sys 849 5 lecture burr deburring and edge finishing

8/17/2019 SYS 849 5 Lecture Burr Deburring and Edge Finishing

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Surface Treatment, Finishing and Integrity:Special Case of Machined Edge Finishing –

Burr and Deburring

June 3th 2014

Dr. Seyed Ali Niknam

Laboratory of Products, Processes and Systems Engineering (LPPSE)

Department of Mechanical Engineering

École de technologie supérieure (ETS)

Course outline

1. Burr definition

2. Burr formation mechanism, shapes and classifications

3. Factors governing burr formation

4. Burr size minimization/optimization

5. Burr formation/size modeling

6. Burr measurement and detection methods

7. Burr removal (deburring) and edge finishing

2Niknam, Seyed Ali – June 3rd 2014


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1.Burr definition

Exit burrs observed when Drilling Al 6061-T6Zedan et al., Machining & Machinability of Materials, 2012

Turning burrs

Slot milling burrsNiknam and Songmene., Journal of Engineering and Manufacture, 2013

b) Limited & non visible burrb) Large burr formation

A burr is a extended body over the workpiece surface.

Definition of burrs according to ISO 13175

4

Burr definition



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A Short History of the Burr

• Metal burrs first appeared ~3000 B.C. (5000 years ago) at the

beginning of the Bronze Age (in Thailand as well as in

Mediterranean area)

• Burrs in iron and steel appear first about 1000 B.C. (3000

years ago).

Source: Gillespie, in Proc. 7th Int’l Conf. on Deburring and Surface Conditioning, UC-Berkeley, 2004


Burr Formation Studies

1958 Keiji Okushima - First publisher of burr

formation mechanics

Source: Gillespie, in Proc. 7th Int’l Conf. on Deburring and Surface Conditioning, UC-Berkeley, 2004



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Burrs are everywherethere is an edge!

Why are we interested to burrs ?

Source:(Aurichet al , CIRP Annals, 2009)


Burrs are everywhere

there is an edge!





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Their presence :

1. Represents 30% of the finishing cost of the component;

2. Reduces the quality of components in an assembly;

3. Causes injury to workers during handling (Gillespie, 1999);

4. Is the main reason for tool change in milling of aluminium alloys(Lee, 2004)

9

Category of expenses due to presence of burr


Source: (Aurich et al , CIRP Annals, 2009)


Breakdown of manufacturing

expenses (Bosch)




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2. Burr formation mechanism, shapesand classifications

Burr formation mechanism

Burr/breakout formation model:

(a) initiation, (b) development and (c) final burr formation

Source: (Niknam, Ph.D thesis, ETS, 2013)



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Burr formation mechanism

Source:(Hashimura,et al., ASME Manufacturing journa l , 1999)


Burr formation process




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Burr Formation Sequence in Al2024-O(SEM Images)

Source: Laboratory for Manufacturing and Sustainability, UC-Berekley


Edge Quality Standard

Burr Burr

Burr

Theoretical workpiece edge

(Gillespie, Journal of Manufacturing Engineering, 1996)

Source: (Aurich et al , CIRP Annals, 2009)



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Measurement values of burr

Source: (Schäfer, 1975)


Various Types of Burrs in Machining




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Advanced Cutting Mechanics: Milling

One of the most versatile processes available. 3D effects become very important!

Source: www.mmsonline.com


Advanced Cutting Mechanics: Milling

Milling terms/conventions

Source: www.mmsonline.com



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Types of Burrs in Milling

Slot milling burrs

Face milling burrs

Source: (Lee, Ph.D thesis, UC-Berekley, 20 04)


Milling burr classification

Source: (Nakayama, Arai, CIRP Annals, 1987)



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Milling burr classification-Location



Milling burr classification-Shape

Source:(Hashimura,et al., ASME Manufacturing journa l , 1999); (Chern, Ph.D thesis, UC-Berekley,1993)



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Milling burr classification-Classification

Source:(Hashimura,et al., ASME Manufacturing journa l , 1999); (Kishimoto et al., Bull. Jpn. Soc. Precis. Eng, 1981)


Milling burr classification-Example




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Drilling Burr formation mechanism



Drilling Burr Mechanism

© 2009 Laboratory for Manufacturing and Sustainability, UC-Berekley



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Drilling burr formation

Source: R. Furness, Ford


Drilling Burr Classification

Source: (Kim, Journal of Engineering materials and technology,2000)



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Burr Formation in Intersecting Holes

Problems:

Limited accessibility of the burr

Burr not tolerable in flow-through areas

© DaimlerChrysler AG


Burr Formation in Intersecting Hole




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Geometry Variation in Intersecting Holes



Comparison of burr shapes




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3. Factors governing burr formation


Factors governing burr formation

Source:(Aurichet al.,CIRP Annals, 2009)



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1. Machined part (geometry, dimension, mechanical properties, etc.)

2. Cutting parameters(cutting speed, feed rate, depth of cut, etc.)

3. Cutting tool (material, shape, geometry, rake angle, lead angle, helix angle, etc.)

4. Machine tool (rotational speed, dynamic strength, etc.)

5. Manufacturing strategy (tool path, coolant, back cutting, lubrication condition ,etc.)

6. Other parameters(e.g. cutting forces)

37

This summary is still inadequate due to complex interaction effects between processparameters

The factors governing milling burrs can not be separated to Direct and Indirect factors

Critical Factors governing burr formation


Other governing factors on burr formation

• Built-Up Edge, or BUE (layers of welded work

material) may form at the tip of the tool.

• Especially prevalent in machining of aluminum.




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Other governing factors on burr formation

Tool Wear

Source:(Schey, McGraw-Hill , 1987)


Tool Wear




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Grain boundary effects



Edge radius effects

Conventional cutting Micro cutting




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Case study 1

Investigation of factors governing

slot milling burr formation

By

Seyed Ali Niknam and Victor SongmenePublished in

Journal of Engineering and Manufacture in March 2013

44

List Burr name

B1 Exit up milling side

B2 Exit bottom bur

B3 Exit down milling side burr

B4 Top down milling burr

B5 Top up milling burr

B6 Entrance bottom burr

B7 Entrance up milling side burr


Main objective Statistical tools and experimental study are used to determine the dominant

cutting parameters on burrs size (height and thickness) during slot milling of

AA 2024-T351 and AA 6061-T6

© Niknam and Songmene, Journal of Engineering and Manufacture, 2013



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List Burr name

B1 Exit up milling side

B2 Exit bottom bur

B3 Exit down milling side burr

B4 Top down milling burr


B6 Entrance bottom burr

B7 Entrance up milling side burr


Statistical tools and experimental study are used to determine the dominant

cutting parameters on burrs size (height and thickness) during slot milling of

AA 2024-T351 and AA 6061-T6

Main objective



Experimental procedure

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3 Axes Machining Center Cutting trials configuration

Optical microscope for burr size measurementProfilometer for surface roughness

measurement




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Most of existing research works characterized the burr height.

From a deburring perspective, the burr thickness is of interest.

Burr thickness describes the time and method necessary for deburring a workpiece.

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Burrs geometrical description



48

The statistical terms and techniques used:

1. ANOVA ; 2. Pareto Analysis; 3.Main effect plot ; 4. Interaction effect

analysis; 5. Regression model

Experimental Plan

Experimental parameters Level

1 2 3

A: Material AA 6061-T6 - AA 2024-T351

B: ToolCoating TiCN TiAlN TiCN+Al2O3+TiN

Insert nose radius, Re (mm) 0.5 0.83 0.5

C: Depth of cut (mm) 1 - 2

D: Feed per tooth (mm/z) 0.01 0.055 0.1

E: Cutting speed (m/min) 300 750 1200

Lubrication condition: Dry



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Milling exit burrs

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1. B2 burr is formed by a loss of material from B1 burr2. Transition from primary to secondary burr formation is observed

3. Larger Re leads to primary B2 burr where the depth of cut is smaller than

the Re or very close to it.



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0 2 4 6 8 10 12

Contribution to variation (%)

ADACEEDDAB

E:SpeedBDAEBE

B:ToolCE

C:DepthA:Material

DECD

D:FeedBC

Sig. at 5%Not sig.

0 10 20 30 40 50


CDACCEDDBEAD

A:MaterialABDEEEAE

E:SpeedBDBC

B:ToolC:DepthD:Feed

Sig. at 5%Not sig.

Exit up milling side burr (B1)

Very sensitive to cuttingparameters

B1 Height B1 Thickness




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0 2 4 6 8 10 12


ADACEEDDAB

E:SpeedBDAEBE

B:ToolCE

C:DepthA:Material

DECD

D:FeedBC

Sig. at 5%Not sig.

0 10 20 30 40 50


CDACCEDDBEAD

A:MaterialABDEEEAE

E:SpeedBDBC

B:ToolC:DepthD:Feed

Sig. at 5%Not sig.

Very sensitive to

cutting parameters

B1 Height B1 Thickness

Exit up milling side burr (B1)



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Similar Procedure has been used when analyzing the top and entrance burrs

Interaction effect plots




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53

3D Surface Plot of optimum conditions



54

3D Surface Plot of optimum conditions




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Burr size can be reduced significantly by selecting appropriatecutting parameters and cutting tools.

Depth of cut, feed per tooth and tool (insert nose radius andcoating) were found as the dominant process parameters onmost of the burrs.

For the most of the burrs studied, the dominant process

parameters on burr height have the opposite effect on burr

thickness.

Dislike few reported works in literature, burr size in slot milling

have no linear relationship to others.

Partial conclusion


56



3. Burr size detection and estimation

4. Burr removal (Deburring)

Prof D. Dornfeld in 2009 has pointed out the mostimportant research Problematic on burr




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Design & Process integration




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Burr minimization design



Burr minimization in macro-planing




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Burr minimization in micro-planing



Exit Order Sequence (EOS)

Orientation of insert intool holder

Orientation of material beingdeformed which constructs

the burr




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EOS Fundamentals



EOS : Tool & workpiece interaction




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The exit order of the cutting tool has important effects on burr formation andinfluences burr position and burr dimensions

Orientation of the material

being pushed out orbroken (depending on

ductility of the material)

Process parameters

Insert geometry Feed direction Workpiece edge orientation

EOS mechanism

Source:(Hashimuraet al., ASME Manufacturing Journal , 1999)


EOS vs Burr Size

6 different EOS modes




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EOS vs Burr Size Depending upon cutting edge orientation,exit burrs form preferentially on the:

machined surface or the transition surface

Rigid workpiece

Sharp cutting edges and negligible nose radius



EOS as a Process Planning Tool

EOS helps

- Choose a suitable tool insert geometry (axial, radial rake

angles, lead angle)

- Select suitable cutting parameters (feed, speed, DoC etc)

- Select suitable tool radius

- Calculate optimum offset from w/p edge in case of a

shoulder or other machining constraints



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Tool Path Planning for BurrMinimization

Planar milling operation tool diameter D, workpiece characteristic size M



Burr Minimization Tool Path Planning

Minimize burr formation by changingtool path (tool engagement)




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Burr minimization tool path zigzag tool path for clean up



Machined with burr minimizationtool path

Machined with regular tool path





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Analytical models

Certain levels of assumption is required

Requires the experimental observation of burr formation process [Toropov et al, 2005]

Consistent results can not be always obtained

Simulation models : Results are dependent to [Toropov , 2000]:

Exactness of input boundary conditions (usually simplified)

Software applied (ABAQUS, DEFORM, LS-DYNA, etc)

Additional experimental data (e.g. Flow stress coefficients)

Empirical models

Applicable only for a narrow range of process parameters

Varies based on a change in tool and material

Costly and time consuming

Burr prediction models



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FEM- simulation of burr formation

Source: (Sartkulvanich, Ph.D Thesis, Ohio state university, 2007)



Source: (Deng et al., Int. J. of Advanced Manuf acturing Technology, 2009)



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Burr formation process in

simple orthogonal cutting

Source: (Deng et al., Int. J. of Advanced Manuf acturing Technology, 2009)


Orthogonal cutting with positive rake angle



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Orthogonal cutting with large chip load


Orthogonal cutting with negative rake angle



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• Mostly use Johnson & Cook stress flow rule

• Rarely 3D simulations models are reported for milling

• The principle of Hydrostatic bowl on burr formation is still unclear.

Sartkulvanich, 20 07


Source: (Leopold and Wohlgemuth ,Springer , 2010)


FEM- simulation of drilling burr formation




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FE Mesh




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Meshed Drill

Meshed in AbaqusModel Meshed in DEFORM




Drilling Simulation In DEFORM Drilling Simulation in Abaqus




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Case study 2

Modeling of Burr Thickness in

Milling of Ductile Materials

By

Seyed Ali Niknam and Victor Songmene

Published in

Int. J. of Advanced Manufacturing Technology in 2013


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B1 thickness is the longest and thickest milling bur.

It could be controlled by process parameters

89

To develop the predictive model of exit up milling side burr (B1)thickness as a function of cutting parameters.

Objective:

© Niknam and Songmene, Int. J. of Advanced Manufa cturing Technology,2013


90

The assumptions used:

1. Burr formation in the exit zone is

modeled as an orthogonal process.

2. The model is based on the burr

formation geometry.

3. The transition from chip formation to

burr formation occurs at the transition

point.

4. The work done for chip formation is

equal to that done for burr formation.




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Analytical Modeling

Where:

Symbol Units Description Bt (mm or μm) Burr thickness

f t mm/z Feed per tooth

β0 (deg) Initial negative shear angle

a p mm Axial depth of cut

σe (N/mm2) Yield strength

k 0 (N/mm2) Yield shear strength

F t N Tangential force

0

00

20

tan

tan4

1

cos2

et pt

k

Ba F

According to (Lauderbaugh, 2009), yield strength is the only statistically significant

material properties on exit burr formation amongst young modulus, thermal diffusivity,

and ultimate strength.

Bt ≈

Material properties (σe & k 0)

f (Cutting parameters)

f (Cutting tool)



92

0

00

20

tan

tan4

1cos

2

e

t pt

k

Ba F

0 0

0

( + )

=

212 1cos tan

12 4 Atan

According to Von misses criteria:

The β0 = 20○ under various cutting conditions and material studied [Ko and Dornfeld, 1991].

30

ek

= - t t e p

F B

a A

0 0

0

( + ) =

2

t e p t

12 1

cos tan12 4 F - a Btan

Analytical Modeling




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Experimental parameters

Level

1 2 3

A: Depth of cut (mm) 1 - 2

B: Feed per tooth (mm/z) 0.01 0.055 0.1

C: Cutting speed (m/min) 300 750 1200

Lubrication condition: Dry ; Tool diameter (D : 19.05 mm)

Experimental verification

18 tests were conducted in total for verifications



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Correlation rate

97.22%

Correlation rate

98%

AA 2024-T351 AA 6061-T6




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95

The only unknown parameter in model is F t

The F t can be computationally measured

= -t

t

e p

F B

a A

paeaca

prercr

ptetct

a K ah K F

a K ah K F

a K ah K F

)()(

)()(

)()(

1. Mechanistic force model [Altintas , 2000]

t

r

d = × ( ( )) + × ( )

d = × ( ( )) + × ( )

tc j j p te p

rc j j p re p

F K h a K d a

F K h a K d a

Computational Modeling



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The effect of cutting speed on milling and drilling burrs size is statistically

insignificant (Lauderbaugh, 2009; Mian et al , 2011.

The effect of cutting speed on resultant force can be considered negligible

Computational Modeling




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Partial conclusion

101

The burr formation in exit zone

was modeled.

B1 thickness was analytically and computationally modeled.

The models do not require the experimental measurements of shear

angle (Φ), friction angle ( λ) and tool chip contact length (L).

Bt ≈

Material properties (σe , k 0 and K c)

f (ac , f t )

f (Tool geometry)



6. Burr measurement and detectionmethods


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Burr detection and measurement methodsBurr detection and measurment

methods

In-processOut-process

ContaclessWith contact

Electro-MechancialOptical

1. Optiocal microscope

2. Broscope/endscope

3. Scanning electron

microscope (SEM)

1. Light slit method

2. Laser traiangulation

3. Fring pattern projection

4. Autofocus methods

5. Confocal microscopy

1. Eddy-current sensor

2. Inductive senor

3. Computer tomography

1. Process monitoring

2. Moment

3. Force

4. Sound emission

analysis

1. Styullus method

2. Metallographical

methods

(Niknam and Songmene, Ph.D Thesis, ETS, 2013)


Burr detection and measurementmethods

Three main burr size measurement systems:

1. Mechanical systems

2. Electrical systems

3. Optical systems



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Inductive Measurement Technique

Source: Patent by Gratsensorik, Manfred Jagiella; 2002 -05-16


Burr sensors

Source: Patent by Gratsensorik, Manfred Jagiella; 2002-05 -16



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Burr detection and measurementmethods



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7. Burr removal (deburring) andedge finishing

Deburring Process

Deburring includes all operations which are used toremove a produced burr from simple hand deburringto high tech surface finishing by NC controlled robots.As a result of years of research, vast numbers ofmethods have been developed. Some typical

deburring methods are introduced here with someresearch efforts.



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Deburring Technologies

Objectives of deburring

- Remove burr- Finish edge or otherwise condition the edge

- Insure burr is “firmly attached”

- Reduce burr size

- Facilitate handling/assembly

- Protect workers from injury

Facilitating deburring

- Locate burrs

- Predict burr size, shape and variation

- Determine accessibility

- Assist in deburring process set up (tool path, etc.)

- Evaluate deburring approaches for burr condition


Classification of deburring operations

1. Mechanical Deburring Operations

2. Thermal Deburring Operations

3. Electrical Deburring Operations

4. Chemical Deburring Operations




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Deburring Technologies

The most frequently used deburring processes :

No. Deburring process No. Deburring process

1

Manual deburring

6 Barrel deburring

2

Brush deburring

7 Centrifugal barrel finishing

3

Bonded abrasive deburring

8

Robotic deburring

4

Abrasive jet deburring

9

Electro chemical deburring

5

Mass finishing 10

Vibratory finishing



Mechanical Deburring Operations



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Thermal Deburring Operations

Torch or flame melting

Thermal energy method

Plasma flame

Plasma-glow deflashing

Hot wire

Resistance heating

Laser deburring

Electronic discharge machining (EDM)


Electrochemical barrel tumbling

Electrochemical vibratory finishing

Electrochemical roll flow finishing

Electrochemical spindle finishing

Electrochemical recipro finishing

Electrochemical orboresonant finishing

Electrical Deburring Operations

Electrochemical moving electrode

Electrochemical mesh deburring

Electrochemical brush deburring

Electrochemical deburring

Electropolish deburring



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Chemical barrel finishing

Chemical vibratory finishing

Chemical roll flow finishing

Chemical spindle finishing

Chemical centrifugal finishing

Chemical Deburring Operations

Chemical magnetic finishing

Ultrasonic (chemical)

Chemical fluidized bed

Chlorine gas deburring


Manual deburring

High flexibility than other methods;

Does not take much time for small burr;

Cheaper for small burrs;

(Niknam, Ph.D Thesis, ETS, 2013)



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Disadvantages: It generates a lot of surface scratches;

Deburring time is high for large burr;

It is difficult to attach the pieces (miniature pieces for example);

It is difficult to define the manual deburring standards;

There is a lack of manual deburring study;

Does not show a great motivation for industrial workers;

It is difficult to deburr some complex parts;

The deburring result is sometimes inconsistent;

Deburred edges are not uniform

Manual deburring


Burrs around Hole on Plane

Micro burr Drilling burr




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Magnetic abrasive deburring



Experimental Deburring of Micro Burrs




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Deburring by Permanent Inductor



Brush Deburring

Deburring and Finishing with Brushes




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Brush Deburring

Benefits of NAF Brushes:● Deburr and finish in one step

● Highly compliant on complex part geometry

● Ideal for automated deburring in CNC centers

● Do not alter part dimensions

Operating Information:

● “Flexible file” filaments provide deburring action

through abrasion

● Surface speeds are slow, generally below 3,500 SFPM

● Penetration of the brush face is required



Brush Deburring




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Brush Deburring



Brush Deburring




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Brush Deburring



Brush Deburring




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Robotic deburring

Fast

Cheaper than CNC deburring

High consistency and repeatability

Can work in noisy and dirty conditions

require minimal intervention human

Can remove most of the type of burrs

Can be worked in automation



Bonded-abrasive Deburring Low price;

Large variety of choices;

some varieties may improve the surface condition;

Adaptable to manual or automatic equipment;

Sometimes affects the surface quality;

Effects on residual stresses;

Dust emission;

Changes the part dimensions;

Sometimes generate new burrs;

Changes the color of the part;

Lack of access to certain sides of part;

Low life;

Disadvantages

Advantages




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Thank you

sys 849 5 lecture burr deburring and edge finishing

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