1)
Step 3 - Identify Calculation Zones	27	(1)
Step 4 - Helpful Ideas for Calculations	27	(2)
Step 5 - Calculations for Zone 1	29	(2)
Step 6 - Calculations for Zone 2	31	(1)
Updating Coordinate Sheet	32	(1)
Writing the CNC Program	32	(1)
Formulas for Contouring	33	(10)
Contour Point Between Two Lines (Lathe)	33	(1)
Contour Point Between Line and Arc	34	(5)
Intersecting Contour Point	34	(1)
Tangent Contour Point	35	(4)
Calculating the Sharp Point	39	(1)
Contour Point Between Two Arcs	40	(3)
Intersecting Arcs	40	(1)
Tangent Arcs	41	(2)
Using Cutter Radius Offset	43	(24)
General Concepts	43	(2)
Benefits Of Cutter Radius Offset	44	(1)
Controlling Cutter Radius	44	(1)
Radius Offset Commands	45	(1)
Commands G40-G41-G42	45	(1)
Using the D-offset Number	45	(1)
Basic Programming Techniques	46	(1)
Cutter Radius Activation	46	(1)
Cutter Radius Application	47	(1)
Cutter Radius Cancellation	47	(1)
D-offset Stored Amount	47	(2)
Equidistant Centerline - G40 Mode	48	(1)
Equidistant Centerline - G41/G42 Mode	48	(1)
Drawing Dimensions - G40 Mode	48	(1)
Drawing Dimensions - G41/G42 Mode	48	(1)
Radius vs Diameter	48	(1)
Contour Lead-In and Lead-Out	49	(5)
Methods For Lead-In - Linear Motion	49	(3)
Methods For Lead-In - Arc Motion	52	(1)
Methods For Lead-Out - Linear Motion	53	(1)
Methods For Lead-Out - Arc Motion	53	(1)
Program Example	53	(1)
Internal Contours	54	(4)
Linear Slot Machining	54	(1)
Circular Slot Machining	55	(1)
Finishing Internal Contour	56	(2)
Maintaining Dimensional Sizes	58	(2)
Basic Rule	58	(1)
Handling Dimensional Tolerances	58	(2)
Handling Cutter Radius Offset Errors	60	(2)
Common Errors	60	(1)
Offset Programmed Too Late or Too Early	61	(1)
Offset Start or End on an Arc	62	(1)
Tool Nose Radius Offset	62	(5)
Command Point and Radius Center	62	(1)
Tool Tip Orientation	63	(1)
Common Tool Nose Radius Errors	64	(3)
Part Reversal in Milling	67	(22)
Project Description	67	(1)
Material and Setup Conditions	67	(1)
Cutting Tools	68	(1)
Material Removal	68	(1)
Machining Process	69	(1)
Clamping 1	69	(1)
Clamping 2	70	(1)
Program Zero Selection	70	(2)
First Clamping	70	(1)
Second Clamping	71	(1)
Programming Methods	72	(1)
Tool Length Settings	72	(2)
First Clamping	73	(1)
Second Clamping	74	(1)
Using the WORK OFFSET Method - G54-G55	74	(2)
Common Toolpath	76	(1)
Program Listing - Work Offsets G54-G55	77	(2)
Program Listing - Work Offsets G54-G55 - with Subprograms	79	(2)
Using the Local Coordinates Method - G52	81	(2)
Program Listing - Local Coordinate System G52	83	(2)
Using the Datum Shift Method - G10	85	(1)
Program Listing - Datum Shift G10	86	(2)
Summary	88	(1)
Using Tapered End Mills	89	(8)
Types of Tapered End Mills	89	(2)
Tool Material	90	(1)
Range of Taper Angles	90	(1)
Flat Tip Tapered End Mills	90	(1)
Ball Tip Tapered End Mills	91	(1)
Effective Diameter Calculation	91	(5)
Flat Tip	91	(2)
Stock Removal	93	(1)
Ball Tip with Specified Radius	94	(1)
Flat Tip with Added Blend Radius	94	(2)
Tapered Holes	96	(1)
Special Purpose G-Codes	97	(26)
Single Direction Positioning - G60	97	(1)
Special Cutting Modes	98	(3)
Exact Stop Check G09 - G61	99	(1)
Automatic Corner Override - G62	100	(1)
Tapping Mode - G63	100	(1)
Normal Cutting Mode - G64	101	(1)
Stored Stroke Limits Definitions - G22 - G23	101	(2)
Spindle Fluctuation G25 - G26	103	(1)
Machine Zero Commands - G27 - G28 - G29 - G30	104	(4)
Primary Machine Zero Return - G28	104	(2)
Return from Machine Zero - G29	106	(1)
Machine Zero Return Position Check - G27	106	(2)
Secondary Machine Zero Return - G30	108	(1)
Position Register - G92/G50	108	(10)
G92 Position Register for Milling	109	(2)
G50 Position Register for Turning	111	(2)
Tool Change Position	113	(4)
Conversion of G50 to Geometry Offset	117	(1)
Skip Command - G31	118	(1)
Other Seldom Used G-codes	119	(4)
Tool Length Offset Negative - G44	119	(1)
Tool Length Offset Cancel - G49	119	(3)
Conclusion	122	(1)
Tool Length Offset Change	123	(8)
Tool Length Offset	123	(1)
Offset Adjustment	124	(4)
Practical Application	124	(1)
Programming Method 1 - No Offset Adjustment	125	(1)
Programming Method 2 - With Offset Adjustment	125	(1)
Programming Method 3 - Advanced Macro Method	126	(2)
Offset Adjustment - Setup for Two Parts	128	(3)
Method 1 - One Work Offset + One Length Offset	128	(1)
Method 2 - Two Work Offsets + One Length Offset	129	(1)
Method 3 - Two Work Offsets + Two Length Offsets	130	(1)
Block Skip Applications	131	(12)
General Applications	131	(1)
Similar Parts Applications	132	(2)
Programming a Trial Cut	134	(3)
Trial Cut for Milling	134	(2)
Trial Cut for Turning	136	(1)
Irregular Stock Removal	137	(3)
Variable Stock in Milling	137	(2)
Variable Stock in Turning	139	(1)
Summary of Rules	139	(1)
Block Skip Within A Block	140	(2)
Conflicting Words	140	(1)
One Program - Two Materials	140	(2)
Numbered Block Skip Functions	142	(1)
Standard and Rigid Tapping	143	(6)
Standard Tapping Method	143	(3)
Basic Principles	143	(1)
Why Underfeed?	144	(1)
Feed-In Slower - Feed-Out Faster	144	(2)
Rigid Tapping Method	146	(3)
Basic Principles	146	(1)
Benefits	146	(1)
Setup	147	(1)
Possible Problems	147	(1)
Programming Approach	147	(2)
Polar Coordinates	149	(6)
Definition and G-codes	149	(2)
Polar Coordinates and Planes	150	(1)
G15 - G16 Polar Coordinates	151	(1)
Programming Format	151	(4)
Toolpath Direction	153	(1)
Applications in Planes	154	(1)
Subprogram Development	155	(14)
Definition and Usage	155	(1)
Drawing Evaluation	156	(1)
Subprogram Planning	156	(2)
Depth Control	157	(1)
Width of Cut Control	157	(1)
Cutting Tool Selection	157	(1)
Developing the Subprogram	158	(4)
Method 1 - Full Width and Full Depth	158	(1)
Method 2 - Full Width and Divided Depth	159	(1)
Method 3 - Smaller Width and Full Depth	160	(2)
Round Pocket Subprogram	162	(3)
Single Depth Pocket with Stepovers	162	(2)
Multidepth Pocket with Stepovers	164	(1)
Rough and Finish Cuts with a Subprogram	165	(4)
One Toolpath for Two Cuts	165	(2)
Lead-in and Lead-Out	167	(1)
Common Contour Toolpath	167	(1)
Main Program	168	(1)
Turning and Boring in Depth	169	(30)
Program Zero Selection	169	(1)
Corner Radius and Back Angle Selection	170	(1)
Cutter Radius Offset	171	(1)
Imaginary Tool Point	172	(1)
Stock Allowance	172	(4)
Contour Shape	173	(1)
Cutting Tool Used	173	(1)
Stock Allowance in X and Z axes	173	(1)
Grinding Allowance	174	(2)
Tool Approach Techniques - Lead-In	176	(3)
Approaching the Front Face	176	(1)
Approaching a Diameter	176	(1)
Approaching a Chamfer	177	(1)
Approaching a Radius	177	(2)
Approaches to Avoid	179	(1)
Tool Retract Techniques - Lead-Out	179	(3)
Retract from a Face	179	(1)
Retract from a Diameter	180	(1)
Retract from a Chamfer	180	(1)
Retract from a Radius	181	(1)
Retracts to Avoid	181	(1)
One Job - Two Operations	182	(2)
About Jaws	182	(1)
Single Setup - Two Chuckings	183	(1)
Two Setups - Two Operations	184	(1)
Multi Cut Facing	184	(1)
Width of Cut Distribution	184	(1)
Breaking Corners	185	(1)
Direction Specification	186	(1)
Using Tailstock	186	(3)
Types of Tailstock	187	(1)
Programming a Tailstock with a Bar Stopper	187	(2)
Using 45-degree Tool	189	(3)
Machining Thin Stock	192	(1)
Adjusting Chuck Pressure	192	(1)
Using an Inner Plug / Outer Ring	192	(1)
Using Special Split Jaws	192	(1)
G70/G71/G72 Cycle Methods	193	(5)
Programming Formats - G71	193	(1)
Programming Formats - G72	194	(2)
G70 - Finishing Cycle	196	(1)
G71 and G72 Compared	196	(2)
Programming Undercuts	198	(1)
Hard Turning	198	(1)
Programming Tapers	199	(16)
What is a Taper?	199	(1)
Taper Definitions	199	(1)
Taper per Foot	200	(3)
Taper Ratios	203	(2)
Taper Defined as Percentage	205	(1)
Taper Angle Defined in D-M-S	206	(1)
Taper Length and Angle	206	(5)
Chamfers	206	(1)
45° Chamfer	207	(2)
Start Chamfer with a Clearance	209	(1)
End Chamfer with a Clearance	209	(1)
Other Chamfers	210	(1)
Tapers with Leads	211	(4)
Taper with a Lead Chamfer	212	(1)
Taper with a Lead Fillet	213	(2)
Techniques for Grooving	215	(12)
Tooling for Grooves	215	(2)
Cutting Width	215	(1)
Cutting Depth	215	(1)
Groove Location	216	(1)
Setting the Command Point	216	(1)
Plunge and Retract Method	217	(1)
G75 Cycle	217	(1)
Grooving for Precision	218	(3)
Machining Procedure	219	(1)
Programming Procedure	220	(1)
Deep Grooving	221	(1)
Grooves with Tapers - O-Ring Grooves	222	(3)
Grooves with Tapers - V-Pulley Grooves	225	(2)
Insert Selection	225	(1)
Depth Calculation	226	(1)
Tool Setup and Program	226	(1)
Techniques for Threading	227	(16)
Types of Thread Forms	227	(2)
UN - Unified National and Metric	227	(1)
Other Thread Forms	228	(1)
Thread Depth Calculation	229	(1)
Infeed Methods	230	(1)
Tool Motions	231	(1)
Cutting Conditions	231	(1)
Acceleration and Deceleration	231	(1)
Cutting Depth	232	(1)
Hand of Thread	232	(2)
External Threading - Right Hand Thread	232	(1)
External Threading - Left Hand Thread	233	(1)
Internal Threading - Right Hand Thread	233	(1)
Internal Threading - Left Hand Thread	233	(1)
Sample Thread Evaluation	234	(2)
Initial Data	234	(1)
Cutting Conditions	234	(1)
Number of Threading Passes	235	(1)
Distribution of Depth Cuts	236	(1)
G32 Threading Method	236	(4)
Radial Infeed Example	237	(1)
Flank Infeed Example	237	(1)
Tapping with G32	238	(2)
G92 Threading Method	240	(1)
G76 Threading Method	241	(2)
Programming Format	241	(2)
Restrictions in Threading	243	(8)
Thread Programming Basics	243	(1)
Threading Feedrate	244	(1)
Standard Example	244	(1)
Final Threading Program - Single Start	245	(1)
Special Example	245	(2)
Final Threading Program - Multi Start	246	(1)
Slow Spindle Speed	247	(1)
Metric Applications	247	(1)
Long Thread Programming	248	(3)
Defining a Long Thread	248	(1)
Lead Error	249	(1)
Number of Decimal Places	250	(1)
Practical Thread Milling	251	(22)
Thread Milling - General	251	(1)
Helical Interpolation	251	(1)
Is Helical Interpolation Available?	252	(1)
Benefits of Thread Milling	252	(1)
Selecting Tools	253	(2)
Initial Factors	253	(1)
Types of Thread Milling Cutters	254	(1)
Accuracy Issues	254	(1)
Thread Mill Data	255	(1)
Cutting Direction	255	(3)
External and Internal Thread Milling	255	(1)
Climb Milling and Conventional Thread Milling	255	(1)
Right Hand and Left Hand Thread Milling	255	(1)
External Thread Milling Illustrated	256	(1)
Internal Thread Milling Illustrated	257	(1)
Helix - Helical Curve	258	(2)
Programming External Threads	260	(6)
Tooling Selection	260	(1)
Cutting Conditions	261	(1)
Lead-In and Lead-Out	261	(1)
Cutter Radius Offset	262	(1)
Program Development - External Thread	262	(4)
Programming Internal Threads	266	(5)
Tooling Selection	266	(1)
Cutting Conditions	266	(1)
Lead-In and Lead-Out	267	(1)
Cutter Radius Offset	267	(1)
Program Development - Internal Thread	268	(3)
Pipe Thread Milling	271	(1)
Thread Milling Software	272	(1)
Knurling on CNC Lathes	273	(4)
Knurling Operations	273	(2)
Tooling Selection	273	(1)
Knurling Pitch	274	(1)
Programming and Machining Techniques	275	(1)
Tool Motions	275	(1)
Depth and Feedrate	275	(1)
Troubleshooting	276	(1)
Four-Axis Lathes	277	(6)
General Setup	277	(1)
Tool Tip Numbers	278	(1)
Programming Method	278	(5)
Spindle Speed and Feedrate	278	(1)
M-Functions	279	(1)
Synchronization Functions	279	(1)
Program Structure	279	(4)
Pallet Changers	283	(6)
Types of Automatic Pallets	283	(2)
Rotary Pallets	283	(1)
Shuttle Pallets	283	(1)
Setup and Work Areas	284	(1)
Programming Methods	285	(1)
M60 Function	285	(1)
General Format	285	(1)
Programming Example	286	(3)
Initial Conditions	286	(1)
Part Program	286	(3)
Working with Planes	289	(18)
Mathematical Planes	289	(1)
Machine Planes	290	(1)
G-codes for Plane Selection	290	(1)
Effect of Planes in Programming	291	(4)
Planes and Circular Motion	291	(2)
Planes and Cutter Radius Offset	293	(2)
Working With Planes In Detail	295	(6)
G17 with G41 and G02	295	(1)
G17 with G42 and G03	296	(1)
G18 with G42 and G03	297	(1)
G18 with G41 and G02	298	(1)
G19 with G41 and G02	299	(1)
G19 with G42 and G03	300	(1)
Using Right-Angle Attachment	301	(6)
Basic Concepts	301	(1)
Side Face Drilling	302	(2)
Side Face Milling	304	(3)
Programming Cams	307	(10)
Overview of Cams	307	(1)
Cam Drawing Example	308	(2)
Cam RISE and FALL - Sections Evaluation	309	(1)
The RISE Section	310	(2)
Calculating Radius Length	311	(1)
Calculating XY Coordinates	311	(1)
The FALL Section	312	(3)
Calculating Radius Length	313	(1)
Calculating XY Coordinates	314	(1)
Summary	314	(1)
Writing the Program	315	(2)
Introduction to Macros	317	(16)
Special Introduction	317	(1)
Skills Required	317	(1)
Macro is an Option	318	(1)
Common Features and Applications	318	(1)
Macro Structure	319	(8)
Macro Definition and Call	320	(2)
Variable Declarations and Expressions	322	(1)
Macro Functions	323	(3)
Branching and Looping	326	(1)
Macro Development - Bolt Circle	327	(6)
Evaluation of Drawings	328	(1)
Bolt Hole Macro Features	329	(1)
Assignment of Variables	330	(1)
Internal Calculations	330	(1)
Other Calculations	330	(1)
Final Considerations	331	(1)
Macro Call	332	(1)
Did You Know That ... ?	333	(2)
References and Resources	335	(4)
Index	339