If extra fixtures are available for production runs, a larger oven may be more economical than a smaller one. Generally, it is more time and energy efficient to do large loads rather than small ones because of the additional time required for loading, heating, cooling and unloading multiple loads. Allow a space equal to one diameter between fixtures for hot gas and cooling-water spray to circulate. If 100 fixtures must be cleaned each hour, then the oven should be sized to hold 250 to 450 pieces. Allow an additional 30 min for loading, unloading and washing. Computer-aided design systems are useful for laying out complex shapes.įor paint and powder coating, cycle times generally run 2 to 4 hr for paint and powder fixtures, depending on the amount and type of coating on the fixtures and the oven temperature. The manufacturer should be able to help select the correct size for your application. The oven must be large enough to allow spaces between the parts for hot burner gases and cooling-water spray to circulate.
The oven must be sized to accommodate the largest pieces to be cleaned and the quantity of parts necessary to keep up with production. Sizing the Unit To select a burn-off oven, determine the correct size and appropriate features for your application. The fire must start before the system sprays water.
The ramp-and-soak control system sprays water if the oven temperature exceeds a variable maximum temperature limit that is programmed or selected by the operator. Be sure that the oven you select has an up-to-date control system.įIGURE 2. Today’s burn-off ovens run no longer than necessary to do the job. Some ovens can determine when the process is over, shutting off automatically. It is now possible to remove large amounts of combustible materials quickly and safely. Modern high-performance afterburners produce very low emissions, and some control systems can sense the amount of vapor in the oven and control it at a safe level to prevent fires. Over the years, many improvements have been made in burn-off oven technology. Burn-off ovens do a good job of removing the plastic, even in the small holes found in dies. Torching creates smoke, which can be harmful to the environment and to the employees doing the stripping.
Chemical stripping results in disposal cost and presents potential liability if hazardous chemicals are used. Traditional cleaning methods are chemical stripping or using a torch to burn off the unwanted plastic residue. Extrusion and injection-molding equipment used in the production of plastic products can become covered with plastic. Burn-off ovens also are used for de-bonding brake shoes and stripping insulating resin from electric alternators. The ovens eliminate disposal problems and the potential liability associated with chemicals. Many automotive engine rebuilders have replaced chemical-cleaning systems with burn-off ovens to remove the oil and grease from blocks, heads and other components prior to rebuilding.
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