Industrial oven operating efficiency is an excellent benchmark in the discussion of operating costs. When convection oven designers and manufacturers talk about oven uniformity, they are almost always referring to consistency of the recirculated air temperature profile across the length, width and height in the process chamber of an empty oven. This result in lots of air movement without providing sufficient airflow around the parts. Poorly designed airflow can short circuit the product. The last contributing factor to oven temperature uniformity I will mention deals with getting the air where it needs to be in order to transfer the heat to the product. Insufficient or deteriorating insulation in older ovens can cause significant uniformity issues. Other heat losses - to a concrete floor or through the walls and roof - also affect temperature uniformity. In a continuous oven, extreme unbalance can shorten the process length of the oven because the ends cool down as a result of the ambient air infiltration. In a batch oven, this usually results in cold spots around the door.

If the oven is severely underpressurized relative to the room, cold room air will find its way into the oven. If the oven is severely overpressurized relative to the room, process air will spill or leak out of the oven.

the air pressure in the room or building where the oven is physically located. This refers to the internal air pressure in the oven vs. (For more on air changes, see the sidebar, “Typical Air Changes and Target Uniformity for Various Processes.”)Īnother significant factor contributing to oven temperature uniformity is the oven balance. Think of it as the number of times per minute that the air volume within the oven passes over the heat source and through the fan. Oven air change is simply the ratio of the recirculated air volume divided by the interior volume of the oven, or the oven process chamber.

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