Calibrating Artwork Scaling Factors for Heated Platen Brass Chases
Calibrating artwork scaling factors offsets brass thermal expansion and substrate heat shrinkage to achieve exact register alignment on hot platen presses.
Contact Pyrometry Metrology
Thermal Analysis
Surface temperature measurement of moving paper webs utilizes direct contact sensors to monitor heat transfer during calendering and drying. Engineers apply contact pyrometry metrology to verify the surface temperature of drying cylinders and heated nip rolls in paper machines. Accurate calibration guarantees that the thermal energy supplied to the web is uniform, which prevents localized over-drying or moisture variations that lead to paper cockling.
Contact Mechanism
Mechanical thermocouple probes must exert a consistent, controlled pressure against the moving surface to obtain reliable readings. Friction between the probe and the rotating drum can generate localized heat, which necessitates specific sensor geometries and materials like ribbon thermocouples to minimize friction errors. Proper mounting prevents the sensor from bouncing or losing contact, ensuring the logging of true thermal profiles during continuous production runs.
This continuous physical engagement ensures that the thermal energy transferred to the board during corrugation is sufficient to cure starch adhesive lines without scorching the linerboard fibers.
Measurement Tolerance
Physical wear on the sensor tip over extended operating hours changes the heat transfer coefficient of the contact junction. Calendering rolls running at high speeds can accelerate probe degradation, which introduces measurement drift that requires frequent recalibration against known reference sources. Optical sensors provide non-contact alternatives when surface speeds or scratching risks make physical contact impractical.