TM 1-1500-204-23-11
h. Blunt Cut. The blunt cut joint is formed by
Speciic Technical Manual), Laminating resin (See
machining the damage cleanup hole edge as described
System Speciic Technical Manual), Mixing cups and
in paragraph 6-4. No other machining is required.
sticks, Wiping Cloth, Silicon Carbide Abrasive Paper.
6-16. WET LAYUP METHOD. Wet layup is a process
(2) Procedure. Follow these steps to perform
in which dry woven cloth is impregnated with a liquid
Method 1 of dry cloth impregnation.
adhesive and then cured to form a laminate. The wet
(a) Create a template of the repair plies
layup process is used to manufacture substructure
according to paragraph 5-6f.
details, and to make repair patches for complex
contoured surfaces which cannot accept a lat precured
(b) Have a the following available.
repair patch. There are several disadvantages to
this process; it is messy to perform, there is little
1.
A layup tool. A layup tool is
control over the resin content, and the laminates
a pre-manufactured tool.
The
exhibit reduced mechanical properties due to the large
damaged part or another part
degree of porosity present. Porosity is caused by air
identical to the damaged one may
entrapped in the laminating resin and by poor iber
be used as a layup tool. Lightly
wetting during impregnation. This porosity cannot be
sand the surface of the layup tool
removed under the vacuum pressure that is normally
to remove any protrusions. Wipe
used for consolidation of the laminate.
sanded area with a clean dry
wiping cloth to remove sanding
a. Background. Following impregnation of dry
residue.
cloth with liquid resin and cutting of individual plies
2.
Flat Surface. This surface will be
by the dry cloth technique or the Vacuum Assisted
used during impregnation of the
Impregnation technique, two methods for ply layup
composite fabric. It can also be
are described: individual ply technique and the lat
used for ply layup when the lat
ply collation. The individual ply technique applies to
ply collation method is used. It
the fabrication of patches or repair details where part
should be at least 12 inches larger
than the composite fabric cut in
each resin impregnated ply be applied individually to
step ((c)) below.
the part or tool surface. The second technique, lat
ply collation, is the preferred method. This technique
NOTE
allows all resin impregnated plies to be laid up on
a lat plate and then transferred to the part or tool
Selvage edge is only included for maintaining
surface for forming and curing.
the correct warp direction during the layout
process, it should never be included in a
b. Process Control Sheet. Create a process con-
repair ply itself.
trol sheet for each repair which contains the following:
(c) Determine the required number of plies,
1.
Repair conducted referencing the system
ply orientations, and fabric material from
speciic technical manual, including page
the system speciic technical manual.
number, igure number and/or item number
Cut one ply of composite fabric large
2.
Repair materials used, including expiration
enough so enough layers of material
dates and lots
can be cut out with the template cre-
3.
Resin mix time
ated in step ((a)). Including warp trac-
4.
Hot bonder program
ers (if applicable) or leaving the selvage
5.
Cure start time
edge on the fabric material cut for this
6.
Hot bonder printout tape
step will aid in aligning the templates
later in this procedure. If the repair
c. Method 1, Dry Cloth Impregnation. The follow-
involves more than six plies of mate-
ing describes the tools, equipment, materials and pro-
rial, you may divide the number of plies
cedures needed to perform dry cloth impregnation.
into groups and repeat this procedure
for each group; this will minimize waste
(1) Tools, Equipment and Materials Require-
and provide ease of handling.
d. These items are required to perform dry cloth
impregnation: Gloves (latex, nitrile, etc.), Eye pro-
(d) Cut a sheet of release or vacuum bag
tection, Cutting tools, Layup tool, Squeegee, Paint
ilm big enough to fold over and fully
brush, Templates, Smooth worktable or 1/4-inch caul
cover the fabric. Ensure the ilm is at
plate, Scale, Transparent non-porous ilm (vacuum
least 2 inches larger than the dry fabric
bag, release ilm, etc.), Repair fabric (See System
on each side
6-39
