Category: Processes
Intelligent welding systems
It is important to develop intelligent welding systems to ensure defect free welds in automation welding systems employed for critical application areas: Nuclear,aerospace,defence ,power,piping and petro chemical industries.There is tremendous growth in computer science,electronics,control systems and integration of various sub systems to enhance productivity.- Data science in welding technology: Information collected helps for improvement of decision making process,process improvement,error detection,error prevention
- Welding processes: Several inputs and associated outputs
- Data mining processes
- Machine learning
- Deep learning
- Reinforcement learning
- Analysis and control of complex welding system
- Sensor technology to collect large volume of data
- Analysis of data
- Welding parameters: Adjustable; current,current waveform,heat input,wire feed speed,travel speed,arc voltage; All provide system data
- IWMT(Intelligent Welding Manufacturing Technology): Self optimisation,Intelligent feed back
- New data analysis technique:1Process analysis and methodologies2.Software3.Data mining4.Deep learning5.Reinforcement learning6.Computer science Algorithms7.Data analysis/analytical techniques
- Arc welding: Sensors;Indirect sensing-conventional,vision,sensor fusion
Induction brazing
Inductor coil provides radiation heat due to high frequency current flowing through the water cooled coil. The component kept in the coil or coil kept in the assembly facilitates heating of assembly where pre placed filler kept in the joint gap gets melted. Capillary action fills completely the joint gap. Mass production applications like drills , reamers , and automobile components are easily done by this process.
Furnace brazing
Furnace brazing requires heating system (electrical , gas , induction ) for heating the metal assembly containing the preplaced filler in the joint gap. Capillary action fills the joint. Batch , continuous and vacuum type are used for different applications like valves , automobile products , aerospace components.
Flame brazing
Flame obtained from chemical reaction of oxygen and fuel gas can be used to heat the base metals and melt the filler metal placed at the joint locations. The capillary action fills the joint gap completely to make the joint. Oxyy - acetylene flame is widely used for manual and automatic system. Several applications can be done easily with this method. Most popular is silver brazing for steels.
Resistance welding
Heat generation by resistance to the flow of current is used to develop resistance spot, seam, projection, upset butt, and flash butt welding processes. Other processes like a foil-butt seam, High-frequency butt seam processes have been developed for specific applications. Sheet metal fabrication requires mass production processes like spot, seam, projection welding where lap joints are used. Butt welding processes like upset butt and flash butt are used for the rod to rod, tube to tube, or ring type joints. Automobiles, railways, power plants and several other industrial sectors require these processes for mass production with good quality. Current research under my guidance includes a comparison of direct and indirect spot welds for cold-rolled steel sheets. You may contact for hard copies of published articles.
Solid phase welding
There are several advantages if welding can be carried out without the melting and solidification of metals. Solid-phase welding processes namely friction welding (FW), explosive welding (EXW), Induction pressure welding (IPW), ultrasonic welding (USW) and several cold pressure welding (CPW) processes satisfy this requirement and hence facilitate welding of many dissimilar metal combinations. These are required for electrical, transition pieces and many other critical products manufacture.
Diffusion bonding where coalescence is produced using pressure, temperature and time with or without using filler in a controlled atmosphere finds a variety of applications in many critical component manufacturers required for nuclear, aerospace and defense sectors.
Friction welding process has many variants.1.Inertia drive2.Continuous drive3.Orbital4.Positional arrest.5Radial6.Friction stir7.Friction surfacing8.Friction stud etc.Each of the process is employed for specific applications in various industrial sectors.
Explosive welding
1. Parallel configuration: Target plate is hit by flyer plate with high impact energy causing mechanical and metallurgical bond.Explosive selection,packing density,stand off distance are required conditions to get weld strength. Dissimilar metal combinations :Al-cu,Al-steel,Al-stainless steel,Al-titanium,Cu-stainless steel,Ti-stainless steel,Brass -steel are some of the plate to plate cladding applications.Dissimilar metal tube to sheet welds find use for heat exchangers.
2.Angular configuration: In this system flyer plate is oriented at the recommended angle to the target plate.
Safety for handling and storage of explosives is very important and operation to be carried out in specific areas not populated .
Beam welding
Electron beam welding (EBW) and LASER beam welding (LBW) are the two processes required for unique applications where single pass welding on variety of metals and alloys mainly required for defence , nuclear and aerospace applications need to be done with very high reliability.
Electron beam welding
Accelerated electrons are converged and focussed at the metals to be welded to get very high energy density.Beam size is of the order of 0.5 mm.Acceleration voltages will be several kilo volts and beam current in milliamperes.Welding speeds will be in the range 0.5 to 2 meters per minute depending on thickness.As welding is performed in high vacuum environment ,defects are eliminated.Materials which are highly reactive like titanium,zirconium,aluminium alloys can be welded successfully for strategic applications.WELDING IS PERFORMED IN SINGLE PASS EVEN FOR VERY HIGH THICKNESSES USING KEYHOLE TECHNIQUE.As high as 300mm thickness is welded using high power machines commercially available.
LASER beam welding
LASER stands for light amplification by stimulated emission of radiation.There are commercially available solid state and gaseous LASER machines in different power capacities to weld small thicknesses to 25 mm.LASER is a versatile tool and can be used for cutting,drilling,surface alloying,hardening, welding, engraving and trimming applications.
Arc welding
The welding of metals is by melting the two surfaces and allowing the molten metal to mix with the molten filler in case used to form a homogenous joint on solidification. Shielded metal arc welding (SMAW or MMAW) is a very popular method and has several advantages due to its flexibility for shop floor as well as site applications.
Gas tungsten arc welding (GTAW) uses inert gas as shielding gas and a non consumable tungsten electrode provides the arc for melting the base metals and filler rod. This process is employed where high joint quality is required. Gas metal arc welding (GMAW) uses a consumable wire continuously melted with an arc for higher deposition rates. Higher productivity is achieved with CO2 – gmaw and inert gas shielded gmaw. Submerged arc welding ( SAW ) , Electro gas welding (EGW) and elctro slag welding processes are required to be used for heavy thickness welding applications.
Plasma arc welding (PAW) is a special process which is a variation of GTAW.This process uses a plasma column generated by a specifically designed nozzle. This facilitates single pass welding for deep penetration welding for critical applications.
selection of power sources