GUIDED BY:P Prof. Hiren Pal

PREPARED BY-RITU CHOUDHARY (130080125027)

SHELAT SHIVAM (130080125029)SMIT PATEL (130080125030)

SUTHAR MILAN (130080125031)

LASER BEAM MACHINING & LASER BEAM WELDING

B.V.M. ENGINEERING COLLEGE YEAR 2015-16

CONTENTS INTRODUCTION

LASER

LASER BEAM MACHINING

PARAMETERS AFFECTING LBM

ADVANTAGES & DISADVANTAGES OF LBM

LASER BEAM WELDING

ADVANTAGES & DISADVANTAGES OF LBW

REFRENCES

INTRODUCTION Laser Beam Machining or more broadly laser material

processing deals with machining and material processing like heat treatment, alloying, cladding, sheet metal bending etc.

Such processing is carried out utilizing the energy of coherent photons or laser beam, which is mostly converted into thermal energy upon interaction with most of the materials.

LASER Laser stands for light amplification by stimulated emission of

radiation.

The underline working principle of laser was first put forward by Albert Einstein in 1917.

Laser is a device which generates or amplifies light.

Stimulated emission of electromagnetic radiation.

The lasing process Lasing process describes the basic operation of laser, i.e. generation of

coherent (both temporal and spatial) beam of light by “light amplification” using “stimulated emission”.

Mechanism of energy transfer in laser beam

Energy bands in materials

Lasing action

LASER BEAM MACHININGPrinciple :

Laser beam can very easily be focused using optical lenses as their wavelength ranges from half micron to around 70 microns.

Focused laser beam as indicated earlier can have power density in excess of 1 MW/mm2.

As laser interacts with the material, the energy of the photon is absorbed by the work material leading to rapid substantial rise in local temperature.

This in turn results in melting and vaporisation of the work material and

finally material removal.

MECHANISM:

The schematic of laser cutting unit

laser beam machining.mp4

ADVANTAGES The ability to cut almost all materials

No limit to cutting paths as the laser point can move in any paths

No cutting lubricants are required

No contact between the tool and work piece, hence no forces are induced and as a result it is not necessary to provide the work holding system to hold the work piece.

The fragile materials are easy to cut on a laser without any support.

No tooling cost or associated wear costs due to it.

DISADVANTAGES High capital investments and high operating costs.

Laser holes are tapered to some extent.

Heat affected through the lasers may change the mechanical properties of the metallic materials and alloys.

Reflected laser lights can lead to safety hazards.

Assist or cover gases are required for safety purposes.

APPLICATIONS Used for making very accurate sized holes as small as 5 microns in metals,

ceramics and composites without warpages.

Widely used for fine and accurate drilling and cutting of metallic and non-metallic materials.

Electronic and automotive industries.

LASER BEAM WELDING It is a fusion welding technique in which coalescence is produced by

heating the work piece due to impingement of the concentrated beam of stimulated electrons coming from the laser source.

In LBW process, the laser beam is directed by flat optical elements, such as mirrors and then focused to a small spot at the work piece using either reflective elements or lenses.

It is a non-contact process, requiring no pressure to be applied.

Inert gas shielding is generally employed to prevent oxidation of the molten puddle and filler metals may be occasionally used.

Types of Laser beam weldingSolid-State laserGas LaserSlow axial flow gas laserFast axial flow gas laserTransverse Flow

ADVANTAGES Less heat affected zones, hence work piece distortions are minimized.

No electrodes are required.

Tool wears are minimized as lbw being a non-contact process.

Welding in areas that are not easily accessible with other means of welding can be done.

Permits joining of small, closely spaced components with tiny welds.

DISADVANTAGES Joints must be accurately positioned laterally under the beam and at a

controlled position with respect to the beam focal point.

Maximum joint thickness that can be welded is limited.

Weld penetrations of larger than 19 mm are difficult to weld.

The rays of laser are harmful to human body and needs precautions.

Laser Welding.mp4

REFRENCES www.google.com www.slideshare.net Wikipedia www.nptel.com

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