Laser beam welding-cutting

Laser beam welding (LBW) is a welding technique used to join multiple pieces of metal through the use of a laser. The beam provides a concentrated heat source, allowing for narrow, deep welds and high welding rates.The laser beam welding has high power density (on the order of 1 MW/cm2) resulting in small heat-affected zones and high heating and cooling rates. The spot size of the laser can vary between 0.2 mm and 13 mm, though only smaller sizes are used for welding. The depth of penetration is proportional to the amount of power supplied, but is also dependent on the location of the focal point: penetration is maximized when the focal point is slightly below the surface of the work piece.A continuous or pulsed laser beam may be used depending upon the application. Millisecond-long pulses are used to weld thin materials such as razor blades while continuous laser systems are employed for deep welds.LBW is a versatile process, capable of welding carbon steels, HSLA steels, stainless steel, aluminum, and titanium. Due to high cooling rates, cracking is a concern when welding high-carbon steels. The weld quality is high, similar to that of electron beam welding. The speed of welding is proportional to the amount of power supplied but also depends on the type and thickness of the work pieces. The high power capability of gas lasers makes them especially suitable for high volume applications. LBW is particularly dominant in the automotive industry.

LBW machine's characteristics at CEWAC

Characteristics of Cabin:

Brand and Type :TruLaser Cell 3010Dimensions of cabin 1000 x 500 x 400 mmMax length (X):600 mmMax length (Y):300 mmMax length (Z):200 mmWorking speed X ,Y and Z axis:150 mm/sAccuracy: 20 m

Laser source characteristics: Brand and Type:TRUMPF TRUPULSE 203Type of laser :Pulsed YAGAverage power:200WMax. pulse power:8 kWMax. pulse energy:90 JPulse duration:0,3 - 50 msBeam quality:12 mmmradMin. diameter laser light cable:300 mCooling water temperature range:6 - 28 C

Photos :

Source TruPulse 203Cabine laser TruLaser Cell 3010

Hybrid laser welding

The combination of laser welding with another weld process is called a "hybrid welding process". This means that a laser beam and an electrical arc act simultaneously in one welding zone, influencing and supporting each other.There are three main types of hybrid welding process, depending on the arc used: TIG, plasma arc or MIG augmented laser welding. While TIG-augmented laser welding was the first to be researched, MIG/MAG is the first to go into industry and is commonly known as hybrid laser welding.

For welding metallic objects, the laser beam is focused to obtain intensities of more than 1 MW/cm2. When the laser beam hits the surface of the material, this spot is heated up to vaporization temperature, and a vapor cavity is formed in the weld metal due to the escaping metal vapor. This is known as a keyhole. The extraordinary feature of the weld seam is its high depth-to-width ratio. The energy-flow density of the freely burning arc is slightly more than 100 kW/cm2. Unlike a dual process where two separate weld processes act in succession, hybrid welding may be viewed as a combination of both weld processes acting simultaneously in one and the same process zone. Depending on the kind of arc or laser process used, and depending on the process parameters, the two systems will influence each other in different ways.The combination of the laser process and the arc process results in an increase in both weld penetration depth and welding speed (as compared to each process alone).

Laser provide: GMAW LBW HLW

Deep penetration High welding speed Low distortion High welding speed

Arc provide: Wider weld pool Gap-brinding capabilityComparison between gas, laser and hybrid welding

Shield gas

HLW machine's characteristics at CEWAC

Laser source characteristics: Brand and Type:TRUMPF HL3006 DType of laser :Nd-YAG continu.Power:3 kW Fiber optic : 600 m

Characteristics of robot:

Brand and Type :KUKA KR-30-HA 6 axes + Table DKP-400 2 axes

Characteristics of laser head:

Brand and Type :TRUMPF BEO 70 F150Focusing optics:150 mm

Characteristics of hybrid head:

Laser :TRUMPF BEO 70 F200MIG :FRONIUS LASER HYBRIDEFocusing optics:200 mm

Source characteristics MIG

Brand and Type :FRONIUS TPS4000 (400 A)Wire diameters: 1mm or 1.2 mm

Photos :

Source laser

Hybrid headRobot KUKA 6 Axes + table 2 axes

Electron Beam Welding (EBW)

Electron Beam Welding is a welding process utilizing a heat generated by a beam of high-energy electrons. The electrons strike the work piece and their kinetic energy converts into thermal energy heating the metal so that the edges of work piece are fused and joined together forming a weld after Solidification.The process is carried out in a vacuum chamber at a pressure of about 2*10-7 to 2*10-6 psi (0.00013 to 0.0013 Pa). Such high vacuum is required in order to prevent loss of the electrons energy in collisions with air molecules.The electrons are emitted by a cathode (electron gun). Due to a high voltage (about 150 kV) applied between the cathode and the anode the electrons are accelerated up to 30% - 60% of the speed of light. Kinetic energy of the electrons becomes sufficient for melting the targeted weld. Some of the electrons energy transforms into X-ray irradiation. Electrons accelerated by electric field are then focused into a thin beam in the focusing coil. Deflection coil moves the electron beam along the weld.Electron Beam is capable to weld work pieces with thickness from 0.0004 (0.01 mm) up to 6 (150 mm) of steel and up to 20 (500 mm) of aluminum. Electron Beam Welding may be used for joining any metals including metals, which are hardly weldable by other welding methods: refractory metals (tungsten, molybdenum, niobium) and chemically active metals (titanium, zirconium, beryllium). Electron Beam Welding is also able to join dissimilar metals.

Vacuum environment necessityThe emissive element and the electrodes are placed in the gun. The piece to be welded is located in the welding chamber.Since the collision of free electrons and gas molecule, which would induce beam dispersion and a decrease in the carried power density, the gun and the piece to be welded are vacuum pumped.The dimension of the welding chamber depends on the dimension of the parts to be welded with its positioning equipment and can vary from few litres up to few ten m3.Electron Beam processThe electrons are small particles of matter with small mass. When they are accelerated they hit the piece transferring their kinetic energy into thermal energy ensuring metal melting creating plasma of metallic vapours.The E.B. welding process is a high energetic process allowing to use very high power up to ten's of kWon small surfaces of 5/10 of mm diameter. However, the total heat input is actually much lower than that of any arc welding process.

Principals advantages of the electron beam welding process: very small deformations after welding, very thick materials (exceeding 60 mm with steel) in one pass, possibility to weld all the steel, copper, nickel materials, aluminium, metals sensitive to oxygen and other gases as zirconium, titanium no filler metal and no gas, high welding quality. The welds obtained are exceptionally pure, high reliability, high reproducibility, high productivity.

Disadvantages of Electron Beam Welding (EBW):

Expensive equipment; High production expenses; X-ray irradiation.

EBW machine's characteristics at CEWAC

Brand :TECHMETAType :MEDARD 43Photos :

Chambers tubular extention :200 mm x 500 mm

Characteristics :

Power :6 kW Accelerating tension :20 to 60 kVBeam current :1 to 100 mAChambers dimensions :500 x 500 x 500 mmMovement :CNCMax length X and Y axis :200 mm - accuracy 25 mMax speed X and Y axis: 3 m/minMax speed C axis (rotation) :120 RPMChambers vacuum :10-4 mbarBeams deflection : Max angle :+/- 6 Frequency :0.1 to 2000 Hz

Friction-Stir Welding (FSW)

Friction-stir welding (FSW) is a solid-state joining process (the metal is not melted) that uses a third body tool to join two facing surfaces. Heat is generated between the tool and material which leads to a very soft region near the FSW tool. It then mechanically intermixes the two pieces of metal at the place of the joint, then the softened metal (due to the elevated temperature) can be joined using mechanical pressure (which is applied by the tool), much like joining clay, or dough. It is primarily used on aluminum, and most often on extruded aluminum (non-heat treatable alloys), and on structures which need superior weld strength without a post weld heat treatment. Frictional heat is generated between the wear-resistant welding components and the work pieces. This heat, along with that generated by the mechanical mixing process and the adiabatic heat within the material, cause the stirred materials to soften without melting. As the pin is moved forward, a special profile on its leading face forces plasticized material to the rear where clamping force assists in a forged consolidation of the weld.

A number of potential advantages of FSW over conventional fusion-welding processes have been identified:

Good mechanical properties in the as-welded condition Improved safety due to the absence of toxic fumes or the spatter of molten material. No consumables A threaded pin made of conventional tool steel, e.g., hardened H13, can weld over 1 km (0.62 mi) of aluminium, and no filler or gas shield is required for aluminium. Easily automated on simple milling machines lower setup costs and less training. Can operate in all positions (horizontal, vertical, etc.), as there is no weld pool. Generally good weld appearance and minimal thickness under/over-matching, thus reducing the need for expensive machining after welding. Low environmental impact.

However, some disadvantages of the process have been identified:

Exit hole left when tool is withdrawn. Large down forces required with heavy-duty clamping necessary to hold the plates together. Less flexible than manual and arc processes (difficulties with thickness variations and non-linear welds). Often slower traverse rate than some fusion welding techniques, although this may be offset if fewer welding passes are required.

FSW machine's characteristics at CEWAC

Brand :ESABType :ESAB 53 UTL and STLPhotos :

Characteristics :

Degree of freedom :2D Max length X and Z axis :6 m and 0.6 mWelding speed: 2 m/minForging force :100 kN MAX thickness in one pass:30mm ALU

Robotic Friction-Stir Welding (RFSW)

Friction stir welding is a mechanical welding process, which is easily automated and monitored. Automatic tool change, automated loading and unloading, and the possibility of extending the workspace by using coupled linear axes and/or component positioners represent clear advantages in the field of automation. For Friction Stir Welding of thin sections up to 6 mm modern industrial robots are also suited and represent an alternative machine concept to specially designed FSW machines. They feature an enormous flexibility combined with low invest costs compared to special machines.The flexibility of the robot not only makes it possible to realize 3D weld contours, but also to generate other tasks such as milling or positioning thanks to modular tool change. In this way, friction stir welding can be integrated into automated manufacturing operations.

FSW machine's characteristics at CEWAC

Brand:Friction Stir LinkType:FSL robotic cellRobot:ABB IRB 7600 + horizontal or vertical positioner

Characteristics :

Workspace hemisphere:2.5 m diameter Welding speed: 2 m/minForging force :10.3 kN MAX thickness in one pass:6 mm ALU