CNC Lathe Turning - AIT

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Advanced Integrated Technologies (AIT) offers CNC lathe
turning services for both short and long run production, for
customers all over the world. AIT utilizes 5 axis multi-purpose
machines which allow us to both turn and mill features into a part,
all within the same machine.

Our Daewoo lathes are precision
machine tools that are designed for versatility and speed. We turn
almost any material, but the vast majority of our CNC lathe turning
is done in aluminum and stainless steel. If you need lathe turning or
milling services, AIT is your provider.


Lathe turning is the process of shaping material by spinning the raw material and then bringing a cutting tool into contact with the spinning raw material. Many people’s first exposure to this process is with a wood lathe, where wood is spun and then shaped by a person using a sharp chisel like tool. As the cutting tool touches the raw material, it essentially “peels” the material away. CNC lathe turning is simply doing this with a lathe that is computer numeric controlled (CNC), or in other words, controlled by a computer program and servo motors.

CNC lathe turning has come a long way since the early days. The essence of the CNC lathe turning process hasn’t changed that much, but the details are far advanced. Today’s machines use indexable replaceable carbide or diamond insert cutters to reduce tooling cost, improve consistency, and speed up tool change over. Also most machines today run fully enclosed, and force high pressure coolant into the cutting zone to keep material and cutting tools cool, and to flush away the chips that are peeled off the raw stock. These and other advances have brought CNC lathe turning into the twenty-first century.







CNC lathe turning is divided into several broad categories. At one end of the spectrum is screw machine work, which is a multi-spindle high production machine. These typically produce simpler parts, like a bushing for example, but in very high volume. This keeps the per part cost very low. At the opposite end of the spectrum are 5 axis live tool machines. These can produce highly complex geometry by combining lathe turning with milling capability, all within the same machine. This often eliminates second milling operations, and thus helps in keeping the final part price low. AIT utilizes 5 axis live tool machines for our CNC lathe turning services, in order to be very flexible with short run production.
Email or Call 870-269-4367 to request a quote
Find CNC Machine Shops and CNC Milling Turning at A-I-T.Com.

CNC Machine Shops - A Great Contribution in the Business World

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By John Balentine
The word 'machine' is derived from a Latin word 'machina'. A machine is a device that is used to perform any task. It is a device with some parts attached to it that perform or directs in performing a particular task. A person who is an expert in machines is known as a machinist. A place, room or building where machining is done is known as machine shops. Latest trends and technology has also brought about a drastic change in controlling machines. Earlier machines were controlled by human labor by now it is controlled by computer numerical control which is an abbreviation of CNC.
Nowadays large numbers of machine shops have switched to CNC machine shops. Some shops are specialized in producing only one type of products whereas; others accommodate for mass production like aerospace industry, automotive industry and furniture making etc.
CNC machine shops have allowed businesses to expand and provide services which they could never think of before the introduction of CNC machine. The biggest advantage of these shops is that they are precise and provide multiple shapes with minimum wastage.
It is always better to seek services from a CNC shop then to invest in establishing your own CNC milling department. This will be cost effective since you will be saving a whole bundle of money which you would have spent in buying and owing your own CNC shop. It is always better to take advantage from CNC machine shops available as they have already invested a lot of money in buying the desired equipments.
Another advantage of getting your work done from CNC shops is that your department will not have to sit idle when there is no work regarding such machines. This will be a waste of money since your employees will not be working on a daily basis but you will have to pay them salary for the entire month.
Even though the machines are self controlled, safety measures must be taken seriously to avoid any accidents or mishaps. These machines do not produce a lot of noise and wastage but even then the operators are advised to wear safety goggles and earplugs.
CNC machine shops require expert operators to control the machine. These operators usually have a desk job, they write programs which help the machine to operate effectively and efficiently. Any mistake in the program will result in producing defective products.
Even though the machines are self controlled they still need a set of instructions to work effectively, appropriate tools to produce the desired outcome, placement of raw material is very essential to obtain the desired outcome and last but not the least an operator to push the start button to start the machine.
In a CNC machine shop it is very important to make sure that the employees are trained and up to date with the latest technologies. Each employee must meet the standards of the company in order to ensure that the products that are produced are of high quality.
CNC machine shops provide their clients with unique services which no other machine shop can offer unless they have the same equipment and tools.
Find CNC Machine Shops and CNC Milling Turning at A-I-T.Com.

6 Important Things to Consider Before Buying a New CNC Milling Machine

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By Jimmy Dales

In today's industrial mechanical business industry, traditional milling machines have become obsolete ever since the innovation of Computer Numerical Control (CNC) milling machines which have helped many companies to produce wide spectrum of components on a large scale without neglecting precision and accuracy. It has proven that these machines have the ability to boost one's productivity and profitability. As a result of technology advancement, this explains CNC machining centers are capable to perform complex milling operations which subsequently enables companies fabricate more useful components.
If you are a business owner who has a few older CNC machining centers - you might be having difficulties whether you should a newer version or remain the old ones. Here are several things that you need to consider before buying a new CNC milling machine:
1. The size of your components produced - For instance, if your business requires machines which are capable to fabricate large or small components - ideally, you would need a larger milling machine to manufacture large components and smaller machines vice versa. If there is no change of the component size, it is not necessary to change your old CNC machining centers.
2. The complexities of the component design - Basically, newer models usually have its own distinctive number of axes - which represents its simultaneous movement of the cutting tools, for instance, 4-axis and 5-axis machines. If you are planning to perform positioning work on complex multi-parts over a long period of time, then you need to have advanced machining centers to perform intricate parts production operations. If your business only requires 3-axis CNC milling machines, it means that you are only capable to produce low difficulty components.
3. The actual condition of the machine used - If your current machining centers have been frequently sent for maintenance, you are required to bear the high maintenance cost over the long term. When it comes to a situation where it is worth to invest in CNC milling machines rather than spending on the maintenance, it is wisely that you consider purchasing new models to replace the older machines.
4. The actual productivity of the machine - You would need to buy new CNC machining centers if you want to offer fast turnaround time to your clients. Newer models have updated integrated control software which can hasten repetitive high precision milling operations. If you have productivity problems with your old machining centers, it will affect your turnaround time and subsequently it will affect your reputation over the long term.
5. Dealing with the precision issue - If your CNC milling machines have precision issues - for instance, the components produced are far from the precision range, it will affect the quality of components and you will likely to receive complaints from your clients. In order to avoid this problem, you need to find CNC machining centers which are capable to perform high precision cutting and drilling operations effectively.
6. The machine cleanup cost - Newer models have efficient chip management feature that can keep the chips out and the internal cutting tools clean. If you are not experiencing cleanup cost problems - stick with the old CNC milling machines to perform milling operations as usual.
Hope that you can make a wise decision whether you should buy a new CNC milling machine by considering several things as mentioned above.
If you think that it's not necessary to buy any machining centers at this moment - why not try outsourcing your CNC milling task now! See how it can boost your productivity and profitability of your business.
Searching for companies which provide high quality and affordable CNC milling service can be indeed a time-consuming process.
To speed up the search process - If you are looking for high quality parts production service, try out Abtech's professional precision engineering services - For more information about it - CLICK HERE.
If you have a new project or an existing project that needs a new approach which requires CNC milling solutions, please visit this website - ABTech-Precision-Engineering.com

CNC Vedio NMV5000 - 5 Axis Simultaneous Machining

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CNC Machine Auction

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By David Karlson

Are you looking to save money on your CNC purchase? One of the best places to look is a CNC machine auction. Before wasting your time, do some research on the exact type of machine you need. Then, if possible attend the previewing of the auction items. This way you can look over the items before bidding on anything.
There could be a variety of different CNC machines available at a CNC machine auction. Which type do you need? Is it a milling machine or a tube bending machine? These are important points to note before any bidding begins.
What type of auction should you attend? You have several otpions, one is an auction for a manufacturing facility that is going out of business and needs to liquidate it's assets. Another, is an auction house that is auctioning off items for a specific client. There are websites that cater specifically to machines and CNC machine auctions.
Sometimes a CNC machine auction may allow you to inspect the merchandise prior to any bidding. In other cases, you are not allowed to carefully inspect the machines. As in the case with any type of auction, it is buyer beware. It is much better for you if you have some experience with these types of mashines. In addition, try to bid on a machine that appears to be rarely used.
Some people even have had some luck on ebay when searching for a good CNC machine auction. The reason why more people are turning to auctions for CNC machines is because of the popularity of these machines these days and the downturn in the economy. Companies are looking at cheaper ways to upgrade their current machinery and to reduce costs to compete in todays economic uncertainty.
A CNC machine auction is similar to any other auction in that you must know the item you are bidding on. Do your homework and there is a good chance that you will get yourself a bargain.
We have combined a great deal of information into one complete site about CNC or computer numerical control. Visit our site today for all your CNC related inquiries including CNC motion control
http://www.computer-numericalcontrol.com/
By D. Karlson
 

Thermwood - 5 Axis CNC Router at John Cox's Creature Workshop

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Concept car CAD/CAM- CNC 5 axis machining

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New CNC Machine = lASMC-510P Super Maxi VERTICAL MACHINING CENTER

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Acra ASMC-510P Super Maxi Vertical Machining Center



 


Acra Model ASMC-510P Super Maxi VERTICAL MACHINING CENTER
Specifications: ASMC-510P Super Maxi Specifications: ASMC-510P Super Maxi
Travel, X (Long.) 20" Travel, Y (Cross) 16"
Travel, Z (Vert.) 18" Table size 23.5x14.9"
Spindle speeds 8,000 ATC type Carousel, 16
CNC control Mitsubishi 64M Rapids 1181XY,789Z
Spindle HP 10 Spindle taper, drive BT40(CT opt)
Spindle nose to table 3.5-21.65" Table load capacity (lbs) 500
Servo drives 1.3 HP AC Type of ways Recirc. Linear
Rigid tapping Yes Accuracy +/-0.0002"/12"
Repeatability +/-0.0001" Net weight (lbs) 5,500
Country of origin Taiwan
ACRA VERTICAL MACHINING CENTER MODEL ASMC-510P SUPER MAXI CENTER
Three Free and Easy Services: Click here.
 MITSUBISHI 64M CONTROL Featuring
  • Ballscrews are double nuit designed, anchored at both ends

  • Ribbed Meehanite cast iron

  • Minimal operator lean-in for easy loading 
    Specification:
  • Longitudinal travel (X-axis) - 20"

  • Cross travel (Y-axis) - 16"

  • Vertical travel of head (Z-axis) - 18"

  • Table work area - 23.5 x 14.9"

  • Distance table surface to spindle nose - max./min. - 3.5"/21.6"

  • Spindle speed range - 8,000 RPM

  • Spindle drive motor - 10 HP

  • Spindle taper - BT40 (CT40 optional)

  • Rapid traverse rate: - X and Y-axis - 1181 IPM, Z-axis 789 IPM

  • Table lod capacity - 500 lbs.

  • Cutting feedrate - 0.04 to 196 IPM


  • Tool magazine capacity - Carousel, 16 (20 opt.)

  • Max. tool dia. - 3.15"

  • Max. tool length - 9.8"

  • Tool selection system - Bi-directional

  • Tool weight, maximum - 15.4 lbs.

  • Distance spindle center to column face - 14.6"

  • Overall machine height - 97

  • Required floor space - 90" x 90"

  • Net weight – approximately - 5,500 lbs.

  • Machine accuracy Positioning +/-0.0002"/12", Repeatability +/-0.0001"

  • Mitsubishi AC servo motor 1.3 HP

  • Air required - 80 psi

  • Standard Mitsubishi 64M CNC control features:


  • Program storage - 600 m

  • Tool length compensation

  • Cutter compensation

  • Tool offsets, 200 sets

  • Inch/Metric conversion

  • Workpiece coordinate, 54 sets

  • RS232C interface

  • Least input increment 0.001 mm (0.0001")
    Standard machine items:
  • MPG Handwheel

  • Heat Exchanger for NC cabinet

  • Air blow system

  • Auto Way Lube





  • Work Light

  • Pilot Lamp

  • Leveling bolts and pads

  • Manuals and toolbox 








  • AMADA WASINO DV-1 CNC FORM GRINDER

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    Grinders
    State New
    ID Number
    Make AMADA WASINO DV-1 CNC FORM GRINDER
    Description THE ULTIMATE IN CNC FORM GRINDING WITH CCD IMAGE MEASUREMENT.
    Revolution in Optical Profile Grinding technology with the profile grinding centre fitted with up to 7 contolled axis
    Automatic operation for grinding profile shapes in parts as fine profile punches, including rotation, side clearences, front clearence with full automation of measurement of workpiece by CCD and automatic correction/compensation to sub-micron accuracy.
    100mm diameter rotary table.
    Table travel 300/250/80mm.
    Wheelhead reciprocation slide 80mm.
    Reciprocation speeds 30-400/min.
    Wheel speed 2,000-20,000rpm.
    Available with 10 pallet auto-loader
    Email: enquiries@colingladwell.com

    New CNC Machine

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    Hardinge CNC Lathes...

    Talent - Universal Bar & Chucking. 45-78mm Bar
    Elite - Bar & Chucking with C-Axis & live tooling
    Quest GT – Super Precision Gang slide
    Quest – High performance, Multi Tasking & SP
       

    Bridgeport Mills & Machining Centres...

    Series 1 – Manual Turret Mills, with CNC option
    XP – Low cost range of VMC’s
    P3 – Range of VMC’s from 450 to 1500
    XP3 – High performance VMC’s from 600 to 1500
    HSC500 – High speed VMC, 40,000rpm
    5AX – High performance full 5-Axis
    480 – High speed Drilling, Tapping Milling VMC’s
    APC – Auto pallet changer VMC's 480, 700 & 1000
    HMC700 – Twin pallet Horizontal, 4-Axis
       

    Grinding Machines...

    Kellenberger – Manual & CNC Cylindrical Grinders
    Bridgeport FGS - 5-Axis Viper Grinding technology
    Hauser – Jig Grinders
    Tschudin – High production Cylindrical Grinders
    Tripet – CNC Internal & OD Grinders

    Machine Tool

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    According to USMTC, machine tool sales in December 2010 were 75.2% (units) and 113.8% (real dollars) more than in December 2009. Since January 2004, there have been only 11 months that have recorded higher unit sales than December 2010. Over the same time period, there have been only seven months that have recorded higher real dollar sales than December 2010. Given the sales of not just December but the last four months of 2010, it is fair to say that machine tool sales have returned to normal. In fact, orders for machine tools are so strong that deliveries are being pushed out. Machine tool components, such as ball screws and controllers, are in short supply, making it even more difficult for builders to meet demand. In 2010, machine tool sales were 61.1% higher than in 2009, almost certainly a record. I look for the peak annual growth rate to reach the low 70% range around the March-April time frame. Since machine tool sales are as strong as they have been in quite some time, I expect the annual growth rate to start slowing down after the first quarter of 2011. For more on machine tool sales and the leading indicators, go here.

    Knowing Machining in Japan

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    DMG/Mori Seiki’s Greg Hyatt, who heads the company’s Machining Technology Laboratory, offers a booth tour for editors during JIMTOF 2010.


    In late October/early November, DMG/Mori Seiki hosted a press junket to Japan to visit Mori’s Iga and Nara manufacturing campuses as well the 25th edition of JIMTOF, the Japan International Machine Tool Fair. This is the first JIMTOF since the business collaboration between Mori Seiki and DMG was established. Their joint JIMTOF booth featured 15 new models among the 34 machines on display. The show also marked the introduction of the company’s X-Class machines to the Japanese market (these machines were introduced to the U.S. market at IMTS). The X-Class is a machine line engineered to offer rigid, stable machining as well as lower energy consumption and an attractive price point. Here’s some detail about that new line.

    The company’s booth also displayed a number of interesting machined parts, including winning entries to the company’s Cutting Dream contest. This contest is open to manufacturing companies, schools and research institutions engaged in machining in Japan. Check out this slideshow of those winning entries.

    JIMTOF is held at Tokyo’s Big Sight complex located on a man-made island filled with buildings sporting very interesting (i.e. non-traditional, sorta “out there”) architecture. Nearly 115,000 visitors attended the show despite the rainy weather (there was a typhoon in the area at that time). I managed to snap photos of a handful of interesting technologies that caught my eye at the show and you can see them in this slideshow.

    Thanks to all at DMG/Mori Seiki for hosting such an interesting, informative and fun trip to the Land of the Rising Sun. Domo arigato!

    CNC Machine Controls

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    The CNC (computer numerical control) system of a machine tool includes the control unit itself, as well as less visible parts of the motion-control system such as the servomotors, drives and axis positioning devices. These components are part of any CNC machine tool, but they might be bought separately and retrofitted later on older machines that are upgraded or refurbished. Also part of the control system are sensors that may allow the control to make certain real-time decisions during unattended or lightly attended machining processes. These can include probes for measuring the position of the part or machined features, as well as monitoring systems for detecting the presence of the tool or the force that is being exerted in the cut.

    Knowing your machine

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    A CNC operator MUST understand the makeup of the CNC machine tool being utilized. While this may sound like a basic statement, a CNC user must be able to view the machine from two distinctly different perspectives. Here in key concept number two, we will be viewing the machine from a programmer’s perspective. Much later, in key concept number seven, we will look at the machine from an operator’s viewpoint.

    Basic machining practice – the key to success with any CNC machine
    Many forms of CNC machines are designed to enhance or replace what is currently being done with more conventional machines. The first goal of any CNC beginner should be to understand the basic machining practice that goes into using the CNC machine tool. The more the beginning CNC user knows about basic machining practice, the easier it will be to adapt to CNC.
    Think of it this way. If you already know basic machining practice as it relates to the CNC machine you will be working with, you already know what it is you want the machine to do. It will be a relatively simple matter of learning how to tell the CNC machine what it is you want it to do (learning to program). This is why machinists make the best CNC programmers, operators, and setup personnel. Machinists already know what it is the machine will be doing. It will be a relatively simple matter of adapting what they already know to the CNC machine.
    For example, a beginner to CNC turning centers should understand the basic machining practice related to turning operations like rough and finish turning, rough and finish boring, grooving, threading, and necking. Since this form of CNC machine can perform multiple operations in a single program (as many CNC machines can), the beginner should also know the basics of how to process workpieces machined by turning so a sequence of machining operations can be developed for workpieces to be machined.
    This point cannot be overstressed. Trying to learn about a particular CNC machine without understanding the basic machining practice related to the machine would be like trying to learn how to fly an airplane without understanding the basics of aerodynamics and flight. Just as a beginning pilot will be in for a great number of problems without understanding aerodynamics, so is the beginning CNC user have difficulty learning how to utilize CNC equipment without an understanding of basic machining practice.
    Learning about a new CNC machine – the key points
    From a programmer’s standpoint, as you begin to learn about any new CNC machine, you should concentrate on four basic areas. First, you should understand the machine’s most basic components. Second, you should become comfortable with your machine’s directions of motion (axes). Third, you should become familiar with any accessories equipped with the machine. And fourth, you should find out what programmable functions are included with the machine and learn how they are programmed.
    Machine components
    While you do not have to be a machine designer to work with CNC equipment, it is important to know how your CNC machine is constructed. Understanding your machine’s construction will help you to gauge the limits of what is possible with your machine. Just as the race car driver should understand the basics of suspension systems, breaking systems, and the workings of internal combustion engines (among other things) in order to get the most out of a given car, so must the CNC programmer understand the basic workings of the CNC machine in order to get the most from the CNC machine tool.
    For a universal style slant bed turning center, for example, the programmer should know the most basic machine components, including bed, way system, headstock & spindle, turret construction, tailstock, and work holding device. Information regarding the machine’s construction including assembly drawings is usually published right in the machine tool builder’s manual. As you read the machine tool builder’s manual, here are some of the machine capacity and construction questions to which you should find answers.
    What is the machine’s maximum RPM? How many spindle ranges does the machine have (and what are the cut-off points for each range? What is the spindle and axis drive motor horsepower? What is the maximum travel distance in each axis? How many tools can the machine hold? What way construction does the machine incorporate (usually square ways, dovetail, and/or linear bearing ways)? What is the machine’s rapid rate (fastest traverse rate)? What is the machine’s fastest cutting feedrate?
    These are but a few of the questions you should be asking yourself as you begin working with any new CNC machine. Truly, the more you know about your machine’s capacity and construction, the easier it will be to get comfortable with the machine.
    Directions of motion (axes)
    The CNC programmer MUST know the programmable motion directions (axes) available for the CNC machine tool. The axes names will vary from one machine tool type to the next. They are always referred to with a letter address. Common axis names are X, Y, Z, U, V, and W for linear axes and A, C, and C for rotary axes. However, the beginning programmer should confirm these axis designations and directions (plus and minus) in the machine tool builder’s manual since not all machine tool builders conform to the axis names we show.
    As discussed in key concept number one, whenever a programmer wishes to command movement in one or more axes, the letter address corresponding to the moving axes as well as the destination in each axis are specified. X3.5, for example tells the machine to move the X axis to a position of 3.5 inches from the program zero point in X (assuming the absolute mode of programming is used.
    The reference point for each axis
    Most CNC machines utilize a very accurate position along each axis as a starting point or reference point for the axis. Some control manufacturers call this position the zero return position. Others call it the grid zero position. Yet others call it the home position. Regardless of what it is called, the reference position is required by many controls to give the control an accurate point of reference. CNC controls that utilize a reference point for each axis require that the machine be manually sent to its reference point in each axis as part of the power up procedure. Once this is completed, the control will be in sync with the machine’s position.
    Accessories to the machine
    The third area a beginning CNC user should address is related to other possible additions to the basic machine tool itself. Many CNC machine tools are equipped with accessories designed to enhance what the basic machine tool can do. Some of these accessories may be made and supported by the machine tool builder. These accessories should be well documented in the machine tool builder’s manual. Other accessories may be made by an after-market manufacturer, in which case a separate manual may be involved.
    Examples of CNC accessories include probing systems, tool length measuring devices, post process gauging systems, automatic pallet changers, adaptive control systems, bar feeders for turning centers, live tooling and C axis for turning centers, and automation systems. Truly, the list of potential accessory devices goes on and on.
    Programmable functions
    The programmer must also know what functions of the CNC machine are programmable (as well as the commands related to programmable functions). With low cost CNC equipment, often times many machine functions must be manually activated. With some CNC milling machines, for example, about the only programmable function is axis motion. Just about everything else may have to be activated by the operator. With this type of machine, the spindle speed and direction, coolant and tool changes may have to be activated manually by the operator.
    With full blown CNC equipment, on the other hand, almost everything is programmable and the operator may only be required to load and remove workpieces. Once the cycle is activated, the operator may be freed to do other company functions.
    Reference the machine tool builder’s manual to find out what functions of your machine are programmable. To give you some examples of how many programmable functions are handled, here is a list a few of the most common programmable functions along with their related programming words.
    Spindle control
    An "S" word is used to specify the spindle speed (in RPM for machining centers). An M03 is used to turn the spindle on in a clockwise (forward) manner. M04 turns the spindle on in a counter clockwise manner. M05 turns the spindle off. Note that turning centers also have a feature called constant surface speed which allows spindle speed to also be specified in surface feet per minute (or meters per minute)
    Automatic tool changer (machining center)
    A "T" word is used to tell the machine which tool station is to be placed in the spindle. On most machines, an M06 tells the machine to actually make the tool change. Tool change (on turning centers) A four digit "T" word is used to command tool changes on most turning centers. The first two digits of the T word specify the turret station number and the second two digits specify the offset number to be used with the tool. T0101, for example specifies tool station number one with offset number one.
    Coolant control
    M08 is used to turn on flood coolant. If available M07 is used to turn on mist coolant. M09 turns off the coolant.
    Automatic pallet changer
    An M60 command is commonly used to make pallet changes.
    Other programmable features to look into
    An M60 command is commonly used to make pallet changes.
    As stated, programmable functions will vary dramatically from one machine to the next. The actual programming commands needed will also vary from builder to builder. Be sure to check the M codes list (miscellaneous functions) given in the machine tool builder’s manual to find out more about what other functions may be programmable on your particular machine. M codes are commonly used by the machine tool builder to give the user programmable ON/OFF switches for machine functions. In any case, you must know what you have available for activating within your CNC programs.
    For turning centers, for example, you may find that the tailstock and tailstock quill is programmable. The chuck jaw open and close may be programmable. If the machine has more than one spindle range, commonly the spindle range selection is programmable. And if the machine has a bar feeder, it will be programmable. You may even find that your machine’s chip conveyor can be turned on and off through programmed commands. All of this, of course, is important information to the CNC programmer.

    The Basics Of Computer Numerical Control

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    Fundamentals Of CNC
    While the specific intention and application for CNC machines vary from one machine type to another, all forms of CNC have common benefits. Though the thrust of this presentation is to teach you CNC usage, it helps to understand why these sophisticated machines have become so popular. Here are but a few of the more important benefits offered by CNC equipment.


    The first benefit offered by all forms of CNC machine tools is improved automation. The operator intervention related to producing workpieces can be reduced or eliminated. Many CNC machines can run unattended during their entire machining cycle, freeing the operator to do other tasks. This gives the CNC user several side benefits including reduced operator fatigue, fewer mistakes caused by human error, and consistent and predictable machining time for each workpiece. Since the machine will be running under program control, the skill level required of the CNC operator (related to basic machining practice) is also reduced as compared to a machinist producing workpieces with conventional machine tools.
    The second major benefit of CNC technology is consistent and accurate workpieces. Today’s CNC machines boast almost unbelievable accuracy and repeatability specifications. This means that once a program is verified, two, ten, or one thousand identical workpieces can be easily produced with precision and consistency.
    A third benefit offered by most forms of CNC machine tools is flexibility. Since these machines are run from programs, running a different workpiece is almost as easy as loading a different program. Once a program has been verified and executed for one production run, it can be easily recalled the next time the workpiece is to be run. This leads to yet another benefit, fast change-overs. Since these machines are very easy to setup and run, and since programs can be easily loaded, they allow very short setup time. This is imperative with today’s Just-In-Time product requirements.
    Motion control – the heart of CNC
    The most basic function of any CNC machine is automatic, precise, and consistent motion control. Rather than applying completely mechanical devices to cause motion as is required on most conventional machine tools, CNC machines allow motion control in a revolutionary manner. All forms of CNC equipment have two or more directions of motion, called axes. These axes can be precisely and automatically positioned along their lengths of travel. The two most common axis types are linear (driven along a straight path) and rotary (driven along a circular path).
    Instead of causing motion by turning cranks and handwheels as is required on conventional machine tools, CNC machines allow motions to be commanded through programmed commands. Generally speaking, the motion type (rapid, linear, and circular), the axes to move, the amount of motion and the motion rate (feedrate) are programmable with almost all CNC machine tools.
    Accurate positioning is accomplished by the operator counting the number of revolutions made on the handwheel plus the graduations on the dial. The drive motor is rotated a corresponding amount, which in turn drives the ball screw, causing linear motion of the axis. A feedback device confirms that the proper amount of ball screw revolutions have occurred.
    A CNC command executed within the control (commonly through a program) tells the drive motor to rotate a precise number of times. The rotation of the drive motor in turn rotates the ball screw. And the ball screw causes drives the linear axis. A feedback device at the opposite end of the ball screw allows the control to confirm that the commanded number of rotations has taken place.
    Though a rather crude analogy, the same basic linear motion can be found on a common table vise. As you rotate the vise crank, you rotate a lead screw that, in turn, drives the movable jaw on the vise. By comparison, a linear axis on a CNC machine tool is extremely precise. The number of revolutions of the axis drive motor precisely controls the amount of linear motion along the axis.
    How axis motion is commanded – understanding coordinate systems It would be infeasible for the CNC user to cause axis motion by trying to tell each axis drive motor how many times to rotate in order to command a given linear motion amount. (This would be like having to figure out how many turns of the handle on a table vise will cause the movable jaw to move exactly one inch!) Instead, all CNC controls allow axis motion to be commanded in a much simpler and more logical way by utilizing some form of coordinate system. The two most popular coordinate systems used with CNC machines are the rectangular coordinate system and the polar coordinate system. By far, the most popular of these two is the rectangular coordinate system, and we’ll use it for all discussions made during this presentation.
    One very common application for the rectangular coordinate system is graphing. Almost everyone has had to make or interpret a graph. Since the need to utilize graphs is so commonplace, and since it closely resembles what is required to cause axis motion on a CNC machine, let’s review the basics of graphing.
    As with any two dimensional graph, this graph has two base lines. Each base line is used to represent something. What the base line represents is broken into increments. Also, each base line has limits. In our productivity example, the horizontal base line is being used to represent time. For this base line, the time increment is in months. Remember this base line has limits – it starts at January and end with December. The vertical base line is representing productivity. Productivity is broken into ten percent increments and starts at zero percent productivity and ends with one hundred percent productivity.
    The person making the graph would look up the company’s productivity for January of last year and at the productivity position on the graph for January, a point is plotted. This would then be repeated for February, March, and each month of the year. Once all points are plotted, a line or curve can be drawn through each of the points to make it more clear as to how the company did last year.
    Let’s take what we now know about graphs and relate it to CNC axis motion. Instead of plotting theoretical points to represent conceptual ideas, the CNC programmer is going to be plotting physical end points for axis motions. Each linear axis of the machine tool can be thought of as like a base line of the graph. Like graph base lines, axes are broken into increments. But instead of being broken into increments of conceptual ideas like time and productivity, each linear axis of a CNC machine’s rectangular coordinate system is broken into increments of measurement. In the inch mode, the smallest increment is usually 0.0001 inch. In the metric mode, the smallest increment is 0.001 millimeter. (By the way, for rotary axes the increment is 0.001 degrees.)
    Just like the graph, each axis within the CNC machine’s coordinate system must start somewhere. With the graph, the horizontal baseline started at January and the vertical base line started at zero percent productivity. This place where the vertical and horizontal base lines come together is called the origin point of the graph. For CNC purposes, this origin point is commonly called the program zero point (also called work zero, part zero, and program origin).
    For this example, the two axes we happen to be showing are labeled as X and Y but keep in mine that program zero can be applied to any axis. Though the names of each axes will change from one CNC machine type to another (other common names include Z, A, B, C, U, V, and W), this example should work nicely to show you how axis motion can be commanded.
    The program zero point establishes the point of reference for motion commands in a CNC program. This allows the programmer to specify movements from a common location. If program zero is chosen wisely, usually coordinates needed for the program can be taken directly from the print.
    With this technique, if the programmer wishes the tool to be sent to a position one inch to the right of the program zero point, X1.0 is commanded. If the programmer wishes the tool to move to a position one inch above the program zero point, Y1.0 is commanded. The control will automatically determine how many times to rotate each axis drive motor and ball screw to make the axis reach the commanded destination point. This lets the programmer command axis motion in a very logical manner.
    With the examples given so far, all points happened to be up and to the right of the program zero point. This area up and to the right of the program zero point is called a quadrant (in this case, quadrant number one). It is not uncommon on CNC machines that end points needed within the program fall in other quadrants. When this happens, at least one of the coordinates must be specified as minus.
    Understanding absolute versus incremental motion
    All discussions to this point assume that the absolute mode of programming is used. The most common CNC word used to designate the absolute mode is G90. In the absolute mode, the end points for all motions will be specified from the program zero point. For beginners, this is usually the best and easiest method of specifying end points for motion commands. However, there is another way of specifying end points for axis motion.
    In the incremental mode (commonly specified by G91), end points for motions are specified from the tool’s current position, not from program zero. With this method of commanding motion, the programmer must always be asking "How far should I move the tool?" While there are times when the incremental mode can be very helpful, generally speaking, this is the more cumbersome and difficult method of specifying motion and beginners should concentrate on using the absolute mode.
    Be careful when making motion commands. Beginners have the tendency to think incrementally. If working in the absolute mode (as beginners should), the programmer should always be asking "To what position should the tool be moved?" This position is relative to program zero, NOT from the tools current position.
    Aside from making it very easy to determine the current position for any command, another benefit of working in the absolute mode has to do with mistakes made during motion commands. In the absolute mode, if a motion mistake is made in one command of the program, only one movement will be incorrect. On the other hand, if a mistake is made during incremental movements, all motions from the point of the mistake will also be incorrect.
    Assigning program zero
    Keep in mind that the CNC control must be told the location of the program zero point by one means or another. How this is done varies dramatically from one CNC machine and control to another. One (older) method is to assign program zero in the program. With this method, the programmer tells the control how far it is from the program zero point to the starting position of the machine. This is commonly done with a G92 (or G50) command at least at the beginning of the program and possibly at the beginning of each tool.
    Another, newer and better way to assign program zero is through some form of offset. Commonly machining center control manufacturers call offsets used to assign program zero fixture offsets. Turning center manufacturers commonly call offsets used to assign program zero for each tool geometry offsets. More on how program zero can be assigned will be presented during key concept number four.
    Other points about axis motion
    To this point, our primary concern has been to show you how to determine the end point of each motion command. As you have seen, doing this requires an understanding of the rectangular coordinate system. However, there are other concerns about how a motion will take place. Fore example, the type of motion (rapid, straight line, circular, etc.), and motion rate (feedrate), will also be of concern to the programmer. We’ll discuss these other considerations during key concept number three.
    Telling the machine what to do – the CNC program
    Almost all current CNC controls use a word address format for programming. (The only exceptions to this are certain conversational controls.) By word address format, we mean that the CNC program is made up of sentence-like commands. Each command is made up of CNC words. Each CNC word has a letter address and a numerical value. The letter address (X, Y, Z, etc.) tells the control the kind of word and the numerical value tells the control the value of the word. Used like words and sentences in the English language, words in a CNC command tell the CNC machine what it is we wish to do at the present time.
    One very good analogy to what happens in a CNC program is found in any set of step by step instructions. Say for example, you have some visitors coming in from out of town to visit your company. You need to write down instructions to get from the local airport to your company. To do so, you must first be able to visualize the path from the airport to your company. You will then, in sequential order, write down one instruction at a time. The person following your instructions will perform the first step and then go on to the next until he or she reaches your facility.
    In similar manner, a manual CNC programmer must be able to visualize the machining operations that are to be performed during the execution of the program. Then, in step by step order, the programmer will give a set of commands that makes the machine behave accordingly.
    Though slightly off the subject at hand, we wish to make a strong point about visualization. Just as the person developing travel directions MUST be able to visualize the path taken, so MUST the CNC programmer be able to visualize the movements the CNC machine will be making BEFORE a program can be successfully developed. Without this visualization ability, the programmer will not be able to develop the movements in the program correctly. This is one reason why machinists make the best CNC users. An experienced machinist should be able to easily visualize any machining operation taking place.
    Just as each concise travel instruction will be made up of one sentence, so will each instruction given within a CNC program be made up of one command. Just as the travel instruction sentence is made up of words (in English), so is the CNC command made up of CNC words (in CNC language).
    The person following your set of travel instructions will execute them explicitly. If you make a mistake with your set of instructions, the person will get lost on the way to your company. In similar fashion, the CNC machine will execute a CNC program explicitly. If there is a mistake in the program, the CNC machine will not behave correctly.
    Program: O0001 (Program number) N005 G54 G90 S400 M03 (Select coordinate system, absolute mode, and turn spindle on CW at 400 RPM) N010 G00 X1. Y1. (Rapid to XY location of first hole) N015 G43 H01 Z.1 M08 (Instate tool length compensation, rapid in Z to clearance position above surface to drill, turn on coolant) N020 G01 Z-1.25 F3.5 (Feed into first hole at 3.5 inches per minute) N025 G00 Z.1 (Rapid back out of hole) N030 X2. (Rapid to second hole) N035 G01 Z-1.25 (Feed into second hole) N040 G00 Z.1 M09 (Rapid out of second hole, turn off coolant) N045 G91 G28 Z0 (Return to reference position in Z) N050 M30 (End of program command)
    While the words and commands in this program probably do not make much sense to you (yet), remember that we are stressing the sequential order by which the CNC program will be executed. The control will first read, interpret and execute the very first command in the program. Only then will it go on to the next command. Read, interpret, execute. Then on to the next command. The control will continue to execute the program in sequential order for the balance of the program. Again, notice the similarity to giving any set of step by step instructions.
    Other notes about program makeup
    As stated programs are made up of commands and commands are made up of word. Each word has a letter address and a numerical value. The letter address tells the control the word type. CNC control manufacturers do vary with regard to how they determine word names (letter addresses) and their meanings. The beginning CNC programmer must reference the control manufacturer’s programming manual to determine the word names and meanings. Here is a brief list of some of the word types and their common letter address specifications.
    O – Program number (Used for program identification) N – Sequence number (Used for line identification) G – Preparatory function X – X axis designation Y – Y axis designation Z – Z axis designation R – Radius designation F – Feedrate designation S – Spindle speed designation H – Tool length offset designation D – Tool radius offset designation T – Tool Designation M – Miscellaneous function (See below) </LI>
    As you can see, many of the letter addresses are chosen in a rather logical manner (T for tool, S for spindle, F for feedrate, etc.). A few require memorizing.
    There are two letter addresses (G and M) which allow special functions to be designated. The preparatory function (G) specifies is commonly used to set modes. We already introduced absolute mode, specified by G90 and incremental mode, specified by G91. These are but two of the preparatory functions used. You must reference your control manufacturer’s manual to find the list of preparatory functions for your particular machine.
    Like preparatory functions, miscellaneous functions (M words) allow a variety of special functions. Miscellaneous functions are typically used as programmable switches (like spindle on/off, coolant on/off, and so on). They are also used to allow programming of many other programmable functions of the CNC machine tool.
    To a beginner, all of this may seem like CNC programming requires a great deal of memorization. But rest assured that there are only about 30-40 different words used with CNC programming. If you can think of learning CNC manual programming as like learning a foreign language that has only 40 words, it shouldn’t seem too difficult.
    Decimal point programming
    Certain letter addresses (CNC words) allow the specification of real numbers (numbers that require portions of a whole number). Examples include X axis designator (X), Y axis designator (Y), and radius designator (R). Almost all current model CNC controls allow a decimal point to be used within the specification of each letter address requiring real numbers. For example, X3.0625 can be used to specify a position along the X axis.
    On the other hand, some letter addresses are used to specify integer numbers. Examples include the spindle speed designator (S), the tool station designator (T), sequence numbers (N), preparatory functions (G), and miscellaneous functions (M). For these word types, most controls do NOT allow a decimal point to be used. The beginning programmer must reference the CNC control manufacturer’s programming manual to find out which words allow the use of a decimal point.
    Other programmable functions
    All but the very simplest CNC machines have programmable functions other than just axis motion. With today’s full blown CNC equipment, almost everything about the machine is programmable. CNC machining centers, for example, allow the spindle speed and direction, coolant, tool changing, and many other functions of the machine to be programmed. In similar fashion, CNC turning centers allow spindle speed and direction, coolant, turret index, and tailstock to be programmed. And all forms of CNC equipment will have their own set of programmable functions. Additionally, certain accessories like probing systems, tool length measuring systems, pallet changers, and adaptive control systems may also be available that require programming considerations.
    The list of programmable functions will vary dramatically from one machine to the next, and the user must learn these programmable functions for each CNC machine to be used. In key concept number two, we will take a closer look at what is typically programmable on different forms of CNC machine tools.

     

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