Baking ovens

Final adjustment of solvent selection must be done under actual field conditions. In many baking coatings a significant fraction of the solvent is lost in the baking oven, yet the tables of relative evaporation rates are based on 25°C air. Information on evaporation rates for a small number of solvents as a function of temperature up to 150°C has been published (73). 

Beishon, R. J. (1969). An Analysis and Simulation of an Operator s Behavior in Controlling Continuous Baking Ovens. In A. de Brisson (Ed.), The Simulation of Human Behavior. Dunuod Paris. 

Figure 3. Cross section of typical assembly paint bake oven.

Figure 4. Location of thermocouples for paint bake oven survey.

A network structure model has been developed from which a parameter that correlates well with physical measures of paint cure can be calculated. This model together with a kinetic model of crosslinking as a function of time and temperature has been used to evaluate the cure response of enamels in automotive assembly bake ovens. It is found that cure quality (as measured by the number and severity of under and overbakes) is good for a conventional low solids enamel. These results are in agreement with physical test results. Use of paints with narrower cure windows is predicted to result in numerous, severe under and over bakes. Optimization studies using SIMPLEX revealed that narrow cure window paints can be acceptably cured only if the bake time is increased or if the minimum heating rate on the car body is increased. 

C.2 Engineering Consideration. The primary engineering considerations in prebaking are the selection and maintenance of baking ovens. Several types of ovens such as forced air convection ovens, conduction ovens, and infrared heated ovens are commonly employed. The main requirements for baking hardware are ... 

Comparison of the data in Tables III-A and IV-A suggests that the BA/CHDM enamels are slightly harder and less elastic than the DDA/CHDM enamels. However, considerable more data would be needed to confirm this observation, which is mildly surprising in view of the slightly longer chain length of BA. The tests used here are imprecise, and they can be affected by variables such as location in the baking oven, film thickness and variations in test panels. 

The rate limiting step In this side reaction Is the reaction of Isocyanate and water. The Importance of this reaction depends on the polarity of resin, the level and type of catalyst, and the humidity In the bake oven. The effect of this reaction Is to reduce the number of urethane crosslinks but Increase the number of urea crosslinks. The total crosslink density will likely decrease since two Isocyanate groups are necessary to form one urea link while only one isocyanate group is required to form a urethane link. If excess isocyanate groups are present, this reaction will consume the excess Isocyanate and Increase the crosslink density. This reaction can occur not only in the bake oven but also on aging of the coating if unreacted isocyanate groups are present after cure. 

Stars of the only two compositions which are well approved. Take of powder (gunpowder) four ounces, of saltpeter two ounces, of sulfur two ounces, of camphor half an ounce, of steel filings two treseaux, of white amber half an ounce, of antimony (sulfide) half an ounce, of (corrosive) sublimate half an ounce. For double the efficacy it is necessary to temper all these powders with gum agragante dissolved in brandy over hot cinders. When you see that the gum is well swollen and fully ready, to mix with the said brandy, it is necessary forthwith to mix them in a mortar with the powder, the quicker the better, and then to cut up the resulting paste into pieces. These stars are very beautiful and very flowery. Note that it is necessary to put them to dry in a pastry or baking oven after the bread has been taken off of the hearth. 

Silicone elastomers can be used for paper coatings, nipples, teething rings, seals for baking ovens and refrigerators etc. 

When the silvered flask has been baked and evacuated to the highest possible vacuum, it must be sealed off at the prepared constriction. If, because of the design of the baking oven or of the vacuum system, it is inconvenient to make the seal at the required place, an alternative procedure can be employed. A second constriction is made in the pun ... 

Silicone rubber tubes are mainly utilized in medical and food technology e.g. as transfusion tubes, catheters and tubes for drinks. Silicone cables are widely utilized in applications for which thermal stability, weathering resistance and chemical resistance are required e.g. baking ovens, hot lamps and electrical connections for electrical motors and transformers. 

Intermediate and low-grade clay refractories Annealing furnaces, runner brick, sleeves and nozzles, ladles, oil refineries, stills, incinerators, vaults, flues, furnace stacks, (lig( sters, bake ovens, dryers, carburetors, etc. 

The low heat sag values.relate to the ability of fabricated parts to withstand automotive assembly line paint bake-oven cycles— an ability which could eliminate the requirement for a separate offline painting operation and permit use of the same paints used for steel components. 

Plans have been submitted for a catalytic afterburner. The installed afterburner is to incinerate a 3000-acfm contaminated gas stream discharged from a direct-fired paint baking oven at 350°F. The following summarizes the data taken from the plans ... 

The conventional type of bake oven is used. Electrodeposited coats are usually baked from 5 to 30 min at temperatures varying from 225 to 400 F. The air velocity through the oven can be comparatively low, due to the very small quantities of organic volatiles in the paint coat. The time/teraperature requirements are dictated by the resin system and are similar to those required for conventional dip or spray paints—usually 5-25 min at 225-400 °F air... 

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