2.2 SYSTEM PERFORMANCE TEST PROCEDURE - CRACKED-CHROME PANELS.
CAUTION
Use care in handling and storing the panels. Do not drop, hit, or place mechanical stress on the test panels. Do not attempt to bend or straighten the test panels. Do not expose the test panels to temperatures above 212°F (100°C).
Thorough ultrasonic cleaning of cracked-chrome panels after each use is mandatory. The panels are easily damaged by rough handling or when dropped. Damaged or degraded panels SHALL be immediately replaced.
The cracked-chrome panels are used to evaluate the liquid penetrant system’s performance. They provide a side-by-side comparison of in-use liquid penetrant materials with a reference standard of the same material that was set aside prior to the material being put into service. The cracked-chrome panels readily show small or gradual changes in penetrant material sensitivity. Tests made with cracked-chrome panels do not provide useful information on background fluorescence caused by surface roughness or the ability of a liquid penetrant to reveal small cracks in the presence of severe background fluorescence caused by surface roughness or porosity.
2.2.1 Equipment and Materials Required for Cracked-Chrome Panel Test. Equipment and materials needed to perform the cracked-chrome panel test are listed below:
• In-use penetrant, remover, and developer.
• Reference penetrant, remover, and developer.
• Small glass or paper containers.
• 2 each acid brushes or swabs.
• 2 each cracked chrome panels. (Cracked-chrome panels are delivered from the manufacturer in sets of two. These panels SHALL be used together and not substituted with any other panels. When one panel is damaged or degraded the whole set SHALL be replaced.)
• Hydrophilic fluorescent liquid penetrant line and associated equipment. (The cracked-chrome panel may also be performed with method A, B, and C penetrant material.) (See paragraph 2.2.6 thru paragraph 2.2.8)
2.2.2 Procedure for Cracked-Chrome Panel Test.
a. Wipe the cracked-chrome panels with a clean lint free cloth dampened with solvent. Allow to dry and examine under ultra violet light. If residual penetrant is present, clean the panels in accordance with (see paragraph 2.11).
b. Pour a small quantity of working bath material and reference material in separate glass or paper containers. To avoid contaminating the entire reference sample, the reference material SHALL NOT be applied to the cracked-chrome panel directly from its storage container.
c. Apply penetrant by brushing, swabbing, or flowing. Brushing or swabbing is preferred since it permits better control over the quantity of penetrant applied. Use the working materials on one panel and the reference materials on the other. Use separate brushes or swabs for the working material and the reference. Allow the penetrant to dwell for 5-minutes.
d. Perform a pre-rinse of 20-seconds or less. Allow just enough time to remove the surface penetrant. (Coarse spray of plain water at no more than 40 psi with a water temperature between 50 and 100°F)
e. Apply remover by immersing the panels in their correlating working bath and reference material. Removal time will be very short, between 10- to 20-seconds.
f. Perform a final rinse of 20-seconds or less. (Coarse spray of plain water at no more than 40 psi with a water temperature between 50 and 100°F)
g. Apply correlating working bath and reference developer by immersion, flowing, or spraying. (Ensure water-suspended developers are mixed well before applying.)
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h. Place in clean drying oven. Do not allow to sit in the dryer for an extended period, remove as soon as the panels are dry.
i. Allow developer to dwell for 5-minutes. The dwell begins after the panels are completely free of moisture.
j. Examine the panels side-by-side under black light, first noting the overall brightness and color of the indications.
Second, examine each in detail by following individual indications across both panels. Note the presence, absence, or diminishing of crack indications on the working bath panel as compared to the reference sample panel and observe the difference in continuity, size and color. Any distinct difference SHALL be cause for additional testing to determine if the penetrant, remover, or the developer caused the difference in the indications.
2.2.3 Testing for Failed Penetrant. If the system performance test indicates a loss of sensitivity or brightness, use a set of clean, dry cracked-chrome panels to repeat the material test procedure (see paragraph 2.2.2) with the following changes:
use the reference samples of remover and developer on both panels. If crack indications on the two panels show clearly visible differences in sensitivity, brightness or color, the penetrant SHALL be replaced.
2.2.4 Testing for Failed Emulsifier/Remover. If there is little or no difference in the crack indications during the penetrant performance test, clean the panels and repeat the performance test procedure to test the emulsifier/remover. Use reference penetrant on both panels and apply the working sample of remover to one specimen and reference remover to the other panel at the appropriate point in the process. Apply reference developer to both panels. If crack indications on the two panels show clearly visible differences in sensitivity, brightness or color, the remover SHALL be replaced.
2.2.5 Testing for Failed Developer. If there is little or no difference in the crack indications during the remover performance test, clean the panels and repeat the performance test procedure to test the developer. Use reference penetrant and remover on both panels and apply the working developer to one panel and the reference developer to the other panel at the appropriate point in the process. If crack indications on the two panels show clearly visible differences in sensitivity, brightness or color, the developer SHALL be replaced.
2.2.6 Lipophilic Penetrant Systems. The removal step is the only difference in performing the cracked-chrome panel test on a lipophilic process. Simply skip step d in the procedure and modify step e so that the panels are immersed in emulsifier and immediately removed. Allow the emulsifier to dwell for 10 to 20 seconds and proceed to step f.
2.2.7 Water Washable Penetrant Systems. For water washable systems the remover and developer steps need to be modified. Skip steps d and e, proceed to step f. Wash the panels as long as necessary to remove all visible penetrant. Do not over wash, the cracks on these panels are shallow and the trapped penetrant can be easily removed by over washing. Since aqueous developer cannot be used with water washable penetrants, a nonaqueous or a dry power developer must be used. Dry the panels in the drying oven and then spray a light even coat of nonaqueous developer on the panels or dip the panels in dry powder developer. Proceed to step i and finish the procedure.
2.2.8 Solvent Removable Penetrant Systems. Solvent removable penetrant systems (spray cans) do not require a 7-day system performance test because the materials are not subject to reuse or degradation. The cracked chrome panel test is required before a new batch of material is put into to service. The material previously used becomes the reference so it is important to test the new material before the old material is completely used up. The remover and developer steps need to be modified; skip steps d, e, and f. The removal step is to wipe the panels with a separate clean dry cloth and then perform another wipe with a separate solvent dampened cloth, repeat the solvent wipe until no penetrant is visible. The developer application step is to spray a light even coat of nonaqueous developer on the panels. Proceed to step i and finish the procedure.
2.3 SYSTEM PERFORMANCE TEST WITH THE PSM STARBURST PANEL (DEPOT ONLY).
The system performance test utilizing the PSM panel is a daily check of the entire penetrant system. The panel’s polished half contains five star shaped cracks and is used to monitor changes in penetrant sensitivity, while the grit blasted half is used to test the removal process of the penetrant system. The PSM panel test is ideally suited for high volume workloads because it can be processed directly in the working material along with the first batch of parts at the beginning of the workday.
Because the panel is used strictly with in-use penetrant materials, no reference standards are needed. Facilities with automatic or semi-automatic penetrant systems that do not use traditional working bath tanks SHALL use the PSM panel solely as their system performance test. Laboratories with traditional penetrant lines SHALL use the Cracked-Chrome Panel Test as their system performance test but MAY use the PSM panel as an optional test.
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T.O. 33B-1-2
2.3.1 Procedure for Performing the PSM Starburst Panel Test.
NOTE
Facilities using automatic or semi-automatic systems SHALL process the PSM panel as they would a routine test part. Times, temperatures, water and air pressures will vary accordingly. Consult the ALC NDI manger for specific guidance.
a. Dip, brush, or spray the PSM panel with in-use penetrant. Use the same criteria as a test part with suspected fatigue cracks. Test at room temperature. (30-minute dwell time)
b. Pre-rinse the PSM panel. (Coarse spray of plain water at no more than 40 psi for 30- to 120-seconds with a water temperature between 50 and 100°F)
c. Immerse or spray PSM panel in remover. Use the same remover time as used to process a normal part. (30 to 120 seconds)
d. Perform the final rinse. (Same criteria as in step b)
e. Dip the PSM panel in developer. (If water suspended developer is used ensure the solution is mixed well before dipping the panel.)
f. Place the PSM panel in the dryer oven and remove immediately once the panel is dry. (Dryer oven should be preheated to 140°F or less; facilities using automatic or semiautomatic systems refer to the process order for dryer oven temperature.)
g. Let the panel dwell for 15-minutes.
h. Inspect and evaluate indications on the PSM panel.
2.3.2 Response of PSM Panels. PSM Panels are manufactured to provide a minimum number of indications for each penetrant sensitivity level. The panels SHALL show, as a minimum, the number of indications permitted during calibration and listed as follows:
Minimum Number of Indications:
Sensitivity Level Number of Indications
Level 1 and 2 3 Indications
Level 3 4 Indications
Level 4 5 Indications
2.3.3 Reading PSM Starburst Indications. Examine the panel for the number of starburst indications as well as the brightness of the indications. The PSM panel test is a flaw indication quality comparison from one test to another and the inspector must be able to observe a difference in the panel’s appearance. An increased background fluorescence, decrease in the number of flaw indications, decrease in flaw indication definition, or decreases in brightness are all indicators of a penetrant process problem. For example if the developer is malfunctioning, crack centers may still be seen, but may not be as bright as normal. When using aqueous developers, the developer SHALL provide a uniform coating over the chrome surface.
Failure of the aqueous developer to wet the chrome may mean the solution strength is low, or the wetting agent has degraded.
Washability and background fluorescence must also be interpreted. The grit blasted side of the PSM panel is used for this purpose. High and ultra-high sensitivity systems leave a fluorescent background on the panel’s grit blasted area. Other systems may leave no background. Neither condition is alarming unless it represents a change from the normal system performance. Higher than normal background may indicate low remover concentration, short remover dwell time, or an ineffective pre-wash. Lower than normal background may indicate high remover concentration, excessive remover dwell time, or inadequate developer application. If a performance problem is noted, additional testing is required to determine the cause. For laboratories using a traditional hydrophilic penetrant line refer to (see paragraph 2.2.2) and perform the cracked chrome panel test to systematically eliminate each possible cause until the problem area is identified. For laboratories using semi-automatic are automatic systems each section of the system needs to be inspected to determine if the preset parameters are correct and all equipment is functioning normally.
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2.3.4 Cleaning PSM Panels. PSM Panels SHALL be thoroughly cleaned immediately after use in accordance with (see paragraph 2.11). In addition, PSM panels SHALL be wiped with a clean, lint free, solvent dampened cloth and examined under ultra-violet light for residual penetrant prior to use. If residual penetrant is present, perform a thorough cleaning again.
NOTE
PSM panel indications will degrade with handling and repeated use. Gradual changes in indication appearance are not readily noticed. Careful handling and thorough ultrasonic cleaning is mandatory.
2.4 INSPECTION BOOTH CHECKS.
NOTE
Inspection booth checks do not require documentation unless specifically stated else where in this Technical Order or other directives. The frequency of the checks are at the supervisor’s discretion unless otherwise directed by this Technical Order.
The inspection booth and process SHALL be checked to verify the following:
a. Verify the inspection booth is of adequate size for the parts to be inspected.
b. Verify the booth is not used to store parts, consumables, or standards.
c. The inspection booth SHALL be cleaned frequently and background fluorescence from spilled penetrant kept to a minimum.
d. Black light bulbs and filters SHALL be kept clean and ambient light levels checked when filters or bulbs are replaced.
e. Check black light intensity and document at least once each day or prior to use.
f. Inspect filters for fit and excessive dirt, developer, cracks, and chips.
g. Position black lights so they do not shine into the technician’s eyes.
2.5 SURFACE WETTING TEST.
a. Apply a small amount of penetrant with a cotton swab to the clean, shiny surface of commercially available aluminum foil.
b. Allow penetrant to dwell for 10-minutes.
c. The penetrant should wet the surface and not retract or form beads.
2.6 PENETRANT BRIGHTNESS TEST - (DEPOT ONLY).
Perform this test on all Type I fluorescent penetrants as follows:
a. Pour 10 milliliters of IN-USE penetrant into a graduated cylinder. Allow the penetrant to drain down the inside cylinder walls. Add or remove penetrant as required to achieve exactly 10-milliliters. Clean the outside of the cylinder.
b. Fill the graduated cylinder to the 100 ml level with an acetone (Specification 0-A-51F). Stopper the cylinder and slowly invert the graduated cylinder several times to mix the contents. Do not shake or agitate the cylinder vigorously.
c. Using tweezers, insert a quartered piece of filter paper into the cylinder mixture, withdraw the paper and set it aside to air dry for a minimum of 5-minutes.
d. Discard the contents of the graduated cylinder and clean the cylinder with an approved solvent (Specification O-C-265 or equal). Dry with clean filtered compressed air.
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T.O. 33B-1-2
e. Pour 10 ml of REFERENCE SAMPLE penetrant into the graduated cylinder. Allow the penetrant to drain down the inside cylinder walls. Add or remove penetrant as required to achieve exactly 10 ml. Clean the outside of the cylinder.
f. Fill the graduated cylinder to the 100 ml level with acetone. Stopper and slowly invert the graduated cylinder several times to mix the contents. Do not shake or agitate the cylinder vigorously.
g. Using tweezers, insert a quartered piece of filter paper into the cylinder mixture, withdraw the paper and set it aside to air dry for a minimum time of 5-minutes.
h. When both filter papers (in-use and reference) are dry, compare the fluorescent brightness of the filter papers to each other under black light. If a noticeable difference of fluorescent brightness is noted, the fluorescent properties of the in-use production line penetrant have deteriorated and the fluorescent sensitivity will probably not be acceptable.
Follow accepted activity standards to process and perform additional testing or to discard the contaminated/degraded material.
i. At the conclusion of the fluorescent brightness testing, rinse the cylinder with water, and clean with acetone. Dry with clean filtered compressed air.
2.6.1 Penetrant Rapid Brightness Test (FIELD LABS). A rough check of penetrant baths can be accomplished by comparing their appearance on an absorbent material, preferably filter paper. Perform this test on all Type I fluorescent penetrants as follows:
a. Place a drop of the working bath penetrant on the absorbent material, preferably the filter paper.
b. Place a second drop of penetrant from the reference standard on the same absorbent material near the drop from the working bath.
c. When the two drops merge, examine under a black light for difference in color and brightness. If significant difference in color and brightness is noted additional testing is required. (See paragraph 2.2.3)
2.7 TESTING CONCENTRATION OF WATER BASED (METHOD ‘‘A’’) PENETRANTS.
There is a small number of approved Method ‘‘A’’ penetrants currently containing water as a major component. The few approved water washable penetrants are formulated to provide a similar sensitivity performance as Method ‘‘B’’ or ‘‘D’’
penetrants. Some savings may be realized in disposal cost of the more environmentally friendly penetrants. It should be noted that any penetrant that has been in-use SHOULD be tested for contaminants prior to disposal. It is not unusual for hazardous material, mainly heavy metals to build up in in-use penetrants from test parts and lubricants. Because water is a main constituent and evaporation losses may affect the penetrant performance, a periodic water concentration check is required.
The refractometer method described in (see paragraph 2.9) SHALL be used to check concentration of water-based penetrants in the absence of specific manufacturer procedures. If the manufacturer provides specific water concentration test procedures the manufacturer’s procedures SHALL take precedent.
2.8 TESTING LIPOPHILIC EMULSIFIER (METHOD ‘‘B’’).
Penetrant is an unavoidable contaminant of lipophilic emulsifier. It is carried into the emulsifier on the surface of parts where it dissolves and is washed off during immersion and drain process. Since emulsifier and penetrant are capable of being mixed in all concentrations, even small quantities of fluorescent dye will cause the emulsifier to fluoresce. The fluorescent brightness increases with increasing dye content, but it is impossible to visually estimate penetrant contamination by observation of the tank surface. Emulsifier will continue to function when contaminated with penetrant; however, when the penetrant concentration reaches a certain level the emulsification action slows and eventually stops. The penetrant material specification (SAE-AMS-2644) requires a 4-to-1 mixture of emulsifier to penetrant to leave no more residual background than the uncontaminated emulsifier.
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2.8.1 Lipophilic Emulsifier Removability Test.
NOTE
The annealed type 301 or 302 stainless steel panel may be locally manufactured. It is a two-inch by four-inch, 16-gauge (0.060) panel. The panel SHALL be ultrasonically cleaned or vapor degreased and grit blasted on both sides using 100 mesh, aluminum oxide grit (not beads), using 60 psig air pressure, with the gun held approximately 18- inches from the panel surface. After blasting, the panel SHALL be ultrasonically cleaned in acetone or other suitable solvent. Ensure the panel is dry and free of residues after cleaning. Handle the panel by the edges and protect it from contamination by wrapping in tissue paper.
Locally manufacture a simple stand large enough to hold the panel and maintain a 60° (±15°) angle. The stand will prevent pooling during dwell.
2.8.1.1 The removability test requires using the annealed type 301 or 302 stainless steel panel. In-use lipophilic emulsifiers SHALL be periodically tested for contamination in accordance with (see Table 1-1). The process for performing the removability test is as follows:
a. Immerse the panel in the working penetrant bath and allow it to drain for 10- minutes at approximately a 60° (±15°)
a. Immerse the panel in the working penetrant bath and allow it to drain for 10- minutes at approximately a 60° (±15°)