Silicone Coating Line System

MWES’s 65-inch gravure silicone coating line includes many different components, from unwinding to rewinding to produce a variety of items in the client’s product lineup. Each stage in the system was selected for an important function for the complete manufacturing process. The web handling system was engineered for maximum diversification for all types of processes.

The process begins with the paper being loaded into the shaftless unwind. The MWES-designed unwind system is capable of handling roll diameters between 15 to 52 inches and weighing up to 5,000 lbs. with complete floor pick-up capability. Core diameters can range from 3 to 6 inch inside diameter. The module has an infeed pull roll nip and dancer-operated tension control system capable of precise web tensions from 0.5 to 2.5 PLI. An Accuweb web guide is also included on the unit to provide accurate positioning of the substrate as it moves to the downstream processes.

A single-color flexographic print module is also configured in the mainframe of the unwind module. Water-based inks can be applied with a sleeved plate cylinder and mandrel and a ceramic Anilox roll printing system. The ink delivery is accomplished via an enclosed doctor blade system and Graymills fluid delivery unit. The paper then travels into a 54-inch long IR drying system where the ink is dried to prevent smudging. The printing is applied to the backside of the web and provides the capability to customize products in line with individual client needs.

After the printing application, the web goes into the three rolls offset gravure coater. The coater is capable of applying a wide variety of coat weights of 100% solids or emulsion-based release coatings via ceramic laser engraved gravure rolls and a Harris and Bruno enclosed doctoring system. The Applicator Roll design has a quick change rubber-covered sleeve system and mandrel for quick width changeover. The coating rolls can be set up to operate with the operator HMI controls to provide a wide variety of speed ratios to deliver precise coat weight and coverage on the web. The nips are designed with precision bearings and pneumatic cylinder loading. Gap control is set by the operator manually and measured with displacement feedback devices to deliver precise measurement feedback.

Immediately downstream of the coater module is a 45-foot-long Advanced Systems Inc. two-zone flotation drying system powered by natural gas. The dryer can heat the web to 450°F to properly cure the applied coatings. The unique attributes of the flotation drying technology keep the web drying profile very efficient and the paper curl to a minimum.

A chill module containing three 14-inch diameter chrome mono-flow chill rolls is provided for cooling the web after exiting the dryer. The chill rolls are capable of reducing web temperatures immediately exiting the dryer back to ambient conditions of 75-90°F. This module also has an integrated pull roll and nip and load cells to maintain precise web tensions throughout the drying system.

A 40-ton air-cooled chiller was installed to provide cold water at temperatures as low as 45-50°F to the chill rolls as well as the coater impression and gravure rolls. Ductwork was provided on the chiller to divert air inside or outside of the coating room to take advantage of the heat reclamation in the winter months.

After the web temperature had been dropped from the drying and curing process, a CMS moisturizer unit was located in line to add a thin layer of water back onto the backside of the substrates via a hydrophilic roll system. This unit will remove any remaining curl in the substrate developed from the applied coatings.

The last step of the process is the rewind module. The MWES rewind is outfitted with single-position shaftless or shafted winding capability for producing rolls from 15 to 50-inch diameter and 65 inches web width. A core diameter capability of 3 or 6 inches is available. An air-loaded layon roll provides the enhanced winding capability to produce the roll hardness specifications required for a wide variety of substrates. The unit also has a shear slitting station for web trimming and multi-roll slitting. Upstream of the slitter is an Accuweb pivoting web guide unit to provide accurate positioning of the substrate before slitting and winding. Tension control at the rewind is also maintained by a dancer-operated tension control system capable of precise web tensions from 0.5 to 2.5 PLI.

The drive and control system onboard the machine consists of Allen Bradley AC vector drives and a Safety PLC system. The safety PLC monitors all machine functions and the interlocked guard and operator safety systems. Operator controls are accomplished by HMI screens located on pivoting arms at each end of the line. The control system includes an ignition systems-based operating system that manages the maintenance, diagnostics, and recipe systems available. Local operator controls and an emergency stop system are also located along the line in required positions.