2. Project Background
Custom Rubber Company is
producing dog toy with machines
that do not have a previse
temperature control.
The temperature in some area of
the heat chamber is always
exceeding the desired range (350±
10 °F) for about 10 °F. Some areas
might have lower temp.
High temperature causes splits on
the edge of toys. Low temp causes
under cure.
3. Project Description
Solve the heat distribution problem; enhance the
product passing rate.
First Hypothesis
the temperature is not distributed evenly in the
heating chamber due to heat loss around the edge of
the heat chamber
4. Heat Analysis on Original Machine
Top View Side View
Max Temp: 161.39 °C
Min Temp: 57.72 °C
Max Temp: 151.11°C
Min Temp: 87.72°C
Set Temp: 160°C, 165.56 °C
5. About the Insulation Material
Type: Pyropel MD-18
Form: Semi-rigid Fiberboard
Thickness: 1/4 in
Thermal Conductivity at 200 ºF : 0.31
Thermal Conductivity at 400 ºF : 0.36
Continuous Use Temperature: 550 ºF
7. Heat Analysis – 1st
Cycle
Max Temp: 172.22 °C
Min Temp: 80.33 °C
Max Temp: 153.94 °C
Min Temp: 88.67 °C
Top View Side View
Set Temp: 171°C, 171 °C
Back
8. Results
Before
Temp Diff of top side:
103.67°C ,
64.24%
Temp Diff of side:
63.39°C
41.95%
After
Temp Diff of top side:
91.67°C
53.23%
Temp Diff of side:
65.27°C
42.40%
9. Heat Analysis – 2nd
Cycle
Set
TC3-Ext.Fixed Platen: 350 ºF,
TC4-Int. Fixed Platen: 350 ºF
TC1-Ext. Movable Platen: 360 ºF
TC1-Ext. Movable Platen: 360 ºF
Took 1 picture every 1min 10sec
8 samples/cycle
10mins per cycle
Randomly chose 3 cycles
We currently lack series
temperature data for the original
machine
10. Results
Without Insulation Board
Setting(°C) Means std dev % of difference
160
161.11
NA
0.0063
160
161.11
NA
0.0063
165.56
165.56
NA
0
165.56
165.56
NA
0
With Insulation Board
Setting(°C) Means std dev % of difference
176.67
176.53 0.86 -0.00071
176.67
176.32 0.85 -0.0018
182.22
182.29 0.42 0.00035
182.22
182.25 0.12 0.00012
11. Results
Bad parts number due to machine issue (Split &
under cure) decreased
Before: 37.5 splits & 1.25 under cure /shift
Now: 3.55 splits & 0.33 under cure /shit
12. Top of the Machine
The major heat loss is through
the top edges of the heat
chamber
Hard to add insulation board
on the top – air tubes
Solution
Install a roof
reduce the direct contact
between the heat chamber
and the surrounding cold air
13. Second Cause -Thermocouples
Custom Rubber Co. are using different types of
thermocouples on different machines
Mostly used K type and J type thermocouples
Question:
Do different types of thermocouples give standard
temperature feedbacks?
Are all feedbacks from thermocouples are reliable?
15. Boiling Water Calibration
Calibrated both types of thermocouples in boiling
water to see if both of them gives feedback
around 100°C
Type K: 98.79°C
Type J: 104.07°C
5.28°C (41.5 F)temperature difference
Temp setting for one machine with K type
thermocouples may not suitable for those with J
type thermos couples
All new purchased thermocouples need to be
calibrated before using
16. On-site Experiment
Replaced my K type
thermocouples with the
original ones installed in the
machine
One gave feedback of
134.43°C; the other gave
130.04°C
Old thermocouples might
have errors on testing –
Calibrate them periodically
Magnetic influence –
provide a layer of insulators
on the thermocouples
17. Conclusion
Possible solutions to solve the heat
distribution problem
Providing insulation boards to the
edges of the machine
Installing a roof on the top of the
machine
Calibrating all the thermocouples
periodically
18. Acknowledgements
Dr. Clare Rimnac – for her advice, help and
support
Dr. Alexis Abramson – for her technical advice,
thermometer and thermal couples.
John Bellett – for giving me relevant documents,
information and suggestions.
Charlie Braun – for giving me a chance to have
this project in Custom Rubber Co.
Maintenances – for adding insulation boards and
helping me to do the thermocouple experiment
