Issue link: https://www.e-digitaleditions.com/i/1051901
100 percent (no modulation or control) while the convection oven cycled to maintain oven temperature at 400°F. IR-convection test. Figure 10 shows the temperature profile of the three parts processed through a combination of IR and convection. As you can see, the 18-gauge steel part reached temperature in 5 minutes while the largest part (the 2-inch casting) reached temperature in approximately 29 minutes. Even though the first part reached temperature 24 minutes faster than the casting, it was only 40°F hotter than the heavy metal casting and wasn't above our over-bake limit of 450°F. is is due to the recirculation fans inside the convection oven, which acted as an air conditioner for the small-gauge parts. e advantage of the IR-convection combination while cur- ing or preheating multiple parts is the flexibility that it offers. This type of flexibility can ease an industrial customer's mind: Not one part inside the oven is being under- or over- cured, and all necessary quality specifications are being met. is test produced approximately the same percentage sav- ings as the IR-convection test for large geometrical parts. Figure 6 Temperature profile for 300kW IR-convection oven with part reaching 350°F in 38.6 minutes Figure 7 300kW IR-convection oven used 131.5kWh to get the part temperature to 350°F Figure 4 Temperature profile for 300kW convection-only oven Figure 5 Temperature profile for 300kW convection-only oven with part reaching 350°F using 177kWh convection oven. Most customers who desire to use this style of batching want to reduce cycle time, which improves throughput and eliminates the need for multiple recipes. In our example, we'll again examine the benefits of electric IR inside a convection oven. Our testing for this application was with a standard 300kW electric convection oven (see Figure 1) that was retrofitted with approximately 127kW (ten 12.735kW heaters) of electric IR (see Figure 2). is test examined whether three different parts of various thickness and weight (shown in Figure 9) could be heated simultane- ously without over-baking the small parts or under-curing the larger part. e first part was made of 18-gauge steel, the second part was made of 12-gauge steel, and the third part was a 2-inch-thick heavy metal casting. ermocouples were placed on the three parts at different points to make sure they reached the desired temperature of 350°F. is temperature point was selected based on the fact that many powder cure temperatures range from 350°F to 400°F with over-bake protection typically up to 450°F. During the IR-convection test, the IR was left on at 16 POWDER COATING, November 2018