There are numerous benefits for all that work:
- More parts between reapplication of the mold release
- More parts before build-up occurs
- Easier demolds (less force)
- Quicker demolds
- Mold re-conditioning/stripping is easier and takes less time
- Less mold wear/damage
- Better molded part cosmetics
- Fewer defects
Proper stripping and cleaning pays for itself many times over.
- Pay attention to cure time
Not following proper cure times for mold sealer and mold release agents can result in diminished release performance, a dull mold surface and other issues. Dedicating the time for the mold to cure properly will enable an optimal release.
To determine the best cure times, follow the mold release supplier’s recommendations for your molding conditions and the specific release you are using. For semi-permanent releases that cure at ambient temperature, 15 to 30 minutes between coatings is generally enough, however, the longer you can wait, the better the cure will be. (Semi-permanent releases allow for the production of multiple parts before re-application is required, thereby decreasing labor and increasing productivity.)
Temperature, humidity and airflow will all impact the cure of the mold release. Therefore, it is always recommended to allow for longer cure times at low temperatures. (The specific cure time is dependent on the chemistry and environment, but a general industry guideline is to double the cure times for every 10 degrees below ambient temperatures.) In high humidity environments, air flow is necessary to allow the semi-permanent sealers and release agents to cure.
- Avoid over-applying of release agents
On big molds with hard-to-reach surfaces, dripping, running or puddling is likely to occur if a release agent is over applied. Poor mold release application will prove particularly troublesome for parts with complex geometries.
If applying by hand, always use a fresh, clean set of cloths for each coat of release. A 100% bleached, white cotton cloth is preferred. As you continue to use the cloth, it can become loaded with dust, start to breakdown or the release agent can begin to gel in the cloth. All of these flaws can cause streaking on the surface, which is a tell-tale sign that it’s time to replace the applicator cloths with clean ones.
Some releases’ production processes lend themselves to spray application of the release agent. When using these products, high-quality spray guns are the best choice of equipment. High-quality spray guns provide a better spray pattern/adjustability, controlled throughout and good atomization. Plastic spray bottles should be avoided. Because many solvent-based, semi-permanent mold releases are sensitive to moisture, it is important to use a dry air source when spraying; this is easily accomplished by equipping air lines with moisture traps.
- Know your product
There are many different types of semi-permanent mold releases available. Information about the product’s benefits, limitations, cure times, proper uses and more should be documented and well understood by the workforce. Key instructions from the supplier of the release system regarding use, handling, storage, etc. should be easily seen and/or available to workers and supervisors. It sounds simple, but the majority of composites manufacturing shops have no visible procedures for mold cleaners, sealers, releases, etc. How are operators and supervisors to perform their job adequately when procedures and data sheets are in an office drawer?
- Treat it right
Properly preparing and storing your products for future use will extend their lifespan. A tightly closed container can make all the difference with products sensitive to air and moisture. Also, semi-permanents need to be properly rotated while stored according to the mold release manufacturer’s recommendations to prevent old, out-of-shelf-life product from accidentally being used. Using products beyond their shelf life can lead to poor performance, as well as damage the parts or the molds.