AWS Classification of Filler Metals. .. welding, and inspection techniques are described to aid the ing Society (AWS) Certified Welding Inspector (CWI). INSPECTION. TECHNOLOGY. WORKBOOK. FIFTH EDITION. Published By. American Welding Society. Education Services. This is a preview of "AWS. AWS D Structural Steel Code: Second Printing Edition. Code clinic * Welding Inspection Technology Sample CWI. Fundamentals.
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WELDING INSPECTION TECHNOLOGY. DISCLAIMER. The American Welding Society, Inc. assumes no responsibility for the information contained in this. pdf. WELDING INSPECTION TECHNOLOGY WORKBOOK FIFTH EDITION of the above Q What AWS document describes the rules for the CWI certification . This third edition of the Welding Inspection Handbook has been prepared by the estab- technologies makes the job more complicated lished by the AWS.
HMiesring Processes While it is not mandatory that the inspector be a qualified welder, any hands-on welding experience is benefi- cial. In fact, many welding inspectors are selected for that position after working as a welder for some time. History has shown that former welders often make good inspectors. First, the inspector should realize the important advantages and limitations of each process, The inspector should also be aware of those discontinuities which may result when a par- ticular process is used.
This certification, which is awarded by the American Welding Society, carries a lot of weight both nationally and internationally. The main responsibility of a CWI is to make sure that welders follow specified guidelines in order to manufacture a product that is of highest quality and more importantly safe for the consumer.
CWIs essentially guarantee that every weld made in a welded assembly is free of defect. As you can imagine this is a great responsibility. However, with proper training and a sound quality assurance program a CWI can enhance the marketability and prosperity of his company.
Having a CWI on staff is not required of all manufacturers, but it certainly helps.
Even if you do not need to qualify welders or procedures, the knowledge of a CWI can go a long way insuring quality and improving welding operations efficiencies within a plant. In order to become a CWI you need to meet the following requirements: Pass a vision test Have a combination of qualifying education and related work experience. You must meet one of the following: Associate or higher degree in engineering technology, or a physical science with minimum work experience of 3 years.
Minimum work experience is 4 years High school diploma or high school equivalency diploma plus 5 years or work experience At least 8th grade completed plus 9 years of work experience Less than 8th grade requires 12 years of work experience If you meet both requirements then follow these steps: Fill out the AWS Certified Welding Inspector Exam Application.
Choose an examination site. This is a quick welding process and can be performed continuously. Welding rod[ edit ] A plastic welding rod, also known as a thermoplastic welding rod, is a rod with circular or triangular cross-section used to bind two pieces of plastic together.
They are available in a wide range of colors to match the base material's color.
Spooled plastic welding rod is known as "spline". An important aspect of plastic welding rod design and manufacture is the porosity of the material. A high porosity will lead to air bubbles known as voids in the rods, which decrease the quality of the welding. The highest quality of plastic welding rods are therefore those with zero porosity, which are called voidless. Heat sealing [ edit ] Heat sealing is the process of sealing one thermoplastic to another similar thermoplastic using heat and pressure.
The direct contact method of heat sealing utilizes a constantly heated die or sealing bar to apply heat to a specific contact area or path to seal or weld the thermoplastics together.
Heat sealing is used for many applications, including heat seal connectors, thermally activated adhesives and film or foil sealing.
Common applications for the heat sealing process: Heat seal connectors are used to join LCDs to PCBs in many consumer electronics, as well as in medical and telecommunication devices. Heat sealing of products with thermal adhesives is used to hold clear display screens onto consumer electronic products and for other sealed thermo-plastic assemblies or devices where heat staking or ultrasonic welding is not an option due to part design requirements or other assembly considerations.
Heat sealing also is used in the manufacturing of bloodtest film and filter media for the blood, virus and many other test strip devices used in the medical field today. A variety of heat sealers are available to join thermoplastic materials such as plastic films : Hot bar sealer, Impulse sealer, etc.
Freehand welding[ edit ] With freehand welding, the jet of hot air or inert gas from the welder is played on the weld area and the tip of the weld rod at the same time. As the rod softens, it is pushed into the joint and fuses to the parts.
This process is slower than most others, but it can be used in almost any situation. Speed tip welding[ edit ] With speed welding, the plastic welder, similar to a soldering iron in appearance and wattage, is fitted with a feed tube for the plastic weld rod.
The speed tip heats the rod and the substrate, while at the same time it presses the molten weld rod into position. A bead of softened plastic is laid into the joint, and the parts and weld rod fuse. With some types of plastic such as polypropylene, the melted welding rod must be "mixed" with the semi-melted base material being fabricated or repaired.
These welding techniques have been improved over time and have been utilized for over 50 years by professional plastic fabricators and repairers internationally. Speed tip welding method is a much faster welding technique and with practice can be used in tight corners.
A version of the speed tip "gun" is essentially a soldering iron with a broad, flat tip that can be used to melt the weld joint and filler material to create a bond. Extrusion welding[ edit ] Extrusion welding allows the application of bigger welds in a single weld pass.
Welding rod is drawn into a miniature hand held plastic extruder, plasticized, and forced out of the extruder against the parts being joined, which are softened with a jet of hot air to allow bonding to take place. Contact welding[ edit ] This is the same as spot welding except that heat is supplied with thermal conduction of the pincher tips instead of electrical conduction.
Two plastic parts are brought together where heated tips pinch them, melting and joining the parts in the process. Hot plate welding[ edit ] Main article: Hot plate welding Related to contact welding, this technique is used to weld larger parts, or parts that have a complex weld joint geometry.
The two parts to be welded are placed in the tooling attached to the two opposing platens of a press. A hot plate, with a shape that matches the weld joint geometry of the parts to be welded, is moved in position between the two parts.
The two opposing platens move the parts into contact with the hot plate until the heat softens the interfaces to the melting point of the plastic.
When this condition is achieved the hot plate is removed, and the parts are pressed together and held until the weld joint cools and re-solidifies to create a permanent bond.
Hot-plate welding equipment is typically controlled pneumatically, hydraulically, or electrically with servo motors. This process is used to weld automotive under hood components, automotive interior trim components, medical filtration devices, consumer appliance components, and other car interior components.
Main article: IR welding Similar to hot plate welding, non-contact welding uses an infrared heat source to melt the weld interface rather than a hot plate. This method avoids the potential for material sticking to the hot plate, but is more expensive and more difficult to achieve consistent welds, particularly on geometrically complex parts.
Heat Sealing is a very mature technology that has been around since the s.
High frequency electromagnetic waves in the range of Radio Frequencies can heat certain polymers up to softening the plastics for joining. Heated plastics, under pressure weld together.
Heat is generated within the polymer by the rapid reorientation of some chemicals dipoles of the polymer, which means that the heating can be localized, and the process can be continuous. Only certain polymers, which contain dipoles can be heated by RF waves, in particular polymers with high loss power.