 Hello friends, myself Dr. N. S. Kartikar, Assistant Professor, Department of Mechanical Engineering, Valachandra Institute of Technology, SolarPur. Today we are going to see the presentation on Welding of Plastics Part 5. Learning outcome for this presentation. At the end of this session, student will be able to understand the need and importance of welding of plastics. Welding will be able to apply welding technique in real time. The content for this presentation, the flow will be like this, introduction, need of welding of plastics, classification of plastic welding, infrared welding, one of the type of welding we will discuss in detail. In the introduction, let us see little bit about the plastic material, need of plastic material product, plastic part manufacturing in various categorization, single part and assembly. As we know for designing any particular product or assembly, we required first stage that is selection of material. Whenever we are going to compare one material with the other material, we are going to compare with their optimized properties, positive advantages properties by all means. And plastic material have distinct kind of positive properties like easily moldable, it can be having a bad conductor of electricity, corrosive resistance and so many properties are there. Likewise to take the advantage of the same for the particular designing of the product so that product will be sustained into the respective working condition on environment, many a times plastic material can be used. Plastic part can be manufactured as a singular element or it may be combined together to form an assembly for a particular product assembly. In that case, let us see the need of welding of plastic, likewise to assemble any particular number of plastic elements, we required to join together and that is by the means of welding. Particularly repair and maintenance, packaging, dissimilar material joining, need of the situation are some of the particular needs for welding of plastics. Joining of plastic basically goes with the mechanical joining with the fasteners, adhesive bonding with the particular chemical adhesives and lastly the welding that we are going to see in detail. At this stage of this session, are you able to recall or share some of the applications of welding of plastic joints, which you had used or seen earlier anywhere in real time. Just think about recall and enlist, I think you had written the number of applications where you feel you had seen your experience about the welding of plastic is necessary. Let us go with the classification of plastic welding. Welding process is categorized into the two segments, external heating and internal heating. External heating requires the heat energy and that can be passed with the convection and conduction mode. Whereas, internal heating is goes with the particularly conversion of mechanical energy into the heat energy through the surface friction, some of the examples of external heating, hot tool, hot gas and so on. Whereas, internal heating examples are ultrasonic welding, friction welding, laser welding and RF welding. Let us discuss in detail about the infrared welding. Infrared welding IR welding is a welding technique that uses a non-contact heating method to melt and fuse thermoplastic parts together using the energy from infrared radiation. The process was developed in the late 1900, but due to the high capital cost of IR equipment, the process was not commonly applied in the industry until price dropped in the year 1990s. Infrared welding typically uses a range of wavelengths from 800 to 11,000 nanometer on the electromagnetic spectrum to heat, melt and fuse the interface between two plastic parts. Through the absorption and conversion of IR energy into the heat, laser welding is a similar joining process that applies IR radiation at a single wavelength. Thus, there are many different welding techniques that use IR heating with the three major modes being surface heating through transmission IR welding known as TT IR and IR sticking. A variety of heating configurations have been applied to these techniques such as scanning, continuous illumination and mask welding. IR welding typically uses the wavelengths from 800 to 11,000 nanometers on the electromagnetic spectrum. Wax interact with IR radiation through the reflection transmission and absorption. Incident IR radiation can either be reflected of the surface of the plastic transmitted through the plastic or absorbed into the plastic as other forms of energy including thermal energy. The ratio of these three interactions depends on the wavelength of the IR radiation and the receiving plastics properties. Amorphous plastics are generally optically clear and can transmit almost all incident IR radiation. For this reason, they are commonly used in TT IR. Crystalline plastics can diffuse incident IR radiation between the amorphous and crystalline boundaries, reducing the transmittance and increasing the absorbance of material. The higher the absorptivity, the result is more heat generation for given IR resource. In fraroid welding, additives such as clarifying agents can be used, increase a plastics transmittance while dyes and pigments can be used, increase the absorbance of the material. Increasing amount of these additives can decrease the strength of both the material and the weld joint. IR sources Potential IR welding sources includes quartz lamps and ceramic heaters which can generate a wide range of IR wavelengths. Laser welding employs IR sources that operate at a single wavelength such as CO2 lasers, ND-Yag lasers, laser diodes, etc. Quartz lamps produce wavelengths of around 1000 to 5000 nanometers and ceramic heaters produce wavelengths of around 5000 to 10,000 nanometers. IR welding techniques Surface heating It includes heating and melting of the interface between plastic parts with the IR radiation and forcing the parts together into molten joint that solidifies as one part. Through transmission IR welding, it is a joining of IR transparent part to the second part such that the IR radiation travels through the transparent part and heat the surface of the second part. IR wavelengths are generally within 800 to 1050 nanometers. To make a transparent part absorbent to IR radiation, the addition of dyes or colorants such as carbon black can be used. Highly absorbent thermoplastic film can be placed at the joint to receive the IR radiation and melt the interface during welding. IR staking includes the localized welding of thermoplastic stirred from one part into the cavity of non weldable part to form mechanical fasteners. Thus, surface IR radiation can also be used to soften the plastic stirreds and press it into a button shaped forming head force the stirred to deform into the shape of forming head before solidifying. IR system generally rely on one of three surface heating methods scanning continuous illumination and mask welding. In the scanning the particularly for a few seconds the product to be joined to each other is exposed for infrared source for a very few seconds whereas continuous illumination goes with more time. In the mask welding the flow of IR source goes from one end to the other end whereas continuous illumination it is exposed continuously with the IR source. In the third type mask welding the exposed portion is going to be there for which welding is to be there and unexposed portion is masked so that it will not undergone with the IR source. The various material that can be joined together polycarbonate, acrylic, polystyrene and so on. Let us see the one particularly infrared welding process in a five step. You can see that the load rather the jobs are held into the fixtures and in five steps the joining of particular two distinct elements can be done. The IR source is kept in between the two elements to be joined for a few seconds that can be seen in step two melt phase and after specific period of time it can be removed it can be seen in the phase three open phase and further the two elements are pressed one with the other that is known as seal phase, phase number four and after it the particularly product can be offloaded unloaded and it can be seen into the fifth phase. This various advantages are as follows like cost effective in comparison to the laser welding, continuous and easily automated process and so on. Limitations more expensive than the other thermal plastic welding process and applications the medical IV bags are IR welded to achieve minimum flash and particulate generation for smooth and clean fluid flow. So many applications are there which are as follows. Thank you for this particular presentation. Thank you.