Consistent ambient temperatures are non-negotiable for successful 3D laminating. The material needs to be sufficiently heated to allow it to form and activate glue without overheating to the point of changing the gloss level, texture or, in worse case, tearing the material as it wraps around the substrate. The glue line needs to be brought to optimum activation temperatures yet still allowed to cool before releasing the operating pressure. Ambient temperatures have a major impact on this process.
Avoid temperature extremes: Temperatures below 65F or above 90F can cause serious problems. Below 65F makes glue activation difficult because cold core materials absorb the heat too quickly, cooling the glue before it has a chance to activate. Temperatures above 90F can lead to the glue remaining soft when it comes out of the press. Since the glue hasn’t solidified before the pressure was released, the 3DL can creep back or pull away from profiles and edges as it begins to cool and shrink.
Avoid temperature swings: Although a broad range of acceptable operating temperatures exists, pressroom temperatures should remain as constant as possible. Otherwise, operators are trying to hit a moving target.
Sudden changes are the most detrimental. Operating presses near external overhead doors is far too risky and pits operators against the odds, often having to adjust for 10- to 15-degree temperature swings in a matter of minutes. Furthermore, presses can develop a “cold side” or “cold corner” as a result of cold air blowing through the room. Uneven heat across the press bed greatly reduces product quality and increases scrap rates.
There is more to temperature control than ambient temperatures. Anything that is brought into the environment becomes part of the environment. Producers may keep their pressroom at 72F, yet, if the substrate and laminate are brought into the pressroom at well under 65F, all that effort was for naught.
The principles for substrate and material temperatures are virtually the same as ambient temperatures with some qualifications.
Avoid temperature extremes: Just like ambient temperatures, materials below 65F can cause serious problems. Glue activation becomes extremely difficult as cold core materials absorb the heat too quickly, cooling the glue before it has a chance to activate. Operators will be forced to overheat the laminate in order to reach acceptable glue line temperatures, leading to surface quality changes, “blowouts,” and more.
When it comes to the upper end of the spectrum, things are a little different. Though it is possible to press successfully in a room that is 90F, pressing with a substrate that warm is extremely difficult. Glue line temperatures need to drop to somewhere around 120F or below before pressure is released or the laminate will begin to lift away from interior profiles and edges.
Avoid temperature swings: Major swings in material temperatures are never a good idea.
Use thermometers to frequently check substrate, laminate, membrane and platen temperatures. A thermometer is also useful in checking temperatures as the product exits the press to make sure it’s not coming out too hot and that acceptable glue line temperatures have been reached.
More pressroom tips
Avoid close proximity to debris-producing equipment: Locating a press next to a router is simply a bad idea. Anything that produces debris that can be seen with the naked eye can leave a deposit underneath the laminate that will show through after pressing.
Avoid all sources of excessive air flow: Keep air flow as gentle as possible. Never position any part of the process from glue application or beyond anywhere near a door that is frequently opened to the outside.
Avoid high humidity: The higher the humidity, the longer it takes for glue to dry, and the more the glue tends to dive into the board, causing insufficient glue levels on the edges. Longer dry times can also mean parts are pressed before they are dry which can lead to “pillowing,” where the overlay pulls away from the substrate to form a large bubble.
Avoiding high humidity levels will also go a long way in reducing scrap rates and edge delamination.
Source: Bill Formella is a longtime veteran in the 3D laminating industry with extensive involvement in every facet including machinery, materials, supplies, as well as training and technical support. He is the Technical Applications specialist for Smartech International and writes the Tech|Tips - 3DL blog. For information contact Smartech at 704-362-1922, SmartechOnline.com. You can also contact Bill at [email protected].
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