Heat Lamp Heat Bonder Heat Blanket Hot Air System Heat Press Forming 7-24 Figure 7-42.  Heat press. Figure 7-41.  Heat blankets. Figure 7-40.  Heat bonder equipment. A heat bonder is a portable device that automatically controls  heating based on temperature feedback from the repair area.  Heat bonders also have a vacuum pump that supplies and  monitors the vacuum in the vacuum bag. The heat bonder  controls the cure cycle with thermocouples that are placed  near the repair. Some repairs require up to 10 thermocouples.  Modern heat bonders can run many different types of cure  programs and cure cycle data can be printed out or uploaded  to a computer.  [Figure 7-40] Infrared heat lamps can also be used for elevated temperature  curing of composites if a vacuum bag is not utilized.  However, they are generally not effective for producing  curing temperatures above 150 °F, or for areas larger than two  square feet. It is also difficult to control the heat applied with  a lamp, and lamps tend to generate high-surface temperatures  quickly. If controlled by thermostats, heat lamps can be useful  in applying curing heat to large or irregular surfaces. Heat  bonders can be used to control heat lamps. A heat blanket is a flexible heater. It is made of two layers  of silicon rubber with a metal resistance heater between the  two layers of silicon. Heat blankets are a common method  of applying heat for repairs on the aircraft. Heat blankets  may be controlled manually; however, they are usually used  in conjunction with a heat bonder. Heat is transferred from  the blanket via conduction. Consequently, the heat blanket  must conform to and be in 100 percent contact with the part,  which is usually accomplished using vacuum bag pressure.  [Figure 7-41] Hot air systems can be used to cure composite repairs, and  are mainly restricted to small repairs and for drying the repair  area. A heat generator supplies hot air that is directed into an  insulated enclosure set up around the repair area after vacuum  bagging has been deployed. The hot air surrounds the repair  for even temperature rise. During the press forming process, flat stacked thermoplastic  prepreg is heated to above melt temperature (340–430 °C,  or 645–805 °F) in an oven, rapidly (1–10 seconds) shuttled  to a forming die, pressed to shape, and consolidated and  cooled under pressure (700–7,000 kPa, or 100–1,000 psi).  [Figure 7-42]  In production, press forming dies usually are  matched male-female sets constructed of steel or aluminum.  However, rubber, wood, phenolics, and so on can be used  during prototyping. The die set can be maintained at room  temperature throughout the forming-consolidation cycle.  But, the use of a hot die (120–200 °C, or 250–390 °F) allows  control of the cooling-down rate (avoiding part warpage and  controlling morphology in semicrystalline thermoplastic  prepreg, such as PEEK and polyphenylene sulfide) and  extends the forming window promoting better ply slip. 