LightResin Transfer Molding Mold Construction and Part Processing

1
CMTI L-RTM and Closed Molding Workshop Elkhart,
Indiana Friday December 15, 2006
Light-Resin Transfer MoldingMold Construction
and Part Processing
James R. Noonan Saint-Gobain L-RTM
Specialist Email Address James.R.Noonan_at_Saint-Gob
ain.com
2

• What is Needed to Start
• Of Course You Need
• 1) Complement Mold (usually a
• female) with a wider flange
• 2) Build the L-RTM Contra-Mold to perfectly fit
  the complement mold just as if a part was already
  molded between the two molds
• What Else?

Saint-Gobain J.R. Noonan 2006
3
How Wide A Flange

• Area of Part (in inches2) X (8 psi positive at
  fill engaged resin pump)
• Area of Vacuum Flange (in inches2) X (-13.5 psi
  negative)

Example Assumes 8 psi injection pressure to
total fill of part cavity no head loss in
pressure as part fills 6 sq. ft. part 864 sq.
in. 864 sq. in. part X 8 PSI 6,912 pounds total
pressure Assume 6 in. perimeter around the part
is vacuum flange 12 sq. ft. (total area) 6 sq.
ft. (part area) 6 sq. ft. vacuum flange 864
sq. in. 864 sq. in. vacuum flange X -13.5 PSI
11,664 pounds pressure -11,664 6,912 -4,752
clamping pressure A stable trouble free
mold What if part was (4.75 ft X 4.75 ft) 3,249
sq. in. yet flange area stayed the same?
(3.6 in. wide flange) Now part pressure could be
3,249 sq. in. X 8 PSI 25,992 pounds
pressure 25,992 11,664 14,328 lbs.
potentially in excess of clamping pressure - risk
of hydraulically separating the mold if it is
injected at 8 PSI fluid pressure to complete
fill. (same flange width 25,992-20,412
5580 lbs.)
Saint-Gobain J.R. Noonan 2006
4

• Check list
• Sheet wax, freeman is the best
• Resin port connection
• Vacuum catch pot connection port
• Vacuum flange connection port
• Speed fittings
• Vacuum regulator (absolutely necessary, if using
  vacuum pump)
• 1/4, 3/8, 1/2 , 5/8 inch PP or PE hose
• Vacuum Catch Pot
• Scotch tape
• Sealing tape (usually a yellow or gray mastic
  adhesive)
• Clamps (plastic pliers type)
• Replacement O-rings (viton) for ports (maintain
  vacuum seal)
• Small vacuum pump or Air pressure Venturi vacuum
  pump
• Vacuum gage
• Forceps clamps (like long nose pliers but look
  like surgeons forceps clamps) or plastic hose
  clamps to crimp the vacuum hoses.
• PP Polypropylene, PE Polyethylene
• Metal Straight edge rulers (6, 12, 36 inch) with
  at least 1/16 inch increments
• Small metal 6 in. ruler in 1/64 inch increments

Saint-Gobain J.R. Noonan 2006
5

• Check list (continued)
• Spring steel scrapers (to scrape and smooth the
  sheet wax)
• Modeling clay (preferable water malleable)
• P-40 hard clay (heat and soften with 60 watt
  bulb)
• Heat gun (if mold has tight bends and recesses,
  to soften sheet wax)
• Super glue
• Fine point magic markers
• Mushroom seal and its complement profile
• Wing seal and its complement profile
• String or gun roving glass
• Fillet tools or small diameter dowels to conform
  wax to tight radiuses
• PVA
• Clear tooling gel coat
• Clear tooling resin (preferably a vinyl ester)
• 3/4 oz. continuous strand mat
• C-veil (optional depending on surface profile
  desired on the L-RTM
• Contra-tool)
• 1.5 chop strand mat
• Low to no dust environment for mold construction
  (optimum temp for

Saint-Gobain J.R. Noonan 2006
6
To Begin
Pick the smaller of the molds you have
available (4 to 6 square feet is a good starting
mold) where the flange is all on the same
plane. Why? Because you will be more likely to
have initial success and you will be more likely
to test different glass loading and resin types.
You will try new ideas because a failure will not
cost you much. The same plane on the mold
means that vacuum seal will be optimum. In Short
--- you will LEARN MORE by experimenting with a
small mold. Watch out for the we picked it
because this mold is a pain to do via open mold
Saint-Gobain J.R. Noonan 2006
7

• If possible, pick a mold/part that uses a core
• Why?
• Because a cored part will allow you to learn more
  about resin flow and how inserts affect flow. It
  will also allow you to vary Core thickness with
  glass loading and resin viscosity. You will have
  more opportunity to understand how each of these
  affect the other.
• You will also gain a better understanding for
  strength vs. thickness, stiffness vs. thickness,
  weight vs. changes in glass/resin/core.
• You will also gain a better understanding as to
  how glass packing (compression) affects resin
  flow.
• In Short --- you will LEARN MORE and the success
  of all future molds is far more likely.

Saint-Gobain J.R. Noonan 2006
8
Application of Vacuum During L-RTM Mold
Construction
Note Vacuum Canal On First Wax Layer
This Mold Marine Locker 1/8th in. laminate on
either side of ¾ in. core. Vacuum canal gap of
.040 mils. Vac wax layer .125 Core ¾ in. Top
wax layer .125
Vacuum Holds Wax to Female Mold Surface
Saint-Gobain J.R. Noonan 2006
9
Spray PVA and then Gelcoat over the wax. When
Gelcoat has gelled, slowly apply vacuum to - 6
psi. Maintain this vacuum constantly until the
molds hand lay-up glass lamination is complete.
- 6 PSI vacuum line
Saint-Gobain J.R. Noonan 2006
10
Hatch Cover 7 to 9 layers of 1.5 oz in the
product cavity area and 9 to 11 layers of 1.5 oz
on the vacuum flange area. Vacuum held on the
mold the entire time. Note the glass layered
over the sides. Holds male to female and resists
pull back and warping.
Original work, investigation and presentation by
CMTI/Purdue University
11
Business side of completed L-RTM hatch cover mold
Product Cavity Vacuum Port
Wing seal
Positioning Locator
Resin Raceway
Mushroom seal
Resin Injection Port
Vacuum Port for Flange Vac
Original work, investigation and presentation by
CMTI/Purdue University
12
Typical Industry L-RTM Contra-Mold
Specification Schematic by Saint-Gobain Jim
Noonan 10/5/06
Positive stop at mushroom seal area Installed.
However, one could install it at later date if
needed by using plastic spacer (glued in).
1/2 in. wide resin raceway .125 thick strip of
wax (total actual depth of raceway .125 .125
.250
3/8 in.
Mushroom Seal Profile .395 high X .193 thick
.085 top wax layer
Positive stop Approx. 1/4 in wide
Wing Seal Profile
Product Cavity area for part .125 in thick
¾ in.
.177 vacuum flange wax layer Better to use .150
wax to accept production variability in mush.
seal production
Compression contact of mushroom cap estimated to
be .013 to .033 in. depending on mush. cap height
very minimal if positive stop is used better
to use .150 vacuum flange wax
Stem is .400 high X .213 thick
.040 canal wax layer to pull vacuum on top wax
layer
.040 canal wax layer Gap to pull 8 to 6 PSI
vacuum on top wax layer
Future location of Mushroom seal XXXX Mushroom
Seal .190 to .210 high _at_ cap
Note Production lots of Mushroom cap seal vary
greatly in dimension even with same Mfg. (some as
low as .180)
Saint-Gobain J.R. Noonan 2006
13
Vacuum Source Full Negative Atmosphere (-28 in.
Hg)
Typical Infusion Function L-RTM Schematic
Potential shape placement of 1.5 oz. glass on
A and B side of the part if catch pot fills
before left side (opposite of resin port side)
fills leaving dry spot (see red circle) scheme
like this directs resin flow where you want it.
Shift this glass placement as needed. Have the
1.5 oz. glass just touch the area where the dry
spot generally occurs. Put the 1.5 next to the
core on both the A B side of part.
Clamp here for leak check and/or in case resin
leaks into vacuum clamp
Resin source 100 to 200 cpds. Resin Hot Pot
Left Side Potential Dry Spot
Resin Catch Tube Insert
Vacuum Gage Full Negative Atmosphere (-28 in.
Hg) Monitors Vacuum Clamp Flange Pressure
Vacuum Regulator Takes -28 in. Hg to -14 in. Hg
Clamp either place once part is filled
Vacuum Source Full Negative Atmosphere (-28 in.
Hg)
Clamp here for leak check
Vacuum/Resin Catch Pot
Vacuum Source ½ Negative Atmosphere (-14 in. Hg)
Put resin tube to catch pot down to near bottom
of pot and cut end at an angle
Saint-Gobain J.R. Noonan 2006
14

• Mold Construction Strategy
• Location of the ports

RESIN INJECTION POINT
Dry Spots Likely
Even Fill Likely
Vac
Vac
Flange Vacuum
Potential Fill Trouble
Trouble Free Fill
Saint-Gobain J.R. Noonan 2006
15
Put Small Perferations in the Core
Bottom layer of wax with canal structure holds
top layer of wax down tightly to the entire mold.
Insures wax conformability to bends and folds in
the mold. Vacuum also resists resin pull (lift)
on wax as it cures and shrinks. Vacuum is held
for the entire time it takes to hand lay-up the
mold with fiberglass
Saint-Gobain J.R. Noonan 2006
16
B Side Blemish Free L-RTM Contra-Mold
Specifications Schematic supplied by
Saint-Gobain, Jim Noonan October 2006 Resin Port
left and Right Side Profile (See Next Slide for
Vac Port)
No positive stops for Mushroom area Install them
at later date if needed.
Part Used as Profile -- No Sheet Wax Used in
Center Product Cavity. Part formed from infusion
using 2 layers of S600-V250-S600 1 in. Core
1/2 in. wide resin raceway .125 thick strip of
wax (total actual depth of raceway .125 .125
.125 .375
1/2 in to 3/8 in.
Mushroom Seal Profile .395 high X .193 thick
Wing Seal Profile
Product cavity area for part 1.250 in. thick
(Part Actual Thickness .125 laminate on A
B side of 1in. core)
.020 Polyethylene Tape Supports Profile Under
Infusion Pressure (resists deformation)
1 in.
.125 vacuum flange wax layer
Positive stop Approx. ¼ in wide
1 in. Perf. Core
Stem is .400 high X .213 Thick
Future location of Mushroom seal XXX Mushroom
Seal .185 to .200 high _at_ cap
.125 Actual part in female mold cavity
Note Production lots of Mushroom seal cap vary
greatly in dimension even with same Mfg. (some as
low as .180)
Mushroom cap minimum compression of .065 in. (cap
will compress approx .066 to .070). Thus,
potential net addition to mold cavity of 0 to
-.005 in. This means part thickness could be
approximately .250 to .245 in (.125 .125 -.005)
not including core.
Mushroom cap minimum height .190 Wax spacer for
cap .125 Net contact before
compression .065 Net space from female aft comp
.125
James R. Noonan, Saint-Gobain 2006
17
Lay-Out for No Mark On B Side of Part (No
Vacuum Catch Pot Mark)
Part Used as Profile -- No Sheet Wax Used in
Center Product Cavity. Part formed from infusion
using 2 layers of S600-V250-S600 1 in. Core
Vacuum Port Area Profile L-RTM Mold Layout
Vacuum Gage Port
Glass/Resin Product Cavity
Wing Seal Profile
Vacuum Flange Clamp Area
Mushroom Seal
Vacuum Catch Port
Stops Resin Raceway Resin Flow
.125 in. Thick Mosites Silicone
.125 Vacuum Flange Wax Layer
Vacuum Port
Resin Port
Positive Stop
Resin Raceway
.125 Part thickness profile for 2 layers of
S450-V180-S450 glass or 2 layers of 900 UniConform
1 in.Perf. Core
James R. Noonan, Saint-Gobain 2006
18
Actual part used to make product cavity
area sheet wax used only on technical flange

• Infusion of upper L-RTM Contra-Tool
• 3 layers of Uniconform 900 in product cavity.
• 4 layers of Uniconform 900 in technical flange
  area
• No Skinning or pre-fab before infusion
• Dramatic reduction in Labor to produce L-RTM mold
• Significant improvement in L-RTM mold quality,
  strength and clarity
• Very minor use of milled fiber filler to
  achieve radius
• at right angle contact of mushroom seal and wing
  seal profile

Finished L-RTM Contra-tool filled perfectly and
produced high quality parts
James R Noonan, Saint-Gobain 2006
19
.020 Polyethylene Tape over .125 wax
Marine Hatch Cover
White Mushroom Seal Profile - makes the grove for
the green mushroom seal placement
Identical process as previous slides except this
L-RTM mold used .125 inch sheet wax covered with
.020 black polyethylene tape for the technical
flange. The polyethylene tape releases cleanly
form the resin infused over it. We made one
L-RTM upper tool from this plug. The only
increased work for the production of a second
tool was to replace the white mushroom seal
profile which detached with the 1st tool,
everything else was intact and ready to go for
the next L-RTM tool to be infused over this same
plug. Normally, the entire wax plug is destroyed
when the L-RTM mold is removed from the profile
plug.
James R. Noonan, Saint-Gobain 2006
20
Retro-Fitting an Existing L-RTM Mold to Stop
Resin Flow Allow Resin To Fill The Part MOSITES
RUBBER COMPANY SILICONE RUBBER SEAL
Resin Injection Point
Mosites Silicone Rubber cut to shape and stops
resin flow at raceway so part fills completely
Vacuum Catch Pot Port
Saint-Gobain J.R. Noonan 2006
21
L-RTM Observations Efficient Vacuum Leak
Detection Mold Separation Pressure
Saint-Gobain J.R. Noonan 2006
Original work, investigation and presentation by
CMTI/Purdue University
22
Original work, investigation and presentation by
CMTI/Purdue University
23
Vacuum Valve -2
Vacuum Gauge - 2
Vacuum Test
Clamping-Vacuum Area Constant Vacuum
Vacuum Valve - 1
Vacuum Gauge -1
Resin Supply Line (Before Injection, Pinch
Off Securely For Vacuum Test)
Vacuum Lines
Part-Vacuum Area Essentially no vacuum where
resin is present
Original work, investigation and presentation by
CMTI/Purdue University
24

• Draw vacuum at both Contra-Mold gauges (15-in. Hg
  for vacuum gauge-1, 28-in. Hg for vacuum gauge-2)
  then close off both check valves.

• If both gauges hold their vacuums, obviously --
  no leaks.

• If vacuum gauge-1drops vacuum gauge-2 holds,
  then
• the clamp area vacuum is secure -- no leakage to
  outside
• or between mold sections, but part area is
  leaking to the
• outside (possibly vacuum lines or o-ring seals,
  resin
• supply line, even mold porosity or hairline
  fracture).
• Leakage at the resin-supply line will allow air
  to enter
• track into the part. Leakage at the suction pot
  and related
• suction lines, if very minimal - can cause little
  effect or if
• major - failure to remove air and to not fill the
  mold
• properly.

Original work, investigation and presentation by
CMTI/Purdue University
25

• If vacuum gauge-2 drops vacuum gauge-1 holds,
  then the part area vacuum is secure -- no leakage
  to outside or between mold sections, but clamp
  area is leaking to the outside (possibly vacuum
  line component seals, wing seal, even mold
  porosity or hairline fracture or a leaky seam if
  the flange has been widened). If only low-level
  leakage is present adequate vacuum can be
  maintained, then a part can be infused with
  little risk.

• If vacuum gauge-2 drops vacuum gauge-1
  increases, then there is leakage between the part
  area and the clamp area. There may also be
  leakage to the outside. If, when the vacuum
  levels in both sections are equalized, there is
  no further loss in vacuum, then there is only
  leakage past the mushroom or dynamic seal, not to
  the outside. Such a leak will not cause air
  entry into the part, only resin leakage into the
  clamp area. It may not be prohibitive. Usual
  cause glass is under the mushroom seal.

Original work, investigation and presentation by
CMTI/Purdue University
26
Over-pressurizing when injecting resin
Original work, investigation and presentation by
CMTI/Purdue University
27
Original work, investigation and presentation by
CMTI/Purdue University
28
Communication
½ atoms. vac
Full atoms. vac
(Resin/Glass)Glass to Resin Ratio is not Wt.glass
Wt.resin By Industry Convention, it is Wt.glass
(Wt.glass Wt.resin)
Original work, investigation and presentation by
CMTI/Purdue University
29

• Playing Learning
• Very, Very Important

Saint-Gobain J.R. Noonan 2006
30
Original work, investigation and presentation by
CMTI/Purdue University
31
The End But in reality it is just the beginning
Thank You Very Much For Your Time
James.R.Noonan_at_saint-gobain.com
Very Helpful Website http//www.ecn.purdue.edu/CM
TI/CARL/LRTM
Saint-Gobain J.R. Noonan 2006