|
|
ALLOWABLE MAXIMUM WATT DENSITY
|
| How
to Order: |
| 1. |
When ordering Cartridge Heaters specify:
a.
Overall Length
b.
Heated Length
c.
Nominal Diameter
d.
Lead Figure
e.
Lead Length
f.
Voltage and Wattage
Diameter and length are determined by the
space available and the requirements for even heat distribution.
The standard leads consists of staggered 1" and 1-1/2"
nickel pins.
|
|
3. |
Determine:
Fit = maximum inside diameter of hole minus minimum O.D. of sheath
Example:
a 3/8" Cartridge Heater in a .375 ± .001 reamed hole
would have a .007 fit .376 - .369 = .007
Check the required temperature against the
watt density and fit indicated on the graph above.
|
| 2. |
|
Example: |
a 3/8" diameter Mighty Watt, 3"
long overall (with standard 3/8" cold end), rated at 300
watts
.371 x 3.14 x 2-1/4" = 2.63 sq. in. heated area.
|
|
|
4. |
To extend heater
life:
A.
Decrease the watt density by:
| 1. |
increasing the diameter |
| 2. |
increasing the heated
length |
| 3. |
increasing the number
of units used |
| 4. |
reducing the wattage,
allowing for longer heat-up time. |
B. Use
a tighter fit.
C.
Consult Ogden for alternative design recommendations. |
SELECTION OF OGDEN CARTRIDGE HEATERS
See separate
listing for Stock Cartridge Heaters.
Heater life is a function of several variables: operating temperature,
heater fit, control, heat absorptivity characteristics of material
being processed, watt density, contamination, etc.
Immersion Heaters
Immersion Heaters are intended to be used in liquids at all times.
The heated portion must always be immersed. Sheath must be free
of grease or foreign material for adequate thermal conductivity.
Protect terminals from contaminants.
Fit Tolerances
The hole into which a cartridge heater is inserted, should be
reamed to the nominal diameter of the heater. Might Watt and
Bullet Heaters are .002" - .006" undersized. If close
hole tolerances are not maintained, operating life of the heater
will be reduced. The heated area of the cartridge should not
extend beyond the hole. See watt density graphs.
Spacing
As a general rule, it is not recommended to space heaters in
a die or platen any closer to each other than the diameter of
the heater.
Contamination
Contamination consists of any foreign matter such as plastic,
oil, grease, dirt or water entering through the terminal end.
Proper Care and Maintenance
1. Heaters
should be stored in a dry area, especially during periods of
high humidity.
2. Protect leads from abuse and abrasion.
3. Maintain temperature control and accessories in good
working condition to avoid over temperature operating conditions.
4. All cartridge heaters (especially of swaged design)
have hygroscopic tendencies and can accumulate moisture in shipping
and storage. Low heater insulation (less than 1 meg ohm) can
be baked in an oven for several hours or started at low voltage
to eliminate moisture.
Removal
Removal of heaters from one die to another is not recommended.
Testing Information
Quality control standards on Ogden Cartridge Heaters include
the following inspection procedures;
1. Resistance test.
2. Voltage breakdown test (Hypot)
3. Inspection of physical size.
 |
|
|