The main material used in PVC, but ABS cellulose acetate. After all the material have been mixed, its is transported the first of a 'two roll mill' where its is then banded onto one roll. The material passes through a series of roller usually decreasing thickness as the process continues. The rollers have a surface area between 160 and 220 degrees this is required in the production of PVC. The distance between the rollers controls sheet thickness. Machines usually have three pairs of nip roller points this enables the material to gradually be reduced in thickness.
The film is then tranfered to a 'post calender chain' , a series of cooler rollers where the temperature of each roller decreases in temperature by 2-5 degrees celcius.
The film is finally rolled onto rolls, the entire process is shown below.
The film thickness of thin sheet material such as plastic sheets needs to be known as it will influence properties such as the sheet stiffness - i.e.
ReplyDeleteThis film thickness would only be suitable for small poster frames.
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