Oven-curing

Fig. 2. Rigid foam laminating line 1, material tank 2, agitator 3, metering pump 4, heat exchanger 5, bottom facet toU 6, bottom facet alignment device 7, top facet toU 8, top facet alignment device 9, mixing head 10, traverse assembly 11, top nip toU 12, bottom nip toU 13, take-up conveyor top belt with adjustable height 14, take-up conveyor bottom belt 15, curing oven 16, laminate 17, side-trim saws 18, cutoff saw (traversing) 19, laminated-panel stack...

Filter P per Processing. In the fabrication of fuel oil and air filters for vehicles such as motorcycles and diesel locomotives, heat processing of the filter paper is required to cure the resin (usually phenoHc) with which the paper (qv) is impregnated (see Phenolic resins). The cure-oven exhaust, which contains water vapor, alcohols, and dimers and trimers of phenol, produces a typical blue haze aerosol having a pungent odor. The concentration of organic substances in the exhaust is usually rather low. 

Catalysis is utilized in the majority of new paper filter cure ovens as part of the oven recirculation/bumer system which is designed to keep the oven interior free of condensed resins and provide an exhaust without opacity or odor. The apphcation of catalytic fume control to the exhaust of paper-impregnation dryers permits a net fuel saving by oxidation of easy-to-bum methyl or isopropyl alcohol, or both, at adequate concentrations to achieve a 110—220°C exotherm. 

The uncured wool from the forming conveyor is separated into pelts , which are converted into pipe sections by being wrapped around a heated mandrel, and the wall thickness set by counter rollers. The sections are then passed through a curing oven before being trimmed, slit, covered and packaged. 

Figure 11.4 The glass wool manufacturing process. 1 Tank 2 forehearth 3 spinners 4 conveyor 5 curing oven 6 trimmers 7 slitters 8 bandsaw 9 guillotine 10 rolling machine.

Single plates are usually cured in special devices (curing ovens or curing chambers, cf., e.g., [25] ) that control humidity as well as temperature. In continuous plate production, the drying of the pasted ribbon is correspondingly controlled. Furthermore, in continuous manufacture final curing can occur after the plates are separated and inserted into the containers. 

Ageing ovens are similar in nature to post-cure ovens requiring very accurate temperature control systems and monitoring for volume throughput of circulating air to ensure compliance with the requirements of specification testing. 

Filter paper processing, cure-oven exhaust in, 10 109... 

Ehnholt et al.8 produced a broad paper covering raw materials, and in-process and final-product measurements. While the uses are primarily in the food industry, the rancidity was often caused by microorganisms. One case involved off-flavor materials being produced in drying and curing ovens. Marker compounds (concomitant) released during the breakdown process (of saturated and unsaturated compounds) were nonenal, decenal, and octenone for the unsaturated aldehydes and ketones, and nonanal, decanal, and octanone for the saturated molecules. A 10-m folded path gas cell was used with an FT-IR for measurements down to 1 Lig/m3. 

Fig. 114. The rocket chamber with the cured propellant is removed from the curing oven, according to Dykstra [11].

The final operation in propellant manufacture is the curing of the binder. The shaped material is placed in a curing oven for 16-48 hr at 80-110°C. The temperature and duration of this operation depend on the composition of the mixture, the dimensions of the charge and the physical properties desired. 

Following the application of paint, the item is passed through a drying or curing oven. The methods employed include convection, infrared or ultraviolet heating or combinations thereof. The particular methods depend on the types of paints being used, economics, and production requirements. Once dried, the items are sent for inspection and final packaging or assembly. 

It is most important to realize that at this time the full properties of the material are not yet developed, and the molded polyurethane has to be returned to the curing oven for the period recommended by the system supplier. The curing time varies depending on the chemistry of the system. The maximum properties of the cast polyurethanes are developed after a further 1 to 2 weeks at ambient temperature. 

Several factors must be taken into account when the exact grade of material is chosen. The first is the pot life of the system. The pot life controls the time it takes to fill the mold, allowing any entrapped bubbles to rise and to gel off so that it can be placed in the curing oven. This represents a large portion of the physical cycle time. 

The location of the temperature probes is very important to obtain the correct temperature of the curing ovens. They must be in the air, away from direct heat from any elements. 

Everything inside an operating oven must be considered to be at the set temperature. Large walk-in ovens could have high concentrations of solvent or isocyanate vapors. Proper PPE must be worn when entering them. If too long a time is spent in a curing oven, dehydration can occur. 

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