use electric infrared elements, or sources.
Electric infrared sources are heated by
current flowing through a resistance heating
element. The element and the material
surrounding the element are heated to an
All well designed electric ovens exhibit the
• vertical and horizontal zoning: To provide
an effective, flexible, and efficient
application of electric infrared heating to
a specific process.
• Precise layout and distribution of
elements: To incorporate shape factors,
overcome an edge effect, and provide greater
• Insulated reflective panels to reradiate
heat: To provide reradiation, even when
panels may be dirty.
• Insulated element wiring to provide
additional life: To extend significantly the
life of the infrared elements.
• Non-contact temperature sensors for
control: To provide the optimum in
• Rigid, non-vibrating structure: To
lengthen the life of the elements.
• Custom control: To meet the specific needs
of the process and the operators.
Equipment for paint drying
The provision of an oven in a production
shop ensures speeding up of the paint drying
operation. Depending upon the rate of
production, the oven can be either batch
type of tunnel type.
Batch type electric oven
This type of oven is largely used where
there is batch production and where the
volume does not justify a conveyorised
Examples: General engineering workshops and
fabrication shops, where different types of
equipment are manufactured and production
volume is low.
Tunnel type electric oven
This type of oven is preferred where
production volume is fairly large and
Examples: Continuous production plants
manufacturing sheet metals components for
Tractors two - wheelers, power tillers,
typewriters, fans, refrigerators, air
Stoving involves heat transfer from the heat
source to the coating or paint film and two
methods in general use for this purpose are
convection and radiation. The method of
stoving is recommended after taking into
consideration the size, weight, shape and
material of the component to be dried.
Convection heating is carried out by heating
the air surrounding the article to be stoved.
This is generally done by having a heating
chamber where air is heated and the heated
air is circulated inside the oven chambers
by means of fans. Normal sources used to
heat the inlet air are electricity, gas,
steam or oil.
Convection ovens are suitable for both batch
and continuous operation, depending on the
A limitation of the convection type oven is
that it will usually require to be started
twenty minutes to half an hour before
stoving operations can begin. This is
because the air inside the oven will have to
be heated to the required temperature, and
this takes time.
Normally, the temperature in a convection
oven is thermostatically controlled, so that
the heat and therefore the fuel consumption
is regulated depending upon the amount of
work entering the oven.
As the object is heated by circulation of
air, any shape and size of object can be
dried by convection heating.
This method is generally used for drying of
large castings, machined components and
objects having a non uniform weight
This is attained by heating the source so
that the source starts emitting infra-red
radiation and this radiation heats up the
paint film. The infra-red emission can be
directed towards the object to be heated by
means of suitably shaped reflectors if
necessary. The absorption of the radiation
takes place at the surface of the charge,
and infra-red heating is thus essentially a
surface heating process.
Since infra-red radiation is emitted in
straight lines from the source or reflector,
plain surfaces are most readily treated. In
infra-red paint stoving, the temperature
attained by the paint film depends upon the
intensity of radiation on the painted
surfaces, the time of exposure, and the mass
of the article. The colour of the paint also
plays a part in the speed with which the
surface is heated. Black paints tend to
absorb more heat, whereas a glossy white
paint requires a longer time of exposure.
For infra-red heating, infra-red gas burners
working of LPG gas, infra-red bulbs or
infra-red electrical heaters can be used.