Branch : Mechanical Engineering�Semester : 6th

Subject : Advance Manufacturing Process

Chapter : 03

Topic : CNC

Faculty : Er. R PATTANAYAK

Mayurbhanj School Of Engineering, Baripada

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CNC

Machines

Computerize d Numerical Controlled Machines

What is a CNC machine?

In contrast to the conventional Lathe machines where operators give input and control the working, CNC machine is a machine which does machining process with the help of computerized control units which give it instructions regarding:

1. Tool Control: Tool and tool parameters
2. Units, incremental or absolute positioning
3. Feed rate and spindle speed
4. Coordinate System
5. Coolant Control: On/Off, Flood, Mist
6. Coordinates: X,Y,Z

CNC

Machines

Types

There are five different types of CNC machines gives as follows:

1. CNC Lathe Machine
2. CNC Milling Machine
3. CNC Router Machine
4. CNC Laser Cutting Machine
5. CNC Plasma Cutting Machine

Working

CNC working principle consists of following steps:

• Controlled by G and M codes.
• These are number values and co-ordinates.
• Each number or code is assigned to a particular operation.
• Typed in manually to CAD/CAM by machine operators.
• G&M codes are automatically generated by the

computer software

Programmi

ng Software

CNC machines use software to perform their work . They can do both 2D and 3D processes on it. For 2D works, we use G-Codes and M-codes. These codes are specified to do certain operations on the lathe machines , These codes are arranged together to make a complete program on the CNC machine, These programs then guide the machine to perform the desired processes in an orderly manner.

Programmi

ng Soft wares

For 3D works, we use certain software’s like:

1. Master Cam
2. Dell-Cam
3. Pro E

The software Pro E can even perform processes in 4D. The procedure is carried out at first we make a drawing on CAD, convert it into CAM and then the machining is done on the part being manufactured.

Types of

CNC

Control Units

These are the major companies providing control units for the CNC machines to be operated:

• SIEMENS
• MECH 3
• FANUC
• GSK
• Pentode

Advantages

1. High Repeatability and Precision e.g. Aircraft parts
2. Volume of production is very high
3. Complex contours/surfaces need to be machined. etc
4. Flexibility in job change, automatic tool settings, less scrap
5. More safe, higher productivity, better quality
6. Less paper work, faster prototype production,

reduction in lead times

Disadvanta

ges:

1. Costly setup, skilled operators
2. Computers, programming knowledge required
3. Maintenance is difficult

Thank You