Long Oven Cycle

One of the major disadvantages of using structural epoxy adhesives is the cost and time required for long cure cycles. The number of fixtures, energy use, and production times (either at room temperature or in an oven) required have discouraged many from exploring epoxy adhesives as an alternative to mechanical fastening. 

Oven heating Ovens are the most common source of heat for bonded parts, even though it requires long curing cycles because of the heat-sink action of large assemblies. Ovens may be heated with gas, oil, electricity, or infrared units. Good air circulation within the oven is essential to prevent non-uniform heating. Ovens that can reach temperatures up to 450 1°C are available. ... 

Oven heating is the most common source of heat for bonded parts, even though it involves long curing cycles because of the heat-sink action of large assemblies. Ovens may... 

Portions of these paints were oven aged for 10 days at 60 °C, as an indication of long-term stability. Freeze-thaw tests were also run that consisted of five cycles at -25 °C. 

There is more than one correct cure cycle for EVA. Like most polymers with peroxide promoters, it is good practice to raise the bond-line temperature rapidly to avoid peroxide decomposition before an adequate cure has been obtained. One cycle that has been proven uses two steps, one at 100 C for evacuation and adhesion, the other at 150°C for long-term oven cure. This cycle provides a high throughput with only one laminator. 

Small production runs are processed by compression or transfer molding at 800 to 3,000 psi and 104 to 188°C mold shrinkage is 2 to 4 percent. Long production runs are more economical by injection molding at 5,000 to 20,000 psi, 188 to 252°C, and a 25 to 90 sec cycle. Extrusion requires post-cure in a 316 to 427°C hot-air oven, typically 60 ft/min steam post-cure can run 1200 ft/min. Calendering typically runs 5 to 10 ft/ min. 

Temperature Compatibility. If pin-in-paste soldering is to be used, check that components are temperature-compatible with the oven reflow process. The high temperatures and long exposures associated with oven reflow soldering may cause unsuited molded component bodies to melt or warp. Connector contact normal force may be affected if the molded connector body softens or distorts. Solder joints or wire bonds internal to some devices may become disbanded, and some, such as electrolytic capacitors, may leak or even explode as a result of an oven reflow cycle. Check the component manufacturer s specification for thermal hmits and compatibihty with oven reflow soldering. 

---