GLUING, PRESSING & MATERIALS
Heat: 3DL expands when heated, especially across the
width of the material. The process of eliminating wrinkles
starts with finding the minimum acceptable temperature
and preheat time necessary to form the laminate over the
substrate and activate the glue.
In order to eliminate stretching of 3DL during preheating, it is important to bring the membrane and 3DL together
at the start of the cycle without pulling the 3DL up into the
upper chamber. This is best done by creating a “belly” in the
membrane as the press closes. A belly that is too large or too
small both present a problem. For optimum performance, the
belly needs to drop very slightly below the bottom surface of
the separation frame between the membrane and 3DL.
Milky “stretch” marks on 3DL surface
Recently I worked with a 3DL component producer that was
experiencing wrinkles across the width of very large parts. After
working our way through the process, the primary culprit was an
excessively large membrane belly upon press closing.
Immediately after eliminating the
large wrinkles by reducing the press
temperature, preheat time and membrane belly, we began to see what looked
like stretch marks. However, there were
no differences in surface quality to the
touch. It was just a slight irregularity in
appearance in certain lighting.
This is a problem that is rarely seen but can appear when trying to make fine changes to temperature and preheat time. When
the 3DL has not been conditioned completely via heat to stretch
evenly throughout all of its layers, this type of issue can arise. The
solution is simple – make very slight increases in press temperatures and/or preheat times until the problem disappears.
Source: Bill Formella is a 25-year veteran in the 3D laminating industry. 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 firstname.lastname@example.org.
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