TASK 70-21-15-130-001
1 . General.
CAUTION:
ULTRASONIC CLEANING AND RINSING MUST NOT BE APPLIED TO SOFT METALS SUCH AS ALUMINUM AND MAGNESIUM WITHOUT SPECIFIC APPROVAL IN THE PROCESS DOCUMENT. SPECIAL TESTING CAN BE REQUIRED FOR THESE MATERIALS.
This cleaning process is applicable to fragile parts. It will remove contamination, oil deposits, and organic material, without the risk of damaging the part (acoustic panels, for example).
2 . Equipment.
Subtask 70-21-15-130-011
A.The following equipment is required for the application of this process:
(1)Safety equipment and devices which are standard equipment in surface treatment shops such as: eye bath, emergency showers, protective clothing against electroplating products, and means for neutralizing acid or alkaline splashing.
(2)Processing plant for neutralizing waste and used solutions.
(3)Efficient ventilation system for extracting and neutralizing vapors.
NOTE:
The ultrasonic cleaning energy will heat the cleaning solution due to its own energy. This needs to be taken into consideration in any application that requires strict temperature control.
CAUTION:
ULTRASONIC ENERGY WILL TEND TO INCREASE THE TEMPERATURE OF THE WORKING BATH, SO COOLING AS WELL AS HEATING CAPABILITY MAY BE NECESSARY. THE BATH OPERATING TEMPERATURE RANGES MUST BE CAREFULLY MONITORED.
(4)Processing tank with temperature control.
(a)The tank should be made of stainless steel and be equipped with either a heat exchanger or heating coil capable of controlling the working solution at the minimum and the maximum operating temperatures established for the tank.
(b)The tank should be clearly labeled with the minimum operating level.
(c)The tank must be provided with an automatic timer interlock to shut off the ultrasonic equipment and a low solution level shut-off interlock.
(d)The tank should be provided with a minimum solution level marker, and identified and clearly labeled with the chemical contents, power density, frequency of the ultrasonic unit, and rated capacity in gallons (or liters).
(5)Generator Requirements:
(a)The generator must be a fixed power rating and not be adjustable by the operator.
(b)The generator shall be rated at a minimum frequency of 19 kHz.
(c)Transducers should be equipped with sweep frequency modulation for optimum cleaning efficiency.
(6)Fixture Requirements:
CAUTION:
IT IS CRITICAL THAT THERE BE NO DIRECT MECHANICAL CONTACT BETWEEN THE ENGINE COMPONENT AND THE ULTRASONIC TRANSDUCER OR THE TANK. IF CONTACT DOES OCCUR, HOLD THE PARTS AND CONSULT YOUR GEAE REPRESENTATIVE FOR DISPOSITION.
(a)The parts must be suspended in the tank completely independent of the tank sidewalls, tank bottom, or transducer surface.
(b)The fixtures can be hung from the lip of the tank if the points of contact are insulated or dampened from the ultrasonic transducer or the tank.
(c)It is recommended that parts are placed at least 2 inches from the ultrasonic transducers or the tank walls and bottom. Parts should never be closer than 1 inch from the tank walls and bottom. They should be submerged at least 1 inch below the top of the solution. If large parts cannot be submerged, surface agitation is recommended to disturb the air/liquid interface. If the parts have holes and/or cavities, the parts must be rotated to be sure that all of the holes and/or cavities are filled with cleaning solution and all of the air is removed.
(d)Part-to-part or metal (rack)-to-part contact during ultrasonic cleaning should be minimized. If more than one part is cleaned at a time, it is recommended that the parts are positioned/fixtured so that it is impossible for the parts to touch one another during the ultrasonic cleaning.
(e)Fixtures should be designed to maximize mesh-opening size.
(f)Fixtures should be fabricated from plastic or plastic coated metal to minimize the risk of part damage at the point of contact with the fixture.
3 . Materials.
Subtask 70-21-15-130-012
 
Solution for Ultrasonic Cleaning - Table 1
 
Solution
No.
Operating Temp °F (°C)
 
Mild Alkaline Cleaner
S1046
120-150 (50-66)
 
Alkaline Solution
S1047
120-150 (50-66)
 
Alkaline Degreasing/Rust Removing Solution
S1140*
150-170 (65-77)
 
NOTE:
* Do not use S1140, Ardrox 185 and Ardrox 185L to clean Aluminum, Magnesium, Copper Base Alloys, Electroplated Steels, Conversion Coated Aluminum and Sealed Anodized Aluminum Surfaces.
4 . Requirements.
Subtask 70-21-15-130-015
B.A demonstration of the procedure is necessary for each new application and each model type of ultrasonic equipment to achieve internal approval to clean hardware using an ultrasonic system. Unless special requirements are stated in the process document, the internal approval package must include the following data as a minimum:
(1)Identification of following process parameters involved in the cleaning procedure:
(a)Description of tank dimensions (length, width, height) and actual volume (gallons/liters) of solution used.
(b)Description of generator and frequency used.
(c)Watts/square inch (watts/square cm).
(d)Watts/gallon (watts/liter).
(e)Description of High End Modulation (sweep frequency) range.
(f)Process time in tank (range) permitted per procedure.
(g)Fixture identification number and description of how supported.
(h)Solution concentration and temperature ranges.
(i)Description of temperature control (heat exchanger).
(j)Rinse cycle(s) time, water temperature, and water purity.
(k)Description of drying cycle.
(l)Description of special storage/handling of the parts before, during, and after the cleaning.
(m)Description of steps taken to make sure that cavities are flooded before the ultrasonic cleaning.
(2)Identification of the function responsible for controlling the process and facility.
(3)The name and grade of all products used in the cleaning operation.
(4)Identification of the following information regarding Chemical Cleaning Process Control:
(a)Initial make-up of chemical cleaning solution.
(b)Frequency of chemical cleaning solution and rinse water analysis.
(c)Maintenance of chemical cleaning solution and rinse water (by addition of cleaner, other chemicals, filtering, etc.).
(d)Record generation and retention if applicable.
C.A maximum ultrasonic process time shall be established and controlled. The typical ultrasonic cleaning process is usually less than 30 minutes (or 2 cycles of 15 minutes each). The ultrasonic rinsing process is usually less than 12 minutes (or 2 cycles of 6 minutes each). If these times are exceeded, the following demonstrations of the ultrasonic cleaning process shall be successfully completed before processing production parts:
(1)A fluorescent penetrant inspection is to be performed before and after an ultrasonic exposure test. The intent of the fluorescent penetrant inspection is to document that no cracks were initiated and no cracks increased in size during the planned ultrasonic cleaning process. The ultrasonic exposure test shall be completed using 2X (2 times) the maximum permitted ultrasonic time exposure of the component using the processing parameters developed for the application. However, the solution used for this test should be water in place of the alkaline cleaning fluids.
(2)A demonstration of the cleaning procedure is necessary on a stock loss coupon of the alloy in question. This demonstration must use 2X (2 times) the maximum permitted ultrasonic cleaning and rinsing times, the maximum permitted temperatures, and the maximum permitted cleaning solution concentration developed for the application. Stock loss testing is to be performed per ARP 1755.
D.Filtration and cleanliness requirements should be established for the cleaning solutions.
5 . Procedure.
Subtask 70-21-15-130-013
WARNING:
ALKALINE SOLUTIONS ARE VERY ACTIVE AND CAUSE SERIOUS BURNS. AVOID CONTACT WITH SKIN, EYES, AND CLOTHING. IF CONTACT OCCURS, WASH IMMEDIATELY WITH ABUNDANT QUANTITY OF WATER. AVOID BREATHING VAPORS.
WARNING:
OPERATOR SHOULD WEAR FACE SHIELD, GLOVES, PROTECTIVE CLOTHING, AND PROTECTIVE SHOES.
E.Fill tank with the cleaning solution specified for the application to the rated capacity of the tank. If the solution is to be heated, turn on the heater and monitor temperature.
F.New and cold solutions should be degassed prior to use. The time required for degassing solutions will vary depending on the tank capacity and temperature. 30 minutes is usually adequate to degas heated solutions. If the solution has been previously degassed but has been allowed to cool, 10 minutes is usually adequate to degas the heated solution. Evidence that a solution has been adequately degassed is when air bubbles are no longer being generated by the liquid.
G.Position parts to be cleaned in required fixture.
H.Turn off ultrasonic generator.
NOTE:
The ultrasonic generator should be "OFF" during loading and unloading of parts.
CAUTION:
THE PART OR FIXTURE MUST NOT COME INTO DIRECT CONTACT WITH THE TANK SIDEWALL, TANK BOTTOM, OR TRANSDUCER SURFACE DURING OPERATION OR MECHANICAL DAMAGE TO THE PART COULD OCCUR.
I.Load the fixtured part(s) into the tank to required depth. If the part has holes and/or cavities, care should be taken to ensure that all areas of the part are flooded with cleaning solution.
J.Turn on the ultrasonic generator and clean for amount of time specified for the specific application. If appropriate, confirm that the High Sweep Modulation accessory is in use.
K.Turn off the generator and remove the fixtured part(s) from the ultrasonic tank. Drain solution from the part and rinse carefully.
CAUTION:
TITANIUM PARTS MAY BE DAMAGED WHEN EXPOSED TO CHLORIDE CONTENT BEYOND ACCEPTABLE LIMITS.
L.For metallic parts, rinse by immersion in hot water at minimum 150ºF (66ºC) as follows:
(1)If this procedure is used on titanium, titanium is subject to the following requirements regarding chloride. Refer to TASK 70-00-05-800-006, Water Types (paragraph 3., Definitions and Test Protocol).
(a)If parts will be exposed to subsequent processing that operates above 500°F (260°C) (for example, welding or heat treating), the final rinse water used on the parts must not exceed 50 ppm chloride (10000 ohm-cm minimum resistivity, 100 Microsiemens/cm maximum conductivity).
(b)For parts that will not be exposed to subsequent processing that operates above 500°F (260°C), the final rinse water used on the parts can be potable water that must not exceed 250 ppm chloride (1800 ohm-cm minimum resistivity, 550 Microsiemens/cm maximum conductivity).
WARNING:
WHEN USING COMPRESSED AIR FOR CLEANING, COOLING, OR DRYING, DO NOT EXCEED 30 PSIG (207 KPA). WEAR EYE PROTECTION AND DO NOT DIRECT COMPRESSED AIR AT SELF OR OTHERS.
CAUTION:
PARTS MUST BE THOROUGHLY DRY PRIOR TO FPI INSPECTION. WATER ON THE PARTS MAY DEGRADE THE SENSITIVITY OF THE PROCESS, ESPECIALLY FOR THE WATER WASHABLE PENETRANT PROCESS.
M.Dry the part by one of the following two methods:
(1)Flash dry the part as follows:
(a)Keep the part submerged until the part reaches a temperature sufficient to provide for flash drying.
NOTE:
The time required will vary with part size, water temperature and tank size. Proper flash drying is indicated by seeing the water on the surface of a part start to "flash" or "whisk" off as the part is being removed from the hot water tank.
(b)Remove the part from the water. The part will flash dry as soon as it is removed from the water. Use repositioning, suction, blotting with a clean, absorbent material, or by blowing off with an oil and water filtered shop air gun to remove excess water.
(2)You can substitute drying the part in an air re-circulating oven for the dwell time in the hot water.
(a)Remove the part from the water. You can remove excess water by repositioning, suction, blotting with a clean absorbent material, or blowing the water off with an oil and water filtered shop air gun.
(b)Move the part to the oven and dry at 200°F ± 25°F (93°C ± 14°C) until the part reaches the oven temperature and all traces of surface water are removed.
6 . Quality Assurance.
Subtask 70-21-15-130-014
N.Visually check the part to see that all the dirt and contaminants have been removed.
O.Tank agitation should be minimized.
P.Solution temperatures should be less than 170°F (77°C).
Q.Processing time should be minimized. Usually 5 minutes in an ultrasonic cleaning and rinsing tank is recommended.
R.The number of parts cleaned at one time should be controlled and monitored because the shape, size, and number of parts being cleaned at one time impacts the cleaning process.
S.Extreme care should be taken when ultrasonically cleaning soft metals such as aluminum or titanium.