Similar to the manufacturing process for hot-press-dried Transformerboard, unbleached Kraft pulp along with pure water constitutes the basis of calendered board. The special properties of calendered board are produced on a board machine with a hot-air-dryer and sequencing calender. The whole manufacturing process chain from preparation of the pulp, forming and drying of the sheet material is monitored and controlled by modern process control systems. The development and in-line installation of a highly sensitive metal detector guarantees board free from metallic particles.
Field of Application
Typical applications of calendered board are curved pieces like cylinders with small diameters, punchings, stamped pieces and machine-formed parts in power, distribution and special transformers.
Transformerboard TI is manufactured in the Rapperswil plant in Switzerland according to standard of IEC 60641-3-1, type B 2.1. The range of density is from 1.10 g/cm³ to maximum 1.30 g/cm³; the range of thickness from 0.5 mm to 3.0 mm. Transformerboard TI can be classified as a high-density material.
Form-Val is manufactured at the St. Johnsbury plant in Vermont/USA according to standard of ASTM D4063, Type 2.2.1. The range of density is from 0.80 g/cm³ to maximum 1.05 g/cm³; the range of thickness from 1.0 mm to 4.0 mm. Form-Val can be classified as a low-density material.
Hi-Val is manufactured at the St. Johnsbury plant in Vermont/USA according to standard of ASTM D4063, Type 2.2.1. The range of density is from 0.90 g/cm³ to maximum 1.15 g/cm³; the range of thickness from 0.8 mm to 5.0 mm. Hi-Val can be classified as a medium-density material.
Pressboard TD12: Using lower purity fiber material, but the same board-manufacturing technology, results in a calendered product with relaxed electrical and mechanical properties. Pressboard TD12 was developed about two decades ago for the production of punched and embossed parts for distribution transformers. Pressboard TD12 features good flexibility and easy impregnation. To distinguish it from “normal kraft” Transformerboard, Pressboard TD12 is dyed reddish. The range of density is from 1.10 g/cm³ to maximum 1.30 g/cm³, for thicknesses of 0.5 mm to 3.0 mm. Pressboard TD12 is only used in distribution transformers.