With the rapid development of CTP technology, as well as the CTP plate price keeps decreasing, the use of CTP plates is also rapidly surpassing the traditional PS plate. Is there any difference of PS plate and CTP plate’ requirements on the aluminum base plate? Haomei likes to make a comparison.
1. Difference in the thickness of aluminum base plate
The thickness of the aluminum base plate for CTP plate is generally 0.280 mm, which is slightly thicker than the PS plate(the thickness of the PS plate base is 0.270mm ± 0.005mm). Some CTP plate producers also use a 0.275mm aluminum base plate with a thickness tolerance of ± 0.005mm. When the aluminum plate is thicker, it is not easier to bend.
2. Difference in width of aluminum coil
The width tolerance of aluminum coils is required to be ≤ ± 0.5mm, preferably no tolerance. There are also clear requirements for the cutting quality of aluminum coils, that is, there should be no burrs or curling on both sides of the aluminum coil after slitting.
3. Longitudinal and transverse uniformity of the base plate
The longitudinal and transverse thickness tolerances of the aluminum base plate shall be ≤± 0.005mm. Too large tolerance will affect the platemaking. And the parameters set by the CTP platemaking machine generally do not allow random adjustment.
4. Difference between CTP plate and PS plate on the electrolytic performance
Because the CTP plate are mostly used for high-end color printing, the basic grain value should be thinner than that of of PS plates. The CTP Ra is generally 0.45 to 0.60㎛, and the ideal value is 0.45 to 0.55㎛. The Ra value of the PS plate is generally 0.60 to 0.80㎛.
In order to get a fine and uniform grain layer, the composition of the aluminum base plate is very important, that is, the aluminum alloy elements and their respective content.