Thermic calculations
Generalities
Basic rules for cartridge
Adjustment of the CCHC
Mould heating example
Heat loss by natural convection

 

 

Adjustment of the CCHC


Technical data > Thermic calculations > Adjustment of the CCHC

Adjustment according to the temperature of utilization

Charts of the maximum adjustments for the assembly of the CCHCs according to the temperature of utilization :
 
  • The curbs, given for information only, represent the limits not to be exceeded. They integrate many thermal and expansion parameters, but in no case they can replace real tests on an installation.
     
  • The ON/OFF cycles reduce the heaters' life.
  • When the number of cycles is superior to : once an hour, multiply the maximum acceptable charge by 0.8 and for once a minute, multiply the charge by 0.7.
  • Example : for an utilization at 500C (932F) and a hole fit of 0.1mm, the charge must be lower than 30W/cm (193W/in) and with a regulation of 1 cycle/mim, it must be lower than 21W/cm (135W/in).

Charts of the maximum adjustments for CCHC 6,35 to 20

 

For CCHC 1/4" - 3/8"

 

6,5 - 8 - 10

J = maximum fit

Charts of the maximum adjustments for CCHC 6.35 to 10


 

For CCHC 1/2" - 5/8" - 3/4"

 

12,5 - 16 - 20

J = maximum fit

Charts of the maximum adjustments for CCHC 12.5 to 20


If the specific charge of the selected cartridge is higher than the charge shown on the charts, you will have to make the following modifications :
  • Use a larger number of cartridges with a lower specific charge.
  • Use a cartridge which is longer or with a bigger diameter.
  • Reduce the hole fit of assembly as far as it is possible.
  • Permit a longer rise of temperature and reduce heat losses with a good thermal insulation.
The regulation of temperature is an important factor to consider.
The on/off control is often used.
Regulations with thyristor are the best and permit a longer life as they eliminate the on/off cycles.
  • Protect the connection leads from liquid projections and wear possibilities.
     
  • Avoid that wires go into the casing which holds the cartridge.

 

Technical drawing

During the definition of the adjustment, take into account the CCHCs' tolerances and the boring, taking the most unfavorable case, that is :
The min. of the CCHC
The max. of boring


Example :
Example of adjustment.
Alsage = boring
Ajustement = adjustment
Drawing of CCHCs adjustment.

 

Schematization of the boring's intervals of tolerance compared with the CCHC

 Schematization of the boring's intervals of tolerance. Mind out :
Refer to the adjustment charts according to the temperature and the charge (W/cm2).
Nominal CCHC's tolerance Boring
H7 H11 K7 P7
Tolerance Adjustment
max.
min.
Tolerance Adjustment
max.
min.
Tolerance Adjustment
max.
min.
Tolerance Adjustment
max.
min.
6.35 - 6.5 -0.03
-0.05
+0.015
0
0.03
0.045
+0.09
0
0.03
0.14
+0.005
-0.010
0.02
0.055
-0.009
-0.024
0.006
0.041
8 -0.04
-0.06
+0.015
0
0.04
0.075
+0.09
0
0.04
0.15
+0.005
-0.010
0.03
0.065
-0.009
-0.024
0.016
0.051
9.52 - 10 -0.04
-0.07
+0.015
0
0.04
0.085
+0.09
0
0.04
0.16
+0.005
-0.010
0.03
0.075
-0.009
-0.024
0.016
0.061
12.5 - 12.7
15.87 - 16
-0.05
-0.08
+0.018
0
0.05
0.098
+0.11
0
0.05
0.19
+0.006
-0.012
0.038
0.086
-0.011
-0.029
0.021
0.069
19.05 - 20 -0.06
-0.10
+0.021
0
0.06
0.121
+0.13
0
0.06
0.23
+0.006
-0.015
0.045
0.106
-0.014
-0.035
0.025
0.086