Statistical Techniques for Evaluation of Non-Destructive Testing Data

Statistical methods for image and pattern analysis are vital to any successful inference from the NDE derivation. Statistical analysis of the NDT sample data is an effective means of reducing the uncertainty and thereby increasing the confidence in the process. It is not economical and sometimes practical to inspect or assess all surfaces and components, so statistical sampling and analysis often is the only feasible approach. Engineers should be skilled in conducting comprehensive statistical Root Cause analysis to failures which have a safety or regulatory consequence.
The Type1 and Type2 errors in statistics clearly determine the extent of reliability on the results. This quantification is needed in order to certify a product as fully compliant or not. The degradation rate of material strength is also determined by using statistical analysis. Some of the statistical analysis methods that is applicable to NDT data is as follows

· Multi-variate analysis
· Regression Analysis
· Probability /Distributions /Hazard Functions
· Sampling Analysis and Hypotheses testing
· Conditional probabilities.

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AUT/NDT weld testing and inspection system

The field of Non-Destructive Testing (NDT) in weld testing and inspection is advancing rapidly through the innovations of Automated Ultrasonic Testing (AUT) technology. The AUT technology has replaced radiographic inspection techniques as the NDT industry standard system for the testing especially in pipelines, in power stations and on chemical plants. Auto UT setups are slightly complicated, with lots of belts, cogs, pulleys and motors. As AUT Technology has evolved, it has created an industry desire for its more reliable, time-effective, cost-lessening and better weld defect detecting results. Its reliance on the software is quite high, hence the chance of error is minimised.

Automated Ultasonic Testing (AUT) is recognized as the most reliable and beneficial weld testing method. AUT is a highly reliable methods as it focuses on the method and interpreting and managing the acquired data as well. The phased arrays used in AUT systems such as UT Scan offer additional improvements over conventional multiprobe ultrasonics and radiography, both for onshore and offshore use. AUT offers the important advantage of process control, as welds can be inspected much more quickly and data feedback is also supplied in this manner.

AUT is particularly useful in the construction industry as it saves significantly on construction costs by process control and the use of Engineering Critical Assessment to minimize the reject rate. In AUT of pipeline girth welds a number of separate fixed angle probes or a pair of phased array probes are mounted on a band strapped around the pipe and are positioned each side of the weld and driven around the pipe's circumference.As the probes travel around the pipe, ultrasonic data are collected from the weld and the software calculates flaw sizes and positions for display. Very fast circumferential speeds (~100mm/s) are called for, since, to keep pace with construction, it is necessary to complete a weld inspection every 2-4 minutes. AUT is replacing radiography for pipeline girth weld inspections worldwide.

The advantages of conventional AUT over radiography are: -

* No radiation hazard.
* Better process control of welding through rapid feedback, giving lower reject rates.
* Improved defect evaluation by using Engineering Critical Assessment (ECA) criteria.
* Faster inspections.
* Rapid and reliable data interpretation from specialised output display.

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What is Metallurgical Failure Analysis?

What is Metallurgical Failure Analysis?
By Susan Hutson

Metallurgical Failure Analysis describes the course of analyzing the failure of a metal. A Metallurgical engineer is well equipped to scrutinize a metal product malfunction. A mishap or failure of a metal component is always complex, whether it is in a simple consumer product or in a multifaceted component mechanism.

It is hard to figure out the actual 'cause' of such failures by taking into consideration just one or two 'facts' relating to it. The causes may relate to the failure in many different ways thereby revealing more of the true picture.

A metallurgist's analysis of metallurgical failure include the examination and documentation of the failure site; when, where and how the failure occurred, preservation of evidence if accidental failure, standards and library reviews, engineering calculations, file and data analysis and synthesis, on site photographs and visual examination, identifying defects non destructively (e.g. ultrasonic, radiography and magnetic particle inspection), metallographic exams, appropriate chemical analyses, Energy Dispersive Spectroscopy analysis (EDS analysis), expert witness testimony, and report preparation. The ultimate objective is to find the 'root cause' of the failures, which lies beneath each observation.

Some common causes which lead to metallurgical failure are:
· Failure in design structure
· Insufficient quality assurance
· Insufficient protection / control of the environment
· Casting discontinuities
· Manufacturing defects
· Assembling errors
· Inappropriate maintenance
· Maltreatment
· Improper material and heat treatments
· Fastener failures
· Unanticipated operating conditions

It is an important regulation in many branches of the manufacturing industry to use failure analysis as a vital tool to develop new products and improve the existing ones. The root causes of failure should be chiefly based upon the 'facts' with regard to the analysis. This combined with the experience, skills and knowledge of a metallurgist will lead to sound conclusions and solving of issues at hand and even the 'seemly unessential' facts may turn out to be strengths for future metallurgical success.

MSI Testing and Engineering Inc., with its experienced metallurgical engineers, conducts accurate metallurgical failure analysis in the industries of steel production, power generation, foundry, forgings, aerospace, boiler / presser vessels, titanium, railroad, shipbuilding, springs, automotive, farming, heat exchangers, medical implant, fasteners, food industry equipment, transportation, heat treating, and shafts and bearings.

Bizymoms has partnered with Msi Testing and Engineering Inc, who conducts metallurgical failure analysis in numerous industries including everyday household items, giving their client accurate reports. Visit http://www.msitesting.com today!

Heat Exchanger Tube Bundles Inspection using UT

Heat exchangers are used by many industries, especially in oil refineries and chemical plants. Their purpose is to exchange heat from one place to another, usually from one liquid to another liquid. The continued efficiency of this device demands regular heat exchanger inspection to determine whether or not the integrity of the equipment.

Where are Heat Exchangers Found?

Most homes also have a heat exchanger of some kind. The most common household heat exchanger can be found in a refrigerator. In hot countries air conditioners are common; another kind of heat exchanger. Cars contain them too - the radiator removes the excess heat from the radiator fluid by making use of the natural airflow caused by the car's forward progress.

A similar principle applies in large industry where heat needs to be transferred from one place to another. The most common type of heat exchanger found in oil refineries and other large plants is the "shell and tube heat exchanger".

This design employs a large shell, usually a very large diameter tube that can withstand high pressures. It contains a bundle of tubes inside. The heat exchanged is from two different fluids. One fluid flows through the shell of the exchanger while the other flows through the tube bundle. The two fluids do not make direct contact with each other, but the difference in their respective heat values is changed through the indirect contact that is made.

A shell and tube heat exchanger is a complex design. The internal tubes are often of differing types and design in order to achieve different results. Some tubes may be plain while others may be finned horizontally or longitudinally. The tubes may also be composed of different materials and different thermal conductivity. They may be made from stainless steel, carbon steel, brass, copper or cupronickel, for example.

Because of their complex nature it is necessary to have a regular the equipment regularly inspected. This can determine the wall thickness of the tubes, which are subject to pitting and corrosion as well as erosion over time. The condition of the entire tube bundle can be charted and evaluated through a highly detailed inspection using a device called an Internal Rotary Inspection System.

The Internal Rotary Inspection System works through ultrasonic testing and it is non-destructive in nature. The Internal Rotary Inspection System probe has to be inserted into a tube which is then filled with water.

The Internal Rotary Inspection System probe has a small mirror that rotates and focuses an ultrasonic beam onto the wall of the tube. The mirror rotation is driven by a small turbine, which in turn is driven by water pressure as it is pumped into the tube. The Internal Rotary Inspection System probe is slowly pulled out of the tube at a rate of about one inch or 25 millimetres per second, recording the condition of the internal wall of the tube as it progresses.

The results gained from a heat exchanger inspection using an Internal Rotary Inspection System probe is generally extremely accurate. Its accuracy can be as good as to within .005 inches, or .13 millimetres. Of course, in order to gain this level of accuracy it is necessary for the tubes to be thoroughly cleaned down to bare metal prior to the inspection.

C. J. Rose writes on the subject of tube bundle and heat exchanger cleaning and onshore/offshore environmental safety for Sureclean, global industrial waste management experts. Topics include HP & UHP water jetting, tank/vessel cleaning, vacuum transfer/pumping, industrial painting, asbestos management/removal, HVAC/duct management, NORM management. For videos see http://www.sureclean.com/video

Materials Testing and Non Destructive Tests
By D. Garcia

Nondestructive testing is a broad classification of analysis techniques used in science and industry to evaluate the properties of a material, component or structure with no causing destruction. As Non Destructive Testing does not permanently vary the article being inspected, it is a highly-valuable method that can save both Cash and time in merchandise evaluation, Analysis, and examination. Ordinary Non Destructive Testing methods include ultrasonic, magnetic-particle, liquid penetrant, radiographic, and eddy-current testing.

Non Destructive Testing methods might rely upon utilize of electromagnetic radiation, sound, and inherent properties of resources to Analyse samples. This includes several kinds of microscopy to examine peripheral surfaces in point, although sample research techniques for metallography, optical microscopy and electron microscopy are usually destructive as the surfaces have to be made Smooth-textured through polishing or the sample have to be electron transparent in thickness. The inside of a sample can be Studied with penetrating electromagnetic radiation, such as X-rays, or with sound Twists in the situation of ultrasonic testing. Contrast relating a defect and the bulk of the sample can be enhanced for visual examination by the unaided eye by using liquids to access fatigue cracks. Single method (liquid penetrant testing) involves using dyes, fluorescent or non-fluorescing, in fluids for non-magnetic resources, as a rule metals. One more commonly used method for magnetic resources involves using a liquid suspension of fine iron particles applied to a part while it is in an externally applied magnetic field.

Personnel Qualification is an notable aspect of non-destructive evaluation. Non Destructive Testing techniques rely powerfully on person skill and skill for the correct assessment and explanation of test results. Proper and sufficient training and certification of NDT personnel is therefore a have got to to ensure that the capabilities of the techniques are fully exploited. There are a quantity of available international and regional values covering the certification of competence of personnel.

Structures can be complicated systems that undergo several loads throughout their life. Several complicated structures, such as the turbomachinery in a liquid-fuel rocket, can also cost millions of Money. Engineers will commonly develop these structures as coupled second-order systems, in the vein of dynamic construction components with springs, masses, and dampers.

In Non Destructive Testing, the composition undergoes a dynamic input, such as the tap of a hammer or a controlled impulse. Crucial properties, such as displacement or increase of velocity at altered points of the formation, are measured as the corresponding output. This output is recorded and compared to the corresponding output set by the passing on function and the known input. Differences may well indicate an inappropriate model.

Non Destructive Testing plays a Important role in ensuring cost valuable maneuver, safety and reliability of plant, with resultant benefit to the district. Is used in a broad range of engineering areas and is used at almost any stage in the production or life cycle of many components. The mainstream applications are in aerospace, power generation, automotive, railway, petrochemical and pipeline markets.

Daniel Garcia is engineer of Materials Testing

Aerospace NDT - Non-Destructive Testing

By John Routledge

The field of NDT is varied, there are various Non destructive Testing (NDT) methods used for inspection of aircraft, powerplant, and components in aircraft. The effectiveness of any particular method of NDT depends upon the skill, experience, and training of the person(s) performing the inspection process. Each process is limited in its usefulness by its adaptability to the particular component to be inspected.

The product manufacturer or the Federal Aviation Administration (FAA) generally specifies the particular NDT method and procedure to be used in inspection. These NDT requirements will be specified in the manufacturer's inspection, maintenance, or overhaul manual; FAA Airworthiness Directives (AD); Supplemental Structural Inspection Documents (SSID); or manufacturer's service bulletins (SB). However, in some conditions an alternate NDT method and procedure can be used. This includes procedures and data developed by FAA certificated repair stations under Title 14 of the Code of Federal Regulations, 14 CFR part 145.

Title 14 CFR part 43 requires that all maintenance be performed using methods, techniques, and practices prescribed in the current manufacturer's maintenance manual or instructions for continued airworthiness prepared by its manufacturer. If the maintenance instructions include materials, parts, tools, equipment, or test apparatus necessary to comply with industry practices then those items are required to be available and used as per part 43.

NDT levels.

Air Transport Association (ATA) Specification 105 provides guidelines For Training and Qualifying Personnel In Non destructive Testing Methods.

a. Level i Special.
Initial classroom hours and on-the-job training shall be sufficient to qualify an individual for certification for a specific task. The individual must be able to pass a vision and color perception examination, a general exam dealing with standards and NDT procedures, and a practical exam conducted by a qualified Level II or Level III certificated person.
b. Level i/Level ii.
The individual shall have an FAA Airframe and Powerplant Mechanic Certificate, complete the required number of formal classroom hours, and complete an examination.
c. Level iii.
(1) The individual must have graduated from a 4 year college or university with a degree in engineering or science, plus 1 year of minimum experience in NDT in an assignment comparable to that of a Level II in the applicable NDT methods: or
(2) The individual must have 2 years of engineering or science study at a university, college, or technical school, plus 2 years of experience as a Level ii in the applicable NDT methods: or
(3) The individual must have 4 years of experience working as a Level ii in the applicable NDT methods and complete an examination.

The success of any aerospace NDT methods and procedures depends upon the knowledge, skill, and experience of the aerospace NDT personnel involved. The person(s) responsible for detecting and interpreting indications, such as eddy current, X-ray, or ultrasonic NDT, must be qualified and certified to specific FAA, or other acceptable government or industry standards, such as MIL-STD-410, Non destructive Testing Personnel Qualification and Certification, or Air Transport Association (ATA) Specification 105 Guidelines for Training and Qualifying Personnel in Non destructive Testing Methods. The person should be familiar with the test method, know the potential types of discontinuities peculiar to the material, and be familiar with their effect on the structural integrity of the part.
Eddy current inspection detects flaws in conductive materials.

Magnetic particle inspection is for flaw detection in ferromagnetic materials.
Dye penetrant inspection or liquid penetrant inspection LPI locates surface-breaking cracks or defects in all non-porous materials whcih might be, for example, fatigue.

Flaw detection and processes.

Inspection personnel should know where flaws occur or can be expected to exist and what effect they can have in each of the aerospace NDT test methods. Misinterpretation and/or improper evaluation of flaws or improper performance of aerospace NDT can result in serviceable parts being rejected and defective parts being accepted.
All NDT personnel should be familiar with the detection of flaws such as: corrosion, inherent flaws, primary processing flaws, secondary processing or finishing flaws, and in-service flaws. The following paragraphs classify and discuss the types of flaws or anomalies that may be detected by aerospace NDT.

a. Corrosion detection. This is the electrochemical deterioration of a metal resulting from chemical reaction with the surrounding environment. Corrosion is very common and can be an extremely critical defect. Therefore, NDT personnel may devote a significant amount of their inspection time to corrosion detection.

b. Inherent Flaws. This group of flaws is present in metal as the result of its initial solidification from the molten state, before any of the operations to forge or roll it into useful sizes and shapes have begun. The following are brief descriptions of some inherent flaws.

Primary pipe is a shrinkage cavity that forms at the top of an ingot during metal solidification, which can extend deep into the ingot. Failure to cut away all of the ingot shrinkage cavity can result in unsound metal. called pipe, that shows up as irregular voids in finished products.

Blowholes are secondary pipe holes in metal that can occur when gas bubbles are trapped as the molten metal in an ingot mold solidifies. Many of these blowholes are clean on the interior and are welded shut into sound metal during the first rolling or forging of the ingot. However, some do not weld and can appear as seams or laminations in finished products.

Segregation is a non-uniform distribution of various chemical constituents that can occur in a metal when an ingot or casting solidifies. Segregation can occur anywhere in the metal and is normally irregular in shape. However, there is a tendency for some constituents in the metal to concentrate in the liquid that solidifies last.
Porosity is holes in a material's surface or scattered throughout the material, caused by gases being liberated and trapped as the material solidifies.

Inclusions are impurities, such as slag, oxides, sulfides, etc., that occur in ingots and castings. Inclusions are commonly caused by incomplete refining of the metal ore or the incomplete mixing of deoxidizing materials added to the molten metal in the furnace.

Cooling cracks can occur in casting due to stresses resulting from cooling, and are often associated with changes in cross sections of the part. Cooling cracks can also occur when alloy and tool steel bars are rolled and subsequently cooled. Also, stresses can occur from uneven cooling which can be severe enough to crack the bars. Such cracks are generally longitudinal, but not necessarily straight. They can be quite long, and usually vary in depth along their length.

Shrinkage cracks can occur in castings due to stresses caused by the metal contracting as it cools and solidifies.
c. Primary Processing Flaws. Flaws which occur while working the metal down by hot or cold deformation into useful shapes such as bars, rods, wires, and forged shapes are primary processing flaws. Casting and welding are also considered primary processes although they involve molten metal, since they result in a semi-finished product. The following are brief descriptions of some primary processing flaws:

Seams are surface flaws, generally long, straight, and parallel to the longitudinal axis of the material, which can originate from ingot blowholes and cracks, or be introduced by drawing or rolling processes.

Laminations are formed in rolled plate, sheet, or strip when blowholes or internal fissures are not welded tight during the rolling process and are enlarged and flattened into areas of horizontal discontinuities.

Flakes are internal ruptures that can occur in metal as a result of cooling too rapidly. Flaking generally occurs deep in a heavy section of metal. Certain alloys are more susceptible to flaking than others.

Forging laps are the result of metal being folded over and forced into the surface, but not welded to form a single piece. They can be caused by faulty dies, oversized dies, oversized blanks, or improper handling of the metal in the die. They can occur on any area of the forging.

Forging bursts are internal or external ruptures that occur when forging operations are started before the material to be forged reaches the proper temperature throughout. Hotter sections of the forging blank tend to flow around the colder sections causing internal bursts or cracks on the surface. Too rapid or too severe a reduction in a section can also cause forging bursts or cracks.

A hot tear is a pulling apart of the metal that can occur in castings when the metal contracts as it solidifies.
Cupping is a series of internal metal ruptures created when the interior metal does not flow as rapidly as the surface metal during drawing or extruding processes. Segregation in the center of a bar usually contributes to the occurrence.
A cold shut is a failure of metal to fuse. It can occur in castings when part of the metal being poured into the mold cools and does not fuse with the rest of the metal into a solid piece.

Incomplete weld penetration is a failure of the weld metal to penetrate completely through a joint before solidifying.
Incomplete weld fusion occurs in welds where the temperature has not been high enough to melt the parent metal adjacent to the weld.

Weld undercutting is a decrease in the thickness of the parent material at the toe of the weld caused by welding at too high a temperature.

Cracks in the weld metal can be caused by the contraction of a thin section of the metal cooling faster than a heavier section or by incorrect heat or type of filler rod. They are one of the more common types of flaws found in welds.
Weld crater cracks are star shaped cracks that can occur at the end of a weld run.

Cracks in the weld heat-affected zone can occur because of stress induced in the material adjacent to the weld by its expansion and contraction from thermal changes.

A slag inclusion is a nonmetallic solid material that becomes trapped in the weld metal or between the weld metal and the base metal.

Scale is an oxide formed on metal by the chemical action of the surface metal with oxygen from the air.
d. Secondary Processing or Finishing Flaws. This category includes those flaws associated with the various finishing operations, after the part has been rough-formed by rolling, forging, casting or welding. Flaws may be introduced by heat treating, grinding, and similar processes. The following are brief descriptions of some secondary processing or finishing flaws.

Machining tears can occur when working a part with a dull cutting tool or by cutting to a depth that is too great for the mate rial being worked. The metal does not break away clean, and the tool leaves a rough, tom surface which contains numerous short discontinuities that can be classified as cracks.

Heat treating cracks are caused by stresses setup by unequal heating or cooling of portions of a part during heat treating opera tions. Generally, they occur where a part has a sudden change of section that could cause an uneven cooling rate, or at fillets and notches that act as stress concentration points.

Grinding cracks are thermal type cracks similar to heat treating cracks and can occur when hardened surfaces are ground. The overheating created by the grinding can be caused by the wheel becoming glazed so that it rubs instead of cutting the surface; by using too little coolant; by making too heavy a cut; or by feeding the material too rapidly. Generally, the cracks are at right angles to the direction of grinding and in severe cases a complete network of cracks can appear. Grinding cracks are usually shallow and very sharp at their roots, which makes them potential sources of fatigue failure.

Etching cracks can occur when hardened surfaces containing internal residual stresses are etched in acid.
Plating cracks can occur when hardened surfaces are electroplated. Generally. they are found in areas where high residual stresses remain from some previous operation involving the part.

e. In-Service Flaws. These flaws are formed after all fabrication has been completed and the aircraft. engine, or related component has gone into service. These flaws are attributable to aging effects caused by either time, flight cycles. service operating conditions, or combinations of these effects. The following are brief descriptions of some in-service flaws.

Stress corrosion cracks can develop on the surface of parts that are under tension stress in service and are also exposed to a cor rosive environment, such as the inside of wing skins, sump areas, and areas between two metal parts of faying surfaces.

Overstress cracks can occur when a part is stressed beyond the level for which it was designed. Such overstressing can occur as the result of a hard landing, turbulence, accident, or related damage due to some unusual or emergency condition not anticipated by the designer, or because of the failure of some related structural member.
Fatigue cracks can occur in parts that have been subjected to repeated or changing loads while in service, such as riv eted lap joints in aircraft fuselages. The crack usually starts at a highly-stressed area and propagates through the section until failure occurs. A fatigue crack will start more readily where the design or surface condition provides a point of stress concentration. Common stress concentration points are: fillets; sharp radii; or poor surface finish, seams, or grinding cracks.

Unbonds, or disbonds, are flaws where adhesive attaches to only one surface in an adhesive-bonded assembly. They can be the result of crushed, broken, or corroded cores in adhesive-bonded structures. Areas of unbonds have no strength and place additional stress on the surrounding areas making failure more likely.

Delamination is the term used to define the separation of composite material layers within a monolithic structure. Ultrasonic testing is the primary method used for the detection of delamination in composite structures.

aviation-database.com has lots of resources for the aircraft industry. The web is a vast source of information. Aviation-database collects the industry into one huge database of contacts. Aerospace NDT Non-Destructive Testing is an article giving technical guidance and you can click on the logo top or bottom to return to the searchable database giving contact details of companies worldwide providing this service.

Types & Features Of Arc Welders, Tig Welders, Mig Welders, & Plasma Cutters

by Chris Harmen

Ask anyone in the industry what the hottest equipment is in the world of automotive service equipment and they'll name items such as plasma cutters, mig welders, and other welding equipment. And, when you try them out and discover the quality of the cuts and welds they make, it's no surprise. This equipment is a cost-effective and easy-to-use option when compared to the work done by earlier technology.

Mig Welders And Other Automotive Service Equipment

This type of equipment comes in a number of convenient types to repair or make almost anything quickly and easily. With these machines, you'll look like a seasoned professional. All you need to do is match the machine to the work you're doing.

Arc Style Machines

The earliest advancement on the traditional torch, arc welders are an entry level of automotive service equipment that are also some of the easiest to use. More commonly known as stick welding, this unit joins thick metals together quickly using an electrode and electric arcs.

Mig Welders

The next step up from an arc welder, mig welders, use a wire feed and produce a lower heat. This prevents metal distortion and allows you to do a higher quality job on thinner metals such as those involved in auto body work.

Mig welders feed a constant stream of wire with a pull of the trigger, but you'll still need to choose your supplies carefully. Wire, for example, comes in easy-to-use flux core wire for a quick job on thicker materials, or a gas/solid wire combination for all other work.

The type of gas you use also makes a significant difference on the weld quality. Argon and CO2 are best for stainless steel and aluminum. To prevent the wire feed from sticking on the weld line, be sure to use a Teflon liner. Finally, you'll need to choose the appropriate wire diameter and tip size.

Once you've chosen the appropriate automotive service equipment, you'll still want to practice on scraps before working on the final piece for the best results. This is particularly true for aluminum and other delicate materials. Also, don't be afraid to watch the gauges and flow meters on the supply lines as well as on the machine itself. In the end, you'll find mig welders quick and affordable while still doing a quality job.

Tig Or Tungsten Inert Gas

Unlike the first two machines mentioned, this style requires a combination of heat and tungsten electrodes to work. One of the biggest advantages to this style of welder is the fact that it heats and joins the two metal pieces together without the need for filler materials. The only exception is argon or other gasses needed to create the shielding.

You'll notice that mig welders join metals together much faster than tig welders. However, tig welders work with higher precision and accuracy, which is great for customized work. Tig machines require more skills and practice to use properly. The possibility of preventing cracked seals or damaging the weld is also significantly decreased.

Plasma Cutters

There's no denying the precision of plasma cutters. To get clean, accurate cuts, these units use an electric arc and gas/air at a high pressure, along with a high-speed wire and low heat setting. You'll also notice that newer lines of plasma cutters have an inverter in place of the transformer. This keeps the temperature of the machine lower and makes it possible to have smaller, lighter machines without jeopardizing safety or quality.

With all of the different styles of plasma cutters available, you'll want to choose carefully. Duty cycle should be one of the main determining factors in your decision. This determines how long you can use this automotive service equipment before having to allow it to cool. Generally, you'll discover that bigger machines can handle thicker metals and run longer to give it a bigger duty cycle.

The other important feature you'll want to make note of is the rating that is assigned to plasma cutters by the manufacturer. This will tell you how long each unit can cut through mild steel before needing to be cooled down. The rating varies, however. If you're working on tempered steel, the length of time you have to make the cut will be far lower. Aluminum, on the other hand, is far easier to cut, and therefore gives you more operating time to work with.

Features Found On Mig, Tig, Arc & Plasma Cutters

Arc Welders

Arc welders are packed full of helpful features to improve the precision of this automotive service equipment and make them easier to use. Unlimited amperage control means you have the ability to create professional welds. Their lightweight and super-sturdy design makes this type of welder highly portable and durable enough to withstand regular wear. You'll also find that some models of arc welders have thermostatic heat protection and a roll bar design to give the unit increased protection against damage.

Mig Welding Equipment

Ranging in size from a small, portable 115v, 20 amp machine to full sized shop automotive service equipment, mig welders are one of the few that combine a relatively low price tag with high quality performance. You can also gain full control over the quality of the weld with a full range of settings. Finally, these machines come with added benefits such as colder running temperatures and some of the best warranty options.

Tig Welders

Even the most basic tig welding machines come loaded full of features. Push button control panels make them easier to use while higher end models let you easily adjust the machines repeatable weld cycles, start, and weld crater. To customize the shape and size of the bead, look for models with true square wave AC output and pulse mode. Lastly, look for models with added safety features such as warning code circuitry and voltage protection.

Plasma Cutters

Like the welders mentioned previously, plasma cutters come with a full range of features. Single-dial controls for quick adjustments, pressure gauges, and built in air pressure regulators put you in full control of this automotive service equipment and result it cleaner cuts.

Additional features such as parts-in-place indicators, line voltage compensation, and thermostatic protection add to the safety of plasma cutters. Finally, if you'll be doing repetitive work with complicated cuts, CNC robotic interfaces on your automotive service equipment will ensure you get consistent, accurate results every time.

Automotive service equipment like mig welders and plasma cutters come in a variety of different types with many different features to get you the best cut or weld possible. In order to achieve the cleanest, most precise repairs, you simply need to match the right automotive service equipment to the job.

Chris Harmen is a writer for ASE Deals, America's top choice for automotive service equipment. ASE Deals offers competitive prices on all tools and repair equipment including mig welders, air compressors, auto lifts and more.

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NDT Applications

Nondestructive Testing Nondestructive testing (NDT) includes an extensive range of analysis techniques that are used to assess the physical attributes of a component or a system. Some of the most popular Nondestructive testing (NDT) methods include ultrasonic, radiographic, magnetic particle, liquid penetrant, eddy current, visual, leak testing, mechanical, welder/welding procedure qualification, Positive Material Identification, Hydrostatic, Ground Penetrating Radar, and Digital Imaging.

With the success rate of Nondestructive testing (NDT) methods, they have become an integral part of the forensic engineering, mechanical engineering, electrical engineering, civil engineering, systems engineering, medicine, and art. The three main things that play major role during Nondestructive testing are (1) Electromagnetic Radiation, (2) Sound, and (3) Inherent Properties of Materials to be tested.

The application areas where Nondestructive testing (NDT) is used include automotive, aviation, construction, power plants, manufacturing, railways, military, and naval industry. NDT has been proved extremely beneficial for product evaluation, troubleshooting, and research as it does not affect the object that being tested in any way. Some of the applied examples of Nondestructive testing are given below:

Weld Verification

The NTD or Nondestructive testing techniques used in welds testing include as industrial radiography using X-rays or gamma rays, ultrasonic testing, liquid penetrant testing or via eddy current and flux leakage. All these tests help to identify cracks in the surface area which are not visible to the naked eye. Welding technique is basically for joining metals, usually the metal joints or connection is prone to extra wear and tear during the product life therefore it is very important to ensure that welding is properly done and all the testing procedures are carefully conducted.

Radiography in Medicine

Radiography has been widely used to image parts or functions of the body. Some elements of human body act in response to radiographic inputs like x-rays or magnetic resonance which help the medical professionals to study the functionality of the human body. It is used to detect bone fractures and diseases and also examine the interior of mechanical systems. Radiography is majorly used in many types of medical treatments and due to its accurate and efficient results has become an integral part of the medical science.

Abcndt.com use reliable non-destructive and destructive testing methods to increase customer satisfaction and lower manufacturing costs. They cater to industries, such as automotive, aviation, construction, power plants, manufacturing, railways, military, and naval industry. ABC Testing Inc. have Certified Welding Inspectors (CWI) doing welding inspections for steel, aluminum, specialized metals like Inconel, Monel and NiAlBrz, and many other alloys.
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Ultrasonic Testing

Different Aspects Of Material Analysis

Different Aspects Of Material Analysis by Andrew Long

Material analysis involves the discovery of the physical and chemical properties of all types of materials, including solids, liquids and gases. From the seemingly infinite number of properties that could be measured or determined, the analyst performs the job of supplying data on those properties which are of primary importance for the particular applications demanded of the materials or that these materials are being tested for.

The analysis of materials can be broken down by the type of material of which the sample is made. The composition of solid bulk material can be analyzed by electron microprobe and x-ray, including energy dispersive x-ray, wavelength dispersive x-ray and x-ray fluorescence. Transmission Electron Microscopy, Scanning Electron Microscopy or Scanning Transmission Electron Microscopy is used to inspect for defects or impurities in solid bulk material analysis. The composition of solid surface material can be analyzed by Electron Spectroscopy, Auger Electron Spectroscopy and Ion Scattering Spectrometry. Analysis of the composition of solid film material utilizes Rutherford Backscattering Spectroscopy or Neutron Depth Profiling.

The analysis of liquids requires different measurement methods. Inorganic liquids are analyzed using Inductively Coupled Plasma, Atomic Emission Spectroscopy or ICP/Mass Spectrometry. Organic liquids utilize Gas Chromatography, Gas Chromatography/Mass Spectrometry, Infrared Spectroscopy or Fourier Transform Infrared Analysis.

Gas analysis uses many of the same methods that are used on liquids. It can employ Gas Chromatography, Gas Chromatography/Mass Spectrometry, Infrared Spectroscopy, gas sensors or Mass Spectrometry.

Any material analysis should be started at the macro or visible level. As soon as this has been accomplished, it is time to move on to the micro level. There are two kinds of modern microscopes: those that use light to form the image and those that use electrons. Although microscopes using light have a history longer than 300 years, they continue to improve constantly. Lens design improvements have practically eliminated serious aberrations. There are now many important and useful ways to obtain light microscope images, depending on the properties being investigated.

One limitation of the standard light microscope in the field of material analysis is the depth of field problem. The introduction of the electron microscope eliminated this problem by using electrons instead of light to illuminate the sample. It produced images that could almost be interpreted intuitively. The key development that made the electron microscope even more useful was the development of energy-dispersive x-ray spectroscopy which was a versatile tool for elemental chemical analysis. This made it possible to obtain both morphological and chemical information at the same time, although significant analysis must still be done on polished samples rather than on rough surfaces.

Ultrasonic nondestructive testing is a versatile technique that can be applied to many material analysis applications. Ultrasonic NDT is probably best known in its more common applications of thickness gauging, flaw detection and acoustic imaging. These high frequency sound waves can also be used to discriminate and quantify some standard mechanical, structural or compositional properties of solids and liquids.

Ultrasonic analysis is based on a basic principle of physics that the motion of any wave will be affected by the medium through which it travels. There are four easily measurable parameters associated with the passage of high frequency sound waves through a material. They are transit time, attenuation, scattering and frequency content. Changes in one or more of these parameters can often be correlated with changes in physical properties of interest to those carrying out material analysis studies such as hardness, elastic modulus, density, homogeneity or grain structure.

Andrew Long writes for scientific websites and a main area for content covers material analysis and x ray analysis and also lab homogeniser products.

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Finding the difference between reverse and straight polarity

When you see the letters AC/DC on your welder, do you think of one of your favorite rock and roll bands? Seriously though, the difference is quite important to the final quality of your welds.

AC (Alternating Current) and DC (Direct Current) is used to describe the polarity of the electric current that the welder generates and in what direction it travels. If you use the wrong polarity for a certain welding rod, your weld strength will not be very good.

The general terms associated with polarity are reverse polarity and straight polarity. These are common to the welding trade. Another way to describe the two terms are electrode positive and electrode negative. Electrode positive is the same as reverse polarity. Electrode negative is the same as straight polarity. Hence the + and the - written on your welder where the cables connect to it.

Any type of welding rod you buy will be labeled as to what polarity should be used for welding with it. Using the correct polarity will ensure the proper penetration and the over all look of the final bead.

If you use the wrong polarity you can tell by the signs. There will be an excessive amount of spatter, you will have bad penetration, and you will have less control of your arc.

Some welding machines have a switch to adjust the polarity. If your welder doesn't have one you will need to switch the welding cables around where they plug into the machine. If you want reverse polarity, you need to make sure the electrode holder is plugged into the + terminal.

The easiest way to tell if you are using the wrong polarity is by the sound and the feel of the weld you are laying down. If you don’t have much experience with stick welding you will have a little more trouble determining the difference. I have seen guys weld all day long with the wrong polarity. Then I would grab their welder to use for couple of minutes and I could tell right away. It all comes down to experience.

If you don’t have much experience stick welding, you will need to double check the way the machine is set up. Follow what the welding rod package tells you to do and do it. If you are using 7018 rods, you will want to make sure it is set up for reverse polarity.

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