Pulsed Nd: YAG Laser Welding

Submitted To:- Mr. Ankit Bansal Section:- M2E86 Submitted By:- Vardaan Sharma 11101297 A-58

ND:YAG LASER WELDING

Nd:YAG lasers can operate in both pulsed and continuous mode, but the other types are limited to pulsed mode. The original and still popular solid-state design is a single crystal shaped as a rod approximately 20 mm in diameter and 200 mm long, and the ends are ground flat. This rod is surrounded by a flash tube containing xenon or krypton. When flashed, a pulse of light lasting about two milliseconds is emitted by the laser. Disk shaped crystals are growing in popularity in the industry, and flash lamps are giving way to diodes due to their high efficiency. Typical power output for ruby lasers is 10–20 W, while the Nd:YAG laser outputs between 0.04–6,000 W. To deliver the laser beam to the weld area, fibre optics are usually employed.

The first type uses one of several solid media, including synthetic ruby and chromium in aluminum oxide, neodymium in glass (Nd:glass), and the most common type, crystal composed of yttrium aluminum garnet doped with neodymium (Nd:YAG).

ND:YAG LASER WELDING MACHINES

Multifunctional Laser  Welding Machine

Mould Laser Spot Welding Machine

Galvanometer Scan Laser  Welding Machine

Multifunctional Laser  Welding Machine

The W series of pulse Nd: YAG laser welding systems are suitable for a wide range of precision spot & seal welding and cutting applications in the electronics, medical, automotive and fine mechanics markets.

Typical applications include:   Welding of stainless steel, aluminium alloy and

other metals  Welding of electron guns, titanium capacitors  Spot welding of optical fibre coupler parts  Welding of containers  Seal welding of lithium batteries.

Technical data

Model W-xxx1)

Laser type Flashlamp-pumped pulsed Nd:YAG laser

Laser wavelength 1064nm

Laser power 50 to 400W depending on model

Laser beam diameter 5-8mm depending on model

Max. laser energy 30-100J depending on model

Pulse width 0.1-10ms, adjustable

Pulse repetition rate 1-200Hz, adjustable

Focused beam diameter <0.2mm

Beam delivery Optical beam delivery with a gas nozzle

Internal cooling Closed water cooling with chiller

Power requirements 380VAC, 3-phase, 50Hz

Mould Laser Spot Welding Machine

The multi-purpose laser welding system is specially designed for the mould industry and used in repairing of precision moulds, such as mould manufacture for digital products, mobile phone, toy, automobile and motorcycle, and moulding industry. Through the repairing of moulds, it is possible to reuse the moulds, save the production cost and improve the working efficiency significantly.

Technical dataModel WY180

3-axis stroke of work bench

X=300mm, Y=200mm (X, Y can be adjusted manually and Z-axis can be manually motorized to lift maximum

250mm.)Bearing of work bench ≤200kg

Device weight 300kg

Power supply 220V±10%/50Hz or 380V±10%/50Hz

Laser parameters Laser parameters

Laser type Nd:YAG pulse

Adjusting range of light spot 0.1-0.3mm

Size of light spot 0.2-3.0mm

Laser wavelength 1064nm

Pulse width ≤20ms

Maximum laser power 180W/200W

Features

The working principle of this laser deposition welding system is to use laser high thermal energy and the melting technology in spot to process the welding and repairing of minute parts. It makes up the shortage of traditional hydrogen arc welding in repairing precision surfaces, avoids the two difficulties of thermal strain and after-treatment, and saves the production period of mould.

Advantages

It is specially designed for the mould industry and the technology is imported from Germany. With unique structure design, it is suitable for repairing of large, medium and small moulds.  

Ceramic converging cavity is imported from the Britain. It is corrosion resistant and high temperature resistant, and has 8-10 years service life. The life of xenon lamp is more than 8 million times.

Use the most advanced light shielding system to eliminate the irritation to eyes by light during working.

The laser head and optics part can be rotated for 360°, upward/downward lifting and forward/backward pushing, suitable for repairing of large, medium and small moulds.

Galvanometer Scan Laser  Welding Machine

This laser welder uses galvanometer scanning method, features high welding speed, high precision and good light beam mode, and is suitable for precision laser spot welding of various parts. During single spot welding, the working efficiency is 4-10 times higher than common laser spot welding because the idle stroke positioning time is significantly reduced. The scanning laser welder consists of YAG solid laser, laser power supply, optical scanning system, 3D adjustable work bench, industrial PC system, cooling system, laser indication system and operating cabinet.

Application

This welder is mainly used in highly efficient laser spot welding or seal welding of mobile phone shielding case, mobile phone metal shell, capacitor metal shell, metal shielding grid in computer, shaver blade, electronic connector and other electronic products.

Technical dataModel WG100/200

Laser type Nd:YAG

Laser wavelength

1064nm

Maximum laser power

100W/200W

Pulse frequency

≤50Hz

Spot welding speed

≤15 spots/s

Size of light spot

0.2-3.0mm

Adjusting range of light

spot0.1-0.3mm

Maximum positioning

speed≤7000mm/s

Welding of Aluminum Using a Pulsed Nd:YAG Laser

Welding of aluminum and its alloys has its specific features. Aluminum oxidizes strongly above its melting

point. The oxidic layer has a high melting point, and it does not melt in the welding process. This layer has a strong ability to absorb gases and vapours, which then get into the weld metal. Oxidic particle layers may lead to the presence of oxidic inclusions in the weld metal, which deteriorates the characteristics of the welded joints.

When welding aluminum, it is necessary to use a higher intensity laser beam on the surface of the workpiece, due to the high reflectivity of aluminum Given the high reflectivity of the radiation from the surface of aluminum, it is preferable to use just an Nd: YAG laser.

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The high thermal conductivity and the high coefficient of expansion of aluminium give rise to major distortions in comparison with steel. The use of highly concentrated laser beam welding provides the preconditions for success in addressing these problems.

In order to obtain high-quality welded joints, it is particularly necessary to prepare the surface prior to laser welding. The oxidic layer along the length of the surface has to be removed. This surface preparation minimizes the formation of defects in welding and the presence of pores and oxidic inclusions in the weld metal

Assessment of penetration welds

Penetration pass 1.2Microstructure the heat-affected zone (Al 99.50 %)

Penetration pass 1.5 Microstructure weld metal (Al 99.50 %)

Penetration Graphs

Effect of pulse energy on the geometry of the penetration passes

Dependence of the width and depth of penetration on the excitation voltage

Pulsed Nd:YAG Laser Seam Welding of Zinc-Coated Steel

The weld ability of zinc-coated steel sheets in a lap joint configuration without a joint clearance by pulsed Nd:YAG laser beam welding. A mechanism for sufficient exhaustion of zinc gas for the formation of acceptable quality welds is proposed.

The pulsed laser beam welding process is controlled by a variety of parameters.These include average peak power density (APPD), mean laser power, traverse speeds and pulse duration.The present study focuses on the effects of these main processing parameter on weld quality. Laser beam welds were produced in 0.7-mm-thick electro galvanized and 0.7-mm-thick galvanneal steel sheets with rectangular power pulses.

Schematic Representation

Schematic of zinc gas movement: A — Between the steel sheets; B — through the keyhole.

Assessment of penetration welds

A — Top view; B — transverse section ofa visually acceptable seam weld produced in galvanized steel M1 at 2 mm/s using low-medium APPD (3.73 x 109 W/m2, EP = 22.5 J, TP = 12 ms), and mean power 396 W.

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A — Top view; B — transverse sectionof a visually acceptable seam weld produced in galvanized steel M1 at 1.5 mm/s using low medium APPD (3.73 x 109 W/m2, EP = 7.5 J, TP = 4 ms), and mean power 363 W.

Welded Samples

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