Honeywell CS071AE User manual

TROUBLE-SHOOTING GUIDE
Description of Problem Possible Causes Possible Corrective Action
86
Blisters • Excessive moisture. • Pre-dry sheet at the temperature
required for the material you are
forming.
• Heat sheet very slowly to forming
temperature.
• Protect sheet from moisture before
using.
• Heating sheet too hot. • Cut down sheet forming
temperature. You may be boiling
the stabilizers out of the material.
• Heating sheet too fast. • Lower element temperatures.
Generally speaking, element
temperatures should not exceed
950°F.
• Increase the distance between the
heating elements and the sheet.
• Uneven heating of the sheet. • Check forming oven for elements
that are overheating.
• Screen out hot spots.
• Heat sensitive material. • Check with plastic supplier on
temperature parameters for the
material involved.
Thinning • Design of the part. • The overall draw ratio of the part is
too great for the starting thickness
of the sheet.
• The part has specific areas on it
that exceed the draw ratios of the
rest of the part.
• Sheet too thin. • Increase the gauge thickness of the
plastic sheet.
• Uneven sheet temperature. • Check for air drafts in the forming
oven.
• Check for hot spots in the forming
oven. May have defective heating
elements.
• Check the sheet for a variation in
thickness.
• Forming technique. • Consider where the part is thinning
and what forming technique would
best address this problem.
• Bad plastic sheet. Melt
index of sheet may be low.
• Have physical properties of the
sheet analyzed.

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Discoloration • Forming temperature too
hot.
• Cut down on the forming
temperature of the sheet.
• Pigment loading too low. • Increase pigment loading.
• Hot spots in forming oven. • Check out heating elements.
Webbing or bridging • Poor mold design or layout. • Redesign mold.
• Use plug assist or mechanical ring
to eliminate webbing.
• Add spacing blocks to take up
excess material.
• Increase draft or radii to webbed
area.
• Slow down the vacuum speed.
• Redesign ring or plug assist.
• If it is a multiple mold, increase the
spacing between parts.
• Wrong forming technique or
bad design on present
technique.
• Select a better forming technique.
• Make mold adjustments to the
current technique. Gussets, etc.
• Incorrect sheet temperature. • In billow forming, the corners of
the sheet may be too hot.
• In snapback forming, the corners of
the sheet may be too cold.
• Screen out appropriate areas of the
sheet.
• High sheet sag. • Cut down the heat of the sheet to
be formed.
• Select a resin with a lower melt
index.
• Vacuum rate too fast. • Slow down the vacuum rate.
• • Use smaller vacuum holes
• Restrict the vacuum flow with ball
or gate valves in the main vacuum
line.
• Insufficient vacuum. • Check the vacuum system for
leaks.
• Increase the number of vacuum
holes.
• Check to see if the vacuum holes
are plugged up.
• Check to see if the vacuum holes
are in the proper area.

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• Selectively increase the size of the
vacuum holes.
• Timing the billow in the
snapback box.
• Get a more sensitive flow valve.
• Put an electric eye in the snapback
box.
Sheet pulls out of clamp
frame.
• Clamp frames warped. • Put a piece of paper in the clamp
frame and see if you can pull it out
without tearing it.
• Clamping pressure too low. • Seals leaking on clamp frames.
• Air pressure to clamp frames
adjusted to low.
• High shrinkage in plastic
sheet.
• Put double-sided adhesive foam
tape with 40-grit emery paper on
the clamp frames.
• If possible, control the orientation
in the plastic sheet.
Lumps and bumps. • Contamination in the sheet. • Cut a cross section of the lump and
examine it to see if looks different
than the plastic matrix. If so, it is
an extruder issue.
• Incompatible plastic mixed
within the sheet.
• Check incompatible lump with an
IR test.
• Compare color of lump with the
rest of the matrix.
• Water droplets on hot plastic
sheet.
• Cut a cross section of the lump and
check for compatibility.
• Bump on the mold. • Look for a depression on the side
of the sheet touching the mold.
• Loose debris on the mold. • Look at the back of the formed part
for loose debris imbedded within
the part.
Texture washout. • Draw ratio of the part too
great.
• Consider a deeper texture.
• Plastic sheet heated too hot,
especially on the texture
side.
• Turn down the texture side heaters
in the oven.
• Cut down the heater cycle time.
• Cut down the overall heat on the
sheet.
• Shade out certain areas of the sheet
to keep it cooler and less
susceptible to thinning.

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Description of Problem Possible Causes Possible Corrective Action
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Texture separation. • Texture too deep for starting
thickness of the sheet.
• Select a different texture.
• Texture has deep furrow
lines in a pattern.
• Select a different texture.
• The material you are using may
have poor hot strength and you
may need to select a different one.
• Excessive shrinkage in the
extruded sheet.
• Draw ratio pretty large, in
excess of 3 to 1.
• Select a tighter texture.
• Change the processing technique
for forming the part.
Sheet won’t fit into clamp
frame.
• Sheet not flat. • Place a weight on the bowed up
area along the clamp frame.
• Preheat sheet to remove stress.
Flow lines on part. • Nerve in the plastic sheet. • Rerun the sheet.
• Chatter due to sloppy chain
drive on the extruder.
• Run material on a good direct drive
extruder.
• Select a deeper texture.
• Melt index of resin erratic. • Blend resin more thoroughly.
• Die lines on the back of the
sheet.
• Rerun sheet.
• Run sheet from the oven at a lower
temperature.
• Select a deeper texture.
Blotchy look on the texture
side of amorphous materials.
• Excessive heat, especially
on PVC containing
materials.
• Cut down the forming temperature
heat.
• Select a better texture. Some hair
cell textures will do this in PVC
containing materials.
• High oven shrinkage. • Check shrinkage and keep within
acceptable limits.
Blotchy look on the texture
side of olefin materials.
• Poor mold contact. • Sandblast mold surface.
• Uneven cooling on the mold • Get a temperature-controlled mold.
• Check cooling lines for blockages.

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Description of Problem Possible Causes Possible Corrective Action
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Inconsistent part. • Uneven heat on plastic
sheet.
• Check for air drafts in the heating
oven.
• Check the sheet for a variation in
gauge.
• Check for power output variations.
• Bad regrind in plastic sheet. • Do an IR or a Brabender test to
confirm compound consistency.
• Part too difficult for the
forming technique being
used.
• Change to a technique that is
suitable.
Warped parts. • Parts are cooling unevenly. • Use temperature controlled tooling.
• Check temperature controlled
tooling for water flow blockages.
• Check the material distribution on
the mold. Is the proper forming
technique being used?
• Check if the plastic sheet is being
pulled tightly against the mold.
Very important in forming the
olefins.
• Check cooling fans for proper
placement.
• Check for plugged vacuum holes.
• Mold too cold. • Preheat the mold.
• Clamp frames too cold. • Preheat the clamp frames. This is
especially important when forming
the olefins.
• Excessive gauge variation
on the finished part.
• Change forming technique to get
better material distribution.
• Insert screens in the oven to shade
out thinning areas.
• Gauge on flat sheet may be all over
the lot. Check various areas of the
sheet for gauge differences.
• Check for hot spots in the oven.
Do the thin spots occur on the
same spot consistently?
• Demolding temperature too
hot.
• Increase cooling cycle.
• Decrease mold temperature.
• Get more cooling fans cooling the
part.
• Overheated sheet. Material • Cut back on oven c
y
cle time or

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sagging too much. heat.
• Poor mold design. • Add a moat if you are dealing with
the olefins.
• Check for plugged vacuum holes.
• Add more vacuum holes.
• Use an alternate forming technique.
• Sandblast the mold in the case of
olefins.
• • Check mold for flexing during the
vacuum cycle.
• Poor part design. • Avoid large flat areas. Crown the
part if possible.
• Put in ribs or cosmetic designs in
the flat areas.
• Avoid severe draw ratios.
Poor detail on part. • Sheet too cold. • Increase heating time in oven.
• Increase heating element
temperature.
• Check oven for consistency.
• Check oven for drafts.
• Insufficient vacuum. • Check for leaks in the vacuum
system.
• Check to see if the system delivers
enough vacuum.
• Check to see if the mold is leaking
vacuum and/or sealing properly.
• Check to see if some vacuum holes
are clogged.
• Check to see if you have enough
vacuum holes.
• Check for the proper location of
the vacuum holes and are they the
proper size.
• Cold clamping frame. • Preheat the clamping frame to get a
better seal.
• Incorrect forming technique. • Change forming technique to best
suit the geometry of the part.
• Em
p
lo
y
a
p
lu
g
assist to
g
et better

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92
material distribution and vacuum
seal.
• Hot strength of material too
great.
• Select a material with less hot
strength.
• Use pressure-forming technique to
make the part.
• Plastic too thick in area with
poor detail.
• Use a different forming technique
to distribute the material better.
• Heat the area with the thick plastic
hotter.
Poor surface finish on part. • Mold surface too rough. • Polish mold surface to a smoother
finish.
• Sandblast the mold surface.
• Chill marks. • Get temperature controlled tool.
• Run current mold hotter.
• Change forming technique to
eliminate chill marks. Adjust
predraw depth.
• Draft angle too severe. • Add more draft to the part.
• Mold surface creates too
much drag.
• Polish mold in selected areas.
• Apply mold release sparingly in
selective areas.
• Air entrapment between the
mold and formed part.
• Add more vacuum holes to the
affected area.
• Sandblast mold surface.
• Dirty sheet. • Clean sheet with isopropyl alcohol
or deionizing airgun.
• Dirty mold. • Clean mold off with airgun or
mechanical means.
• Dirt and debris in the
atmosphere.
• Put in filtering system.
• Clean up the thermoforming area
thoroughly.
• Isolate the thermoforming area.
• Contaminated sheet. • Wipe sheet off before putting it in
the thermoformer.
• Separate sheet out that has
contaminates imbedded into it.
• Voids. • Cull out affected sheets where
possible.
• Scratched surface on sheet. • Interleaf sheet. Handle sheet
carefully.

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• Avoid dragging the corner of the
sheet across the surface of the
textured side.
• Streaks. • Examine what you are cleaning the
sheet with before putting it into the
thermoformer.
• Undispersed pigment in the sheet.
• Poor mixing during extrusion.
Rerun the material.
• Dirty embossing roll during the
extrusion process. Clean the
texture roll.
• Dust and dirt in the
atmosphere.
• Keep the thermoforming area
clean. Put in a filter system if
necessary.
Chill marks. • Mold temperature too low.
Material freezes onto the
mold when it touches it.
• Increase the mold temperature.
• The radius on the part is too
small.
• Redesign the part to accommodate
a larger radius.
• Wrong forming technique is
being used.
• Change the forming technique to
an appropriate one.
• Insufficient draft angle on
the part.
• Increase the draft angle.
• Plug temperature too low. • Increase the plug temperature.
• Cover the plug with an insulative
material.
• Use an insulating material to make
the plug.
• Sheet too hot. • Cut down the oven temperature.
• Reduce the heating cycle.
Dimples on mold side of parts. • Vacuum holes too large. • Decrease vacuum-hole size.
• Sheet too hot. • Reduce the heating cycle or cut
down the oven temperature.
• Dirt or debris on the mold
surfaces.
• Clean the mold frequently during
the forming operation.
• Vacuum rate is too high. • Cut down the vacuum volume.
Color loss or stress whitening
or blushing.
• Sheet too cold. • Heat sheet to a higher temperature
before forming.
• Sheet too hot. • Cut back on heating cycle to
prevent discoloration.

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Description of Problem Possible Causes Possible Corrective Action
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• Reduce the temperature of the
heaters to prevent surface
scorching.
• Reduce the distance the heaters are
in relation to the sheet being
heated.
• Part too thin. • Increase the thickness of the sheet.
• Change the forming technique to
improve the part thickness.
• Shade the oven or turn down the
element temperatures in the area
the part is thinning.
• Mold too cold. • Increase mold temperature.
• Poor mold design. • Change draft angles.
• Increase radii.
• Change mold geometry to reduce
the draw ratio.
Poor material distribution
and/or excessive thinning in
specific areas.
• Uneven heating of the sheet. • Check the heaters to see if they are
set properly.
• Check for faulty heaters.
• Check for drafts or air currents in
the oven.
• Shade oven if element zoning is
not possible.
• Check to see if the elements are too
close to the plastic.
• Excessive gauge variation in
the sheet.
• Check the gauge of the sheet.
• Cold mold. • Increase the mold temperature.
• Check the mold for plugged water
lines.
• Excessive sag. • Cut down sheet temperature.
• Use zone heating to cut down
temperature in the center of the
sheet.

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Shiny streaks on part. • Sheet too hot in certain
spots.
• Control the heat in the hot zone of
the sheet by cutting down the
element temperature in the specific
area.
• Increase the distance between the
heater and the sheet.
• Screen the entire oven to dissipate
the heat more evenly.
• Check the unformed plastic sheet
for shiny spots.
Thin corners on the formed
part.
• Sheet too thin. • Use heavier gauged sheet.
• Poor material distribution. • Reduce sheet forming temperature.
• Change forming technique to get
better sheet distribution.
• Change from female to male mold.
• Sheet temperature too high
at the corners.
• Use screening or control the
temperature of the heating zones.
Excessive shrinkage after part
is removed from the mold.
• Inadequate cooling. • Increase cooling cycle time.
• Reduce the mold temperature.
• Employ better cooling fans.
• Place cooling fans in more logistic
places.
• Use cooling fixtures.
Shrink marks on formed part. • Poor seal edge on the mold. • Repair or improve the seal edge.
• Put in a moat on the mold.
• Mold surface too smooth. • Put as sandblast finish on the mold.
• Inadequate vacuum. • Check mold and vacuum system
for leaks.
• Increase vacuum capacity.
• Check for plugged vacuum holes.
• Add vacuum holes or increase the
size as appropriate.
Difficult to remove part off
the mold.
• Insufficient draft on a male
mold.
• Increase draft.
• Remove the part from the mold as
hot as possible without warping it.
• Male mold temperature too
cold.
• Increase the mold temperature to
keep the part from cooling too
much.
• Mold surface too rough for
the draft angle.
• Smooth out the mold in the areas
that are locking on.

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• Use mold release in areas that are
locking on.
• Air ejection pressure too low
or not long enough.
• Increase or extend air ejection
pressure.
• Add more vacuum holes in
strategic places.
• Wrong mold material used
for the required draft angle.
• Change to the proper mold
material.
• Use an appropriate mold release.
• Undercuts on mold too
severe.
• Reduce the size of the undercuts.
• Increase the air eject pressure.
• Remove the part from the mold
earlier in the cooling cycle.
• Put the mold on a hinged frame.
• Put removable parts on the mold
that come off when the part is
being removed from the mold.
• Use mold release where
appropriate.
Loss of vacuum seal. • Seal edge on the mold is
bad.
• Repair seal edge on the mold.
• Material not holding in the
clamp frames.
• Repair clamp frames or put pins in
them to grip better.
• Clamp frames too cold. • Heat clamp frames up before
running parts.
• Clamp frames not adjusted
properly or not coming up
through the seal edge of the
mold enough.
• Adjust the clamp frame properly.
Sheet tears during forming. • Poor mold design. • Consider changing the mold
geometry.
• Change the forming technique.
• Increase the radii on the part.
• Plastic sheet too hot before
forming.
• Cut down heating cycle.
• Cut down heater temperatures,
especially in specific areas.
• Check for hot spots on sheet.
• Thinner gauges, sheet too
cold.
• Increase heating time.
• Check sheet for uniform
temperature.

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• Poor material distribution. • Check the sheet for uneven
thickness.
• Check for uneven heating.
Plastic sheet sticks to the plug. • Plug temperature is too hot. • Decrease the plug temperature.
• Cover the plug with an insulative
material.
• Use mold release on the plug.
• Wrong material is being
used for the plug.
• Change the material to an
acceptable material.
• Cover the plug with an insulative
material.
Excessive sheet sag. • Sheet heated too hot. • Decrease cycle time.
• Decrease heater temperature.
• Poor hot strength on the
plastic material.
• Select a different material.
• Sheet area too large in
relationship to the depth of
draw.
• Use screening or shading to reduce
the heat in the center of the sheet.
• Change forming techniques.
Sag levels vary from sheet to
sheet.
• Sheet temperature varying. • Check for drafts in the oven.
• Check for power variations.
• Melt index of the plastic is erratic.
• Improper use of regrind. • Avoid mixing regrind with various
melt indexes.
• Avoid using regrind that has little
rheological life left.
• Control the quality of the regrind.
Billow height or depth is
varying.
• Sheet temperature is uneven. • Check oven for drafts.
• Check heating elements for power
variations.
• Check heating elements for proper
operation.
• Screen the oven to control
temperatures in given areas of the
sheet.
• Vacuum or air leaks in the
billow box or seal edge.
• Check the seal in the billow box.
• Air pressure or vacuum
volume too great for the size
of billow box.
• Reduce the vacuum volume or air
pressure to cut down the sensitivity
of the billow. (Widen the
processing window)
• Put in a sag eye in the billow box.

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Sheet whitening. • Sheet too cold. • Increase heating time.
• Increase heating element
temperature.
• Sheet stretched beyond the
yield point of the plastic.
• Change the forming technique.
• Redesign the part.
Part cracks during service life. • Part too thin in specific
areas.
• Increase sheet thickness.
• Use plug assists to distribute
material more efficiently.
• Fill in the thin areas in the back of
the part with epoxy resins.
• Consider changing forming
technique.
• Poor part design. • Consider changing part design.
• Increase the radii on the sharp areas
of the part.
• Part formed too cold and is
not stress relieved.
• Increase forming temperature of
the part.
• Part not assembled properly
or fastened to other
structures improperly.
• Check assembly technique to see if
it commensurate with good
assembly practices.
• Poor selection of materials. • Check to see if the physical
properties of the material selected
are adequate for the part produced.
Parts are brittle. • Improper cooling
temperature on the mold.
• Check to see if the mold is too
cold. Increase mold temperature.
• Check to see if the cooling on the
mold is too abrupt, that is,
excessive spray misting.
• Plastic heated too hot too
quickly.
• Check for charring of the surface
of the plastic and turn down the
heating element temperature.
• Mold lubricant incompatible
with the plastic being used.
• Change mold lubricant.
• Part cleaned with a harmful
chemical during packaging.
• Check cleaning agents you are
using.

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Flat surface of a part not flat. • Flat surface of the mold not
properly reinforced. Oil
canning during the vacuum
cycle.
• Check the mold for rigidity and
durability.
Furrows or lines in the part. • Die lines in the plastic. • Rerun the plastic sheet.
• Form the plastic at a cooler
temperature.
Plastic tears during heating or
forming.
• Poor hot strength in the
plastic.
• Select a more appropriate plastic.
• Plastic is partially burnt
during the extrusion
operation.
• Test the material to see if the
viscosity is OK. Rerun with good
material if necessary.
• High orientation in the
sheet.
• Rerun with the proper orientation.
• Mixed regrind in the sheet. • Use only regrind that is compatible
with the virgin part of the sheet.
• Use good quality regrind.
• Grain texture too deep for
the thickness of the sheet
being used.
• Select a texture that will not
separate during the heating cycle.