CNC MACHINE

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

N0005(FADAL VMC 6030 - VH65)N0010G90G40G80N0015T1M6N0020S500M3N0025G0X-11958Y4N0030G43Z20H1N0035Z25N0040G1Z-5F50N0045X-4N0050Y8923N0055X-11958N0060Y13846N0065X-4N0070Y18769N0075X-11958N0080Y23692N0085X-4N0090Y28615N0095X-11958N0100Y33538N0105X-4

3

ISO MACHINE TOOL AXES DEFINITIONS

AXIS MACHINE TOOL WITH SPINDLE MACHINE TOOL WITH

NO SPINDLE

Z axis of spindle

(+Z) as tool goes away from the work piece

perpendicular to work

holding surface (+Z) as

tool goes away from the

workpiece

MACHINE

TOOL WITH

ROTATING

WORKPIECE

MACHINE TOOL WITH

ROTATING TOOL

HORIZONT

AL AXIS

VERTICAL

AXIS

X radial and

parallel to

cross slide

(+X) when

tool goes away

from the axis

of spindle

horizontal

and parallel

to work

holding

surface

(+X) to the

right when

viewed

from

spindle

towards

work piece

horizontal

and parallel

to the work

holding

surface

(+X) to the

right when

viewed

from

spindle

towards

column

parallel to and positive in

the principal direction of

cutting (primary motion)

Y apply right hand rules

4

RIGHT HAND RULEVertical Machine Horizontal Machine

5

STANDARD LATHE COORDINATE SYSTEM

6

STANDARD MILLING MACHINECOORDINATE SYSTEM

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Motion control in CNC machine

Point to Point control

bull Objective of the machine tool control system is to move the cutting tool to a predefined location

bull Once the tool reaches to the desired position machining is performed

bull Drilling is the example of this kind of control

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

N0005(FADAL VMC 6030 - VH65)N0010G90G40G80N0015T1M6N0020S500M3N0025G0X-11958Y4N0030G43Z20H1N0035Z25N0040G1Z-5F50N0045X-4N0050Y8923N0055X-11958N0060Y13846N0065X-4N0070Y18769N0075X-11958N0080Y23692N0085X-4N0090Y28615N0095X-11958N0100Y33538N0105X-4

3

ISO MACHINE TOOL AXES DEFINITIONS

AXIS MACHINE TOOL WITH SPINDLE MACHINE TOOL WITH

NO SPINDLE

Z axis of spindle

(+Z) as tool goes away from the work piece

perpendicular to work

holding surface (+Z) as

tool goes away from the

workpiece

MACHINE

TOOL WITH

ROTATING

WORKPIECE

MACHINE TOOL WITH

ROTATING TOOL

HORIZONT

AL AXIS

VERTICAL

AXIS

X radial and

parallel to

cross slide

(+X) when

tool goes away

from the axis

of spindle

horizontal

and parallel

to work

holding

surface

(+X) to the

right when

viewed

from

spindle

towards

work piece

horizontal

and parallel

to the work

holding

surface

(+X) to the

right when

viewed

from

spindle

towards

column

parallel to and positive in

the principal direction of

cutting (primary motion)

Y apply right hand rules

4

RIGHT HAND RULEVertical Machine Horizontal Machine

5

STANDARD LATHE COORDINATE SYSTEM

6

STANDARD MILLING MACHINECOORDINATE SYSTEM

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Motion control in CNC machine

Point to Point control

bull Objective of the machine tool control system is to move the cutting tool to a predefined location

bull Once the tool reaches to the desired position machining is performed

bull Drilling is the example of this kind of control

Rudresh Makwana ITNirma University

3

ISO MACHINE TOOL AXES DEFINITIONS

AXIS MACHINE TOOL WITH SPINDLE MACHINE TOOL WITH

NO SPINDLE

Z axis of spindle

(+Z) as tool goes away from the work piece

perpendicular to work

holding surface (+Z) as

tool goes away from the

workpiece

MACHINE

TOOL WITH

ROTATING

WORKPIECE

MACHINE TOOL WITH

ROTATING TOOL

HORIZONT

AL AXIS

VERTICAL

AXIS

X radial and

parallel to

cross slide

(+X) when

tool goes away

from the axis

of spindle

horizontal

and parallel

to work

holding

surface

(+X) to the

right when

viewed

from

spindle

towards

work piece

horizontal

and parallel

to the work

holding

surface

(+X) to the

right when

viewed

from

spindle

towards

column

parallel to and positive in

the principal direction of

cutting (primary motion)

Y apply right hand rules

4

RIGHT HAND RULEVertical Machine Horizontal Machine

5

STANDARD LATHE COORDINATE SYSTEM

6

STANDARD MILLING MACHINECOORDINATE SYSTEM

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Motion control in CNC machine

Point to Point control

bull Objective of the machine tool control system is to move the cutting tool to a predefined location

bull Once the tool reaches to the desired position machining is performed

bull Drilling is the example of this kind of control

Rudresh Makwana ITNirma University

4

RIGHT HAND RULEVertical Machine Horizontal Machine

5

STANDARD LATHE COORDINATE SYSTEM

6

STANDARD MILLING MACHINECOORDINATE SYSTEM

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Motion control in CNC machine

Point to Point control

bull Objective of the machine tool control system is to move the cutting tool to a predefined location

bull Once the tool reaches to the desired position machining is performed

bull Drilling is the example of this kind of control

Rudresh Makwana ITNirma University

5

STANDARD LATHE COORDINATE SYSTEM

6

STANDARD MILLING MACHINECOORDINATE SYSTEM

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Motion control in CNC machine

Point to Point control

bull Objective of the machine tool control system is to move the cutting tool to a predefined location

bull Once the tool reaches to the desired position machining is performed

bull Drilling is the example of this kind of control

Rudresh Makwana ITNirma University

6

STANDARD MILLING MACHINECOORDINATE SYSTEM

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Motion control in CNC machine

Point to Point control

bull Objective of the machine tool control system is to move the cutting tool to a predefined location

bull Once the tool reaches to the desired position machining is performed

bull Drilling is the example of this kind of control

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Motion control in CNC machine

Point to Point control

bull Objective of the machine tool control system is to move the cutting tool to a predefined location

bull Once the tool reaches to the desired position machining is performed

bull Drilling is the example of this kind of control

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Motion control in CNC machine

Point to Point control

bull Objective of the machine tool control system is to move the cutting tool to a predefined location

bull Once the tool reaches to the desired position machining is performed

bull Drilling is the example of this kind of control

Rudresh Makwana ITNirma University

Motion control in CNC machine

Point to Point control

bull Objective of the machine tool control system is to move the cutting tool to a predefined location

bull Once the tool reaches to the desired position machining is performed

bull Drilling is the example of this kind of control

Rudresh Makwana ITNirma University

Straight cut control

bull This systems are capable of moving the cutting tool parallel to one of the major axes at a controlled rate suitable for machining

bull It is not possible to have combine motion in more than a single axis direction

bull Angular cuts are not possible

bull Milling operations to fabricate work piece of rectangular configurations is the example

Rudresh Makwana ITNirma University

Countouring control

bull Most complex

bull Most flexible

bull Most expensive

bull Simultaneous control of more than one axis movement

bull Milling and turning operations are the examples

Rudresh Makwana ITNirma University

Countouring control

bull Most complex

bull Most flexible

bull Most expensive

bull Simultaneous control of more than one axis movement

bull Milling and turning operations are the examples

Rudresh Makwana ITNirma University

25 axis and 3 axis machines

bull A 25 axis machine really has three moving axes but only two axes can move together

bull Simple operations like drilling and most milling fall into this category

bull 3-axis machining requires that all three axes be moving at the same time

bull complex operations like the machining of sculptured surfaces required in molds and airfoils fall into this category

Rudresh Makwana ITNirma University

25 axis milling

Rudresh Makwana ITNirma University

3 axis machining

Rudresh Makwana ITNirma University

5 axis machining

Rudresh Makwana ITNirma University

Control system of CNC machine tool

bull MCU-Machine Control Unit

Rudresh MakwanaITNirma University

Rudresh Makwana ITNirma University

Adaptive Control

bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity

1 Adaptive Control Optimization(ACO)

2 Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

bull Adaptive Control Optimization(ACO)

Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University

bull Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

Control systems of CNC machine tool(Cont)

Open loop control system

bull Feed back is not there

bull Corrective action can not be taken

bull This type of system may be used in a machine tool where output is constant

bull Cutting force and loading of a machine tool do not remain constant

Rudresh Makwana ITNirma University

Closed loop control system

bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output

Rudresh Makwana ITNirma University

Components of CNC machine

Rudresh Makwana ITNirma University

Structure of CNC machine toolRequirements Structure Design

bull CNC machines are designed for long hours of continuous production

bull High magnitudes-multi directional forces

bull Huge quantity of swarf is producedbull Thermal distortions may happen

due to hot chips

bull Heavier structure to provide adequate strength and rigidity

bull Overhangs of cutting forces motor forces and frictional forces are avoided

bull Structure having better swarfdisposle can be made by providing slant bed

bull Sources of heat are evenelylocated to distribute the heat

bull Air conditioning may have to be recommanded to eliminate the distortion of the structure

Rudresh Makwana ITNirma University

25 axis milling

Rudresh Makwana ITNirma University

3 axis machining

Rudresh Makwana ITNirma University

5 axis machining

Rudresh Makwana ITNirma University

Control system of CNC machine tool

bull MCU-Machine Control Unit

Rudresh MakwanaITNirma University

Rudresh Makwana ITNirma University

Adaptive Control

bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity

1 Adaptive Control Optimization(ACO)

2 Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

bull Adaptive Control Optimization(ACO)

Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University

bull Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

Control systems of CNC machine tool(Cont)

Open loop control system

bull Feed back is not there

bull Corrective action can not be taken

bull This type of system may be used in a machine tool where output is constant

bull Cutting force and loading of a machine tool do not remain constant

Rudresh Makwana ITNirma University

Closed loop control system

bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output

Rudresh Makwana ITNirma University

Components of CNC machine

Rudresh Makwana ITNirma University

Structure of CNC machine toolRequirements Structure Design

bull CNC machines are designed for long hours of continuous production

bull High magnitudes-multi directional forces

bull Huge quantity of swarf is producedbull Thermal distortions may happen

due to hot chips

bull Heavier structure to provide adequate strength and rigidity

bull Overhangs of cutting forces motor forces and frictional forces are avoided

bull Structure having better swarfdisposle can be made by providing slant bed

bull Sources of heat are evenelylocated to distribute the heat

bull Air conditioning may have to be recommanded to eliminate the distortion of the structure

Rudresh Makwana ITNirma University

3 axis machining

Rudresh Makwana ITNirma University

5 axis machining

Rudresh Makwana ITNirma University

Control system of CNC machine tool

bull MCU-Machine Control Unit

Rudresh MakwanaITNirma University

Rudresh Makwana ITNirma University

Adaptive Control

bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity

1 Adaptive Control Optimization(ACO)

2 Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

bull Adaptive Control Optimization(ACO)

Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University

bull Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

Control systems of CNC machine tool(Cont)

Open loop control system

bull Feed back is not there

bull Corrective action can not be taken

bull This type of system may be used in a machine tool where output is constant

bull Cutting force and loading of a machine tool do not remain constant

Rudresh Makwana ITNirma University

Closed loop control system

bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output

Rudresh Makwana ITNirma University

Components of CNC machine

Rudresh Makwana ITNirma University

Structure of CNC machine toolRequirements Structure Design

bull CNC machines are designed for long hours of continuous production

bull High magnitudes-multi directional forces

bull Huge quantity of swarf is producedbull Thermal distortions may happen

due to hot chips

bull Heavier structure to provide adequate strength and rigidity

bull Overhangs of cutting forces motor forces and frictional forces are avoided

bull Structure having better swarfdisposle can be made by providing slant bed

bull Sources of heat are evenelylocated to distribute the heat

bull Air conditioning may have to be recommanded to eliminate the distortion of the structure

Rudresh Makwana ITNirma University

5 axis machining

Rudresh Makwana ITNirma University

Control system of CNC machine tool

bull MCU-Machine Control Unit

Rudresh MakwanaITNirma University

Rudresh Makwana ITNirma University

Adaptive Control

bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity

1 Adaptive Control Optimization(ACO)

2 Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

bull Adaptive Control Optimization(ACO)

Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University

bull Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

Control systems of CNC machine tool(Cont)

Open loop control system

bull Feed back is not there

bull Corrective action can not be taken

bull This type of system may be used in a machine tool where output is constant

bull Cutting force and loading of a machine tool do not remain constant

Rudresh Makwana ITNirma University

Closed loop control system

bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output

Rudresh Makwana ITNirma University

Components of CNC machine

Rudresh Makwana ITNirma University

Structure of CNC machine toolRequirements Structure Design

bull CNC machines are designed for long hours of continuous production

bull High magnitudes-multi directional forces

bull Huge quantity of swarf is producedbull Thermal distortions may happen

due to hot chips

bull Heavier structure to provide adequate strength and rigidity

bull Overhangs of cutting forces motor forces and frictional forces are avoided

bull Structure having better swarfdisposle can be made by providing slant bed

bull Sources of heat are evenelylocated to distribute the heat

bull Air conditioning may have to be recommanded to eliminate the distortion of the structure

Rudresh Makwana ITNirma University

Control system of CNC machine tool

bull MCU-Machine Control Unit

Rudresh MakwanaITNirma University

Rudresh Makwana ITNirma University

Adaptive Control

bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity

1 Adaptive Control Optimization(ACO)

2 Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

bull Adaptive Control Optimization(ACO)

Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University

bull Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

Control systems of CNC machine tool(Cont)

Open loop control system

bull Feed back is not there

bull Corrective action can not be taken

bull This type of system may be used in a machine tool where output is constant

bull Cutting force and loading of a machine tool do not remain constant

Rudresh Makwana ITNirma University

Closed loop control system

bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output

Rudresh Makwana ITNirma University

Components of CNC machine

Rudresh Makwana ITNirma University

Structure of CNC machine toolRequirements Structure Design

bull CNC machines are designed for long hours of continuous production

bull High magnitudes-multi directional forces

bull Huge quantity of swarf is producedbull Thermal distortions may happen

due to hot chips

bull Heavier structure to provide adequate strength and rigidity

bull Overhangs of cutting forces motor forces and frictional forces are avoided

bull Structure having better swarfdisposle can be made by providing slant bed

bull Sources of heat are evenelylocated to distribute the heat

bull Air conditioning may have to be recommanded to eliminate the distortion of the structure

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Adaptive Control

bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity

1 Adaptive Control Optimization(ACO)

2 Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

bull Adaptive Control Optimization(ACO)

Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University

bull Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

Control systems of CNC machine tool(Cont)

Open loop control system

bull Feed back is not there

bull Corrective action can not be taken

bull This type of system may be used in a machine tool where output is constant

bull Cutting force and loading of a machine tool do not remain constant

Rudresh Makwana ITNirma University

Closed loop control system

bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output

Rudresh Makwana ITNirma University

Components of CNC machine

Rudresh Makwana ITNirma University

Structure of CNC machine toolRequirements Structure Design

bull CNC machines are designed for long hours of continuous production

bull High magnitudes-multi directional forces

bull Huge quantity of swarf is producedbull Thermal distortions may happen

due to hot chips

bull Heavier structure to provide adequate strength and rigidity

bull Overhangs of cutting forces motor forces and frictional forces are avoided

bull Structure having better swarfdisposle can be made by providing slant bed

bull Sources of heat are evenelylocated to distribute the heat

bull Air conditioning may have to be recommanded to eliminate the distortion of the structure

Rudresh Makwana ITNirma University

Adaptive Control

bull Responsive system which adapt itself to operate at those machining parameter that result in higher productivity

1 Adaptive Control Optimization(ACO)

2 Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

bull Adaptive Control Optimization(ACO)

Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University

bull Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

Control systems of CNC machine tool(Cont)

Open loop control system

bull Feed back is not there

bull Corrective action can not be taken

bull This type of system may be used in a machine tool where output is constant

bull Cutting force and loading of a machine tool do not remain constant

Rudresh Makwana ITNirma University

Closed loop control system

bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output

Rudresh Makwana ITNirma University

Components of CNC machine

Rudresh Makwana ITNirma University

Structure of CNC machine toolRequirements Structure Design

bull CNC machines are designed for long hours of continuous production

bull High magnitudes-multi directional forces

bull Huge quantity of swarf is producedbull Thermal distortions may happen

due to hot chips

bull Heavier structure to provide adequate strength and rigidity

bull Overhangs of cutting forces motor forces and frictional forces are avoided

bull Structure having better swarfdisposle can be made by providing slant bed

bull Sources of heat are evenelylocated to distribute the heat

bull Air conditioning may have to be recommanded to eliminate the distortion of the structure

Rudresh Makwana ITNirma University

bull Adaptive Control Optimization(ACO)

Example of Performance Index(PI)- PI=MRRTWRMRR= Material Removal RateTWR= Tool Wear Rate Rudresh Makwana ITNirma University

bull Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

Control systems of CNC machine tool(Cont)

Open loop control system

bull Feed back is not there

bull Corrective action can not be taken

bull This type of system may be used in a machine tool where output is constant

bull Cutting force and loading of a machine tool do not remain constant

Rudresh Makwana ITNirma University

Closed loop control system

bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output

Rudresh Makwana ITNirma University

Components of CNC machine

Rudresh Makwana ITNirma University

Structure of CNC machine toolRequirements Structure Design

bull CNC machines are designed for long hours of continuous production

bull High magnitudes-multi directional forces

bull Huge quantity of swarf is producedbull Thermal distortions may happen

due to hot chips

bull Heavier structure to provide adequate strength and rigidity

bull Overhangs of cutting forces motor forces and frictional forces are avoided

bull Structure having better swarfdisposle can be made by providing slant bed

bull Sources of heat are evenelylocated to distribute the heat

bull Air conditioning may have to be recommanded to eliminate the distortion of the structure

Rudresh Makwana ITNirma University

bull Adaptive Control with Constraints(ACC)

Rudresh Makwana ITNirma University

Control systems of CNC machine tool(Cont)

Open loop control system

bull Feed back is not there

bull Corrective action can not be taken

bull This type of system may be used in a machine tool where output is constant

bull Cutting force and loading of a machine tool do not remain constant

Rudresh Makwana ITNirma University

Closed loop control system

bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output

Rudresh Makwana ITNirma University

Components of CNC machine

Rudresh Makwana ITNirma University

Structure of CNC machine toolRequirements Structure Design

bull CNC machines are designed for long hours of continuous production

bull High magnitudes-multi directional forces

bull Huge quantity of swarf is producedbull Thermal distortions may happen

due to hot chips

bull Heavier structure to provide adequate strength and rigidity

bull Overhangs of cutting forces motor forces and frictional forces are avoided

bull Structure having better swarfdisposle can be made by providing slant bed

bull Sources of heat are evenelylocated to distribute the heat

bull Air conditioning may have to be recommanded to eliminate the distortion of the structure

Rudresh Makwana ITNirma University

Control systems of CNC machine tool(Cont)

Open loop control system

bull Feed back is not there

bull Corrective action can not be taken

bull This type of system may be used in a machine tool where output is constant

bull Cutting force and loading of a machine tool do not remain constant

Rudresh Makwana ITNirma University

Closed loop control system

bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output

Rudresh Makwana ITNirma University

Components of CNC machine

Rudresh Makwana ITNirma University

Structure of CNC machine toolRequirements Structure Design

bull CNC machines are designed for long hours of continuous production

bull High magnitudes-multi directional forces

bull Huge quantity of swarf is producedbull Thermal distortions may happen

due to hot chips

bull Heavier structure to provide adequate strength and rigidity

bull Overhangs of cutting forces motor forces and frictional forces are avoided

bull Structure having better swarfdisposle can be made by providing slant bed

bull Sources of heat are evenelylocated to distribute the heat

bull Air conditioning may have to be recommanded to eliminate the distortion of the structure

Rudresh Makwana ITNirma University

Closed loop control system

bullFeed back devices monitor the outputbullNecessary corrective action is takenbullhigh system accuracy is achievablebullIt can be used in a system having frequent change in output

Rudresh Makwana ITNirma University

Components of CNC machine

Rudresh Makwana ITNirma University

Structure of CNC machine toolRequirements Structure Design

bull CNC machines are designed for long hours of continuous production

bull High magnitudes-multi directional forces

bull Huge quantity of swarf is producedbull Thermal distortions may happen

due to hot chips

bull Heavier structure to provide adequate strength and rigidity

bull Overhangs of cutting forces motor forces and frictional forces are avoided

bull Structure having better swarfdisposle can be made by providing slant bed

bull Sources of heat are evenelylocated to distribute the heat

bull Air conditioning may have to be recommanded to eliminate the distortion of the structure

Rudresh Makwana ITNirma University

Components of CNC machine

Rudresh Makwana ITNirma University

Structure of CNC machine toolRequirements Structure Design

bull CNC machines are designed for long hours of continuous production

bull High magnitudes-multi directional forces

bull Huge quantity of swarf is producedbull Thermal distortions may happen

due to hot chips

bull Heavier structure to provide adequate strength and rigidity

bull Overhangs of cutting forces motor forces and frictional forces are avoided

bull Structure having better swarfdisposle can be made by providing slant bed

bull Sources of heat are evenelylocated to distribute the heat

bull Air conditioning may have to be recommanded to eliminate the distortion of the structure

Rudresh Makwana ITNirma University

Structure of CNC machine toolRequirements Structure Design

bull CNC machines are designed for long hours of continuous production

bull High magnitudes-multi directional forces

bull Huge quantity of swarf is producedbull Thermal distortions may happen

due to hot chips

bull Heavier structure to provide adequate strength and rigidity

bull Overhangs of cutting forces motor forces and frictional forces are avoided

bull Structure having better swarfdisposle can be made by providing slant bed

bull Sources of heat are evenelylocated to distribute the heat

bull Air conditioning may have to be recommanded to eliminate the distortion of the structure

Rudresh Makwana ITNirma University

Drive System

Two drives are use in CNC machines

1 Spindle drives to provide the main spindle power for cutting

2 Feed drives to drive the axis as per the program

Rudresh Makwana ITNirma University

Spindle drives

bull Large power motors are used

bull Speed varies infinitely

bull DC motors are used speed is controlled by varying

the voltage infinitely

bull Controlled frequency converters-ac drives

Rudresh Makwana ITNirma University

Spindle drives

bull Large power motors are used

bull Speed varies infinitely

bull DC motors are used speed is controlled by varying

the voltage infinitely

bull Controlled frequency converters-ac drives

Rudresh Makwana ITNirma University

Feed drives

bull Stepper motors

Rudresh Makwana ITNirma University

bull Stepper motors (cont)

Low cost

simple construction

high reliability

low maintenance

Rudresh Makwana ITNirma University

bull Servomotors

It consists of a suitable motor coupled to a sensor for position feedback

Increases positional accuracy

Comparison of stepper motor and servomotor

Rudresh Makwana ITNirma University

bull Stepper motors (cont)

Low cost

simple construction

high reliability

low maintenance

Rudresh Makwana ITNirma University

bull Servomotors

It consists of a suitable motor coupled to a sensor for position feedback

Increases positional accuracy

Comparison of stepper motor and servomotor

Rudresh Makwana ITNirma University

bull Servomotors

It consists of a suitable motor coupled to a sensor for position feedback

Increases positional accuracy

Comparison of stepper motor and servomotor

Rudresh Makwana ITNirma University

Recirculating ball screw

bull The rotary motion from the drive motor needs to be converted to the linear motion to move the various axes of the machine tool

bull Normal machine tool comprises Lead screw having square thread for the purpose

bull High friction

bull Backlash

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Slidewaysbull Normal slideways-large amount of friction

bull Rolling friction elements-Linear Motion devices

Rudresh Makwana ITNirma University

Feedback Devices

bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement

bull The common devices used presently are

1 Encoders

2 Linear scales

Rudresh Makwana ITNirma University

Optical rotary encoder

bull Converts rotary motion into a sequence of digital pulses

bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery

bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured

Light sourceRotary disc

Light measuring deviceRudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Slidewaysbull Normal slideways-large amount of friction

bull Rolling friction elements-Linear Motion devices

Rudresh Makwana ITNirma University

Feedback Devices

bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement

bull The common devices used presently are

1 Encoders

2 Linear scales

Rudresh Makwana ITNirma University

Optical rotary encoder

bull Converts rotary motion into a sequence of digital pulses

bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery

bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured

Light sourceRotary disc

Light measuring deviceRudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Slidewaysbull Normal slideways-large amount of friction

bull Rolling friction elements-Linear Motion devices

Rudresh Makwana ITNirma University

Feedback Devices

bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement

bull The common devices used presently are

1 Encoders

2 Linear scales

Rudresh Makwana ITNirma University

Optical rotary encoder

bull Converts rotary motion into a sequence of digital pulses

bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery

bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured

Light sourceRotary disc

Light measuring deviceRudresh Makwana ITNirma University

Slidewaysbull Normal slideways-large amount of friction

bull Rolling friction elements-Linear Motion devices

Rudresh Makwana ITNirma University

Feedback Devices

bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement

bull The common devices used presently are

1 Encoders

2 Linear scales

Rudresh Makwana ITNirma University

Optical rotary encoder

bull Converts rotary motion into a sequence of digital pulses

bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery

bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured

Light sourceRotary disc

Light measuring deviceRudresh Makwana ITNirma University

Feedback Devices

bull A large variety of sensors have been used in CNC machine tools with varying success for providing the necessary measurement of the displacement

bull The common devices used presently are

1 Encoders

2 Linear scales

Rudresh Makwana ITNirma University

Optical rotary encoder

bull Converts rotary motion into a sequence of digital pulses

bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery

bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured

Light sourceRotary disc

Light measuring deviceRudresh Makwana ITNirma University

Optical rotary encoder

bull Converts rotary motion into a sequence of digital pulses

bull Consists of a disc with a number of accurately etched equidistant lines or slots along the periphery

bull The disc is attached to the shaft of the machine whose rotary motion needs to be measured

Light sourceRotary disc

Light measuring deviceRudresh Makwana ITNirma University

Optical rotary encoder

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Absolute Encoder

bull The encoder disc is etched with distinct positions

four track encoder disc

bull It uses natural binary code

Rudresh Makwana ITNirma University

2 Incremental encoder

Consists one track and two sensors

Rudresh Makwana ITNirma University

Feed back devices (cont)

Linear scalebull Direct measurement of the absolute position of the

slide

bull Finely graduated scale made of either glass or SS

bull Scaling unit

bull One is fixed to the stationary part of the machine tool and other to the moving part

bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Absolute Encoder

bull The encoder disc is etched with distinct positions

four track encoder disc

bull It uses natural binary code

Rudresh Makwana ITNirma University

2 Incremental encoder

Consists one track and two sensors

Rudresh Makwana ITNirma University

Feed back devices (cont)

Linear scalebull Direct measurement of the absolute position of the

slide

bull Finely graduated scale made of either glass or SS

bull Scaling unit

bull One is fixed to the stationary part of the machine tool and other to the moving part

bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

2 Incremental encoder

Consists one track and two sensors

Rudresh Makwana ITNirma University

Feed back devices (cont)

Linear scalebull Direct measurement of the absolute position of the

slide

bull Finely graduated scale made of either glass or SS

bull Scaling unit

bull One is fixed to the stationary part of the machine tool and other to the moving part

bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Feed back devices (cont)

Linear scalebull Direct measurement of the absolute position of the

slide

bull Finely graduated scale made of either glass or SS

bull Scaling unit

bull One is fixed to the stationary part of the machine tool and other to the moving part

bull When two gratings overlap each other a Moirefringe pattern is formed and distance moved by the pattern is calculated

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University

Rudresh Makwana ITNirma University