Laser Welding

Introduction

High-precision laser-beam welding of very small, and delicate parts is usually done with a YAG laser which uses high-powered optics and argon shielding gas.

The formability of laser welds is the key to the success or failure of a part. Because of the small heat affected zone, the welds are extremely formable, as long as joint quality is good. In cupping tests, the fracture height is between 80 and 100% of the base material.

If accuracy is essential for your welding application, laser-beam welding offers extremely high precision.

Types of applications and for which laser welding is especially suitable:

• Catheters and Other Medical Devices
• Cutting Laser Welding
• Fine Wires
• GTAW (Gas Tungsten Arc Welding)
• Jewelry
• Micro and Glove Box Service
• Small Parts and Components
• Small Sensors
• Resistance Welding
• Thin Sheet Materials Down To 0.001" Thick

Industries in which laser welding is commonly used:

• automotive industries
• jewelry

A Laser-Welding Facility should include:

• One ore more pulsed, high-power (400-Watt) YAG laser and a High-Purity Chamber
• One ore more X-Y-Z Programmable Positioners Stations
• Precision Seam Welders 12", 24" and 10 foot
• Precision Automatic Welding Lathes from .100" to 36" diameter x 10 feet
• Computer Controlled TIG/Plasma Power Supplies
• Orbital Welding Systems .100 to 4.50" diameter
• Micro TIG/Plasma Power Supplies
• Brazing and Soldering Station
• Resistance Welding Stations

Laser-Welding Process

• non-contact, laser output 2-10 kW
• laser makes "keyhole", liquid steel behind transverse beam solidifies
• weld is about 1 mm wide; surrounding material not distorted
• no finishing/touch-up usually required

Application Example: Structural Chassis components

Laser welding together areas of thicker or higher-strength steels with thinner-gauge steels, a lighter structure (with higher strength areas only where required) can be produced in a single pressing operation. No longer required is additional stamping and forming to make the reinforcement parts and the resistance welding together of the various parts.

Experiments at a UK laboratory have shown that by laser welding together different thickness steels that are formed into a "box-hat" structure of a vehicle and then subjected to a simulated 30 mph collision, it's possible to control the areas within the structure that collapse and those that remain intact, thus providing effective crash management of the vehicle.

Laser Beam Welding -- The Basics

(from Wikipedia) Nd:YAG lasers are being more commonly utilized in automotive parts manufacturing using robotic delivery. CO2 laser welding using a 10 kW system can produce a single pass autogenous weld in ¾” thick stainless steel at 20 ipm (8 mm/s). Systems producing up to 25 kW have been built. Keyhole welding,is a method of laser welding in which a high power continuous-wave laser is focused on the metal to be welded, forming a pocket of ionized metallic gas. This vapor absorbs the laser energy more effectively than the solid material and transfers the heat outward radially from the keyhole, forming a molten region surrounding the vapor.As the beam moves across the work-piece the keyhole is filled in with molten material and solidifies to form a weld. Read more about laser-beam welding and cutting.

For more in-depth knowledge, we also recommend these two books: Laser Welding and Laser Material Processing.

What is a YAG laser?

(from Wikipedia) Nd:YAG is an acronym for Neodymium-doped Yttrium Aluminum Garnet (Nd:Y3Al5O12), a compound that's used as the lasing medium for certain solid-state lasers. The YAG crystal is doped with an active medium, in this case triply ionized neodymium, which replaces another element of roughly the same size, typically yttrium. Generally the crystalline host is doped with around 1 percent neodymium by weight. Nd:YAG lasers are optically pumped using a flashlamp or laser diodes. They are one of the most common types of laser, and are used for many different applications. Read more about YAG lasers.