There is a difference in powder coating ovens. Good engineering of a batch oven or powder coating oven requires that each component must be designed to work together. The key items in design – circulation fan cfm, exhaust fan cfm, supply ducting, and static pressure all must be sized properly. An inexpensive or “budget oven” will lack most needed features.
Ducting – We design our air flow to allow for a complete exchange of air without creating a positive or negative pressure in the oven. Air flows horizontally from the side mounted ducting towards the center of the oven and your product, and then flows vertically upward.
Budget ovens provide only air delivery from around the top parameter and force the air downward. This lack of ducting requires a high velocity of air movement and most often results in a temperature variance of up to 50 degrees from top to bottom. The increased air directed at the floor also causes dust to be airborne and contaminate the product.
Wall thickness – Our oven walls are a standard 4” thick and include stiffeners. They are made of 18 gauge aluminized steel – both inside and outside skins.
There are three reasons why some budget manufacturers use thicker walls.
They use the walls as support and do not have the needed support to hold the burner box
Their air flow creates a high positive pressure which penetrates thru the walls and they try to offset this with thicker walls.
Their oven panels do not have a thermal break on the edges so a lot of heat is transferred from the inside wall to the outside wall via the ends.
The top oven manufactures also use 4″ walls for similar ovens and temperatures – such as Wisconsin Oven, Steelman Oven (uses 3″ walls), Grieve, Despatch, and Precision Quincy.
Wall thermo break – heat will transfer thru any conductive material and in the case of ovens a thermo break is needed to minimize the heat transfer and loss.
We manufacture our oven panels with thermo breaks to achieve a minimum of metal contact from the inside to the outside panel by utilization of slots on the sides of the panels.
Some budget oven manufacturers do not provide this feature and try to reduce the heat transfer by using thicker panels. Some manufacturers require you to assemble the panels on site – you stuff them and then screw them together.
Circulation Fan – One of the most efficient fans is a backward inclined fan. We use a backward inclined plug fan in all our ovens. The efficiency provides for an economical operation and use of electricity. Backward-inclined fans offers lower sound levels and energy costs than other fan types.
Budget ovens tend to use squirrel cage style fans mounted on a shaft with pillow blocks on both sides. These fans require more horse power to achieve the same cfm as the plug fans. The shafts tend to warp in the event of a power failure or shut down during high temperatures
Burner – We use a direct fired air induced burner. Air is force mixed with the gas at the burner nozzle for the best possible combustion and control.
Budget ovens often use an in-line or in-duct burner that uses the circulation air flow to pass over the burner, located in the ducting, to mix with the gas. An in line burner is typically used for makeup air units or dryers and not the best choice for the best performance.
BTU – BTU’s required for an oven is based on the engineering and one factor is the number of air exchanges. Our standard ovens are engineered for 6 air changes per minute. You may only need 500,000 based on the size of oven, but the burner we supply would be rated up to 800,000 btu’s. The actual amount of btu’s used is based on several factors set up at the time of installation. The gas pressure, altitude, air adjustments, and other factors affect the actual btu’s. All burners have a range and are adjusted on site. Most manufacturers state the maximum amount the burner is rated for – although they may never adjust it to this maximum.
Door Frame – Made of heavy 10 gauge steel or larger, these frames support the weight of the doors to prevent sagging and warping. Our frames are built into the oven.
Budget ovens provide little or no structure to support the doors and most often need wheels under the doors.
Doors – Constructed with a design to prevent loss of shape and using heavy metal for strength.
Budget ovens use wall panels as their doors. With all the support on one edge they will sag – gravity will take over.
If you want to save a lot of time and headaches – start with a well designed and built powder coating oven and avoid the budget ovens.
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