machining fundamentals

BACHELOR OF ENGINEERINGBACHELOR OF ENGINEERING

MANUFACTURING TECHNOLOGIESMANUFACTURING TECHNOLOGIES

MACHINING FUNDAMENTALSMACHINING FUNDAMENTALS

by Endika Gandarias

2by Endika Gandarias

Dr. ENDIKA GANDARIAS MINTEGI

Mechanical and Manufacturing department

Mondragon Unibertsitatea  - www.mondragon.edu(Basque Country)

www.linkedin.com/in/endika-gandarias-mintegi-91174653

Further presentations: www.symbaloo.com/mix/manufacturingtechnology

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CONTENTS

BIBLIOGRAPHYCHIP FORMATIONCUTTING TEMPERATURESCUTTING FORCES AND POWERGLOSSARY

by Endika Gandarias

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BIBLIOGRAPHY

BIBLIOGRAPHY

by Endika Gandarias

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The author would like to thank all the bibliographic references and videos that

have contributed to the elaboration of these presentations.

For bibliographic references, please refer to:

• http://www.slideshare.net/endika55/bibliography-71763364 (PDF file)

• http://www.slideshare.net/endika55/bibliography-71763366 (PPT file)

For videos, please refer to:

• www.symbaloo.com/mix/manufacturingtechnology

BIBLIOGRAPHY

by Endika Gandarias

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CHIP FORMATION

CHIP FORMATION

by Endika Gandarias

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Oblique cuttingOrthogonal cutting

by Endika Gandarias

CHIP FORMATION

VIDEO

Faxial

Fradial

Faxial

λ

λ = 0º λ 0º

Introduction

8by Endika Gandarias

CHIP FORMATION

More realistic view of chip formation, showing shear zone rather than shear

plane.

t0 : depth of cut (mm)tc : chip thickness (mm)

Orthogonal cutting model

VIDEOVIDEO

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CHIP FORMATION

by Endika Gandarias

λ

λ

λ = 0º

λ = 15º

λ = 30º

Oblique cutting model

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VIDEO

by Endika Gandarias

CHIP FORMATION

Discontinuous chip Continuous chip Continuous chip with Built-Up Edge

Serrated or segmented chip

VIDEO VIDEO VIDEO VIDEO

It depends on: Workpiece material Tool geometry Cutting conditions

Chip formation types

11by Endika Gandarias

CHIP FORMATION

Chip formation types

Chip formation and cutting temperatures in different workpiece materials:

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CUTTING TEMPERATURES

CUTTING TEMPERATURES

by Endika Gandarias

13by Endika Gandarias

CUTTING TEMPERATURES

The maximum heat generated during cutting is close to the cutting edge, in the chip breaker. This is where the maximum pressure from the material is, and, with the friction between chip and carbide, causes these high temperatures.

Severe temperature gradients within the tool and the chip occurs, and the workpiece remains relatively cool. Heat distribution is:

80% through the chip. 10% through the workpiece. 10% through the tool.

VIDEO

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CUTTING FORCES & POWER

CUTTING FORCES & POWER

by Endika Gandarias

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N = spindle speed (rpm)

Davg = average diameter (mm) Davg = (D0-Df)/2

Vc = cutting speed (m/min)

fn = feed per revolution (mm/rev)

ap = radial cutting depth (mm)

Kc = specific cutting force (N/mm2)

ηm = machine efficiency (0.7-0.8)

Fc = cutting force (N)

Pc = net power (kW)

Pc =Fc × Vc

60 × 103 × ηm

N

CUTTING FORCES & POWER

Fc = kc × ap × fn

[kW]

[N]

TURNING

Q = Vc × ap × fn [cm3/min]

by Endika Gandarias

Mc =Fc × Davg

2[N*m]

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CUTTING FORCES & POWER

TURNING

by Endika Gandarias

N = spindle speed (rpm)

F = feed rate (mm/min)

Fc = cutting force (N)

Ft = thrust or feed force (N)

Fr = radial force (N)

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CUTTING FORCES & POWER

TURNING

EXERCISE: An external turning operation is accomplished for a 60mm rod steel CMC02.1 material using V c=400 m/min. Calculate for the following 2 cases:

by Endika Gandarias

Fc ? [N] Pc ? [kW] Q ? [cm3/min] Mc ? [N*m]

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ap = axial cutting depth (mm)

D = tool diameter (mm)

ae = radial cutting depth (mm)

F = feed per minute (mm/min)

kc = specific cutting force (N/mm2)

Fc = cutting force (N)

Pc = net power (kW)

Q = metal removal rate (cm3/min)

CUTTING FORCES & POWER

MILLING

Pc =Fc × F

60 × 106

Fc = kc × ap × ae

[kW]

[N]

Q =ap × ae × F

1000[cm3/min]

by Endika Gandarias

Mc =Pc × 30 × 103

π × N[N*m]

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Dc = 125 mm ap = 5 mm

ae = 100 mm F = 600 mm/min

EXERCISE: A face milling operation is accomplished for a CMC 02.1 material. It is known:

CUTTING FORCES & POWER

MILLING

Fc ? [N] Q ? [cm3/min]Pc ? [kW] Mc? [Nm]

by Endika Gandarias

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fn = feed per revolution (mm/rev)

vc = cutting speed (m/min)

Dc = drill diameter (mm)

r = positioning angle (º)

kc = specific cutting force (N/mm2)

Ff = feed force (N)

Pc = net power (kW)

Q = Metal removal rate (cm3/min)

CUTTING FORCES & POWER

DRILLING

Ff ≈

[kW]

[N]

Q =Dc × fn × Vc

4[cm3/min]

Pc =kc × Dc × fn × Vc

240 × 103

kc × Dc × fn× sen r

4

by Endika Gandarias

Mc =Pc × 30 × 103

π × N[N*m]

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CUTTING FORCES & POWER

DRILLING

Dc = 12 mm fn = 0,21 mm/rev

r = 59º Vc = 105 m/min

EXERCISE: A drilling operation is accomplished for a CMC 06.1 material. It is known:

Ff? [N]Pc ? [kW]Q? [cm3/min]

by Endika Gandarias

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GLOSSARY

GLOSSARY

by Endika Gandarias

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GLOSSARY

by Endika Gandarias

ENGLISH SPANISH BASQUE

Alloy Aleación AleazioAxial cutting depth Profundidad de pasada axial Sakontze sakoneraBuilt-up edge Filo de aportación Ekarpen sorbatzChip Viruta TxirbilChip breaker Rompe virutas Txirbil hausleaContinuous chip Viruta continua Txirbil jarraiaContinuous chip with built-up edge Viruta continua con filo de aportación Txirbil jarraiko ekarpen sorbatzCool Fresco Hozkirri / FreskoCutting speed Velocidad de corte Ebaketa abiaduraDiscontinuous chip Viruta discontinua Txirbil ez jarraiaDrilling Taladrado ZulaketaEngagement Empañe LausotuaFeed per revolution Avance por vuelta Aitzinamendua birakoFeed per tooth Avance por diente Aitzinamendua hortzekoFeed rate Avance por minuto Aitzinamendua minutukoFlank Flanco / Lateral AlboHardness Dureza GogortasunaMilling Fresado FresaketaNet power Potencia neta Potentzi garbiaOblique cutting Corte oblicuo Ebaketa zeiharOrthogonal cutting Corte ortogonal Ebaketa ortogonalaPositioning angle Ángulo de posicionamiento Posizionamendu angeluPower Potencia PotentziaRadial cutting depth Profundidad de pasada radial / ancho de pasada Iraganaldi zabaleraRake Desprendimiento JaulkitzeRemoval rate Tasa de eliminación Eliminazio tasaRod Barra BarraSerrated or segmented chip Viruta escalonada o segmentada Txirbil mailakatu edo segmentatua

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GLOSSARY

by Endika Gandarias

ENGLISH SPANISH BASQUE

Shear strain zone Zona de deformación por cizalladura Ebakidura bidezko deformazio guneaShearing Cizallamiento Ebakidura / ZizailaduraSpecific cutting force Fuerza de corte específico Ebaketa indar espezifikoaSpindle Cabezal BuruSpindle speed Velocidad de giro Biraketa abiaduraSteel Acero AltzairuThickness Espesor LodieraThrust Empuje BultzadaTool Herramienta ErramintaTurning Torneado TorneaketaWear Desgaste HigaduraWorkpiece Pieza Pieza