Vacuum panel Manufacturing process

In the following sections, some techniques to check the insulating performance of vacuum panels are illustrated, a few of them also being able to be used as a tool for Quality Assurance (QA) and Quality Control (QC) for the manufacturing process. 

This approach allows measurement of both total and partial pressures in the panel, thus providing useful information on the gas ratios, this being useful as an R D tool or to monitor and improve the manufacturing process. However, since this is a destructive and relatively time-consuming test it can only be used for one-off samples. A nondestructive technique to measure total pressure in a vacuum panel has been proposed recently, which is based on the use of a laser beam source coupled to a detection system. 

The vacuum assisted liquid molding process has been used for the manufacture of large composite parts. In this process, a preform is placed in an open mold and a plastic vacuum bag placed on top of the mold. A vacuum is created in the mold using a vacuum pump. A resin source is connected to the mold. As vacuum is drawn through the mold, resin infuses into the preform. Application includes the fabrication of large products with complex geometry such as panels of allcomposite buses, railroad cars, and vehicle components. 

The effect of the temperature increase resulting from the foaming process, on the vacuum level in a panel can also be seen in Table 4.12 which shows the result of an RGA carried out on two test panels encapsulated by an appliance manufacturer. In the getterless panel, the pressure immediately after the foaming is already exceeding the 10 Pa target value and close to the maximum acceptable value (generally set at 50 Pa). 

A 138 - 160 C cure phenolic (service temperature up to 260 C) for processing by vacuum-bag, press or autoclave methods in the manufacture of aircraft interior laminates and crushed core panels. 

In the case of the honeycomb core, this is first degreased, then oven dried and finally vacuum treated to remove all potential sources which could interfere with the final electrical properties, a process unique to radome manufacture. The Rohacell foam, on the other hand, is heat treated at 125°C for 3 h to prevent any further shrinkage during the cure cycle of the sandwich panel. 

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