The coefficient of friction (COF) is a
significant topic in the world of friction coefficient which is defined as a
friction force that oppose shear movements divided by normal style to the
surface. People run different (most people demand consistent COF between 0.25 -
0.3 running normally) quick steps to quickly demand higher friction. The
importance is in how substrates move through and cross print stations, conveyor
belts, to containers, or released from mandrel or loading after processing.
Film with a COF value greater than 0.5 is considered not slipping. COF is
usually determined for the process provided and adjusted to the printer with
ink or varnish as needed.
There are two types of COF: static, the
style needed to start movement, and kinetic, the style needed to maintain
movement. In general, the static COF is more than a greater concern for stacked
or palatial items, while Kinetic COF is used for film roll. COF provides a
relative indication of friction characteristics and is routinely determined in
substrates such as plastic films.
Depending on the packaging application,
high or low can be desired. When the material traction feed system is used, or
if the application calls for an easy-to-hold container where the slippery
surface will be difficult to control, high COF will be profitable. Conversely,
the condition in which an ingredient is drawn through a forming collar, such as
the vertical shape, the contents and seals (VFFS) equipment, low COF is
considered profitable. Likewise, if the dry arm is applied through high-speed
equipment, low COF is usually the best performing.
COF Testing
COF or friction test coefficient is used to
determine the friction force between two ingredients. COF tests are carried out
on various materials such as plastic and polymers, lubricants, ceramic tiles,
etc. After COF testing, the value varies depending on the test material
Why is COF needed in packaging?
So what should COF do with an automatic
packaging line? Lots. More specifically to form a seal form machine, COF
packaging films refer to the 'slip' level that is owned packaging materials
while interacting with various engine parts.
For seal machines fill vertical shapes in
particular, packaging films interact with engine components called pull belts.
The pull belt presses the outside of the film, memorizes between belts and the
forming tube, helps draw it through the packaging system. To optimize
performance, there must be enough friction on the outside of the film to
overcome friction inside. In other words, the inside of the film must be
'slippery' enough to be able to slide on the assembly of the forming tube (FTA)
when the belt pulls drawing movies through the machine.
Factors that influence COF testing
COF can be influenced by a number of
factors including anti-block additives, corona treatment, anti-stat, ink,
varnish, adhesive. Because laboratory testing cannot simulate each element of
each packaging process, the COF should not be considered as an indication of
system specific performance. Instead, the means to reproduce friction is proven
to be successful in a set of certain conditions.
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