CNC Line

Its a line of CNC machine that organized to make a continuous CNC product from one machine to the others.
Sample of CNC Line :

Product Bracket
Operation 1 : Milling
Operation 2 : Drilling & Chamfering
Operation 3 : Turning
Operation 4 : Back Facing & Chamfering.

The CNC Line model is consist of 4 machine, that the position is sequenced by its operation.

start   OP 1   ->   OP 2   ->   OP3  ->  OP 4     finish

Hope with that sample will make you understand.

Tool Geometry Offset and Tool Wear Offset

Tool geometry offset and tool wear offset are possible to divide the tool offset to the tool geometry offset for compensating the tool shape or tool mounting position and the tool wear offset for compensating the tool nose wear. The tool geometry offset value and tool wear offset value can be set individually. When these values are not distinguished from each other, the total of the values is set as the tool offset value.

NOTE : Tool geometry offset and tool wear offset are optioned.

Let me show you if tool geometry offset and tool wear offset are distinguished from each other (picture left) and if they are not (picture right).

Tool Ofsett in CNC program

Usually, several tools are used for machining one workpiece. The tools have different tool length. It is very troublesome to change the program in accordance with the tools. Therefore, the length of each tool used should be measured in advance.

By setting the difference between the length of the standard tool and the length of each tool in the CNC machining can be performed without altering the program even when the tool is changed.

This function is called tool offset.

Program CNC configuration in CNC machine (part 2)

Reffer to the last post in program CNC configuration part 1 here
We will continue to program section configuration, a program section consist of several blocks. A program section starts with a program number and end with a program end code.

Program section configuration                                     Program section
Program number                                                              O0001;
Block 1                                                                           N1 G91 G00 X120.0 Y80.0;
Block 2                                                                           N2 G43 Z-32.0 H01;
Disable execution block                                                   / N3 G00 Z-200.0;
:

:
Block n                                                                           Nn Z0.0;
Program end                                                                   M30;

A block contains information that necessary for machining, such as a move command or coolant on/off command. Adding a slash ( / ) at the start of a block will disable the execution of some blocks.

A program number consisting of address O followed by a four–digit number is assigned to each program at the beginning registered in memory to identify the program.
In ISO code, the colon ( : ) can be used instead of O.
When no program number is specified at the start of a program, the sequence number (N....) at the start of the program is regarded as its program number. If a five–digit sequence number is used, the lower four digits are registered as a program number. If the lower four digits are all 0, the program number registered immediately before added to 1 is registered as a program number. Note, however, that N0 cannot be used
for a program number.
If there is no program number or sequence number at the start of a program, a program number must be specified using the MDI panel when the program is stored in memory

Program CNC configuration in CNC machine (part 1)

There are two types of program in cnc programming, there are main program and subprogram. Normally the CNC operates according to the main program. However, when a command calling a subprogram is encountered in the main program, control is passed to the subprogram. When a command specifiying a return to the main program is ecountered in a subprogram, control is returned to the main program.

The CNC memory can hold up to 400 main programs and subprograms.  A main program can be selected from the stored main programs to oprate the machine.
Usually the program consist of the followong component.

List of G Code in CNC programming

This is the list of G Code in CNC programming, also there is a group number and the function of the G code.

1. The modal G codes are placed in the states described below.

(1) The modal G codes are placed in the states marked with as indicated in Table 3.
(2) G20 and G21 remain unchanged when the clear state is set at power–up or reset.
(3) Which status G22 or G23 at power on is set by parameter G23 (No. 3402#7). However, G22 and G23 remain unchanged when the clear state is set at reset.
(4) The user can select G00 or G01 by setting bit 0 (G01) of parameter No. 3402.
(5) The user can select G90 or G91 by setting bit 3 (G91) of parameter No. 3402.
(6) The user can select G17, G18, or G19 by setting bit 1 (parameterG18) and bit 2 (parameter G19) of parameter No. 3402.

2.G codes other than G10 and G11 are one–shot G codes.

3.When a G code not listed in the G code list is specified, or a G code that has no corresponding option is specified, P/S alarm No. 010 is output.

4.Multiple G codes can be specified in the same block if each G code belongs to a different group. If multiple G codes that belong to the same group are specified in the same block, only the last G code specified is valid.

5.If a G code belonging to group 01 is specified in a canned cycle, the canned cycle is cancelled. This means that the same state set by specifying G80 is set. Note that the G codes in group 01 are not affected by a G code specifying a canned cycle.

6.G codes are indicated by group.

7.The group of G60 is switched according to the setting of the MDL bit (bit 0 of parameter 5431). (When the MDL bit is set to 0, the 00 group is selected. When the MDL bit is set to 1, the 01 group is selected.)

G Code in CNC Programming

G-codes are also called preparatory codes, and are any word in a CNC program that begins with the letter "G". Generally it is a code telling the machine tool what type of action to perform, such as:
- Rapid move
- Controlled feed move in a straight line or arc
- Series of controlled feed moves that would result in a hole being bored, a workpiece cut (routed) to a specific dimension, or a decorative profile shape added to the edge of a workpiece.
- set tool information such as offset.


A number following address G determines the meaning of the command for the concerned block.
G codes are divided into the following two types.

1. One-shot G code
    The G code is effective only in block in which it is specified
    Example :
      N011 G00 X0 Y0 M5; 
        N012 G49 Z250.0 T15 M6;
        N013 G43 Z0 H15;
        N014 S20 M3;
        N015 G99 G82 X550.0 Y–450.0 Z–130.0 R–97.0 P300 F70;
      The G82 also known as drilling cycle is use only one shot.

2. Modal G code
    The G code is effective until another G code of the same group is specified
    Example :
      N010 G01 X0.0 Y0.0 F500 ;
        N020 Z50.0;
        N030 X20.0;
        N040 X25.0 Y15.0;
        N050 GO X0.0 Y0.0:
  
       The G01 is effective in range N010 - N040, until there is another G comand or program end.
     

GENERAL FLOW OF OPERATING CNC MACHINE

When machining the part using the CNC machine tool, first prepare the program, then operate the CNC machine by using the program.

1) First, prepare the program from a part drawing to operate the CNC machine tool.
How to prepare the program is described in the Chapter PROGRAMMING.

2) The program is to be read into the CNC system. Then, mount the workpieces and tools on the machine, and operate the tools according to the programming. Finally, execute the machining actually.



How to operate the CNC system is described in the Chapter OPERATION.

Before the actual programming, make the machining plan for how to machine the part.
Machining plan
1. Determination of workpieces machining range
2. Method of mounting workpieces on the machine tool
3. Machining sequence in every machining process
4. Machining tools and machining
Decide the machining method in every machining process.

Tool coordinate system

If you want to create a CNC Program, you must know also about tool coordinate system.

dont forget to adjust the tools.

Coordinate system

There are easy ways to remember the coordinate system in programming Cnc.
1. Cartesian Coordinate Systems

2. Right hand rule

Kind of axis coordinate in CNC Machine

Before we go to create a cnc program, we must know that every machine have a axis coordinate.
If the machine only have 3 axis coordinate, then it should be look like this

and axis coordinate in lathe machine, generally look like this

and this

You must know the philosophy of the axis coordinate

Information needed in CNC programming

There are information needed in CNC programming, such as :

1. Preparatory Information: units, incremental or absolute positioning

2. Coordinates: X,Y,Z, RX,RY,RZ

3. Machining Parameters: Feed rate and spindle speed

4. Coolant Control: On/Off, Flood, Mist

5. Tool Control: Tool and tool parameters

6. Cycle Functions: Type of action required

7. Miscellaneous Control: Spindle on/off, direction of rotation, stops for part movement

This information is conveyed to the machine through a set of instructions arranged in a desired sequence – Program

Information needed by a CNC Machine

Programming CNC Machines With G-Codes

Ever since the industrial revolution started, the demand to create precise instruments and products is an important factor in large scale manufacturing. Belts, screws, Drills and all movable parts needed to create other products in the assembly line must all be exact and compatible, thus extra care must be taken in order to ensure that all moving parts match perfectly. Computer Numerical Controlled programming has become an extremely important part of this process.
Computer Numerical Controlled Machines are useless without any programming. CNCs rely on pure hard codes in order to execute commands that the Machine Operator wants to do, therefore not only is it needed to learn the mechanics of the whole Computer Numerical Controlled Machine but it is also at the utmost importance that the Machine operator knows how to communicate with the machine, and that is by using G-codes.
Preparatory code/ functions or much commonly called as G-codes are functions in the Computer Numerical Control programming language. The G-codes job is to manage the position of the tool as well as control the step by step commands during the actual work. Basically the G-codes are the most important part of the Computer Numerical Control Programming algorithm.
There are other codes involved in the programming of CNCs such as M-codes that manages the machine, T-codes for managing the tools, and F-codes for the tool feed and tool speed controls. All of these codes are created in a Computer Aided Manufacturing (CAM) software.
G codes as well as the others use the RS-274D as the recommended standard for the Computer Numerical Controlled Machines. This standard was developed by the Electronic Industry association during the 1960s. These standards provide a basis for the creation of Computer Numerical Controlled Programs.
First designs of these standards came from punched paper tapes as the medium standard for data interchange, but now ASCII character bit patterns are the standard for the representation.
G-Codes
Lets discuss the g-codes further, as what I have said earlier G- codes constitute only a part of the Computer Numerical Control Program, in the whole programming algorithm, they are denoted by the letter G, Basically it is a code telling the machine what kinds of actions to perform in a step by step basis, examples of these actions would be rapid move, controlled feed moves that would bore holes, a work piece cut routed to a specific dimension, change a pallet, and set a tool information such as offset.
After creating each part of the codes, the algorithm is compiled in the Computer Aided Manufacturing (CAM) software. The CAM software basically use translators called post processors to output the code optimized for a certain machine type. Often times, post-processors are often used to allow users to enable further customization.
G-codes can also be used to create outputs for Computer Aided Design systems used to design printed circuit boards (PCB). Any software must be customized for each type of machine tool that it will be used to program. Some G-codes are written by hand for volume production jobs.
Some Computer Numerical Controlled machines use conversational programming. Conversational programming is an easier way to program CNC machines because it is more user friendly because it uses a wizard like program that hides the G-codes into plain view. Some Popular examples of this kind of CNC machines are the Southwestern Industries Proto TRAK, Mazaks Mazatrol, and Mori Seikis CAPS conversational software.
Conclusion
With these kinds of further sophistication in programming Computer Numerical Controlled Machines, it is expected in the future that programming would be much easier for its machine operators.

Understanding CNC - Computer Numerical Control

Have you ever asked yourself how machines in a factory know exactly when to stop making the parts theyre supposed to make? Well, this is all because of Computer Numerical Control (CNC). But to understand CNC, you have to know what Numerical Control (NC) is.
HISTORY
NC machines were first introduced after the 2nd world war as mass production became the trend. These machines were given a set of instructions in punched cards. However, these machines were hard-wired and their parameters were difficult to change.
These NC machines still required a great deal of human intervention. To illustrate this point, try to take a look at a drill press. A lot of actions have to be taken in order to manufacture a product. The process is actually so complicated that a person has to do something almost every step of the production process. This created an avenue for errors to take place as the likelihood of fatigue increased with the quantity growth.
CNC then came into the picture when computers were introduced. Punched cards were replaced by floppy disks, cables, and other software transfer media. This made it easier to manage and edit data.
Production and manufacturing were revolutionized by the increased automation of CNC machines. These machines allowed a degree of added control over the quality and consistency of the components that were manufactured without any additional strain on the operators. This reduced the frequency of errors and allowed the operators time to perform additional tasks. Furthermore, this automation allowed a greater degree of flexibility in the way components are held in the manufacturing process.
With the advent of Computer Aided Manufacturing (CAM), even programming CNC machines is a snap. These programs actually take the bulk of the programming process to make the operation less tedious. However, to be an effective programmer of CNC machines, you have to know what the machine youre working on will be doing. That is why machinists are often the best people for the job.
The ease that the machines provide is hinged heavily on the quality of the machine. Low-cost CNC machines oftentimes have many functions that have to be manually activated. High-cost machines, however, are almost fully automated. The operator only has to load or unload workpieces. Once the cycle has been initiated, the operator just has to sit back and watch for any malfunctions. The stress on the operator is so low that some even complain of boredom in the middle of a cycle.
CODING
The programming language that CNC uses is called a G-Code. These codes actually position the parts and do the work. To be able to have a machine work properly, you have to input the correct variables such as axes, reference points, the machine accessories, and whatnot. Every machine has a different set of variables so you have to be careful to take note of the differences.
Aside from the G-Code, logical commands or parametric programming can be used to make the process more time-efficient. This type of programming language shortens lengthy programs with incremental passes. A loop can also be programmed thereby removing the need for coding repetitions.
Because of these features, parametric programming is more efficient than CAM. It allows users to directly and efficiently make performance adjustments. It also allows extensions to the functionality of the machine it is running on.
And that makes CNC.

NC or CNC

CNC or known as Computer Numerical Control, is program to used in operating a process.

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 via handwheels or levers, 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.