Mastering CNC Machining Centers
Course Outline

Course 1: The Basic CNC Machining Center

Lesson 1: The Computer Controlled Machine Tool [ Top ]

The introduction to this lesson identifies the brands and models of control that will be seen throughout the training program. The student will see the four most widely used brands, Fanuc, Haas, Mazak and Okuma CNC controls. Within each brand the student will see the models of control most commonly found in industry.

The lesson begins by identifying the basic operating principles of a CNC machining center. Both vertical and horizontal style machines are covered. Models in which the tool moves, or both the tool and table move, are examined. An explanation of how the computer views these various movements as only tool movements is discussed. The physical limits of the resulting tool movement is explained as establishing the work window or cube.

The mechanical components of the machining center are explained in the next section. The terms established here are used throughout the balance of the instruction when referring to these components. The lesson includes workpiece holding devices such as dedicated fixtures, modular fixtures and vice systems. Manual and pallet loading mechanisms, and several automatic tool handling and retrieval mechanisms.

Next, the lesson presents the basic components of the CNC control itself. The computer screen display, horizontal and vertical soft keys systems, MDI keys, Mode selections switches and manual machine controls are explained. Within each component, a discussion covers the typical variations found on machines including such topics as screen sizes, touch screen, control panel configurations and so on. The basic soft-key menu system is explored revealing part programs, offsets and position data displays. Page and cursor keys are reviewed. Lastly, the differences and similarities between the various brands of control are reviewed.

Lesson 2: The Coordinate Grids on Machining Centers [ Top ]

As the most fundamental part of the CNC machining center and its operation, the coordinate grid is covered in detail in this lesson.

From a general discussion of the grid, the instruction moves into the specific application of the grid to the machining area of the machining center. Next, the units of measure used within the grid, and the axes of movement of the machine, are explained in detail. The rotational axes of movements are introduced as well.

As many errors by operators involve mistaking the signs of coordinates and the signs of machine movements, the next section covers these concepts in detail. The idea and typical application of program zero and machine zero are introduced at this time.

Understanding the use of more than one grid system on a machining center has always been a point of confusion for new operators. The use of multiple zero points, and the resulting grids they establish, are explained in the next portion of the lesson. Further, the specific application of multiple grids as used on Fanuc, Haas, Mazak and Okuma models is covered.

Lesson 3: Machining Center Operations and Tooling [ Top ]

Now that the grid system has been explained, the instruction moves on to discuss the systems involved in positioning of tools within these grids.

The lesson begins with an explanation of the way in which the computer receives and interprets program commands to control the tool and work table movements. The speed of these movements is then broken down further into rapid traverse and feed rates. The concept of reducing cycle time is introduced as well.

The lesson then defines the basic machining movements needed to create a finished workpiece including such items as rough and finish cuts. The concepts of depth of cut, feed rate, and surface speed are then discussed.

The lesson then moves on to explain the specific types of machining movements the machining center can perform: milling, contouring, drilling, and so on. The types of milling cuts and the configuration of the cutters which perform these actions are explained. In addition, other machining operations such as reaming, boring, and tapping are explained, as well as the tools used to perform these operations. Because each machining process requires coolant supplied to the cutting tool, a discussion of the coolant system follows. The removal of the coolant and chips from the machining area is reviewed in the last portion.

Lesson 4: Automatic Machining and Manual Controls [ Top ]

With an understanding of the basic principles of machining center functions and tooling, the student is now ready to perform as a machine tender. This lesson prepares the student to take over an existing job and provides and maintain operations. It includes an explanation of the process of removing completed workpieces, cleaning fixtures, preparing the next workpiece, and locating and properly securing it in the fixture. The Cycle Start, Feed Hold, Emergency Stop, and Reset buttons are covered.

The equivalent manual machine controls are also explained. Comparisons between older- and newer-style control buttons and switches are included. A comparison is made between the names used to identify similar controls on each brand of control.

The controls used on Tool Changers, Pallet Changers and B axis rotary tables are also discussed. The operator then learns to jog the machining center components within each axis of travel using either the jog buttons or the Hand Pulse Wheel and its controls. The next portion explains how to manually HOME or zero return the machine using the controls, and explains when this operation must be performed. The concerns with overtravel and how to overcome that condition is discussed for each brand of control.

Automatic machining begins with details on how to assure the program has reset for the next part and the various codes that perform that function. How to remove, clean, prepare, locate and clamp the next part is examined. How to check the first part using override control and the DTG display is shown on the specific CNC control selected for each trainee.

Course 2: Understanding Part Programs

Lesson 1: Programming Methods of CNC Machining Centers [ Top ]

Whether an operator ever needs to write a program or not, they will be required to read part programs so they can determine the corrective action needed to solve quality problems. This lesson introduces the most common languages used in machining center programming.

The lesson begins by explaining the basic concepts of computer programming languages and then carries the concept into the specifics of machining center programming. Two levels of program preparation are discussed: EIA and Conversational. Since many Conversational languages are normally translated into EIA codes before execution on the machine, a more detailed look at the elements of the EIA coding system is then provided. The need to edit a conversational program to reduce cycle times is discussed.

The concept of blocks and the use of Sequence Numbers to help locate specific blocks within an EIA coded program is examined next. The other elements that make up a block are then revealed including coordinates and codes. The structure of a typical code and a coordinate are then shown. As an example, the G01 code and the coordinates that typically follow are examined along with how the computer interprets that combination as a linear movement to an end-point by the active tool. M codes and several examples are covered next.

The initialization blocks are examined next along with their ability to establish the inch or metric system of coordinate interpretation, set the spindle speed, cancel remaining offsets and so on. Next, the division of the following blocks into Tool Paths with T codes is revealed. The use an automatic tool changer, ATC, to place the correct tool in the spindle is then covered. The codes used to end a program and rewind to the beginning are then revealed.

Next, the lesson looks at the elements of a typical Conversational program as they appear on a machining center control. The Mazatrol language is used as the example with its Unit structure. The Common and Work-Piece Coordinates Unit are examined as equivalent to the initialization blocks shown earlier. The machining Units are then compared to the T codes in EIA programs. The structure of Sequences are then compared to blocks within a tool path along with the Shape and Figure Data. The END Unit is then examined.

In the last part of the lesson students learn about the capabilities added to the standard EIA/ISO programming language by various control manufacturers. As an example of these "language extensions" Macros and Okuma "User Task" programming are shown. Topics include Common Variables and System Variables, conditional branching and unconditional branching using IF and GOTO, value passing to subprograms, math operators, and logic operators. All of these concepts are shown in the context of example part programs.

Lesson 2: EIA and User Task Programming Codes [ Top ]

The previous lesson in this series illustrated the importance of understanding EIA programming techniques, even on those machining centers which use Conversational programming methods. With this understanding, the student is ready to learn how specific EIA codes control machine movements.

The common G, M, S, T, and F codes are covered in the first three sections. Since the process of suppressing leading zeros on some controls can make reading these codes within a program more difficult, this technique is explained. The division of the codes into modal and non-modal groups, and the default codes within each group, is covered in the following section. The concerns with non-linear G00 tool paths and the potential for collisions are also detailed. The codes covered include G01, G02, G03, G04, P addresses. The Plane select codes are also examined, G17, G18 and G19. The next part discusses M07, M08, M09, M05, M01, M00, M06, M03, M04 as well as G94, G95 and F codes.

In the fourth part, Okuma User Task programming is explained in more detail. The goal of this instruction is to teach a machine operator to read and follow the logic of simple User Task commands and subprograms. All basic concepts are covered: variables and how they work, the four types of User Task variables local, common, system, and I/O, and examples of each. The structure of programming using GOTO and IF commands, math operators, and logical operators are also revealed within program examples.

Lesson 3: The Structure of EIA/ISO Part Programs [ Top ]

Now that the purpose of the individual codes within a program have been covered, an explanation of how these codes are organized into blocks and tool paths follows. This lesson breaks a typical program down into initialization blocks, tool paths, reset blocks, and sub-programs. The use sequence numbers or block numbers is reviewed and where to find the display of the number of the currently active block on the screen. This enables an operator to quickly find specific portions of the program when editing or troubleshooting is required. The use of the BLOCK SKIP or DELETE slash code is examined. The use of spaces between codes in a block and the use of colors to identify codes and coordinates. The zero suppression features found on some controls are shown as it impacts the reading of a program without leading and trailing zeros as well as the end-of-block symbol.

The use of G90 and G91 in the initialization block and the interpretation of the codes as either absolute or incremental is examined next. The comparison between a physical address and a set of directions is used to illustrate the differences. The use of the G28 code to return to the reference point is compared to absolute encoders available on each of the controls covered. The use of intermediate points behind a G28 code are explained as a way to avoid obstructions before returning to home.

Next, the use of G40 and G49 to cancel offsets before a tool change are shown along with the G80 code. This is followed by the G20, G21 coordinate selection codes and the impact on the program coordinates when viewed as inch or metric. This leads to a discussion of the correct terminology to use when reading or communicating both inch and metric dimensional values. The concepts of tenths, thousandths and microns are covered.

The application of the codes G54 to G59 along with the use of G15 on Okuma controls is discussed in the specific section. The location of tools paths is covered as it relates to M06 and T codes. Variations in the use of the T address and multiple T addresses are examined. A further discussion on tool life management follows. The application of the G30 code is next. The use of G43 and G44 to apply length offsets is detailed along with the G41 and G42 CRC codes and related D addresses.

Finally the application of sub programs and reset blocks is examined along with the M98 and M99 codes and the P address words.

Lesson 4: The Structure of Conversational Part Programs [ Top ]

Similar to the previous lesson, this lesson covers the programming techniques used in the organization of Conversational part programs. It begins by discussing the Unit as the basic building block of a conversational program. The Units include three types, initialization, tool paths and machining.

Next, the common unit is examined as establishing the material type to be machined, the initial Z axis safe point, the ATC mode, and multi part machining directions. The program zero location established in the WPC unit is discussed nest with control over 4 axis positions.

Probing of the workpiece is explained with the details about the MMS unit and how it places values in the WPC unit. The Offset unit is also explained.

The next section begins by explaining the Unit, Sequence and Figure data to define the type of machining, sequence in which it is machined and the physical shape of the feature.

Conversational controls use a variety of tables and registers to automatically calculate the coordinates, speeds and feeds, tool changes, and all the other information normally included in a tool path. This next section details these tables and the relationship between the values stored there.

Conversational controls have a function called Priority Machining which reduces cycle time by minimizing the number of tool changes throughout the program. Tools remain in the spindle to make as many machining passes as possible on various features. The programming behind this capability is examined.

The last portion of the lesson explains the use of Sub Program, Pallet changing, Indexing, and End units.

Course 3: Machining Center Operator Skills

Lesson 1: Machine Start-up, Computer Memory, and Program Storage [ Top ]

Most CNC machinists begin their careers as machine operators. While the specific duties within shops may vary, generally this job classification includes machine start-up, checking operating systems, and activating a proven part program. This lesson provides the student with an explanation of these procedures.

The lock out/ tag out safety system on the main power switch is explained. Then the three primary systems, way oil, hydraulic and their various sight gauges on the machine are shown. The changes between a warm and cold machine on fluid levels and the concerns with overfilling are discussed. The method of using a refractor gauge to check coolant-to-water ratios is shown. Next, the Hydraulic pressure gages and the importance of maintaining filters is covered. The automatic maintenance check systems built into some controls is examined.

Since part programs have been thoroughly covered in the previous course, this lesson explains how the various parts of a computer control's memory are used to store and execute part programs. The importance of checking available memory capacity before loading new programs and the process of clearing unused programs is stressed. The concepts of bytes, characters, program spaces and hard drive sectors is explained to enable operators to perform calculations regarding available memory.

The nomenclature used on each control to store files, programs and subprograms is covered next. The lesson then explains the process of displaying a directory of programs on each model. The data displayed in these directory screens is then reviewed in detail. The use of SEARCH functions and MDI keypad to locate stored programs names or numbers is also shown.

Lesson 2: Deleting, Loading, and Activating Part Programs [ Top ]

This lesson begins by explaining how various part-program file management systems are designed. It then discusses the capacity of the various storage mediums used including, USB drives, flash cards, laptops, and computer networks like DNC. The READ and PUNCH functions are explained.

Since the control's available memory may not be sufficient to hold a new program, the student is shown how to evaluate and select a program which can be deleted from memory, and to complete the deletion process on each model of control. Techniques for backing up programs are also explained. The programs numbers protected from editing are also revealed

Having learned how to make enough space available within the memory of the control, it is then possible for the operator to learn how to load both EIA and conversational programs.

In the last portion of the lesson, the operator will learn how to make a program active on each brand of control and how to detect the currently active program in each control.

Lesson 3: Understanding Tool Offsets [ Top ]

This lesson begins with a thorough explanation of the concept of tool offsets and how they are applied in both conversational- and EIA-based controllers. Also explained are the concepts of geometry and wear offsets for both tool length and cutter radius compensation.

The concept of program zero and spindle zero, or gauge point, are introduced. The concerns with potential collisions if no length offset or an incorrect tool length offset is entered are stressed. Examples of measuring depths of a drilled hole and how the wear offset would be calculated and the sign of the adjustment determined are examined.

Cutter Radius Compensation is covered next. The technique of programming for the centerline of the spindle is discussed and the need for a correct CRC values to avoid damage to tooling and machinery. The caution of determining how the program was written regarding diameters versus radius values is discussed.

Automatic tool plungers are revealed as a device to measure tool length offsets. The use of preset tools is also covered. The data screens used for the entry of tool offsets are shown for each brand and model of control covered in the program. The programming of G43 and G44 along with the H address words for length and the G41 and G42 and D address words are explained. The G40, H00 and D00 cancel codes are examined next. The issues of programming a movement within an axis after assigning a tool offset are detailed to help explain programming.

The difference in coding for the Okuma and Haas machines are covered in detail in the specific portion of the lesson for each control.

Since conversational controls require more comprehensive entry of tool and cutting conditions data, the Mazak Tool File and Tool Data screens, and the information they display, are explained. The last section covers the use of Cutting Conditions and Material Selection data on a conversational control. The setting of feeds and speeds based on tool and workpiece material types is explained.

Lesson 4: Identifying Quality Problems [ Top ]

Statistical Process Control is one of the most common ways for operators to reduce scrap and rework. It allows the operator to monitor the process and make corrections before any out-of-tolerance parts are produced. The concepts of random variation and assignable cause are defined along with the use of capability studies to discover the extent of normal variation within a process. The histogram is introduced as a measure of distribution of that variation and the shape of the curve produced.

The X-bar and R chart are defined and explanations of how the calculations used to define the a double bar upper and lower control limits are achieved and the location of the limits within the R chart. The methods used to determine the frequency of measurement is examined next. The various type of out-of-control conditions the X-bar and R charts can identify are explained. The use of sub groups and the justification for the use of this technique is revealed as a method of accurate prediction of an out-of-control process before out-of-tolerance parts occur. The CPK ratio is examined and the responsibility the operator has in maintaining the value within an acceptable range.

The studentís role as machinery operator will entail running a workpiece and checking and identifying any quality defects that occur. In addition, the learner must be prepared to identify quality defects as they appear in jobs for which he assumes operational responsibility.

A large portion of the lesson deals with the logical thought processes needed in troubleshooting, providing the student with the most efficient method of finding and eliminating quality problems, with an emphasis on reducing downtime. Also discussed are the causes of common quality defects and the most likely source of each problem. The quality problems covered include surface finish, location of features, and the size of features.

Lesson 5: Correcting Quality Problems and Program Restart [ Top ]

Having learned how to quickly identify the source of quality problems, the student is now instructed in making the adjustments necessary in order to resume production. This lesson first deals with stopping automatic execution once a defect has been found in order to make some of the more common corrections.

The common causes of chatter are examined and the use of override controls as temporary solutions. The use of manual controls such as Feed Hold, Spindle Stop, E Stop, Reset and Coolant Off are discussed. Specific functions such as the Mazak VFC are also shown to Mazak students.

The process of checking for the proper of mounting of a workpiece to a fixture is taught as a troubleshooting technique for certain problems. The use of the override percentage value used to overcome a problem is demonstrated as a tool to calculate a new feed rate or spindle speed as a potential solution.

The lesson goes on to teach the learner how to calculate a tool offset value, and determine its correct sign and address to overcome a specific quality defect. Since this frequently involves calculating with signed numbers, that process is taught next. The use of Wear Offsets and the various capabilities to perform the calculation by using the ADD or INSERT of values is revealed. The offset adjustment capabilities of each control type are discussed.

The next portion of the lesson enables the learner to identify chipped, burned, broken, and worn tools and cutting inserts through visual and tactile inspection. The process of removing, indexing, cleaning and or replacing an insert is then explained. The Program Restart functions available on each control are detailed in the final section. The concerns with selecting a restart block within a program are examined as well.

Course 4: Basic Setup and Programming Skills

Lesson 1: Process Planning, and the Selection and Installation of Workpiece Holding Devices [ Top ]

Because of the wider use of Conversational CNC controls, operators are often given the responsibility of writing workpiece programs. In addition, smaller shops which do not have off-line programming personnel or equipment may require the operator to assume all programming responsibilities on both EIA and conversational controls. This lesson prepares the student by giving him instruction in the task of planning the machining process.

The tasks include the reading and converting of dimensions on part prints to enable the writing of program coordinates, establishing a program zero location from the given print dimensions, and calculating rough-blank dimension requirements. The process of leaving a finishing allowance on surfaces is also explained. The intersection of datum surfaces on a print is explained as a convenient location for the establishment of part zero for machining. The use of zero offsets is also covered with the further explanation of the G54 to G59 codes.

The selection of material properly sized to accommodate all feature dimensions is explained next. As an integral part of planning the machining processes that must be performed, the selection of work holding devices is then discussed. The lesson presents the different types of work holding devices that are normally found in use on machining centers, including modular fixturing systems. The correlation between part zero and orientation of the part in alignment with the the work table axes is examined. The impact these decisions have on the signs of the axes within the quadrants established by part zero are also detailed.

The student is shown the proper procedure for removing and installing fixtures as well as the concerns with location as it impacts potential overtravel conditions. The issues of rigidity against the direction of force created during machining is examined. Cautions on part deformation and radial tool forces are examined. The sequencing of various machining operations is addressed to help reduce such issues.

The cleaning of the machine bed and preparation for a new fixture is highlighted. The concerns with the proper positioning of clamping devices and their supports are examined next. The potential for workpiece distortion, damage and the fulcrum effect are revealed. The concepts of grid plates on modular fixturing with their numbered and lettered locations serves to speed setup and eliminate errors. Dedicated fixtures are also covered along with sine keys or pins.

Both EIA and conversational programs may require pallet changing and indexing. The final portion of this lesson provides the student with information on how EIA programs and conversational units control these functions for each of the brands of CNC control covered in this course.

Lesson 2: Tool Selection, Installation and Priority Machining Functions [ Top ]

With the work holding device selected and installed, the remainder of the set-up of the machine can begin. This lesson continues the process by inspecting the existing tools which will be used for the new job, comparing them to the Tool Layout, and installing any new tools required.

The use of tooling catalogs is examined and the letter and number designations within the ANSI code for the shape and type of insert are detailed. The types of cutting inserts, drills, boring bars, and other tools are covered. The chip breaking features of the cutting edges of tools, chip clearance and how the machining material may influence those features are covered. On drills, reamers and boring bars the relationships between length versus rigidity are highlighted. The associated quality issues of bell mouthed holes are shown. The operator is told to use the existing tooling as much as possible to reduce costs.

The features of Automatic Tool Changers are examined next. The relationships between tool numbers and pocket numbers are covered and the potential need to move tools based on the program being made active. The process of safely indexing a changer, removing, and replacing tools is next. The type of mounting pocket and the orientation of the tool within a pocket is detailed. The spindle orientation codes are examined.

The need to allow clearance between wide tools such as face mills and the impact on the programming of tool changes is shown next. The process of manually changing tools is shown for those tools which are either tool large or too long for the tool changer mechanism. The importance of replacing tools in the established organizational system within the shop is emphasized.

The mechanical tool changer and coding differences between brands are shown in the final portion of the lesson. In the Mazak specific content they learn about the Tool Layout and Tool Data screens and their associations. The lesson also explains the use of the Priority Machining function of conversational programs and its ability to reduce cycle times.

Lesson 3: Locating Program Zero on a New Setup [ Top ]

Several methods have been used to establish program zero based on programmer preference and whether multiple workpieces are being machined on a ganged fixture. The first part details the process of finding the physical location of program zero for the job being set up. The various types of set points which may be on fixtures are defined along with the dialing-in process using dial indicators or edge finders.

The lesson explains how the G54 through G59 modal code series can be used to establish program zero on EIA-based machines and the offset table used to store the values. The use of a Shift value in the table to compensate for adjustments to fixture location are discussed next. The dialing-in process is then examined. An explanation of multiple zero points follows for situations in which multiple workpieces are machined through the use of Local coordinate systems.

The next part of the lesson explains how to locate and enter program zero on a conversational control like the Mazak. This section also details the use of Mazakís MMS unit for locating program zero from within the part program itself or by way of the MDI panel. The Teach function is also detailed.

The extension of the G54 code group through the use of a dot extension and a P address word in a program is examined. The use of G10 commands and L address words within the initializations blocks to automatically load work offsets and other values is covered next.

The following specific portion explains how the G15 and G30 codes are used to establish the program zero and reference point locations on Okuma controls. The G11 Local Coordinate system code is also covered when multiple workpieces are involved.

The establishment of program zero on a Mazak conversational control is covered in the next specific portion of this lesson. Both the use of the WPC and MMS unit are discussed. The use of the MMS function using MDI entry is also shown as an option.

The last portion covers the use of the G52 local coordinate system within a G54 to G59 setting of program zero. The examples display the shifting of zero for multipart fixtures while using a sub-program call for machining. The differences on Haas machines are examined.

Lesson 4: Entering Tool Length Offsets [ Top ]

The method of establishing tool length offsets will vary in shops based on the techniques used to establish program zero and whether preset or non-preset tools are used. This lesson begins by explaining how these factors relate and their impact on the method of entering length offsets.

The following part covers the two most common methods of entering tool length offsets when G54 to G59 codes are used. It begins with an explanation of the use of MDI to load the tool to be measured into the spindle. The use of a gauge block for touching off tools is examined next as indicated in the tool documents. The document will also reveal the T and H address words used within the program to call each tools offset from the offset table. The Reference Tool method of establishing tool length offsets in examined next. The trainee sees a demonstration of a tool being touched off and the values stored. The process of locating the offsets for the remaining tools is then demonstrated. The technique for locating and entering the G54 coordinates for the setup are then covered.

Another technique for entering tool offsets and establishing program zero is shown called the Zero Height Method. It allows non-preset tools to be used, but does not require the resetting of tool length offsets for each new setup. The technique and the math involved is demonstrated.

Part three of the lesson which specific to Okuma students, and part four which is specific to Mazak students, covers entering tool length offsets on each controls.

The Mazak section explains how the tool-length plunger is used on Mazak controls to measure and enter length offsets.

Lesson 5: Cutter Radius Compensation [ Top ]

Part one of the lesson explains the two methods that may be used by the programmer to apply Cutter Radius Compensation (CRC) to tools. They include the Centerline and Tool-edge methods and relative size of the CRC values based on each technique. The concerns with the radius of a tool when machining interior corners is also examined.

In part two, animations illustrate the impact of CRC on tool path movements. It includes learning when and how CRC is activated and deactivated within a tool path and the impact on the tool path in the following blocks. The concept of vectors and how the offset is applied to the positioning as the tool navigates around corners within the tool path. The G41 and G42 codes and the signs applied to each are examined in detail based on the Centerline and Tool-Edge programming methods. The importance of the Plane Select codes in this process is also revealed as it relates to both vertical and horizontal machinery designs.

Part three explains how to locate and display the offset table, read the values entered to determine the technique being used, calculate CRC values when necessary, and enter them into the table.

Part four explains how to correct for various feature dimensions by adjusting the CRC values. The concerns with tools which machine both sides of a part are also explained. The variations found on some Fanuc controls based on parameter settings are then revealed.

Part five covers the use of CRC on Mazak controls and the variations found in EIA and conversational program execution.

Course 5: Advanced Setup Skills

Lesson 1: Circular Interpolation and Manual Program Units [ Top ]

Whether an operator writes programs or not, they will be required to understand and potentially edit tool paths that include include circular interpolation codes.

The first and second parts of this lesson detail the concerns associated with circular interpolation blocks within EIA programs and explains how to read and understand the tool paths created by various programming methods. Part one details the six pieces of information the control needs to produce a circular feature.

Part two explains the importance of determining the start-point, end-point and center-point coordinates associated with the G02 and G03 codes. It also covers the differences in the use of absolute and incremental coordinates and introduces the incremental I, J and K coordinates. The radius method of creating a center point is also shown.

To aid in correcting quality problems associated with circular interpolation blocks, part three includes an explanation to enable the operator to identify which types of programmed blocks can be safely edited and which require action by a programmer. A caution between measuring diameters while working with radius values in the program is discussed. The impact of CRC on circular features and the calculations needed to correct problems are detailed as well. Errors in the location of arc or circular features is examined next.

Part 4 explains how and when EIA codes can be used within a conversational part program. The Mazak Manual Programming Unit is covered as the example.

Lesson 2: Drilling, Reaming, Tapping, and Boring Canned Cycles [ Top ]

Since canned cycles can reduce program size and simplify the programming process, part one of the lesson explains the basic programming and tool movements found in all canned cycles. It includes how they are activated and deactivated by using either a G80 or one of the default codes in the G00 group. The six steps within a canned cycle are examined as well as the impact of absolute and incremental programming methods. The variations found in canned cycles between each brand of control are also explained.

In part two, a detailed look is taken at the various drilling canned cycles including G81, G82, G83 and G73. In part three the tapping cycles G84 and G74 are discussed in detail along with the synchronization between speeds and feeds. Part four covers the boring cycles G76, and G85 to G89.

Part five of the lesson explains what can be safely edited within canned cycle blocks to correct common quality problems.

Lesson 3: Conversational Programming Units for Drilling, Tapping, Boring, and Reaming [ Top ]

Conversational programming has the equivalent to canned cycles for each of the typical machining functions. The functions covered in this lesson are called Point Units in a Mazak conversational language.

Part one of this lesson explains Drilling Units. It includes a detailed look at the Unit, Sequence and Figure data blocks. It also explains how the size of the hole being specified will affect the programming displayed and how multiple-hole patterns can be programmed. In addition to drilling, rough counter bore, rough back bore, reaming, tapping, back counter bore circle milling and counter bore and tap are introduced. The Path and Q data functions are explained along with Plane Check.

Part two covers the data associated with Tapping Units along with the graphic displays available within the Mazak. Tapping of multi-hole patterns is also covered.

Part three covers the four Boring Units while part 4 covers the programming found in Reaming Units and the tooling involved.

Lesson 4: Programming for Linear, Face, and Area Milling [ Top ]

Conversational Units are used to specify the milling process for linear and face machining.

Part one of this lesson covers the Line Unit in a Mazatrol conversational program. The instruction covers the data found in the Unit, Sequence, and Figure blocks for inside, outside, and chamfer cuts. The units include Line Right, Line Left, Line Out. Each position in the unit is examined such as SRV-R, and RGH, Nominal Diameter, Approach X, Approach Y, Chamfer In, Chamfer Out, Dep Z, and the Auto Set function. The automatic calculation of the opposing corners of square features is then discussed.

Part two covers the Chamfer units in Mazatrol programs. The concerns with tool interference in both Z and R are highlighted.

Part three covers the Face Milling units in a Mazatrol program. It includes an explanation of the values that must be entered in the Unit, Sequence, and Figure blocks for the top mill, step milling, pocket milling, and slot programming units. The face milling unit is used as an example to illustrate the typical values entered in the unit for Type, Direction, Depth in Z. The automatic calculation of circumferential speed and feedrate is examined.

In part four, the Area Machining function found on Okuma EIA-based controls is covered. This includes the two Face milling cycles, two Round milling or Step milling processes, and two processes for Pocket milling. The values and functions associated with Arbitrary, FMILR, PMILL, PMILR, LINE RIGHT, LINE LEFT, LINE CENTER, LINE IN, DEPTH, FIN Z, FIN R and SRV-R. The Unit data is then examined as well. The six area machining processes are also examined.

Lesson 5: Verifying and Trial Running a New Program [ Top ]

Whether an operator is writing programs, or running programs produced by an off-line programmer, it is important to learn the steps in safely machining the first piece from a program which has not been run before. In the first part of the lesson, the graphic simulation functions found on a conversational control like the Mazak are explained. The importance of entering and End Unit is highlighted. The confirmation of the Work Number, Unit Number and Tool Number is stressed. The displaying of the Tool Layout screen to locate missing tools is covered next.

The functions demonstrated include Path Check, Sectional Check, XY Plane Check, Section Step, Section Continue, Trace, Shape Check, Shape Unit, Shape Step, Shape Continue and Shape Erase. The graphic display is analyzed to point out different types of tool movements. The 3D functions are examined next. The Scale Store, Plane Change and Scale Change function are also revealed.

In part two, the use of Dry Run, Single Block, and Machine Lock functions on EIA based machines are explained for each control type. The interlock release button is shown. The control of the rapid rate used in Dry Run is examined. The STM switch functions are detailed as well.

In part three, the actual trial run is completed. It includes the use of the Override controls to slow machine movements, the setting of the coolant lines to their proper positions, and the stopping of program execution to check features after each tool path is completed. The use of the Distance-to-Go register is recommended as a tool to detect and avoid potential crashes. The use of the Single Block function to check potential problems is highlighted next.

Lesson 6: Calculating and Entering Program Edits [ Top ]

Once the trial run is completed, the operator may find that some out-of-tolerance features may not be able to be corrected by using tool offsets. In these instances, it will be necessary to calculate and edit new coordinates into the program.

The first part of this lesson teaches the operator how to gather the critical information needed to determine if a coordinate should be adjusted to correct the problem. It begins by confirming whether absolute or incremental programming is being used in the problem area. The operator then learns what information he must have to correctly make a coordinate adjustment. Since coordinates and correction values will have either plus or minus signs, the operator learns how to calculate a new coordinate using signed numbers. A further discussion covers the editing of Cutter Radius Compensation values to adjust for replacement cutters which may be under size.

The second portion of the lesson explains all of the editing functions found on each brand of control and how they are used. This includes demonstrations of the Insert, Alter, and Delete functions. The use of the Search functions to locate blocks or specific words on each control is also demonstrated. The Memory Protect features are also explained.