CNC ROUTER – MAIN ASSEMBLY

SIZE: D
MODEL NAME: CNC_ASSY01
SCALE: 1:2

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Table 1: Basic codes/ Basic Keys GFunction code G00 Positioning (Rapid Traverse) G01 Linear Interpolation (Cutting Feed) G02 Circular Interpolation/Helical Interpolation CW G03 Circular Interpolation/Helical Interpolation CCW G17 XY plane selection G18 ZX plane selection G19 YZ plane selection G20 Input in inch G21 Input in mm G28 G5459 G70 G71 G72 G73 G74 G92 G96 Auto Return to reference point Working coordinate system (1-6 selection) Finishing cycle Stock Removal in turning Stock Removal in Facing Pattern repeating End face peck drilling Maximum Spindle speed Constant Surface speed control M-code M00 M01 M03 M04 M05 M08 M09 M30 M41 M42 Other codes N F T ; U W Function Program STOP Program STOP optional Spindle START CW Spindle START CCW Spindle STOP Coolant ON Coolant OF END of program Spindle gear range 1-LOW (45-1500RPM) Spindle gear range 1HIGH(135-4500RPM) Block Number Feed (mm/min or inch/min) Tool End of block [EOB] Incremental coordinate for xaxis Incremental coordinate for zaxis

ABBREVIATION HOME (ZERO RETURN) JOG

KEY SYMBOL

DESCRIPTION Axis Home Selection : Both axes move to home position JOG feed selection: Mode is step feed MANUAL PULSE GENERATOR: To use Handwheel AUTO Mode Selection: Mode is automatic operation SINGLE BLOCK program execution for test operation. EDIT Mode Selection: for editing program MANUAL PULSE GENERATOR: electronics handwheel, low feed rate MANUAL PULSE GENERATOR: electronics handwheel, medium feed rate MANUAL PULSE GENERATOR: electronics handwheel, high feed rate Automatic operation is started Automatic operation is stopped

MPG AUTO SINGLE BLOCK EDIT MPG x1 MPG x10 MPG x100 CYCLE START CYCLE STOP CLNT ON COOLANT ON: Manual selection of coolant ON COOLANT OFF: Manual selection of coolant OFF POSITION: Shows all coordinates TOOL OFFSET SETTING: Write mode selection, manually input tool offset data PROGRAM: To open existing program, load new program, edit program To cancel input data *same as ‘backspace’ key in computer keyboard To enter data

CLNT OFF POS OFFSET SETTING PROG CANCEL

INPUT To insert every single code into the program To delete code, data, block, program To change program number, input data To terminate the current operation

INSERT DELETE ALTER RESET MDI

MANUAL DATA INPUT

Figure 3: Sample Part

We assume that the machining is a contouring operation along the outer boundary of a simple part, whose nominal geometry is as shown on Fig.3.

The tool size is 0.25 inch, and the feed rate of 6 inch per minute is used.

The cutting speed is required to be 300 rpm. To simplify the program, we ignore the Zaxis motions, and that the home position of the tool is at the correct height, centered on the point located in the machine tool coordinates as (2, 2).

In order to specify the geometry of the motion, we need to compute the location of 5 points from p1 to p5 (later, we shall see that additional points will be needed).

The cutting will proceed along the contour: p0 -> p1 -> p2 -> p3 -> p4 -> p5 -> p1.

// Block 1: start program, use absolute coordinates, spindle speed in rpm, feed in inch/min, select tool no 1001, turn coolant ON, use up milling (CCW in this case)

N010 G70 G90 G94 G97 M04[EOB]

NOTE: we could use M14 instead of M04 and M08 that we shall use in the next block.

// Block 2: cutting on XY plane, set feed, spindle speed,

N020 G17 F6.0 S300 T1001 M08 [EOB]

// Block 3: move to first point in a straight line (linear interpolation). We now need to compute the coordinates of p1, as shown in figure below:

Figure 4 : Calculating p1 coordinate

N030 G01 X3.875 Y3.698 [EOB]

// Block 4: move to p2 in straight line. coordinates of point p2: x = same as p1; y = 4 + 5 + 0.125.

N040 G01 X3.875 Y9.125 [EOB]

// Block 5: move to p3. coordinates calculated as shown in figure below:

Figure 5 : Calculating p3 coordinate

N050 G01 X5.635 Y9.125 [EOB]

// blocks 6, 7, 8: now we need to cut along a circular arc.

Most NC controllers cannot cut along a full circle directly — they need to be programmed once FOR EACH QUADRANT of the arc. In our case, the circular path of the tool goes through tree quadrants, so we need to find two additional points, p31, and p32.

Programming for circular interpolation (moving the tool along a circular arc): Circular arcs are machined only in main planes. The plane is selected by the preparatory functions (G17, G18, G19). The direction of the tool along the arc must be specified (G02, G03, G20 G21, G30, G31).

Four dimension words are needed per block. Two dimension words specify the distance to the end of the arc from current position. Two circular dimension words specify the distance to the arc center. Usually, I, J, K specify the distances parallel to the X, Y, Z axes, respectively.

The I, J, K values are absolute values (unless there is ambiguity). The following figure shows the computations of the next three blocks of motion:

Figure 6 : Circular movement from p3 to p4

The corresponding blocks are:

*NOTE: EOB stands for End Of Block

N060 G03 X5.625 Y9.0 I0.866 J0.125 [EOB]

N070 G03 X6.5 Y8.125 I0.875 J0.0 [EOB]

N080 G03 X7.375 Y9.0 I0.0 J0.875 [EOB]

// block 9: the next move is to point p4 (coordinates computed similar to p3).

N090 G03 X7.366 Y9.125 I0.875 J0.00[EOB]

// blocks 10, 11, 12: all linear interpolation.

Computations for the point p5 are as follows:

p4: y = 9.125; x = 9 + 0.125 tan 67.5 = 9.302

N100 G01 X9.302 [EOB]

NOTE: here we did not specify the Y coordinate, so it will be kept constant !

N110 G01 X3.875 Y3.698 [EOB] N120 G01 X2.0 Y2.0 M30 [EOB]

Take the rest…

Tools :

1. Turning tools
2. Milling tools

Machine:

1. CNC Turning Center
2. CNC Machine Center

Introduction:
The abbreviation CNC stands for computer numerical control, and refers specifically to a computer “controller” that reads G-code instructions and drives the machine tool, a powered mechanical device typically used to fabricate metal components by the selective removal of metal. CNC does numerically directed interpolation of a cutting tool in the work envelope of a machine. The operating parameters of the CNC can be altered via software load program. NC was developed in the late 1940s and early 1950s by John T. Parsons in collaboration with the MIT Servomechanisms Laboratory. CNC was preceded by NC (Numerically Controlled) machines, which were hard wired and their operating parameters could not be changed.

The first CNC systems used NC style hardware, and the computer was used for the tool compensation calculations and sometimes for editing. Punched tape continued to be used as a medium for transferring G-codes into the controller for many decades after 1950, until it was eventually superseded by RS232 cables, floppy disks, and finally standard computer network cables. The files containing the G-codes to be interpreted by the controller are usually saved under the .NC extension. Most shops have their own saving format that matches their ISO certification requirements.

The introduction of CNC machines radically changed the manufacturing industry. Curves are as easy to cut as straight lines, complex 3-D structures are relatively easy to produce, and the number of machining steps that required human action have been dramatically reduced. With the increased automation of manufacturing processes with CNC machining, considerable improvements in consistency and quality have been achieved. CNC automation reduced the frequency of errors and provided CNC operators with time to perform additional tasks. CNC automation also allows for more flexibility in the way parts are held in the manufacturing process and the time required to change the machine to produce different components. In a production environment, a series of CNC machines may be combined into one station, commonly called a “cell”, to progressively machine a part requiring several operations.

CNC machines today are controlled directly from files created by CAM software packages, so that a part or assembly can go directly from design to manufacturing without the need of producing a drafted paper drawing of the manufactured component. In a sense, the CNC machines represent a special segment of 1 industrial robot systems, as they are programmable to perform many kinds of machining operations (within their designed physical limits, like other robotic systems). CNC machines can run over night and over weekends without operator intervention. Error detection features have been developed, giving CNC machines the ability to call the operator’s mobile phone if it detects that a tool has broken. While the machine is awaiting replacement on the tool, it would run other parts it is already loaded with up to that tool and wait for the operator. The ever changing intelligence of CNC controllers has dramatically increased job shop cell production. Some machines might even make 1000 parts on a weekend with no operator, checking each part with lasers and sensors.

CNC checklist before startup

Before starting up the Computer Numerical Control Machine, there are safety rules that must be considered first. First important aspect before starting up the CNC machine is to ensure your own safety, therefore wearing protective gear, such as eye glasses and short sleeved shirts is an important dress code during CNC operation. You should also be careful whenever you are handling tools and sharp edged work pieces to avoid any accidents. You must also ensure that the cutting tools are fastened in the machine spindle to avoid any movement during the cutting operation.

Actual Startup, Operation and Machine Setup of the CNC

The Computer Numerical Machine startup procedure varies depending with the type of machine being used but usually there is a main power switch or a circuit breaker to turn it on. Some machines also require hydraulics or air pressure before it starts up.

When the Computer Numerical Machine starts up, the machine usually starts at its Machine Home Position. The Machine Home Position allows the control and the machine to have a preset starting position for all its axes. After startup, the CNC machine must be sent to this position before the work begins. This position will later be changed to an appropriate location whenever you are machining a particular part of a product.

The Tool Length Offset Value or TLO is the distance from the tip of the tool from the spindle in the Home Position. The TLO must be set for each tool in the current job. The TLO can be set using a height gage, fixture location, as well as the reference tool. When these values are determined, they are stored in the Controller to be used during the program operation.

After setting the Tool Length Offset Value it is time to setup a part origin of a CNC machine. Setting up the part origin on a CNC machine is the same as setting up a conventional machine. It usually involves positioning the axes to a point where the plan designates as its origin. There are many ways to locate the position on the reference point, it is by using edge finders, wigglers or magnifying glasses.

After setting up the whole system for the Computer Numerical Control, it is time to Load the program to the machine. Program loading is different for each machine. Some machines have tape readers to input the program into the Computer Numerical Control Machines memory. Newer machines have internal or external floppy devices to input the program to the machine. After the program is loaded to the machine, the CNC machine is now ready to use.

There are certain instances when you have to change the tools in the Computer Numerical Control manually during machine operations. When a certain machining operation is complete, the program will move the aces to the tool change position and display the next tool needed. It is now the job of the Machine operator to remove and replace it with the next tool.

Extra Care must be taken whenever you are starting operations with the CNC machine, any mistake taken during the part of the operation may lead to serious injuries from the machine operator.

Being a CNC operator takes a lot more than just being able to handle long hours of staring at the monitor or creating an input stack for the programs. What it means is that you have to have outstanding programming capabilities and at least basic machining knowledge.

Job Requirements

A CNC operator has to be knowledgeable about blueprint reading. This is because, basic design concepts and construction is hinged heavily on blueprints. Furthermore, the components that are being manufactured by companies that have CNC machines are based on blueprints of a whole structure. Therefore, if you do not know how to read blueprints, you wont know what to program the machine to do.

Another thing that a CNC operator has to have is familiarization with machine operations. If the operator does not know which machine tools are for which job, or how fast the machine can work, or what the rate of feed is for the machine, or even the depth of the cut needed for the operation, then you wouldnt be productive and the operation would be a failure.

The most obvious thing that an operator would have to know would be the general operating characteristics of the machine. He/she would have to know what the machine runs on—tape, network data input, or floppy. Furthermore, proper data input procedures have to be observed to lower the error ratio. A faulty data input procedure could cause the entire cycle to collapse therefore lowering the level of efficiency.

Working with CNC machines means that you will also be dealing with a lot of computer work. This means that you have to be familiar with basic computer operations. In addition to that, you will have to know how to interpret data in the program output stack.

The companys requirements and the benefits.

some companies require a lot more than what is written above. Oftentimes, they require applicants to be familiar with the system that they use. Other times, they want the applicants to have no less than five years of experience working in a factory or at least working with a CNC machine. Also, some companies require applicants to undertake a specific training program to ensure the employers that the material they are getting is worth the money they will be shelling out.

However, the benefits that can be reaped is quite solid. Salaries and insurances are often negotiable. Working hours are also a snap! All you would have to do is initiate the cycle and then sit back and occasionally check for glitches. Furthermore, these companies often takes care of their operators as there is always a shortage of skilled enough people to take hold of the position.

So, what does it take to be a CNC operator? To synthesize the requirements, you have to be amazingly determined to pass the requirements of the company you are applying for. And then, you have to be able to quickly restructure the program in case of any glitch that the computer might encounter during the process.

The benefits are solid, but passing the requirements is like surviving the gauntlet. Think about this career.

If you think that you will just sit back and relax when you have a CNC machine in your shop, think again. CNC may help you speed up your operations and even make them more efficient. However, CNC is not a wonder robot which will make you disregard all your employees and expect your shop to run on auto-pilot.

Though you will need more people without the CNC technology, you will need only three very, very skilled people. Call these people your friends, your team, whatever. In the long run, they might be just all you need to keep the shop in good shape.

THE PROGRAMMER

The first person is the CNC programmer. S/he is like the playmaker. S/he will create the programs that the CNC machines are intended to execute. Since the programs are in the form of CNC codes fabricated like sentences, he should have mastered these codes because they work like a different language. The regular CNC machine can use up to 50 codes, so thats like learning 50 new words for the newbie.

Also, the programmer should have at least and engineering or machining degree. Remember that the CNC machine will only execute WHAT IT IS PROGRAMMED TO DO. If the program is wrong, the whole operation goes down the drain with it. Moreover,s/he should also be flexible and have a fast turn-around because a CNC machine is often used to machine a huge selection of different work-pieces.

THE OPERATOR

The second person that you need is the CNC operator. S/he will simply recheck the programs loaded to the machine and push the right buttons to get the work done. However, thinking that a CNC operator can have little or NO SKILL AT ALL is wrong. A CNC machine operator must have at least basic machining skills and s/he should have undergone some form of training to run a CNC machine.

These machines can produce very intricate motions, making it possible to make shapes that cannot be created on conventional machine tools. So, the operator should foresee this complexity and know how to cruise with it. The skills that an operator must have though, are lesser compared to the operators of conventional machine tools.

THE TECHNICIAN

The third person that will need is the CNC technician. Although this may still be the programmer, its more convenient to always have a technical expert on-call because in the long run, you may have more than one CNC machine and you may need to prioritize over the other in case both gets crippled at the same time. Just like the programmer, the technician should also be flexible and articulate. CNC offers a lot of complexity when its running right, how much more if its behaving badly?

So, if you are having job openings for positions that need to be handling a CNC machine, ask the applicants first to do a demo for you and make sure that during the demo, they know what theyre doing. An exam may also do wonders too. If they have no experience with any kind of CNC machine, it is advisable that you encourage them to take short courses on CNC.

Eighty-hour courses are available online and hey, its better than nothing. Experts even encourage employers to hire CNC machinists who have finished AND PASSED the National Occupational Competency Testing Institute (NOCTI) assessment just so they could be sure that their CNC machines will go to good hands. After all, a CNC machine is still an asset.

Since the dawn of the CNC (Computer Numerical Control) machines introduction in the machining sector, they have been praised for being accurate, fast, consistent and flexible. Although CNC machines are not totally independent, a lot of major industries depend on these wonder machines. Common CNC-dependent industries include the metal industry and the woodworking industry. However, these industries, when small-time, can be operated by hands.

In this article, you will learn about the industries which are CNC dependent not because they have grown big in time but because they have to. It can be also that they are CNC dependent because their industries demand a low level of tolerance and a high level of sophistication. There are no small-time members of this industry. Lets start discussing.

THE AEROSPACE INDUSTRY

First off, this is already a very sophisticated industry. An engineering degree (solely) will not get you anywhere in the Aerospace industry. Not even within striking range. This industry demands so high from their members so machine shops that belong to this industry trust only the best of the best of CNC machining. In fact, sources say that the term Precision Machining has been coined from this industry.

In the materials they use, the aerospace industry already demands a lot. CNC machines which are used here are mostly capable of handling Inconel, Titanium, Magnesium, Stainless Steel and so much more. From parts of the landing gear, to shuttle seats, to housings, and even oxygen generation, CNC machines play a big part in their manufacturing.

Its not just that. Every CNC machine used in this industry also has to be approved AND RATED by the Federal Aviation Administration (FAA) to be safe and to be surely capable of Precision Machining. A NASA experience is highly praised too.

THE MEDICAL INDUSTRY

If the Aerospace Industry demanded precision above all, the Medical Industry demands sterility as much as precision. Thats something that you may have known since you got your first vaccine. Most CNC machines which work for this industry are multi-spindle and contain multi-turret lathes.

These special features allow the company to turn out components for hospital equipment, pulse meters, blood purification systems and mother medical devices. They are also useful in the mass production of disposable items and non-embeddable components.

High-torque milling and turning spindles are heavily demanded in this industry to enable users to process all substrates currently used in the medical device and orthopedic implant markets. Moreover, CNC machines recommended in the medical industry are those which can properly handle Titanium, Cobalt Chromium, Nitinol and others.

THE MILITARY INDUSTRY

This industrys main concern aside from precision is security. In fact, if you try to search online the CNC-manufactured materials or CNC machines used in this industry, no matter how famous their reputation is, the manufacturer cannot display (pictures of) the materials that they have produced for their clients. They can only display products which they are used in.

This industry deals heavily with Inconel, Titanium, Kevlar, Monel and Hastealloy; so most CNC machines recommended in the Military industry must be able to handle those.

Famous CNC standards evaluators in this industry include the Department of Defense (DOD), the Mil Spec (Military Specifications) and other selected military sectors.

The top managers of these industries also demand their CNC machines to be purchased from CNC machine suppliers which adhere to the International Standards Organization (ISO). And because these industries are CNC-dependent, their shops can occupy a vast amount of space. Basically, that makes no room for old school methods and errors.

Acquiring a CNC machine is more than just buying additional equipment; it also has a social aspect in it. Here is the low down:

PEOPLE-WISE

First, you have to consider the people who are working in your shop. How many people will be displaced if you buy a CNC machine? Keep in mind that a CNC machine is multi-operational; so its possible that a couple of laborers will be erased from the production team. Experts say that the healthy ratio is at least one-sixth (1/6) of your whole labor force.

You will be saving time and effort, yes, and that is the best thing about having a CNC machine. However, you might be worrying about actually terminating people because, to put it bluntly, you wont need them anymore. A CNC machine, just like any machine, will need an operator. Instructions used by a CNC machine for operational execution are composed of CNC words/codes and is in the form of a sentence.

Does one of your people ever have experience with a CNC machine before? Can s/he formulate CNC instructions? If the answer to both questions are yes, then thats absolutely good news. However, if you answered no to at least one of the questions, then there are more things to evaluate.

Are your people capable of fast-learning? If it pains you to terminate them because they have been good employees in the past, train them on how to use the CNC machine and how to compose instructions for it. There are plenty of free training kits online.

COMPANY-WISE

Theres a corporate adage that goes: Innovate or die. Theres a lot of truth in that. A purchase of any CNC machine symbolizes a companys decision to innovate to increase productivity. However, there are a few things that you need to note.

Review your companys history. How long should you innovate drastically in terms of production? CNC equipment is expensive. It is an investment. In the long run, you may be forced to buy new equipment more often. Consider CNC heavily if you feel that your company innovates faster than other companies in terms of the industry that you belong to. After all, you can easily alter designs and material when you have CNC powered operations.

In most companies, Innovation is another word for saving. It means saving time, effort and space. In using CNC machines, the first two factors are sure savings while the third is not. People doing the labor and CNC machines often occupy the same amount of space. Do not romanticize a clearing of clutter effect when you buy a CNC machine. You will keep up, in terms of production; but CNC equipment also occupies a lot of space. So in that aspect, its pretty much the same thing.

Another thing that you have to be reminded of is the level of accuracy that your company needs to produce. Intricate patterns on metal/wood will DEMAND CNC accuracy. So any time that you feel your company is ready for such innovation and accuracy, consider employing CNC in your manufacturing.

At the end of the day, the last aspect that you need to evaluate is you, yourself. As the owner/head manager, you have to KNOW AND UNDERSTAND the CNC machine and the software well. This is the biggest battle that you have to face.

The equation to improvement is simple a really good machine plus a really good operator (you). Do not easily be blinded by the salesmens poetry.

All of these motion types may seem different but they share two things in common, which would be that they are all modal and the endpoint of each motion is specified in motion command. By being modal it means that the motion type would be in effect until changed otherwise.

3 common motion types:

1.)Rapid Motion Type

Rapid motion type is also called Positioning. The way this motion type is used is through utilizing the fastest rate possible of the command motion of the machine. Example uses of rapid motion are moving to clear obstructions, placing cutting tools to and from the desired position, and any program that provides non-cutting in their schemes.

The command that is usually programmed to a CNC machine is G00 because in this command, the end point for the rapid motion would be specified.

The CNC machine, with most controls given, will be able to move as fast as possible in all commanded axes. In the case of rapid motion, one axis may be able to reach its end point before other axes. Straight line movement will not occur with type of rapid command function and the programmer of the machine must take into account that there are no obstructions to avoid. Straight line motion will happen even during rapid motion commands when done with other controls.

2.)Straight Line Motion

This type of motion would allow the programmer of the machine to command perfectly straight line movements within the machine. Unlike the rapid motion type, the straight line motion would allow the programmer to vary the rate of the motion or feed rate to be used during the movement. Examples of using straight line motion would be turning a straight diameter, taper, when milling straight surfaces, and when drilling for this is because these examples require straight cutting movement.

The common word to specify a straight line motion into a machine would be G01, for within this command the programmer will include the preferred end point within each of the axes.

3.)Circular Motion

This motion type would cause the machine to move in the direction of a circular path and is used to generate the radii in machining. When talking about points on circular motion feed rate, it is equal to that of straight line motion.

Other than that of straight line motion and rapid motion, there are two G codes that are commonly used when programming a circular motion into a machine. These are G02 and G03. G02 is used when the programmer desires a clockwise motion into the machine while G03 is used to make an anti-clockwise motion. To know which of the commands to use, the programmer must view the movement with the same perspective as to what the motion of the machine will be, may it be clockwise or anti-clockwise.

Another requirement that would be programmed into a machine that would be using circular motion is that the programmer must specify the radius of the arc that is to be generated. With brand new technological advances in CNC, an R word is now used to specify the radius.

For older controls in CNC machinery, an I, J, and K are used to specify location of the center point of the arc.