The frost line is a term used in
plastic
Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...
film
A film also called a movie, motion picture, moving picture, picture, photoplay or (slang) flick is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, feelings, beauty, or atmosphere ...
manufacturing by
extrusion
Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section. Its two main advantages over other manufacturing processes are its ability to create very complex c ...
. It refers to the point beyond the
die
Die, as a verb, refers to death, the cessation of life.
Die may also refer to:
Games
* Die, singular of dice, small throwable objects used for producing random numbers
Manufacturing
* Die (integrated circuit), a rectangular piece of a semicondu ...
where the temperature of the molten plastic falls below the softening point and the diameter of the extruded plastic bubble stabilizes. The term was borrowed from the notion of "
frost line
The frost line—also known as frost depth or freezing depth—is most commonly the depth to which the groundwater in soil is expected to freeze. The frost depth depends on the climatic conditions of an area, the heat transfer properties of the s ...
" in
soil science
Soil science is the study of soil as a natural resource on the surface of the Earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils; and these properties in relation to th ...
and refers to the frosted appearance of the plastic film above the "frost line".
The distance from the die is called the height of the frost line. It depends on various factors, including the melt temperature, the speed of cooling, the extrusion speed, and the diameter of the bubble. The notion is important, since the higher the frost line, the more difficult to control the uniformity of the film thickness.
For example, a higher frost line due to higher melt temperature and/or lower cooling rate means a longer time to solidify, and a more smooth and transparent film is produced.
{{DEFAULTSORT:Frost Line (Polymers)
Plastics industry