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Books > Computing & IT > General

New Achievements in Evolutionary Computation (Hardcover): Peter Korosec New Achievements in Evolutionary Computation (Hardcover)
Peter Korosec
R3,589 Discovery Miles 35 890 Ships in 18 - 22 working days
Numerical Simulation - From Theory to Industry (Hardcover): Mykhaylo Andriychuk Numerical Simulation - From Theory to Industry (Hardcover)
Mykhaylo Andriychuk
R4,173 Discovery Miles 41 730 Ships in 18 - 22 working days
Theory and Novel Applications of Machine Learning (Hardcover): Er Meng Joo, Yi Zhou Theory and Novel Applications of Machine Learning (Hardcover)
Er Meng Joo, Yi Zhou
R3,605 Discovery Miles 36 050 Ships in 18 - 22 working days
Electronic and Computer Music - An Annotated Bibliography (Hardcover, Annotated Ed): Robert L. Wick Electronic and Computer Music - An Annotated Bibliography (Hardcover, Annotated Ed)
Robert L. Wick
R2,077 R1,892 Discovery Miles 18 920 Save R185 (9%) Ships in 10 - 15 working days

This work is a handy desk reference for academic and public library music reference collections as well as teachers, musicians, and composers. The more than 250 books discussed represent a core bibliography on this late 20th-century phenomenon that is very much in transition as the concepts of electronic and computer merge into a single music, whether acoustic or electronic in origin. Of special interest is an up-to-date listing of on-line sources found on the Internet, including World Wide Web sites and electronic discussion lists. Topics represented include history, literature on synthesis and synthesizers, electronic music instruments and devices, electronic music composition, MIDI (Musical Instrument Digital Interface), the teaching of computer and electronic music, bibliographies and dictionaries. Covered by way of appendices are major dissertations and theses, lists of periodicals that have dealt with the subject, and a compilation of electronic music instrument and device system manuals currently in print.

Advances in Data Mining Knowledge Discovery and Applications (Hardcover): Adem Karahoca Advances in Data Mining Knowledge Discovery and Applications (Hardcover)
Adem Karahoca
R3,610 Discovery Miles 36 100 Ships in 18 - 22 working days
Practical Applications and Solutions Using LabVIEW(TM) Software (Hardcover): Silviu Folea Practical Applications and Solutions Using LabVIEW(TM) Software (Hardcover)
Silviu Folea
R3,634 Discovery Miles 36 340 Ships in 18 - 22 working days
Information and Technology Literacy - Concepts, Methodologies, Tools, and Applications, Vol 3 (Hardcover): Management... Information and Technology Literacy - Concepts, Methodologies, Tools, and Applications, Vol 3 (Hardcover)
Management Association Information Reso Management Association
R8,961 Discovery Miles 89 610 Ships in 18 - 22 working days
Information-Driven Marketing Decisions - Development of Strategic Information Systems (Hardcover): A.Coskun Samli Information-Driven Marketing Decisions - Development of Strategic Information Systems (Hardcover)
A.Coskun Samli
R2,801 R2,535 Discovery Miles 25 350 Save R266 (9%) Ships in 10 - 15 working days

Data have almost no value in and for themselves. What's important is how they are used to create the information one needs to make informed decisions, and this is particularly true in making marketing decisions. Thus, Samli's new book dwells on the art and science of information generation and on how to convert it to practical knowledge. Without information and knowledge, says Samli, the firm faces great risk in the marketplace and its survival probabilities in the long run are very low. Samli explains, first, the various data generating procedures, with special emphasis on data analysis, and second, the procedures for creating information out of data -- all in a clear, systematic presentation that marketing managers will understand and benefit from immediately. Their MIS colleagues, whose goal should be to make data and information decision-maker friendly, will also benefit. A unique, valuable book for both.

The problem is not information overload as some contend, says Samli, but data overload. Data have almost no value in and for themselves. What's important is how data are used to create the information marketers need in order to make knowledgeable decisions. Thus, Samli's newest book dwells on the art and science of information generation and on how to convert it to practical knowledge. Without information and knowledge -- and another essential ingredient, wisdom -- the firm faces great risk in the marketplace and its survival probabilities in the long run are very low, says the author.

Samli starts by presenting the key elements that contribute to an information gap in the use of data for marketing decisions. He describes the evolution of information in decision making, the distinction between data and information, and the reasons why data gathering and processing have become so sophisticated and difficult to use. Samli goes on to discuss data collecting techniques, the dimensions and uses of internal data and their parameters, and identifies the best but most underrated data gathering method: observation. Surveys, experimentation, and research are covered next, including attitude and motivation research, with a careful analysis of how the research operation, as well as its products, should be managed. He goes on to explain how information is elicited from data and how it should be used; then, the various control mechanisms for information systems overall, and ends with his own agenda for the improvement of the entire information-driven marketing decision process. A clear, systematic presentation that marketing managers, and their MIS colleagues (who appreciate the need to make data and information decision-maker friendly), will find valuable and immediately beneficial.

Dynamic Model Development: Methods, Theory and Applications, Volume 16 (Hardcover, New): S. Macchietto Dynamic Model Development: Methods, Theory and Applications, Volume 16 (Hardcover, New)
S. Macchietto
R13,258 Discovery Miles 132 580 Ships in 18 - 22 working days

Detailed mathematical models are increasingly being used by companies to gain competitive advantage through such applications as model-based process design, control and optimization. Thus, building various types of high quality models for processing systems has become a key activity in Process Engineering. This activity involves the use of several methods and techniques including model solution techniques, nonlinear systems identification, model verification and validation, and optimal design of experiments just to name a few. In turn, several issues and open-ended problems arise within these methods, including, for instance, use of higher-order information in establishing parameter estimates, establishing metrics for model credibility, and extending experiment design to the dynamic situation.
The material covered in this book is aimed at allowing easier development and full use of detailed and high fidelity models. Potential applications of these techniques in all engineering disciplines are abundant, including applications in chemical kinetics and reaction mechanism elucidation, polymer reaction engineering, and physical properties estimation. On the academic side, the book will serve to generate research ideas.
- Contains wide coverage of statistical methods applied to process modelling
- Serves as a recent compilation of dynamic model building tools
- Presents several examples of applying advanced statistical and modelling methods to real process systems problems

Nature-Inspired Computing - Concepts, Methodologies, Tools, and Applications, Vol 1 (Hardcover): Management Association... Nature-Inspired Computing - Concepts, Methodologies, Tools, and Applications, Vol 1 (Hardcover)
Management Association Information Reso Management Association
R9,416 Discovery Miles 94 160 Ships in 18 - 22 working days
Data Mining and Knowledge Discovery in Real Life Applications (Hardcover): Adem Karahoca, Julio Ponce Data Mining and Knowledge Discovery in Real Life Applications (Hardcover)
Adem Karahoca, Julio Ponce
R3,610 Discovery Miles 36 100 Ships in 18 - 22 working days
Advanced Video Coding for Next-Generation Multimedia Services (Hardcover): Yo-Sung Ho Advanced Video Coding for Next-Generation Multimedia Services (Hardcover)
Yo-Sung Ho
R3,103 Discovery Miles 31 030 Ships in 18 - 22 working days
A New Archetype for Competitive Intelligence (Hardcover): John J. McGonagle, Carolyn M. Vella A New Archetype for Competitive Intelligence (Hardcover)
John J. McGonagle, Carolyn M. Vella
R2,803 R2,537 Discovery Miles 25 370 Save R266 (9%) Ships in 10 - 15 working days

McGonagle and Vella maintain that competitive intelligence as we know it is just the first step toward the creation of true corporate intelligence. Their book thus explores ways in which new channels of communication and new uses of information and intelligence will change corporations, and how these changes can be anticipated now in an organization's strategic planning, crisis management, benchmarking, reverse engineering, and defensive intelligence activities. In doing so, they introduce readers to new techniques, such as shadow benchmarking and fractal management analysis. Readable, with useful checklists, forms, reminders, and drawing from real world cases, this book will be essential reading for executives in the public and private sectors, and their colleagues in the academic business community.

Vella and McGonagle premise their book on the evidence that modern companies throughout the world are undergoing radical, involuntary transformations, the result of an explosion of raw information suddenly available to them. Not only does this demand new ways to collect, process, and use information, but also a new way to look at and link information sources that until now have been unconnected. After discussing the importance of intelligence today and its greater importance tomorrow, Vella and McGonagle develop the concept of Cyber-Intelligence(TM), then show how it applies to strategy-creation, marketing, crisis management, benchmarking, and other organizational functions. They turn next to data gathering in the context of their Cyber-Intelligence(TM) concept, ending with a thoughtful discussion of where C-I is going next.

Modern Information Systems (Hardcover): Christos Kalloniatis Modern Information Systems (Hardcover)
Christos Kalloniatis
R3,093 Discovery Miles 30 930 Ships in 18 - 22 working days
Accelerated Learning - 3 Books in 1 - Photographic Memory: Simple, Proven Methods to Remembering Anything, Speed Reading: How... Accelerated Learning - 3 Books in 1 - Photographic Memory: Simple, Proven Methods to Remembering Anything, Speed Reading: How to Read a Book a Day, Mindfulness: 7 Secrets to Stop Worrying (Hardcover)
Ryan James
R653 R597 Discovery Miles 5 970 Save R56 (9%) Ships in 18 - 22 working days
The AI Con - How to Fight Big Tech?s Hype and Create the Future We Want (Paperback): Emily M. Bender, Alex Hanna The AI Con - How to Fight Big Tech’s Hype and Create the Future We Want (Paperback)
Emily M. Bender, Alex Hanna
R440 R393 Discovery Miles 3 930 Save R47 (11%) Ships in 5 - 10 working days

A smart, incisive take-down of the bogus claims being made about so-called ‘artificial intelligence’, exposing the real harm these technologies do to our jobs, health, society and environment, who stands to gain from them, and how to fight back.

Is AI going to take over the world? Have scientists created an artificial lifeform that can think on its own? Is it going to replace all our jobs, even creative ones, like doctors, teachers and care-workers? Are we about to enter an age where computers are better than humans at everything?

The answers to these questions, as the expert authors of The AI Con make clear, are 'no', 'they wish', 'LOL', and 'definitely not'. In fact, these fears are all symptoms of the hype being used by tech corporations to justify data theft, motivate surveillance capitalism, and devalue human creativity so they can replace meaningful work with jobs that treat people like machines. Meanwhile, across healthcare, education, media, government and law-enforcement, ‘AI’ products are already being introduced that are unreliable, ineffective, unjust and dangerous.

Packed with real-world examples, pithy arguments and expert insights, The AI Con arms you to spot AI hype in all its guises, expose the exploitation and power-grabs it aims to hide, and push back against it at work and in your daily life.

Advances in Computer Science and IT (Hardcover): Dil Hussain Advances in Computer Science and IT (Hardcover)
Dil Hussain
R3,617 Discovery Miles 36 170 Ships in 18 - 22 working days
CNC Tips and Techniques - A Reader for Programmers (Paperback): Peter Smid CNC Tips and Techniques - A Reader for Programmers (Paperback)
Peter Smid
R1,262 Discovery Miles 12 620 Ships in 18 - 22 working days

OverviewDuring the past decade, Peter Smid wrote dozens of column for Shop Talkmagazine that addressed the full gamut of CNC topics, such as tapping and threading and knurling; program length and memory needs; G-codes, M-functions, cycles, macros … and more still.  Ever since Shop Talk ceased publication, these columns have been unavailable. Now, in CNC Tips and Techniques, we are delighted to bring them back—over 60 of the best of Peter’s columns --- all under one cover, so that you can have full and easy access to the advice Peter has been sharing during the past decade. CNC Tips and Techniques is a treasure trove of Peter Smid’s “lost work†that is certain to be an invaluable addition to your CNC toolkit.  We hope the advice and instructions contained in these readings will help you do your job more efficiently and more effectively – and that you find them a good read besides.  Features Offers more than 60 focused columns which have been thoroughly reviewed since its initial publication and updated as needed to reflect ongoing changes in the field. Columns are presented here in chronological order of when they first appeared. Includes an alternative table of contents, organized by topic. Provides several useful appendices and an extensive index. Appeals to both veterans and newcomers with tips and techniques that can be applied at work and speed up the learning curve.  Peter Smid is a professional consultant, educator and speaker, with many years of practical, hands-on experience, in the industrial and educational fields. During his career, he has gathered an extensive experience with CNC and CAD/CAM applications on all levels. He consults to manufacturing industry and educational institutions on practical use of Computerized Numerical Control technology, part programming, Autocad®, Mastercam® and other CAD/CAM software, as well as advanced machining, tooling, setup, and many other related fields. His comprehensive industrial background in CNC programming, machining and company-oriented training has assisted several hundred companies to benefit from his wide-ranging knowledge.   Mr. Smid’s long time association with advanced manufacturing companies and CNC machinery vendors, as well as his affiliation with a number of Community and Technical College industrial technology programs and machine shop skills training, have enabled him to broaden his professional and consulting skills in the areas of CNC and CAD/CAM training, computer applications and needs analysis, software evaluation, system benchmarking, programming, hardware selection, software customizing, and operations management. Over the years, Mr. Smid has developed and delivered hundreds of customized educational programs to thousands of instructors and students at colleges and universities across United States, Canada and Europe, as well as to a large number of manufacturing companies and private sector organizations and individuals. He has actively participated in many industrial trade shows, conferences, workshops and various seminars, including submission of papers, delivering presentations and a number of speaking engagements to professional organizations. He is also the author of articles and many in-house publications on the subject of CNC and CAD/CAM. For six years he had a monthly column in the ShopTalk Magazine related to CNC programming. During his many years as a highly respected professional in the CNC industrial and educational field, he has developed tens of thousands of pages of high quality training materials. The author welcomes comments, suggestions and other input from educators, students and industrial users. You may contact him at [email protected]. Also by Peter Smid: CNC PROGRAMMING TECHNIQUES An Insider's Guide to Effective Methods and Applications FANUC CNC CUSTOM MACROS Practical Resources for Fanuc Custom Macro B Users   Sample Readings   Programming a Long Thread  Trial Cut for Measuring  Special-Purpose G-Codes  Running the First Part — Economically, That Is   Programming a Long Thread 1.    Programming a Long Thread In the essay Limitations in Threading, the main focus was on limitations in single point threading caused by spindle speed that is either too high or too low. In this essay, we look at the effect of threading feedrate, particularly how it applies to long threads.  What exactly is a long thread may be a subject for some discussion. For the purposes of this article, a long thread is a thread with a ratio of rather small diameter to long threading length. In most everyday threading operations, you will work with threads that have a length relatively short respective to their diameter. These threads, which do not require any physical support at the machine, generally do not present any problems in programming or machining. Machining long threads does have a few challenges, however. Long threads often require suitable support devices, at least a tailstock for basic support, but often a follower rest or a steady rest as well, in order to prevent deflection of the part.  Many CNC machine tool builders provide lathes specially designed for machining long parts, such as shafts and tubular stock. These lathes (often of the flat bed type) are also capable of threading over their entire Z-axis travel. From the CNC programmer's perspective, a possible problem lies with the feedrate for certain imperial threads. Feedrate for threading is always the thread lead, and no rounding is necessary for metric threads. Some imperial threads have to use rounding for feedrate calculation, when the threads per inch (TPI) are converted to the thread lead (cutting feedrate).  As an example of a possible problem of feedrate rounding, consider a single start, standard form 60 degree thread 6.0-12, over the threading length of 70 inches (actual use of the thread is not important for the illustration):  Thread diameter = 6.0 inches Thread per inch (TPI) = 12 Length of thread = 70 inches  Assuming a suitable tooling and part setup, the thread cutting program is easy:  N51 T0500 N52 G97 S550 M03  (SPINDLE SPEED 550 RPM) N53 G00 X6.25 Z0.4 T0505 M08  (START POINT CLEARANCE) N54 G76 P011060 Q005 R0.002  (G76 - BLOCK 1) N55 G76 X5.8978 Z-70.0 R0 P0511 Q0120 F0.0833  (G76 - BLOCK 2 - 0.0833 IPR) N56 G00 X12.0 Z5.0 T0500   (TOOL CHANGE CLEARANCE) N57 M01 All program data look reasonable, but let's focus on the programmed feedrate of F0.0833. For twelve threads per inch, the pitch is 1/12 = 0.08333333, which is also the thread lead and programmed feedrate. Now, consider the feedrate actually used in the program, F0.0833. It has been rounded to four decimal places, as is customary for imperial dimensions. Inevitably, the rounding has brought in a certain amount of inaccuracy. Over one inch length, the error is: 1 - 12 * 0.0833 = 0.0004 inches In most cases, this error can be absorbed by the thread tolerances. Now, consider the same error over a significant thread length, such as our example of 70 inches: 70 * 0.0004 = 0.0280 inches — this is a significant error Because the 0.0833 amount was the correct rounding to four decimal places, any other rounding would make the accumulative error even worse. The solution to this problem is quite simple — just change the programmed feedrate of F0.0833to a new feedrate of F0.083333, from four to six decimal places. Fanuc-type controls allow this method, for the exact purpose of minimizing the accumulative error for long threads. With F0.083333, the error over 70 inches will be: 1 - 12 * 0.083333 = 0.000004 inches * 70 = 0.00028, which is less than three tenths. Older Fanuc and similar controls could not use F-addresses with six decimal places, but the control provided E-addresses, specifically for threading, which did allow six decimal places. The six decimal place accuracy is not required for threads that have lead divisible into four or fewer decimal places, for example 16 TPI = 1/16 = 0.062500. The G76 threading cycle itself will be discussed in two other essays looking at basics and details.   2.    Trial Cut for MeasuringPrecision CNC machining is always a cooperative effort between CNC programmers and CNC machine operators. Programmers can employ certain program features that will enable the machine operators to perform functions that would otherwise be difficult or even impossible. One such method is programming a trial cut for measuring. There are many factors in machining that influence the final size of a part, such as heat, tool deflection, tool wear, and even lubrication to some extent. For those parts that require very tight tolerances, the negative effect of these factors may result in an out of tolerance size and even a possible scrap. Another problem that is quite common is machining certain hard-to-measure shapes, such as a cone on CNC lathes. By using a simple programming method known as the trial cut, CNC programmers can greatly influence the final size of a part. Take the already mentioned cone as an example. Without a suitable custom gauge, a cone is a difficult shape to measure at the machine, as there is no flat spot for the micrometer to use. Even if such a special gauge is available, it will be too late to find out that the cone is out of tolerance. The method of using a trial cut is to provide a special flat area (diameter) that can be easily measured, before the final cone is machined, following a few simple rules. Normally, a cone machined from round stock, such as the 5.0 inch diameter used in the following example, will include G71 roughing cycle and G70 finishing cycle in the part program: N1 G20 T0100 (ROUGHING TOOL) N2 G96 S300 M03 (CUTTING SPEED) N3 G42 G00 X5.2 Z0.1 T0101 M08 (START POINT FOR CYCLE) N4 G71 U0.15 R0.025 N5 G71 P6 Q8 U0.07 W0.02 F0.015 N6 G00 X2.8 (CONE START) N7 G01 X4.6 Z-3.5 F0.008 (CONE END) N8 U0.2 (RETRACT FROM PART) N9 G40 G00 X10.0 Z4.0 T0100 (CLEAR POSITION) N10 M01 N11 T0300 (FINISHING TOOL) N12 G96 S500 M03 (CUTTING SPEED) N13 G42 G00 X5.2 Z0.1 T0303 M08 (START POINT FOR CYCLE) N14 G70 P6 Q8 N15 G40 G00 X10.0 Z4.0 T0300 (CLEAR POSITION) N16 M30 % Although correct, the program above does not offer any means to measure the conical part efficiently. By adding several blocks of trial cut in the program and using the finishing tool (T03), a suitable straight cut can be machined first. When measured, various offsets can be adjusted as necessary — all this is done before any roughing cuts take place: / N1 G20 T0300 (FINISHING TOOL) / N2 G96 S500 M03 (CUTTING SPEED) / N3 G42 G00 X5.2 Z0.1 T0303 M08 (INITIAL POSITION) / N4 X4.925 (DIAMETER TO BE MEASURED) / N5 G01 Z-0.35 F0.008 (LENGTH OF CUT FOR MEASURING) / N6 U0.2 (RETRACT) / N7 G40 G00 X10.0 Z4.0 T0300 (CLEAR POSITION) / N8 M00 (MEASURE DIAMETER - MUST BE 4.925) N9 G20 T0100 (ROUGHING TOOL) N10 G96 S300 M03 (CUTTING SPEED) N11 G42 G00 X5.2 Z0.1 T0101 M08 (START POINT FOR CYCLE) N12 G71 U0.15 R0.025 N13 G71 P14 Q16 U0.07 W0.02 F0.015 N14 G00 X2.8 (CONE START) N15 G01 X4.6 Z-3.5 F0.008 (CONE END) N16 U0.2 (RETRACT FROM PART) N17 G40 G00 X10.0 Z4.0 T0100 (CLEAR POSITION) N18 M01 N19 T0300 (FINISHING TOOL) N20 G96 S500 M03 N21 G42 G00 X5.2 Z0.1 T0303 M08 (START POINT FOR CYCLE) N22 G70 P14 Q16 N23 G40 G00 X10.0 Z4.0 T0300 (CLEAR POSITION) N24 M30 % The first eight blocks are shown with a block skip function, represented by the / symbol. It is more likely that the actual measuring will not be required for each part. This approach to part programming is more efficient because it eliminates a re-cut and greatly enhances accuracy. Setting the block skip mode OFF, CNC operator checks the trial dimension (note the message attached to M00 program stop function), adjusts the suitable offset if necessary, and continues machining with block skip set ON. Note that the trial cut was done with the same tool that will be used for finishing. When selecting trial cut diameter, make sure the tool removes about the same amount of material that is removed in the finishing cut. In the example, the trial cut diameter is 4.925, resulting in the actual depth of cut (5.0 – 4.925) / 2 = 0.0375 per side, which is almost equivalent to the amount of stock left for finishing:  0.07 / 2 = 0.035 per side. The length of such a cut should be sufficient for micrometer (0.35 in the example).  Also, the machining speed and cutting feed rate should be the same for best results. The trial cut is a special cut performed on demand only. Although a lathe example has been presented here, trial cuts have many applications in milling operations as well. The main key is to identify the need first; then, provide a suitable program. 3.    Special Purpose G-CodesAnybody even loosely associated with CNC work is probably familiar with the G-codes, at least with their existence. Preparatory commands, as they are officially called, have a single purpose — they give a specific meaning to other commands in the part program. For example, a programmed command X10.0 can be interpreted as 10 mm, 10 inches, or even as 10 seconds. If this command represents a dimensional program entry, it could be an absolute position or an incremental distance and direction, in rapid or feedrate mode. The exact meaning is defined by one or more G-codes. For example, an incremental feedrate motion of 10 mm will require that G21 (metric mode), G91 (incremental motion), and G01 (linear interpolation) commands are in effect, along with appropriate feedrate.  Many preparatory commands are well known to CNC programmers and operators alike, as they are used in virtually every program, such as those shown in the example. Yet, a list of G-codes for a particular control can be quite long and contain many that are hardly used. Typically, a preparatory command will have two digits following the letter G. Three digit G-codes generally identify the G-code as a particular cycle or function to the CNC machine that uses them; they are not usable anywhere else. Three-digit G-codes are often special macros supplied by a particular machine tool builder. Within the two-digit category of G-codes, there are also several that are fairly common, yet hardly ever used in a part program.  One pair is G22/G23, defined as Stored Stroke Check, ON and OFF respectively. In plain terminology, using these commands allows the programmer to define special three-dimensional zones either as ones that allow a tool from entering or as zones that prohibit a tool from entering. Such definitions may prevent a collision with a certain part of the machine or a fixture.  A relatively recent pair of other G-codes, G25/G26, is used to detect severe spindle fluctuation caused by heat. When G26 Spindle Fluctuation ON is in effect, the control system monitors whether the fluctuation is within specified tolerance range or not. Should the tolerance be exceeded, the control will issue an alarm, warning the user. In order to use this function correctly, a consultation with a service technician is recommended.  Another set of G-codes is a foursome related to the return to machine zero: G27/G28/G29/G30. Whereas the G28 command and, to a large extent, the G30 command are used to move the specified axis or axes to the machine zero (G28 to the primary and G30 to the secondary machine zero), the G27 and G29 are seldom, if ever, used in a typical part program. Command G27 is a machine zero position check. It is programmed with one or more axes and checks whether the position specified corresponds to machine zero position. If not, the program processing stops and alarm is raised by the control. Its practical application has ceased with the demise of G92 (G50) programming (position register). There is no need for this command in a program that uses work offsets (G54 to G59 or higher). G29 is the opposite of G28/G30. Whereas G28/G30 represents a motion to machine zero via an intermediate point, G29 is a motion from machine zero to a specified position via an intermediate point. This command is virtually useless in typical programs.  Another virtually useless command is G44 (tool length offset negative). It may have its adherents, but there is nothing that the ubiquitous G43 command (tool length offset positive) cannot achieve.  A command that may be somewhat of a puzzle is G31, defined simply as the Skip command. This command is indeed a very special one because it is exclusively used with probing on CNC machines (in-process gauging). Its purpose is to move the probe from a clear position, at a feedrate (just like G01), to a position to be probed. Once the probe detects a contact with the material, the motion stops and the remainder of the motion is not completed; it is skipped, hence the command name.  Finally, there are several G-codes in the G6x range, namely G60 (Single direction positioning), G61 (Exact stop check mode), G62 (Automatic corner override mode), G63 (Tapping mode), and G64 (Normal cutting mode). The default is G64, normal cutting mode.  G61 is the modal version of G09, and can be useful for increased precision when a tool has to move around a sharp corner at a high feedrate, particularly if the corner forms a narrow angle. G62 may improve the surface finish when used to cut sharp inner corners in cutter radius offset mode. Its function is to automatically adjust the cutting feedrate. A tapping mode programmed with G63 disables the feedrate override and the feedhold button, and G64 returns the cutting motions to their original programmed mode. Each mode selected replaces any other mode.  G60 stands separately. Its purpose is to force a unidirectional tool positioning, regardless of which direction the tool comes from. It can be used to compensate for some minor backlash, but it does not remove it. Backlash problems require qualified service technicians.  There may be other G-codes not commonly used, but the ones mentioned in this column should provide some understanding of the more common special purpose G-codes.  4.    Running the First Part — Economically, That IsMachining a batch of the same parts in a single production run is probably the most common reason for purchasing a CNC machine. The CNC technology offers a great amount of predictability. There is consistency between parts, dimensional accuracy is maintained over many parts, and the program and setup — once verified — can be used over and over in the future. Yet, even with proven part programs, the production always hits one weak spot when running a new batch. Yes, it is the first part. Every supervisor knows that the first part of the batch is also the most expensive part of the whole batch; its cost of manufacturing proportionally affects all remaining parts. To minimize the cost of making the first part, it is worth looking at several influencing factors and possible solutions. Comparing Programs There is a significant difference between running the first part using a new program and a program that had already been verified. New part programs CNC programs that have never been used must be carefully inspected. Even programs generated by a CAD/CAM system require certain scrutiny, although on a much smaller scale. Programming errors and oversights can find their way into any program in various forms, some quite hard to detect. For example, the depth and width of a cut may be out of a reasonable range, clearances may be too large or too small, spindle speeds and feed rates may be overrated or underrated, a tool may not be the most suitable one for the job, and so on. These oversights are virtually impossible to see in print or even on the screen — they show only when the first part is run on the CNC machine. In addition to the program itself, the machine setup is always new, regardless of whether the program is new or previously verified. Verified part programs These are part programs accepted for production and verified at some earlier date. Keep in mind that only the programs have been verified, not the setups or tools. Setups and tools are subjects to frequent changes; they must be verified every time. Another important consideration is the CNC machine tool being used. Even verified programs have to be checked if they are used on a different machine than the previous time. Decreasing Costs Decreasing the cost of the first part — and, therefore, the whole batch — has to be considered at four levels, all interrelated: Planning Process planners or supervisors have to evaluate many aspects of the production. One of their key considerations is the number of parts produced in a single batch. The more batches per period of time, the more expensive each batch will be, mainly because of the repeated setups. Assuming that more parts produced in a batch will have no negative side effects (for example, on inventory), fewer batches per period of time might provide part of the solution. 5.    Programming CNC programmers can literally do wonders to decrease the cost of the first part through the program. Here are only some ideas. Using consistent tool numbers for commonly used tools saves time during setup, as tool registration and many related offsets will not change. Another very effective programming method is to include one or more trial cuts with the block skip function in the program. These cuts will only be used for the first part testing, but turned off for a full run (except the occasional inspection). Don't forget to provide sufficient comments in the program, so the operator knows the purpose of these special cuts. Another consideration, especially for programs developed manually, is to invest in reliable CNC simulation software. Although no software can simulate every detail of CNC machining, it can be an excellent tool to find errors and areas of improvement. Setup At the machine, the CNC operator is normally responsible for setting up tools and fixtures, registering tool numbers and various offsets, troubleshooting the program, and monitoring the operation. Speeding up the non-productive time required for setup is the most significant single saving available. Modular fixturing, common tooling, general setup consistency, and the operator's skill all add up to make the transition between setup and operation faster and smoother. Machining During machining, the CNC operator relies heavily on the program itself. During the first part run, it should not be enough for the CNC operator to look just for errors or monitor the program flow. Operators can and should do much more at the same time. For example, they can think about optimizing the program for better performance. Speeds and feeds are the most common areas to focus on, but many more “little things†also influence the cost of manufacturing (including the first part). Lowering the cost of the first part should be a team effort. CNC programmers may be the key people in such efforts. However, mutual cooperation of everybody involved will offer many benefits and have a positive effect on the proverbial bottom line.   OPERATIONS  General Cutting Knurling   Lathes Machines Tapping Threading Tools Turning    PROGRAMMING   Programming Techniques Subprograms Toolpaths   CODES, FUNCTIONS, AND MACROS   Codes Functions Macros   CYCLES   THE MATHEMATICS OF CNC   CNC GEOMETRY   WORKING IN THE FIELD

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