Parts of CNC Machine

Turret Head:
All tools have fixed on Turret Head. According to the rotation of turret there are two types
1. Unodirectional turret head:
That means you can call tools nuberwise in one direcion only
Ex. 1,2,3,4,....

2. Bidirectional tyrret head:
This turret works in both direction to change the tool.
This turret takes less time to change the tool.
Ex. 1,8,7,6,5....
Working tool number have shown on "Turret Station" on CNC Machine.

Tool Magzine:
On VMC all tools have fixed on Tool magzine.
There are 3 types of tool magzine

1. Umbrella type tool magzine = 16 tools
2. Drum type tool magzine = 40 tools
3. Chain type tool magzine = More than 40 tools.
Most commonly chain type tool magzine have used. Tools have changed by using ATC (Automatic Tool Changer System) which have controlled by Air Compressor.

Coolant System:
To avoid insert's instant damage & to control the produced heat during production coolant have used in CNC Machine.
Coolant have prepared in the ratio 20:1 ie. Mixture of 20 litre water & 1 litre cutting oil.

Lubrication Oil System:
To provied oil to all rotatory parts of cnc machine lubrication oil system is there.
To control the oil pressure dial & level bottle is there.

Hydraulic System:
This system have used to control the motion of rotatory parts of machine.
For Chuck, tail stock, turret's motion this system have used.

PCMCIA Card:
To store the programs & to carry program from one machine to another this card have used.

Chip Conveyor:
Scrap prouced during production have collected in chip conveyor tray.
From which we can easily seperate scrap from the backside of machine.

Pallet:
It is job holding device like chuck which have used on VMC.
Some VMC have two pallets ie. we can clamp job on 2nd pallet when 1st is used in machine.
It saves our time and makes large quantity production.

Parts of CNC Machine

Sarvomoter/Stabilizer:
Sarvomoter gives speed to rotatory parts of cnc machine & it gives speed to machine for its motion according to axis. Sarvomoter have R,Y&B Three Phase Power Supply.
Stabilizer flows current in the form of pulses. This pulses have converted into techo generator and it gives speed to rotatory parts of cnc m/c.
Stabiliser doea following work:
* Machine's according to axis motion
* It gives speed to rotatory parts of machine
* It controls the voltage
* When needed it step up & step down

We can give feed to sarvomoter from 20,000 to 40,000 rpm (Revolution per minute) and rotate it. but we use 1200 to 2500 rpm spindle speed.

Spindle:
It is the device which rotates chuck and gives speed to it. We can rotate spindle in Clockwise & Anticlockwise directions.

Ball lead screw:
In cnc machine conventional akme or square thread screw is replace by ball lead screw.

Chuck:
Chuck is the device which is use to hold job.
There are two types of chuck.
1. Three jaw chuck
2. Four jaw chuck
And this Jaw's are classified into two types
1. Hard Jaw
2. Soft Jaw
The soft jaw's can be bore according to job's shape. We have to true Job according to marking on Jaws.

Tail Stock:
To hold the job between centre tail stock have used. We have to set tail stock according to job's length on macines table. Here 120° Hardning & Gardning ball bearing centre is used.
To control the pressure of jaws & tail stock pressure key is given.
Kg/cm^2 unit is used.

Classification of CNC Machine

CNC Lathe:
Conventional lathe machine have converted into computerised controlled cnc lathe machine.
This m/c have x & z two main axis. X axis have used for crossfeed means for -x tool goes towards the job & for +x tool goes away from the job.
For longitudinal / horizontal feed Z axis have used mens for -z tool goes towards job according to length & for +z tool goes away from the job.

Vertical Tool Lathe (VTL):
To perform heavyduty work spindle's vertical arrangement have used.
Here lenth cuts on X axis & Diameter cuts on Z axis.

Vertical Machining Center (VMC):
Conventional Milling machine's horizontal spindle arrangement is called VMC.
VMC have X,Y,Z main three axis & tools arrangement is done on Z axis.

Horizontal Machining Center (HMC):
To perform heavyduty work parallel spindle arrangement is used.

Classification of CNC Machine

According to Axis
Axis: Machine moves in the diffrent direction during work. This direction are called as Axis. In CNC mechanism minimum 2 axis and maximum 7 axis are used. In CNC machine X,Y,Z are main 3 axies & U,V,W are parallel axis & A,B,C are rotatory axis.
According to axis machines are available as 4 axis, 5 axis, 6 axis, 7 axis.

According to feed
1. Point to point cut system:
In this system one axis work on feed and other all axis work rapidly.

2. Straight cut system:

3. Counting system:
In this system all given axis work on feed.

Development of Computerised Numerical Control (CNC)

From many years conventional machines had been used in the industries.
These machines were used for production and they were operated manually so,

* Industry had to depend on skilled operators.
* It takes more time for production.
* Quality was not so good.
* Production was less quantity.

So instead of conventoinal machines Numerical Control (NC) machines were developed.

The first NC machines were built in the 1940s and 1950s, based on existing tools that were modified with motors that moved the
controls to follow points
fed into the system on
punched tape.
These machines were controlled by alphabates & numbers.

These early servomechanisms were then replaced with analog and digital computers.
By creating the modern computer
numerical control ( CNC ) or Computerised numerical control ( CNC ) so,

* Now CNC machines were not depended on skilled operators.
* Quality is best than conventional & numerical controlled machines.
* It takes very less time comparetively.
* It makes larges quantity production.