20-00-02/70-00-01
Nickel and Chrome Test Panels
Figure 201
Cleaning
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(13) Method No. 204N: Cleaning Prior to Adhesive Bonding Test.
(a)
Lap sheer specimens shall be prepared and tested in accordance with ASTM D 1002 and the following:
.
Adhesive to be used in testing shall be in accordance with MM – A – 132 Type I Class 3 Form P Group 1 (EA 9394, available from Dexter Adhesives and Structural Materials Division, or equivalent meeting specification requirements).
.
The materials shall be mixed in accordance with the manufacturer's recommendations. All adhesives shall be within shelf life limits provided by the manufacturer. All adhesives used for one test (both degreased with the material under test and baseline panels) shall come from the same adhesive lot.
(b)
Adherent to be 2024 T4 or T6 aluminum prepared as follows: 1 Anodize in accordance with MIL – A – 8625,Type II, Class 1, or AMS 2471. 2 Dip in lubricating oil (MIL – L – 7808 or MIL – L – 23699) and let set for 24 hours
minimum.
3 Degrease.
4 Let Dry.
(c)
Degreasing prior to bond shall be done at the time, concentration, and temperature to be used in production. Baseline test pieces shall be solvent degreased.
(d)
Material shall be bonded using a 0.005 ± 0.002 inch (0,127 ± 0,0508 mm) bond line.
(e)
Material shall be cured at 77 ± 5F (25 ± 15C) for five days minimum.
(f)
Test shall be performed in accordance with ASTM D 1002 with the following
exceptions:
.
Only 2024 aluminum shall be tested.
.
Total number of specimens for each test product shall be ten.
.
The ten specimens shall represent at least two different adhesive joints.
(g)
The average tensile lap shear strength shall not decrease by more than 15% when using the test product compared to those solvent degreased.
Cleaning
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(14) Method No. 204P: Effectiveness of Cleaning Metals (Except Magnesium Alloys) Prior to Painting Test.
(a) Four 2024-T6-aluminum panels shall be processed in accordance with MIL-C-5541, Class 3, or AMS 2474. After coating and prior to painting, the panels shall be dipped in lubrication oil such as Farbest 7220, or any other product approved in accordance with MIL-C-16173, Grade 3, and allowed to set for a minimum of 24 hours prior to cleaning.
1 Clean two of the panels with the test cleaner and two control panels with methyl
ethyl ketone (MEK).
(b)
Paint panels in accordance with maintenance manual painting procedures for components for which cleaner is being tested. (Use primer and topcoat, which are currently being used to coat Honeywell hardware.)
(c)
After processing, dry tape adhesion test shall be performed as follows:
1 Make two parallel, scratch marks on test panel approximately 1 inch (25,4 mm) apart from one another.
2 Wipe test panel clean using isopropyl alcohol in accordance with ASTM D 770. Allow the test area to dry completely (approximately 30 seconds).
3 Remove two complete laps of approximately 1-inch (25,4 mm) wide tape. Remove an additional length at a steady (not jerked) rate and cut a piece of tape approximately 4 inches (101,6 mm) long.
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