MIL-DTL-197L
3.10.6 Method 40B - vacuum-formed plastic skin package. After required cleaning and
drying (see 3.3.3), the open, non-lubricated bearings shall be thoroughly coated as specified in
3.3.4.7 and enclosed in a vacuum-formed package. The plastic sheet shall be checked for
cleanliness prior to draping over the bearing. If the plastic sheet requires cleaning, it shall be
cleaned using best practices to insure that no contaminants or other foreign matter are entrapped
with the bearing prior to draping the sheet over the bearing. The packaged bearing shall show no
cellulose acetate, CAB, or cellulose propionate (use of polyvinyl chloride (PVC) is prohibited).
Material shall be sufficiently transparent to permit ease of reading and identification of bearing
marking and visual examination of the exterior bearing surfaces. In packaging bearings up to 6
inches outside diameter, the plastic sheet shall have a minimum thickness of 15 mils prior to
forming; the minimum thickness after forming shall be 8 mils single thickness at the outside
diameter and 4 mils in the bearing bore. In packaging bearings with outside diameter over 6
inches, the sheet shall have a minimum thickness of 30 mils prior to forming. Doughnut
packages shall be limited to bearings with bore diameter one inch or larger. Dimpling at bore
shall be acceptable for all bearings and may be used as an alternate to the doughnut type pack,
except that dimpling holes shall not be permitted between the inner and outer rings of any
bearing.
3.10.6.1 Vacuum forming. A transparent plastic sheet shall be vacuum formed over the
bearing. Single seal and single shield bearings shall be oriented with the bearing seal or shield
up under the first drape. Bearings with snap rings on the outside diameter shall be oriented so
that the snap ring is on the side opposite to the final seal.
3.10.6.2 Sealing. Plastic shall be sealed at the base edge with a cellulose acetate base in
acetone. Flange type seals are not permitted. The seal shall be positive and shall not impair the
transparency of the package. Small air bubbles formed in the closing shall not be cause for
rejection.
3.10.7 Method 41B - water-vaporproof bag, sealed. After required cleaning and drying
appropriate, and closure completed by means of heat-sealing. The bearings shall then be placed
individually into a water-vaporproof bag in accordance with MIL-DTL-117, type I or II, class E,
style 1, 2, or 3. Entrapped air shall be exhausted from the bag by any suitable means, but not to
the point where undue stress is placed upon the barrier. The bag shall then be heat-sealed. The
strength of the heat seals shall be as specified in 4.4.1, based upon samples made on production
packaging equipment. A carton or box shall be used to complete the unit container (see 3.11).
3.10.7.1 Intimate bags for instrument and instrument precision ball bearings for
method 41B. All intimate bags for instrument and instrument precision ball bearings shall be
nylon 6 at least two mils nominal thickness, certified as meeting Food and Drug Administration
requirements for direct contact with food, in accordance with 21 CFR 177.1500, transparent, and
cleaned to NASA JPG 5322.1, level 100. Alternate bags in accordance with MIL-DTL-117, type
I or II, class E, any style, cleaned to NASA JPG 5322.1, level 100, may be used. Intimate bags
shall be heat sealed so as to prevent free movement of the bearing inside the bag. Sealing shall
take place in an environment meeting the requirements of ISO 14644-1 and ISO 14644-2,
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