Theory of Operations
Rovema VPK Operators Manual
3/2000 VPK REV(B) PANELVIEW 600
4-4
Heat Sealing
Heat sealing is the process of bonding two sections of laminated film.
Laminated film is constructed of at least two layers of material: an
outer layer and an inner layer. The outer layer forms the support and
protective structure of a bag. The inner layer contains the adhesive
that will bond the sides of the outer layer together. Seals are created
when sections of the inner layer are pressed together and heated.
The heat melts the adhesive while the pressure mixes the adhesive
into one layer.
Sealing time, sealing temperature, and sealing pressure are the three
variables that govern the creation of horizontal and vertical seals. When
the SEAL MODE switch on the jaw profile screen is set to AUTO, the
bagmaker will determine the best sealing time. The sealing pressure is
set at the factory and should be sufficient for most heat sealing
applications. This leaves the sealing temperature setting as the most
useful tool that the operator can use to affect the quality of the horizontal
and vertical seals. When adjusting the sealing temperature, here are
some facts to keep in mind: The minimum temperature required to melt
the adhesive layer is approximately 180 Degrees. Temperatures above
350 Degrees tend to burn most laminated films. We suggest that you
set the temperature to around 280 Degrees and increase it towards
320 Degrees until the bagmaker is producing good seals. If you are
unable to produce good bags at below 320 Degrees, adjustments may
have to be made to the sealing time and/or the sealing pressure.
Note:
It is recommended that you set the SEAL MODE switch on the
jaw profile screen to AUTO. If you are unable to achieve quality
seals by changing the sealing temperature, contact the Rovema
Service Department for assistance.