A Better Machine That Takes Advantage of Innovative Technologies
The demand for release coated papers and films was becoming greater than our clients capability with their current equipment. When options for being able to produce wider web widths, larger roll diameters, while utilizing a greater variety of substrates became more of the norm for their orders, their existing coating line was quickly falling behind.
The customer turned to Midwest Engineered Systems to explore a more sophisticated version of their existing process. After analyzing and understanding the customer’s current coating and web handling processes, MWES engineered a new machine that took advantage of innovative technologies that addressed all the varieties of their production demands and issues.
Technologies Used in This Application
MWES’s 65” gravure silicone coating line included many different components, from unwind to rewind to produce the variety of items in the client’s product line up. 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” and 52” and weighing up to 5000 lbs. with complete floor pick-up capability. Core diameters can range from 3” to 6” ID. 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 p.l.i. 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 main frame 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” long IR drying system where the ink is dried to prevent from smudging. The printing is applied to the back side of the web and provides the capability to customize products in line for individual client needs.
After the printing application, the web goes into the three roll 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’-0” long Advanced Systems Inc. two zone flotation drying system powered by natural gas. The dryer has the capability to heat the web up 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” 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 75F-90F. 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 45F-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 has 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 back side 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” diameter and 65” web width. Core diameter capability of 3” or 6” is available. An air loaded layon roll provides enhanced winding capability to produce the roll hardness specifications required for the 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 prior to 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 p.l.i.
The drive and control system on board 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 19” and 10” HMI screens located on pivoting arms at each end of the line. The control system includes an ignition systems based operating system which manages the maintenance, diagnostics, and recipe systems available. Local operator controls and E-stop system are also located along the line in required positions.
Impact to the Customer
The system solution that MWES engineered featured a number of process improvements and designs that helped the new line see an increase in speed, and cost effectiveness. The previous system had a 36” web width capacity where the new line can run up to 65” web widths. Maximum web speeds of 1000 f.p.m. more than double the operating speed of the older unit which was around 400 f.p.m. The new inline printing capability increased efficiency by having just one machine rather than two. The drying capability of the new flotation system also is more sophisticated with a faster and more effective heat transfer process. Lastly, the new line features enhanced web control for a variety of substrate basis weights with expertly designed drive and tension control equipment. These attributes assure the process runs smoothly with minimum manpower.
For more information on this equipment or other web handling needs please contact MWES.