There are many different melting systems used in profile wrapping depending on the required amount of adhesive for the product.
An integral part of producing high quality wrapped profiles, is the maintenance and upkeep required for any melting system.
Here we discuss some of the key components of melter maintenance in order to keep you informed and producing the best quality product possible.
Teflon Coating:
Fluorinated polymer (Teflon ®) is used to coat the part(s) of the melting system that are in contact with the adhesive. This prevents the metal from coming into direct contact with the adhesive and thus allows for cleaning. This coating should be reapplied periodically to treat any melting system which comes into contact with the HMPUR adhesive.
Temperature Control:
Melters need to be heated prior to inserting adhesive cartridges. It is recommended that the machines are programmed to begin the heating process before the work shift starts and the wrapping process begins.
Because the melter is essentially the storage container for the melted adhesive, it is important to regulate the temperature of the glue properly.
Glue temperature is set depending on the amount of glue consumed.
The hose temperature should follow the same regulation structure as the melter in order to ensure proper transference to the slot nozzle, however; it is important to appropriately reduce temperatures of the hose during down time to avoid adhesive build up.
Extended heating of the hose and slot nozzle can cause problems due to the build up of burnt or cured glue.
Watch Out For:
The presence of small yellow-orange lumps at the slot nozzle indicates the adhesive has partially cured and is oxidizing inside the hose. In this case, the hose should immediately be replaced to avoid compromising the profile finish.
Order of Heating Operations:
The sequence of heating operations should follow the following order so as to avoid extended heating of the hose and slot nozzle.
Heat plate or tank melter
Heat thermoregulated hose
Heat wrapping head (slot nozzle).
Once the slot nozzle is heated, the adhesive can be applied.
Filters:
Melters are equipped with filtering systems to block any impurities in the adhesive. To keep the adhesive clean, nitrogen or dry air from membrane dryers should be used to significantly increase the life of the adhesive. This will also reduce the possibility of skin formation which could break up and flow into the slot nozzle during pumping. Ensuring proper use and frequent replacement of the melter filtering systems helps to avoid a variety of visual defects on the profile.
Cleaning:
While some melters are equipped with a second tank for the cleaner and allow for automatic cleaning, it is important to deeply clean gear pumps, hoses, and application heads frequently and accurately to ensure adhesives continue to spread evenly.
Prior to the beginning of any wrapping process, it is recommended to purge some adhesive and clean the external lip of the slot nozzle. This eliminates debris and particles and avoids transference of partially cross-linked adhesive onto the plastic film.
Carefully read SDS information for any solvent-based cleaning products.
The slot nozzle must NEVER be cleaned using tools (ie: brushes or scrapers).
Using these tools could damage the wrapping lip.
Cleaning materials must be softer than the metal. We recommend brass, copper, Teflon, wood or heavy cardboard spatulas instead.
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