August 2, 2024
One important property when it comes to choosing an adhesive is strength. For some adhesives, achieving full strength takes following a specific curing process. If the adhesive does not have enough time to cure or proper the adhesive curing process is not followed, the bond may not last.
What is Adhesive Curing?
Adhesive curing refers to the chemical reaction in which the adhesive fully crystallizes and achieves its full strength. An adhesive’s cure time is the amount of time it takes for this reaction to be complete. Adhesive cure times can vary drastically from a few seconds to a few days depending on the adhesive and the adhesive curing process.
While often confused with dry time, cure time and dry time are slightly different. Dry time refers to the loss of liquid from the adhesive to make it solid. Adhesives that dry will not undergo a chemical change like they would if they cured. This term is typically used with solvent-based or water-based adhesives.
The Different Types of Glue Curing
There are several different methods of adhesive curing. The right one will depend largely on the specific adhesive being used.
Heat Curing
A common adhesive curing method is heat curing. Typically in this process, the adhesives are heated in an oven. The temperature can range anywhere from 140°F to 350°F or more. This process may take a few minutes or several hours depending on the specific adhesive.
Heat curing is common with structural adhesives that can be used to replace welding or mechanical fastening. Epoxy adhesives especially are often heat cured.
Room Temperature Curing
Another popular adhesive curing process is having the product cure at room temperature. Some adhesives will start to cure at room temperature after application. The benefit to this glue curing technique alone is that you usually do not need any extra equipment outside of the necessary dispensing equipment.
Moisture Curing
Sometimes just considered another type of room temperature curing, moisture curing is another method of adhesive curing. Some adhesives will use the humidity in the air or moisture on the substrate to cure. This glue curing method is usually seen with silicone adhesives and cyanoacrylate adhesives. While effective, you need to be careful not to expose the adhesive to moisture before you want the curing process to begin. The level of moisture in the air can also impact the adhesive curing process if it is especially dry or humid.
Anaerobic Curing
Anaerobic curing is a glue curing method used specifically with threadlockers or retaining compounds. These adhesives will begin to cure when they come in contact with metal in the absence of oxygen. Temperature, the type of metal, and how close fitting the component parts are can all impact the anaerobic cure process and time.
Light Curing
Another method of glue curing is through the use of light. This process requires the use of special UV glues that are designed not to cure until they are in the presence of UV light.
Typically, this adhesive curing process also involves the use of UV cure equipment like pens or systems. Under the right wavelength and light strength, these adhesives often cure within a few seconds.
What Factors Impact Adhesive Curing
Different adhesives have different cure times. Some adhesives can cure in a matter of seconds, while others may take several days to reach their full strength. While this cure time largely depends on the adhesives itself, there are other factors at play that can impact this timeline.
Some factors that can impact the adhesive cure time include:
- Temperature
- Humidity
- Light
- The substrates
- The application
- Adhesive thickness
- Storage
Manipulating these properties can speed up or slow down an adhesive’s cure time, but for best results, always follow the manufacturer’s recommendations.
Questions?
If you have more questions about the adhesive curing process or which adhesive is right for you, we want to help. We have a team of adhesive experts available to answer your questions and make recommendations. Just reach out.
