Final Project Cnc.docx

Final project report BS mechanical

Session Fall 2014-18 (Mechanical

Designing and Wood Engraving OF

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Final project report BS mechanical

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Final project report BS mechanical

Project Supervisor: Engineer Ahmed Bilal MUHAMMAD ABID (G.L)

Reg No.14F-US-528--06

Cell No: 0308-3474063 Email: [email protected]

HAMMAD ASLAM

Reg No.14F-US-528--10

Cell No: 0301-5634144 Email: [email protected]

MUHAMMAD AWAIS BASHIR

Reg No.14F-US-528-11

Cell No: 0344-7237102 Email: [email protected]

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Final project report BS mechanical

Department of Mechanical Technology UNIVERSITY OF SARGODHA 2018

It is certified that the project entitled “DESIGNING AND WOOD ENGRAVING OF CNC MILLING MACHINE” submitted by MUHAMMAD ABID, HAMMAD ASLAM and MUHAMMAD AWAIS BASHIR is in scope and standard for the partial fulfillment of award of degree in BS.Technology Mechanical.

INTERNAL EXAMINER

SIGNATURES: -----------------------------------------------------------

DATE: -----------EXTERNAL EXAMINER

SIGNATURES: --------------------------------------------------------DATE: ------------

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Final project report BS mechanical

PROJECT

3 Axis CNC Milling Machine

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Final project report BS mechanical

Contents Chapter 1 ------ Milling Machine 1.1

Introduction.…………………………………………………………..11

1.2

Milling Process.……………………………………………………….12

1.2.1 Face Milling………….………………………………………………..13 1.2.2 Peripheral Milling…………………………………….……………….14 1.3

Milling Cutters ………………………………………………………..14

1.4

Gang Milling …………………….………………………………….. 15

1.5

Mill Orientation ……………………………………….……………...16

1.5.1 Vertical Mill ……………………………………………..………….. 16 1.5.1.1 Turret Mill ………………………………………………..………….18 1.5.1.2 Bed Mill……………………………………………………...………19 1.5.1.3 Drill Mill……………………………………………………………..19 1.5.2 Horizontal Mill………………………………….................................20 1.5.3 Comparative Merits…………………………………………………....21 1.5.4 Difference between Horizontal & Vertical Mill ………………………22 1.5.5 Box Mill ……………………………………………………………….23 1.5.6 C-Frame Mill ………………………………………………………….23 1.5.7 Floor Mill ……………………………………………………………...23 1.5.8 Gantry Mill …………………………………………………………….23 1.5.9 Horizontal Boring Mill ………………………………………………. 23 1.5.10 Jig borer Vertical Mill ………………………………………………..24 6

Final project report BS mechanical

1.5.11 Knee Mill ……………………………………………………………24 1.5.12 Ram type Mill ……………………………………………………….24

Chapter 2 ------ Concept of CNC 2.1

CNC…………………………………………………………………..26

2.2

CNC Milling Machine………………………………………………..26

2.2.1 Operating System……………………………………………………..27 2.3

Numerical Control ……………………………………………………27

2.3.1 Operations ……………………………………………………………28 2.4

Features of CNC ……………………………………………………. 29

2.5

Advantages of CNC Machine ………………………………………..30

2.6

Machine Control Unit ………………………………………………..30

2.6.1 MCU Components …………………………………………………...31 2.7

Numerical Control Mode …………………………………………….31

2.8

Part Program …………………………………………………………32

2.8.1 ISO Standards for Coding ……………………………………………32 2.8.2 G&M Codes…………………………………………………………..34 2.8.3 Absolute Dimensioning System……………………………………..42 2.8.4 Incremental Dimensioning System……………………………….…45 2.9

Tools ……………………………………………………………..…..47

2.10 Pocket Milling ………………………………………………………..49 2.11 Tool Path ……………………………………………………………..49 2.11.1 Linear Tool Path ……………………………………………………..50 7

Final project report BS mechanical

2.11.1.1 Zig-zag Tool Path ……………………………………………….…..50 2.11.1.2 Zig Tool Path …………………………………………………….….50 2.11.2 Non-linear Tool Path ………………………………………………….51 2.11.2.1 Contour-Parallel Tool Path ……………………………………….…51 2.11.2.2 Curvilinear Tool Path………………………………………………..52

Chapter 3 ------ 3 Axis CNC Milling machine 3.1

CNC……………………………….………………………………..…..54

3.2

Axis ………………………………………………………………..…...54

3.3

Assembly Instructions…………………………………………….……54

3.3.1 Parts Size ……………………………………………………………….54 3.3.2 Frame ..………………………………………………………………....57 3.3.3 Frame 2…………………………………………………………………59 3.3.4 Frame 3…………………………………………………………………59 3.3.5 Polished Rod 1 ……………………………………………………….. 60 3.3.6 Polished Rod 2 ……………………………………………………….. 60 3.3.7 Y-Axis ………………………………………………………………....61 3.3.8 Stepper Motor ………………………………………………………….62 3.3.9 X-Axis & Z-Axis …………………………………………………….. 63 3.3.10 Lead Screw Installation ……………………………………………….64 3.3.11 Coupling Assembly ………………………………………………….. 65 3.3.12 Bearing Assembly …………………………………………………… 65 3.3.13 Control Board Assembl…..……………………………………………67 3.3.14 Wiring Assembly………………………………………………..…….68 8

Final project report BS mechanical

3.3.15 Final Product ……………………………………………………….…69 3.4

Electrical Parts ………………………………………………………...69

3.5

Mechanical Parts ………………………………………………………70

3.6

Working ……………………………………………………………….70

3.7

Milling Machine Uses ………………………………………………...71

References …………………………………………………………………...71 Bibliography……………………………………………………………...….73 Internet……………………………………………………………………….73

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Chapter 1

Milling Machine

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Final project report BS mechanical

Milling Machine 1.1 Introduction Milling is the machining process of using rotary cutters to remove material from a work piece by advancing (or feeding) the cutter into the work piece at a certain direction. The cutter may also be held at an angle relative to the axis of the tool. Milling covers a wide variety of different operations and machines, on scales from small individual parts to large, heavy-duty gang milling operations. It is one of the most commonly used processes for machining custom parts to precise tolerances. Milling can be done with a wide range of machine tools. The original class of machine tools for milling was the milling machine (often called a mill). After the advent of computer numerical control (CNC), milling machines evolved into machining centers: milling machines augmented by automatic tool changers, tool magazines or carousels, CNC capability, coolant systems, and enclosures. Milling centers are generally classified as vertical machining centers (VMCs) or horizontal machining centers (HMCs). The integration of milling into turning environments, and vice versa, begun with live tooling for lathes and the occasional use of mills for turning operations. This led to a new class of machine tools, multitasking machines (MTMs), which are purpose-built to facilitate milling and turning within the same work envelope.

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Fig. 1.1 Milling Machine

1.2 Milling Process Milling is a cutting process that uses a milling cutter to remove material from the surface of a work piece. The milling cutter is a rotary cutting tool, often with multiple cutting points. As opposed to drilling, where the tool is advanced along its rotation axis, the cutter in milling is usually moved perpendicular to its axis so that cutting occurs on the circumference of the cutter. As the milling cutter enters the work piece, the cutting edges (flutes or teeth) of the tool repeatedly cut into and exit from the material, shaving off chips (swarf) from the work piece with each pass. The cutting action is shear deformation; material is pushed off the work piece in tiny clumps that hang together to a greater or lesser extent (depending on the material) to form chips. This makes metal cutting somewhat different (in its mechanics) from slicing softer materials with a blade. 12

Final project report BS mechanical

The milling process removes material by performing many separate, small cuts. This is accomplished by using a cutter with many teeth, spinning the cutter at high speed, or advancing the material through the cutter slowly; most often it is some combination of these three approaches. The speeds and feeds used are varied to suit a combination of variables. The speed at which the piece advances through the cutter is called feed rate, or just feed; it is most often measured in length of material per full revolution of the cutter. There are two major classes of milling process:  Face milling  Peripheral milling

1.2.1

Face Milling

In face milling, the cutting action occurs primarily at the end corners of the milling cutter. Face milling is used to cut flat surfaces (faces) into the work piece, or to cut flat-bottomed cavities.

Fig. 1.2 Face Milling

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1.2.2

Peripheral Milling

In peripheral milling, the cutting action occurs primarily along the circumference of the cutter, so that the cross section of the milled surface ends up receiving the shape of the cutter. In this case the blades of the cutter can be seen as scooping out material from the work piece. Peripheral milling is well suited to the cutting of deep slots, threads, and gear teeth.

Fig. 1.3 Peripheral and Face Milling

1.3 Milling Cutters Many different types of cutting tools are used in the milling process. Milling cutters such as end mills may have cutting surfaces across their entire end surface, so that they can be drilled into the work piece (plunging). Milling cutters may also have extended cutting surfaces on their sides to allow for peripheral milling. Tools optimized for face milling tend to have only small cutters at their end corners.

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The cutting surfaces of a milling cutter are generally made of a hard and temperature-resistant material, so that they wear slowly. A low cost cutter may have surfaces made of high speed steel. More expensive but slower-wearing materials include cemented carbide. Thin film coatings may be applied to decrease friction or further increase hardness. They are cutting tools typically used in milling machines or machining centers to perform milling operations (and occasionally in other machine tools). They remove material by their movement within the machine (e.g., a ball nose mill) or directly from the cutter's shape (e.g., a form tool such as a hobbing cutter). As material passes through the cutting area of a milling machine, the blades of the cutter take swarfs of material at regular intervals. Surfaces cut by the side of the cutter (as in peripheral milling) therefore always contain regular ridges. The distance between ridges and the height of the ridges depend on the feed rate, number of cutting surfaces, the cutter diameter. With a narrow cutter and rapid feed rate, these revolution ridges can be significant variations in the surface finish. The face milling process can in principle produce very flat surfaces. However, in practice the result always shows visible trochodial marks following the motion of points on the cutter's end face. These revolution marks give the characteristic finish of a face milled surface. Revolution marks can have significant roughness depending on factors such as flatness of the cutter's end face and the degree of perpendicularity between the cutter's rotation axis and feed direction. Often a final pass with a slow feed rate is used to improve the surface finish after the bulk of the material has been removed. In a precise face milling operation, the revolution marks will only be microscopic scratches due to imperfections in the cutting edge.

1.4 Gang Milling Gang milling refers to the use of two or more milling cutters mounted on the same arbor (that is, ganged) in a horizontal-milling setup. All of the cutters may perform the same type of operation, or each cutter may perform a different type of operation. For example, if several work pieces need a slot, a flat surface, and an angular groove, a good method to cut these (within a non15

Final project report BS mechanical

CNC context) would be gang milling. All the completed work pieces would be the same, and milling time per piece would be minimized. Gang milling was especially important before the CNC era, because for duplicate part production, it was a substantial efficiency improvement over manual-milling one feature at an operation, then changing machines (or changing setup of the same machine) to cut the next op. Today, CNC mills with automatic tool change and 4- or 5-axis control obviate gang-milling practice to a large extent.

Fig. 1.4 Gang Milling

1.5 Mill Orientation Mill orientation is the primary classification for milling machines. The two basic configurations are:  Vertical  Horizontal

1.5.1 Vertical Mill In the vertical mill the spindle axis is vertically oriented. Milling cutters are held in the spindle and rotate on its axis. The spindle can generally be extended (or the table can be raised/lowered, giving the same effect), allowing plunge cuts and drilling.

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Fig. 1.5 Vertical Mill

There are three subcategories of vertical mills:  Bed Mill  Turret Mill  Drill Mill

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1.5.1.1 Turret Mill A turret mill has a stationary spindle and the table is moved both perpendicular and parallel to the spindle axis to accomplish cutting. The most common example of this type is the Bridgeport, described below. Turret mills often have a quill which allows the milling cutter to be raised and lowered in a manner similar to a drill press. This type of machine provides two methods of cutting in the vertical (Z) direction: by raising or lowering the quill, and by moving the knee. Turret mills are generally considered by some to be more versatile of the two designs. However, turret mills are only practical as long as the machine remains relatively small. As machine size increases, moving the knee up and down require considerable effort and it also becomes difficult to reach the quill feed handle (if equipped). Therefore, larger milling machines are usually of the bed type.

Fig. 1.6 Turret Mill

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Final project report BS mechanical

1.5.1.2 Bed Mill In the bed mill, however, the table moves only perpendicular to the spindle's axis, while the spindle itself moves parallel to its own axis.

Fig. 1.7 Bed Mill

1.5.1.3 Drill Mill A third type also exists, a lighter machine, called a mill-drill, which is a close relative of the vertical mill and quite popular with hobbyists. A mill-drill is similar in basic configuration to a small drill press, but equipped with an X-Y table. They also typically use more powerful motors than a comparably sized drill press, with potentiometer-controlled speed and generally have more heavyduty spindle bearings than a drill press to deal with the lateral loading on the spindle that is created by a milling operation. A mill drill also typically raises and lowers the entire head, including motor, often on a dovetailed vertical, where a drill press motor remains stationary, while the arbor raises and lowers within a driving collar.

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Fig. 1.8 Drill Mill

1.5.2 Horizontal Mill A horizontal mill has the same sort but the cutters are mounted on a horizontal spindle. Many horizontal mills also feature a built-in rotary table that allows milling at various angles; this feature is called a universal table. While end mills and the other types of tools available to a vertical mill may be used in a horizontal mill, their real advantage lies in arbor-mounted cutters, called side and face mills, which have a cross section rather like a circular saw, but are generally wider and smaller in diameter. Because the cutters have good support from the arbor and have a larger cross-sectional area than an end mill, quite heavy cuts can be taken enabling rapid material removal rates. These are used to mill grooves and slots. Plain mills are used to shape flat surfaces. Several cutters may be ganged together on the arbor to mill a complex shape of slots 20

Final project report BS mechanical

and planes. Special cutters can also cut grooves, bevels, radii, or indeed any section desired. These specialty cutters tend to be expensive. Simplex mills have one spindle, and duplex mills have two. It is also easier to cut gears on a horizontal mill. Some horizontal milling machines are equipped with a powertake-off provision on the table. This allows the table feed to be synchronized to a rotary fixture, enabling the milling of spiral features such as hypoid gears.

Fig. 1.9 Horizontal Mill

1.5.3 Comparative Merits The choice between vertical and horizontal spindle orientation in milling machine design usually hinges on the shape and size of a work piece and the number of sides of the work piece that require machining. Work in which the 21

Final project report BS mechanical

spindle's axial movement is normal to one plane, with an end mill as the cutter, lends itself to a vertical mill, where the operator can stand before the machine and have easy access to the cutting action by looking down upon it. Thus vertical mills are most favored for die sinking work (machining a mold into a block of metal). Heavier and longer work pieces lend themselves to placement on the table of a horizontal mill. Prior to numerical control, horizontal milling machines evolved first, because they evolved by putting milling tables under lathe-like headstocks. Vertical mills appeared in subsequent decades, and accessories in the form of add-on heads to change horizontal mills to vertical mills (and later vice versa) have been commonly used. Even in the CNC era, a heavy work piece needing machining on multiple sides lends itself to a horizontal machining center, while die sinking lends itself to a vertical one.

1.5.4 Difference between Horizontal and Vertical Mill Table 1.1 Sr. No

Horizontal Milling Machine

Vertical Milling Machine

1

Spindle is horizontal & parallel Spindle is vertical and perpendicular to work table. to the work table.

2

Cutter cannot be moved up & down.

Cutter can be moved up & down.

3

Cutter is mounted on the arbor.

Cutter is directly mounted on the spindle.

4

Spindle cannot be tilted.

Spindle can be tilted foe angular cutting.

5

Operations such as plain milling, gear cutting, form milling, straddle milling, gang milling, etc. can be performed.

Operations such as slot milling,T-slot milling, angular milling, flat milling, etc. can be performed and also drilling, reaming, boring can be carried out.

1.5.5 Box Mill 22

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Box mill or column mill Very basic hobbyist bench-mounted milling machines that feature a head riding up and down on a column or box way.

1.5.6 C-Frame Mill These are larger, industrial production mills. They feature a knee and fixed spindle head that is only mobile vertically. They are typically much more powerful than a turret mill.

1.5.7 Floor Mill These have a row of rotary tables, and a horizontal pendant spindle mounted on a set of tracks that runs parallel to the table row. These mills have predominantly been converted to CNC, but some can still be found (if one can even find a used machine available) under manual control.

1.5.8 Gantry Mill The milling head rides over two rails (often steel shafts) which lie at each side of the work surface.

1.5.9 Horizontal Boring Mill Large, accurate bed horizontal mills that incorporate many features from various machine tools. They are predominantly used to create large manufacturing jigs, or to modify large, high precision parts.

1.5.10 Jig Borer Vertical Mill 23

Final project report BS mechanical

These are built to bore holes, and very light slot or face milling. They are typically bed mills with a long spindle throw. The beds are more accurate.

1.5.11 Knee Mill Knee mill or knee-and-column mill refers to any milling machine whose x-y table rides up and down the column on a vertically adjustable knee. This includes Bridge ports.

1.5.12 Ram-type Mill This can refer to any mill that has a cutting head mounted on a sliding ram. The spindle can be oriented either vertically or horizontally.

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Chapter 2

Concept of CNC

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Final project report BS mechanical

Concept of CNC 2.1 CNC CNC means Computer Numerical Control. This means a computer converts the design produced by Computer Aided Design software (CAD), into numbers. The numbers can be considered to be the coordinates of a graph and they control the movement of the cutter.

2.2 CNC Milling Machine Most CNC milling machines (also called machining centers) are computer controlled vertical mills with the ability to move the spindle vertically along the Z-axis. This extra degree of freedom permits their use in die sinking, engraving applications, and 2.5D surfaces such as relief sculptures. When combined with the use of conical tools or a ball nose cutter, it also significantly improves milling precision without impacting speed, providing a cost-efficient alternative to most flat-surface hand-engraving work. CNC machines can exist in virtually any of the forms of manual machinery, like horizontal mills. The most advanced CNC milling-machines, the multi axis machine, add two more axes in addition to the three normal axes (XYZ). Horizontal milling machines also have a C or Q axis, allowing the horizontally mounted work piece to be rotated, essentially allowing asymmetric and eccentric turning. The fifth axis (B axis) controls the tilt of the tool itself. When all of these axes are used in conjunction with each other, extremely complicated geometries, even organic geometries such as a human head can be made with relative ease with these machines. But the skill to program such geometries is beyond that of most operators. Therefore, 5-axis milling machines are practically always programmed with CAM.

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Final project report BS mechanical

2.2.1 Operating System The operating system of such machines is a closed loop system and functions on feedback. These machines have developed from the basic NC (NUMERIC CONTROL) machines. A computerized form of NC machines is known as CNC machines. A set of instructions (called a program) is used to guide the machine for desired operations. Some very commonly used codes, which are used in the program are: G00

Rapid traverse

G01

Linear interpolation of tool

G21

Dimension in metric units

M03/M04 Spindle start (clockwise/counter clockwise) T01 M06

Automatic tool change to tool 1

M30

Program end

Various other codes are also used. A CNC machine is operated by a single operator called a programmer. This machine is capable of performing various operations automatically and economically. With the declining price of computers and open source CNC software, the entry price of CNC machines has plummeted.

2.3 Numerical Control Numerical control (NC) refers to the automation of machine tools that are operated by abstractly programmed commands encoded on a storage medium, as opposed to manually controlled or mechanically automated via cams alone. The first NC machines were built in the 1940s and ‘50s, based on existing tools that were modified with motors that moved the controls to follow points fed into the system on paper tape. These early servomechanisms were rapidly augmented with analog and digital computers, creating the modern computer numerical controlled (CNC) machine tools that have revolutionized the design process. In modern CNC systems, end-to-end component design is highly automated with CAD/CAM programs. The programs produce a computer file that is interpreted to extract the commands needed to operate a particular 27

Final project report BS mechanical

machine; and then loaded into the CNC machines for production. Since any particular component might require the use of a number of different tools, modern machines often combine multiple tools into a single cell. Modern CNC machines differ little in concept from the original model built at MIT in 1952. Mills typically consist of a table that moves in the Y-axis and a tool chuck that moves in X and Z (depth). The position of the tool is driven by motors through a series of step down gears in order to provide highly accurate movements, or in modern designs, direct drive stepper motors. As the controller hardware evolved, the mills themselves also evolved. One change has been to enclose the entire mechanism in a large box as a safety measure, often with additional safety interlocks to ensure the operator is far enough from the working piece for safety operation. Mechanical manual controls disappeared long ago.

2.3.1 Operations CNC like systems are now used for any process that can be described as a series of movements and operations. These include:

 Laser cutting  Welding  Friction stir welding  Ultra-sonic welding  Flame and plasma cutting  Bending  Spinning  Pinning  Gluing  Fabric cutting  Sewing  Tape and fiber placement  Routing  Picking and placing (PnP)  Sawing 28

Final project report BS mechanical

2.4 Features of CNC CNC systems include additional features beyond what is feasible with conventional hardwired NC. These features, many of which are standard of most CNC machine control units (MCU) where others are optional, include the following  Storages of more than one part. With improvement in computer storage technology, newer CNC controllers have sufficient capacity to store multiple programs.  Various forms of programs input. Hard-wired MCUs are limited to pushed tapes as the input medium for entering part programs, whereas CNC controllers possess multiple data entry capabilities.  Programs editing at the machine tool. CNC permits a part program to be edited while it resides in the MCU computer memory. Hence, the process of testing and correcting a program can be done entirely at the machine site rather than returning to the programming office to edit the tape.  Fixed cycles and programming sub routines. The increased memory capacity and the ability to program the control computer provide the opportunity to store frequently used machining cycles as macros that can be called by the part program. Instead of writing the full instructions for the particular cycle into every program, a call statement is included in the part program to indicate that the macro cycle should be executed.  Interpolation. Linear and circular interpolation is sometimes hard-wired into the control unit, but helical, parabolic and cubic interpolation are usually executed in a stored program algorithm.  Positioning features for set up. Setting up the machine tool for a given work part involves installing and aligning a fixture on the machine tool table. The alignment task can be facilitated using certain features made possible by software option in CNC system. Position set is one of these features. With position set, the operator is not required to locate the fixture on the machine table with extreme accuracy.  Cutter length and size compensation. In older style controls, cutter dimensions had to be set very precisely to agree with the tool path defined in the part program.  Acceleration and deceleration calculation. This feature is applicable when cutter moves at high feed rate. It is designed to avoid tool marks on the 29

Final project report BS mechanical

work surface that would be generated due to machine tool dynamics when cutting path changes abruptly.  Communication interface. Most modern CNC controllers are equipped with RS-232 or other communication interface to allow machine to be linked to other computers and computer driven devices.  Diagnostics. Many CNC systems possess an online diagnostics capability that monitors certain aspects for machine tool to detect malfunctions or sign of impending malfunctions or to diagnose system breakdowns.

2.5 Advantages of CNC Machines CNC machines have several advantages with emphasis on machine tool applications. When the production application satisfies the characteristics needed, CNC yields many benefits over manual production methods. The benefits translate into economic saving for the user company. Some of the advantages are:  Non-productive time is reduced through fewer steps, less setup time, less work piece handling time and automatic tool changes.  Greater accuracy and repeatability  Lower scrap rates  Inspections requirements are reduced  More complex parts geometries are possible  Engineering changes can be accommodated more gracefully.  Simple fixtures are needed  Shorter manufacturing lead times  Reduced parts inventory  Less floor space required  Operator skill level requirements are reduced

2.6 Machine Control Unit (MCU) CNC machine is fitted with MCU which performs the various controlling features under the program control. The MCU may be generally housed in a separated cabinet like cabinet body or may be mounted on the machine itself. Appearance wise it looks like a computer with a display panel generally of small size and a number of buttons to control like machine tool along with a 30

Final project report BS mechanical

keyboard. This control unit controls the motion of cutting tool, spindle speeds, feed rate, tool changes, cutting fluid applications and several other functions of the machine tool.

2.6.1 MCU Components The MCU consists of following components and subsystems:     

Central processing unit Memory Input and output interface Control for machine tool axes and spindle speed Sequence control for other machine tools

This subsystem are interconnected by means of a system bus.

2.7 Numerical Control Mode The controller has number of modes in which they can operate. There could be four possible modes in which controller can function in relation to a machine center.  Termed as point to point mode. In this mode, the control has the capability to operate all the three axis, but not necessarily simultaneously. It would be possible to move the tool to any point (in X and Y axis) and carry out the machining operation in one axis (Z axis) at that point.  Improvement over point to point mode. The machine tool has the capability to carry out a continuous motion in each of the axis direction.  A control system, which has simultaneously motion capability any two axes.  The highest form of control that gives the capability of simultaneous three or more axes motion.

2.8 Part Program

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Part program is a very important software element in the NC manufacturing system. It is a detailed plan of manufacturing instructions required for machining the part as per drawing. The format standardized by ISO. For example: N30 G00 X120 Y45 Z85 N40 G90 N50 G03 X200 I100 J0

F200

2.8.1 ISO Standards for Coding

Table 2.1 Character

Address for

A

Angular dimension around X Axis

B

Angular dimension around Y Axis

C

Angular dimension around Z Axis

D

Angular dimension around 3rd feed function

E

Angular dimension around 2nd feed function

F

Feed function

G

Preparatory function

H

Unassigned

I

Distance to arc center to X

J

Distance to arc center to Y

K

Distance to arc center to X

L

Do not use

M

Miscellaneous function 32

Final project report BS mechanical

N

Sequence number

O

References rewind up

P

Third rapid traverse dimension

Q

Second rapid traverse dimension

R

First rapid traverse dimension

S

Spindle speed function

T

Tool function

U

Secondary motion dimension parallel to X

V

Secondary motion dimension parallel to Y

W

Secondary motion dimension parallel to Z

X

Primary X motion dimension

Y

Primary Y motion dimension

Z

Primary Z motion dimension

2.8.2 G&M CODES

Table 2.2

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G&M CODES Catego ry

Functi on

Motion

Move in a straight line at rapids speed.

XYZ of endpoint

Motion

Move in a straight line at last speed commanded by a (F)feedrate

XYZ of endpoint

Motion

Clockwise circular arc at (F)feedrate

XYZ of endpoint IJK relative to center R for radius

Motion

Counterclockwise circular arc at (F)feedrate

XYZ of endpoint IJK relative to center R for radius

Motion

Dwell: Stop for a specified time.

P for millisecon ds X for seconds

G05

Motion

FADAL Non-Modal Rapids

G09

Motion

Exact stop check

G10

Compensatio n

Programma ble parameter input

Code

G00

G01

G02

G03

G04

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Coordinate

Turn Polar Coordinates OFF, return to Cartesian Coordinates

G16

Coordinate

Turn Polar Coordinates ON

G17

Coordinate

Select X-Y plane

G18

Coordinate

Select X-Z plane

G19

Coordinate

Select Y-Z plane

G20

Coordinate

Program coordinates are inches

G21

Coordinate

Program coordinates are mm

G27

Motion

Reference point return check

Motion

Return to home position

Motion

Return from the reference position

Motion

Return to the 2nd, 3rd, and 4th reference point

Canned

Constant lead threading (like G01 synchronize d with spindle)

G15

G28

G29

G30

G32

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Compensati on

Tool cutter compensati on off (radius comp.)

Compensati on

Tool cutter compensati on left (radius comp.)

G42

Compensati on

Tool cutter compensati on right (radius comp.)

G43

Compensati on

Apply tool length compensati on (plus)

G44

Compensati on

Apply tool length compensati on (minus)

G49

Compensati on

Tool length compensati on cancel

G50

Compensati on

Reset all scale factors to 1.0

G51

Compensati on

Turn on scale factors

G52

Coordinate

Local workshift for all coordinate systems: add XYZ offsets

G53

Coordinate

G40

G41

Machine coordinate system 36

Final project report BS mechanical

(cancel work offsets)

Coordinate

Work coordinate system (1st Workpiece)

Coordinate

Work coordinate system (2nd Workpiece)

Coordinate

Work coordinate system (3rd Workpiece)

Coordinate

Work coordinate system (4th Workpiece)

Coordinate

Work coordinate system (5th Workpiece)

G59

Coordinate

Work coordinate system (6th Workpiece)

G61

Other

Exact stop check mode

G62

Other

Automatic corner override

G63

Other

Tapping mode

G64

Other

Best speed path

G65

Other

Custom macro simple call

G68

Coordinate

G54

G55

G56

G57

G58

Coordinate System 37

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Rotation

Coordinate

Cancel Coordinate System Rotation

G73

Canned

High speed drilling cycle (small retract)

G74

Canned

Left hand tapping cycle

G76

Canned

Fine boring cycle

G80

Canned

Cancel canned cycle

G81

Canned

Simple drilling cycle

G82

Canned

Drilling cycle with dwell (counterboring)

G83

Canned

Peck drilling cycle (full retract)

G84

Canned

Tapping cycle

Canned

Boring canned cycle, no dwell, feed out

G86

Canned

Boring canned cycle, spindle stop, rapid out

G87

Canned

Back boring

G69

G85

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canned cycle

G88

G89

G90

G90.1

G91

G91.1

G92

G92 (alternat e) G92.1

Canned

Boring canned cycle, spindle stop, manual out

Canned

Boring canned cycle, dwell, feed out

Coordinate

Absolute programmin g of XYZ (type B and C systems)

Coordinate

Absolute programmin g IJK (type B and C systems)

Coordinate

Incremental programmin g of XYZ (type B and C systems)

Coordinate

Incremental programmin g IJK (type B and C systems)

Coordinate

Offset coordinate system and save parameters Clamp of maximum spindle speed

Motion

Coordinate

Cancel offset and 39

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zero parameters

Coordinate

Cancel offset and retain parameters

Coordinate

Offset coordinate system with saved parameters

Motion

Units per minute feed mode. Units in inches or mm.

G95

Motion

Units per revolution feed mode. Units in inches or mm.

G96

Motion

Constant surface speed

Motion

Cancel constant surface speed

Canned

Return to initial Z plane after canned cycle

Canned

Return to initial R plane after canned cycle

G92.2

G92.3

G94

G97

G98

G99

M-Codes 40

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Code

Functio n

Category M-Code

Program Stop (nonoptional)

M01

M-Code

Optional Stop: Operator Selected to Enable

M02

M-Code

End of Program

M03

M-Code

Spindle ON (CW Rotation)

M04

M-Code

Spindle ON (CCW Rotation)

M05

M-Code

Spindle Stop

M06

M-Code

Tool Change

M07

M-Code

Mist Coolant ON

M08

M-Code

Flood Coolant ON

M09

M-Code

Coolant OFF

M17

M-Code

FADAL subroutine return

M29

M-Code

Rigid Tapping Mode on Fanuc Controls

M30

M-Code

M00

End of Program, Rewind and 41

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Reset Modes M97

M-Code

Haas-Style Subprogram Call

M98

M-Code

Subprogram Call

2.8.3

What Is Absolute dimensioning system? When programming in absolute, all of your coordinates and movement values will come from the origin (0,0) point. If you want to be in Absolute, the G-code that defines this is G90, which is a modal code.

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Example fig 2.6 (a)

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Example fig 2.6 (b) 45

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2.8.4

What Is Incremental dimensioning system? instead of all of your coordinates/numbers coming from one location (0,0 offset), each move is the distance from your current location.

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Example fig 2.7 (a)

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Example fig 2.7 (b)

2.9 Tools The accessories and cutting tools used on machine tools (including milling machines) are referred to in aggregate by the mass noun "tooling". There is a high degree of standardization of the tooling used with CNC milling machines, and a lesser degree with manual milling machines. To ease up the 48

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organization of the tooling in CNC production many companies use a tool management solution. Milling cutters for specific applications are held in various tooling configurations. CNC milling machines nearly always use SK (or ISO), CAT, BT or HSK tooling. SK tooling is the most common in Europe, while CAT tooling, sometimes called V-Flange Tooling, is the oldest and probably most common type in the USA. CAT tooling was invented by Caterpillar Inc. of Peoria, Illinois, in order to standardize the tooling used on their machinery. CAT tooling comes in a range of sizes designated as CAT-30, CAT-40, CAT-50, etc. The number refers to the Association for Manufacturing Technology (formerly the National Machine Tool Builders Association (NMTB)) Taper size of the tool.

Fig. 2.1 Milling Tools

High speed steels and cobalt end mills are used for cutting operations in milling machines.

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2.10 Pocket Milling Pocket milling has been regarded as one of the most widely used operations in machining. It is extensively used in aerospace and shipyard industries. In pocket milling the material inside an arbitrarily closed boundary on a flat surface of a work piece is removed to a fixed depth. Generally flat bottom end mills are used for pocket milling. Firstly roughing operation is done to remove the bulk of material and then the pocket is finished by a finish end mill. Most of the industrial milling operations can be taken care of by 2.5 axis CNC milling. This type of path control can machine up to 80% of all mechanical parts. Since the importance of pocket milling is very relevant, therefore effective pocketing approaches can result in reduction in machining time and cost. NC pocket milling can be carried out mainly by two tool paths, viz. linear and non-linear.

Fig. 2.2 Pocket Milling

2.11 Tool Path Tool follows two paths  Linear tool path  Non-linear tool path 50

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2.11.1

Linear Tool Path

In this approach, the tool movement is unidirectional. Zig-zag and zig tool paths are the examples of linear tool path.

2.11.1.1 Zig-zag Tool Path In zig-zag milling, material is removed both in forward and backward paths. In this case, cutting is done both with and against the rotation of the spindle. This reduces the machining time but increases machine chatter and tool wear.

Fig. 2.3 Zig-zag tool path

2.11.1.2 Zig Tool Path In zig milling, the tool moves only in one direction. The tool has to be lifted and retracted after each cut, due to which machining time increases. However, in case of zig milling surface quality is better.

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Fig. 2.4 Zig tool path

2.11.2 Non-linear Tool Path In this approach, tool movement is multi-directional. One example of non-linear tool path is contour-parallel tool path.

2.11.2.1 Contour-parallel Tool Path In this approach, the required pocket boundary is used to derive the tool path. In this case the cutter is always in contact with the work material. Hence the idle time spent in positioning and retracting the tool is avoided. For largescale material removal, contour-parallel tool path is widely used because it can be consistently used with up-cut or down-cut method during the entire process.

Fig. 2.5 Contour-parallel tool path

2.11.2.2 Curvilinear Tool Path 52

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In this approach, the tool travels along a gradually evolving spiral path. The spiral starts at the center of the pocket to be machined and the tool gradually moves towards the pocket boundary. The direction of the tool path changes progressively and local acceleration and deceleration of the tool are minimized. This reduces tool wear.

Fig. 2.6 Curvilinear tool path

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Chapter 3

3 axis CNC Milling Machine 54

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3 Axis CNC Milling Machine 3.1 CNC CNC means Computer Numerical Control. This means a computer converts the design produced by Computer Aided Design software (CAD), into numbers. The numbers can be considered to be the coordinates of a graph and they control the movement of the cutter.

3.2 Axis An axis is a direction of motion controlled by the CNC machine control. It can be linear (motion along a straight line) or circular (a rotary motion).

3.3 Assembly Instructions

3.3.1 Parts Size

Fig. 3.1 Main parts

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CNC Wood Engraving

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Fig. 3.2 Main parts

Fig. 3.3 Main parts

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3.3.2 Frame 1  Base: 330mm×2、360mm×3  Angle Support×6、M5*10×12  Spacer×12

Fig. 3.4 Main frame

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Main frame back view

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3.3.3

Frame 2

 Base 220mm×2、360mm×2  Angle Suport×4、M5*10×8  Specer×8

Fig. 3.5 Frame

3.3.4 Frame 3  Angle Support×6、M5*10×16  Spacer×12  Connecting pieces×2

Fig. 3.6 Frame

3.3.5 Polished Rods 1 60

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Size of Polished Rod Supporting Base 1

Fig. 3.7 Polished rods

3.3.6 Polished Rods 2 Size of Polished Rod Supporting Base

Fig. 3.8 Polished rod

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3.3.7

Y-Axis

 M6*10×10  Sliding Block×5  Worktable×1

Fig. 3.9 Y-Axis

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3.3.8

Stepper Motor

Fig. 3.10 Stepper motor

3.3.9 X-Axis & Z-Axis

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Fig. 3.12 X-Axis & Z-Axis

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3.3.10 Lead Screws Installation

Fig. 3.13 Lead screw and installation

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3.3.11 Couplings Assembly Tighten two screws from one side only

Fig. 3.14 Coupling Assembly

3.3.12

Bearing Assembly

Fig. 3.15 Bearing Assembly

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SPINDLE OF CNC:

CNC Spindle 67

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3.3.13

Control board Assembly

Fig. 3.16 Control board Assembly

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3.3.14

Wiring Diagram

Fig. 3.17 Wiring

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3.3.15 Final Product

Fig. 3.18 CNC Milling Machine

3.4 Electrical Parts Following are the different Electrical parts used in this CNC Milling Machine:       

Arduino GRBL-Shield Stepper Driver Power Supply Stepper Motors Milling Spindle Inverter 70

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3.5 Mechanical Parts Following are the different Mechanical parts used in this CNC Milling Machine            

Linear bearings Linear rails Ball circulating spindles Fix spindle bearing and stepper holder Lose spindle bearings Spindle stepper coupling Frame Gantry Linear X- bearing Y-Profile Z-Profile Z-Sliding plate for spindle mounting

3.6 Working Computer numerical control (CNC) has been incorporated into a variety of new technologies and machinery. Perhaps the most common type of machine that is used in this realm is known as a CNC mill. CNC milling is a certain type of CNC machining. Milling is a process that is quite similar to drilling or cutting, and milling can perform these processes for a variety of production needs. Milling utilizes a cylindrical cutting tool that can rotate in various directions. Unlike traditional drilling, a milling cutter can move along multiple axes. It also has the capability to create a wide array of shapes, slots, holes, and other necessary impressions. Plus, the work piece of a CNC mill can be moved across the milling tool in specific directions. A drill is only able to achieve a single axis motion, which limits its overall production capability. CNC mills are often grouped by the number of axes on which they can operate. Each axis is labeled using a specific letter. For example, the X and Y axes represent the horizontal movement of the mill’s work piece. The Z axis designates vertical movement. The W axis represents the diagonal movement across the vertical plane. 71

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The majority of CNC milling machines offer from 3 to 5 axes. More advanced mills must be programmed with CAM technology to run properly. These advanced CNC machines can produce specific shapes that are basically impossible to produce with any manual tooling techniques. In addition, most CNC mills are equipped with a special device that pumps fluid to the cutting tool during the production process

3.7 Milling Machine Uses Following Operations are performed on the Milling machine Plain milling Gear cutting Form milling Straddle milling Gang milling Slot milling T-slot milling Angular milling Flat milling Drilling Reaming  Boring           

References 

Brown & Sharpe 1914, p. 7.



CMMC 1922, p. 122.



Usher 1896, p. 142.



CMMC 1992, pp. 125–127.



"How to use a Milling Machine". American Machine Tools Co.



Encyclopedia Britannica 2011 72

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 Currently the term "miller" refers to machines built when that term was current, as with "phonograph" and "horseless carriage." 

Kramer, Thomas R. (1992). "Pocket Milling with Tool Engagement Detection". Journal of Manufacturing Systems.



Held, Martin (1991). "A geometry-based investigation of the tool path generation for zigzag pocket machining".



Choy, H.S.; Chan, K.W. (February 2003). "A corner-looping based tool path for pocket milling". Computer-Aided Design.



Hansen, Allan; Arab, Farhad (April 1992). "An algorithm for generating NC tool paths for arbitrarily shaped pockets with islands". ACM Transactions on Graphics.



Jeong, J.; Kim, K. "Tool Path Generation for Machining Free-Form Pockets Voronoi Diagrams". Springer Link. The International Journal of Advanced Manufacturing Technology



Persson, H. (May 1978). "NC machining of arbitrarily shaped pockets". Computer-Aided Design



Bieterman, Michael B.; Sandstrom, Donald R. (Nov 11, 2003). "A Curvilinear Tool-Path Method for Pocket Machining". Journal of Manufacturing Science and Engineering



Woodbury 1972, p. 23.



Roe 1916, p. 206.



Woodbury 1972, p. 17.



Roe 1916, caption of figure facing p. 142.



Roe 1918, p. 309.



Woodbury 1972, pp. 16–26.



Baida 1987 73

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Roe 1916, Chapter V: Inventors of the Planer, pp. 50–62.



Woodbury 1972, pp. 24–26.



Roe 1916, p. 165.



Roe 1916, pp. 208–209.



Woodbury 1972, pp. 51–55.



Woodbury 1972, pp. 79–81.



American Precision Museum 1992.



Pease 1952



Noble 1984, throughout.



"Design Guide: CNC Machining" (PDF). xometry.com.

Bibliography 

Usher, John T. (1896). The Modern Machinist (2nd ed.). N. W. Henley. Retrieved 2013-02-01.



Practical treatise on milling and milling machines. Brown & Sharpe Manufacturing Company. 1914. Retrieved 2013-01-28.



A treatise on milling and milling machines. Cincinnati, Ohio: Cincinnati Milling Machine Company. 1922. Retrieved 2013-01-28.



Noble, David F. (1984), Forces of Production: A Social History of Industrial Automation, New York, New York, USA: Knopf, ISBN 978-0394-51262-4, LCCN 83048867.



Roe, Joseph Wickham (1916), English and American Tool Builders, New Haven, Connecticut: Yale University Press, LCCN 16011753. Reprinted by McGraw-Hill, New York and London, 1926 (LCCN 27-24075); and by Lindsay Publications, Inc., Bradley, Illinois,(ISBN 978-0-9179-73-7) 74

Final project report BS mechanical 

Roe, Joseph Wickham (1916), English and American Tool Builders, New Haven, Connecticut: Yale University Press, LCCN 16011753. Reprinted by McGraw-Hill, New York and London, 1926 (LCCN 27-24075); and by Lindsay Publications, Inc., Bradley, Illinois, (ISBN 978-0-914-73-7).

Internet          

www.wikipedia.org www.szmillingmachine.com www.warco.com www.axminster.com www.indiamart.com www.toolco www.engineeringtools.com www.engineeredge.com www.machinex.com www.skyfirecnc.com

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