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A number in parentheses indicates the year of last reapproval. This standard has been approved for use by agencies of the Department of Defense. Scope and orientation of indications that are unacceptable in a specific 1. Conditions where rework or repair is not permitted ing cracks and other discontinuities at or near the surface in should be specified.
Magnetic particle testing may be 1. It is useful for preventive 1. This guide describes be regarded as the standard. SI units are provided for informa- magnetic particle testing techniques that are recommended for tion only.
Since there are safety concerns, if any, associated with its use. It is the many acceptable differences in both procedure and technique, responsibility of the user of this standard to establish appro- the explicit requirements should be covered by a written priate safety and health practices and determine the applica- procedure see Section It should be pointed out, however, that after indications have 2.
Current edition approved Feb. Published April Originally 3 approved in Last previous edition approved in as E - Terminology Particle Methods 3. Because flux lines can not cross, Procedure this spreading action may force some of the flux lines out of the AMS Vehicle Magnetic Particle Inspection material flux leakage.
Flux leakage is also caused by reduc- AMS Magnetic Particles, Non-fluorescent, Dry tion in ferromagnetic material cross-sectional change , a sharp Method dimensional change, or the end of the part.
While there are variations in the Method, Dry Powder magnetic particle method, they all are dependent on this AMS Magnetic Particles, Non-fluorescent, Oil Ve- principle, that magnetic particles will be retained at the hicle, Aerosol Packaged locations of magnetic flux leakage. The amount of flux leakage AMS Magnetic Particles, Fluorescent, Wet Method, at discontinuities depends primarily on the following factors; Dry Powder flux density in the material, and size, orientation, and proximity AMS Magnetic Particles, Non-fluorescent, Wet to the surface of a discontinuity.
Sheet, Strip, and Plate 0. Particle Inspection 4. The entire mass or a portion 2. As previously noted, in order to be detectable, the discontinuity must interrupt the normal path of 4 Available from Society of Automotive Engineers SAE , Commonwealth the magnetic field lines. If a discontinuity is open to the Dr.
Box 7 , Arlingate Ln. AIA , www. Wilson Blvd. The patterns tend to be broad, rather than sharp, and maximum value for that particular discontinuity. When that the particles are less tightly held see Annex A1. Significance and Use 4. The ability of the method to find small to perform an adequate examination. A smoother surface or a pulsed current improves They are available as dry powders fluorescent and nonfluorescent ready for use as supplied see 6. Equipment 8. With the exception of a permanent magnet, all equipment 4.
The current used have been properly applied, and the excess particles properly dictates the sizes of cables and the capability of relays, removed, there will be accumulations of magnetic particles switching contacts, meters and rectifier if the power source is remaining at the points of flux leakage. These accumulations alternating current. Without disturbing the particles, the indications hand carry the equipment, can be obtained from yokes, must be examined, classified, compared with the acceptance portable coils with power supplies, and capacitor discharge standards, and a decision made concerning the disposition of power supplies with cables.
Generally, portable coils provide the material that contains the indication. Capacitor discharge 4. Many portable yokes FIG. This oping a peak wavelength output at or near nm with an restriction may be due to application impracticality, or due to intensity at the examination surface that satisfies 7.
Suitable the specifications governing the examination. Permanent mag- filters are used to remove the extraneous visible light and any nets can lose their magnetic field generating capacity by being harmful UV radiation emitted by the black light bulb.
Some partially demagnetized by a stronger flux field, being damaged, high intensity black light bulbs may emit unacceptable or dropped. In addition, the particle mobility created by AC amounts of blue light that may cause indications to become current or HW current pulsations produced by electromagnetic invisible due to the increase in surface background.
Refer to yokes are not present. Particles, steel filings, chips, and scale E for more detail. When using a mercury vapor bulb a clinging to the poles can create a housekeeping problem. The prod tips that contact the piece should be aluminum, mance. A constant voltage transformer may be used where copper braid, or copper pads rather than solid copper. Examination Area cracking, etc. Open-circuit voltages should not exceed 25 V.
Indications found using fluorescent particles must be to permit the current to be turned on after the prods have been examined under black ultraviolet light. This requires a properly placed and to turn it off before the prods are removed darkened area with accompanying control of the visible light in order to prevent arcing arc burns. The particles are designed for use rescent particle examination is recommended to be a minimum either as a free flowing dry powder or for suspension at a given of foot candles lux.
The intensity of ambient visible concentration in a suitable liquid medium. Control of particle size and shape is required to obtain 50 foot candles lux may be used when agreed on by the consistent results. The particles should be nontoxic, free from contracting agency. Both dry and 7. They are ultraviolet light emitted. Reuse is not a normal practice. They are not to examining parts under UV illumination. Warning— affected by cold; therefore examination can be carried out at Photochromic or permanently tinted lenses should not be worn temperatures that would thicken or freeze wet baths.
They are during examination. Some colored, organic coatings free of interfering debris. If fluorescent materials are involved, applied to dry particles to improve contrast lose their color at the area should also be kept free of fluorescent objects not temperatures this high, making the contrast less effective.
Fluorescent dry particles cannot be used at this high a temperature; the manufacturer should be contacted for the 8. Magnetic Particle Materials temperature limitations.
Refer to 8. If magnetizing positions; c does not always leave evidence of the suspension vehicle is a hydrocarbon, its flash point limits complete coverage of part surface as with the wet technique; the top temperature of usage.
Mixing equipment for bulk d is likely to have lower production rates than the wet reservoirs or manual agitation for portable dispensers is usually technique; and e is difficult to adapt to any type of automatic required to keep wet method particles uniformly in suspension.
The ment is available. The examination is done under visible should be one that best contrasts with the test surface. Because light. Fluorescent wet also available, but are not in general use primarily because of method particles normally glow a bright yellow-green when their higher cost and use limitations. They require a black light viewed under black light, although other colors are available. These requirements are not Non-fluorescent particles are usually black or reddish brown, often available in the field-type locations where dry magnetic although other colors are available.
Dual-colored particles are particle examinations are especially suitable. If sulfur or chlorine limits are specified, use Test 8. They leum distillates vehicles AMS Type 1 or equal are ideal are available in both fluorescent and nonfluorescent concen- for suspending both fluorescent and nonfluorescent magnetic trates.
In some cases the particles are premixed with the particles and are commonly employed. The suspensions suspended and dispersed in petroleum distillate vehicles with- are normally used in wet horizontal magnetic particle equip- out the use of conditioning agents; and b the petroleum ment in which the suspension is retained in a reservoir and distillate vehicles provide a measure of corrosion protection to recirculated for continuous use.
The suspension may also be parts and the equipment used. It is essential, therefore, to select 8. The initial bath concentration of suspended magnetic particles 3 Characteristics—Petroleum distillate vehicles to be should be as specified or as recommended by the manufacturer used in wet magnetic particle testing should possess the and should be checked by settling volume measurements and following: a viscosity should not exceed 3. The concentration of dual-colored particles in accordance with Test Method D, in order not to impede the wet-method bath suspension may be adjusted to best particle mobility see The provided suitable conditioning agents are added which provide material is normally applied by brush before the part is proper wet dispersing, in addition to corrosion protection for magnetized.
Because of the high viscosity, the material does the parts being examined and the equipment in use. Plain water not rapidly run off surfaces, facilitating the examination of does not disperse some types of magnetic particles, does not vertical or overhead surfaces.
Magnetic particle testing may be applied to raw material, semifinished material billets, blooms, castings, and forgings , finished material and welds, regardless of heat treatment or lack thereof. It is useful for preventive maintenance testing. This guide describes magnetic particle testing techniques that are recommended for a great variety of sizes and shapes of ferromagnetic materials and widely varying examination requirements. Since there are many acceptable differences in both procedure and technique, the explicit requirements should be covered by a written procedure see Section It should be pointed out, however, that after indications have been produced, they must be interpreted or classified and then evaluated. For this purpose there should be a separate code, specification, or a specific agreement to define the type, size, location, degree of alignment and spacing, area concentration, and orientation of indications that are unacceptable in a specific part versus those which need not be removed before part acceptance.
ASTM E709 Standard Guide for Magnetic Particle Testing
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Standard Guide for Magnetic Particle Testing1 This standard is issued under the fixed designation E; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. This standard has been approved for use by agencies of the U. Department of Defense. Conditions where rework or repair is not permitted ferromagnetic materials. Magnetic particle testing may be should be specified. It is useful for preventive 1.