Numerical Modelling of the Contact between Lithographic Printing Press Rollers by Soft EHL Theory

Xue, Y-K; Gethin, D. T.; Lim, C H

doi:10.1243/pime_proc_1994_208_381_02

Cited by 5 publications

(10 citation statements)

References 18 publications

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“…Since tribologists, unlike coating specialists, are concerned with load carrying capacity rather than flow rate and film thickness prediction, Reynolds conditions prove sufficient and so it has not been necessary to consider different boundary conditions. Other references of interest are Houpert & Hamrock (1986), Jaffar (1990) and Xue, Gethin & Lim (1994.…”

Section: Introductionmentioning

confidence: 99%

A model for deformable roll coating with negative gaps and incompressible compliant layers

et al. 2003

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A soft elastohydrodynamic lubrication model is formulated for deformable roll coating involving two contra-rotating rolls, one rigid and the other covered with a compliant layer. Included is a finite-strip model (FSM) for the deformation of the layer and a lubrication model with suitable boundary conditions for the motion of the fluid. The scope of the analysis is restricted to Newtonian fluids, linear elasticity/viscoelasticity and equal roll speeds, with application to the industrially relevant highly loaded or ‘negative gap’ regime. Predictions are presented for coated film thickness, inter-roll thickness, meniscus location, pressure and layer deformation as the control parameters – load (gap), elasticity, layer thickness and capillary number, $\hbox{\it Ca}$ – are varied. There are four main results: Hookean spring models are shown to be unable to model effectively the deformation of a compliant layer when Poisson's ratio $\nu\rightarrow 0.5$. In particular, they fail to predict the swelling of the layer at the edge of the contact region which increases as $\nu\rightarrow 0.5$; they also fail to locate accurately the position of the meniscus, $X_M$, and to identify the presence, close to the meniscus, of a ‘nib’ (constriction in gap thickness) and associated magnification of the sub-ambient pressure loop.Scaling arguments suggest that layer thickness and elasticity may have similar effects on the field variables. It is shown that for positive gaps this is true, whereas for negative gaps they have similar effects on the pressure profile and flow rate yet quite different effects on layer swelling (deformation at the edge of the contact region) and different effects on $X_M$.For negative gaps and $\hbox{\it Ca}\,{\sim}\,O(1)$, the effect of varying either viscosity or speed and hence $\hbox{\it Ca}$ is to significantly alter both the coating thickness and $X_M$. This is contrary to the case of fixed-gap rigid roll coating.Comparison between theoretical predictions and experimental data shows quantitive agreement in the case of $X_M$ and qualitive agreement for flow rate. It is shown that this difference in the latter case may be due to viscoelastic effects in the compliant layer.

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Section: Introductionmentioning

confidence: 99%

A model for deformable roll coating with negative gaps and incompressible compliant layers

et al. 2003

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“…The finite thickness of the elastomeric layer increases the effective stiffness of the roller contact, which influences the pressure build-up and film height in the roller contact. [20][21][22][23] In literature, analytical and numerical models are presented to simulate the residual layer thickness in rollerbased imprint systems. 4,24,25 Moreover, when excluding the textures, roller-based imprinting shows a resemblance with forward roll coating and printing.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Elastohydrodynamic lubrication of soft-layered rollers and tensioned webs in roll-to-plate nanoimprinting

Snieder

Dielen²,

Ostayen

2023

Proceedings of the Institution of Mechanical Engineers, Part J:

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This work presents the development of a numerical model for the elastohydrodynamic lubrication of roll-to-plate nanoimprinting with flexible stamps. Roll-to-plate nanoimprinting is a manufacturing method to replicate micro- and nanotextures on large-area substrates with ultraviolet-curable resins. The roller is equipped with a relatively soft elastomeric layer, which elastically deforms during the imprint process. The elastic deformation is described by linear elasticity theory. It is coupled to the pressure build-up in the liquid resin film, which is described by lubrication theory. The flexible stamp, which is treated as a tensioned web, is pre-tensioned around the roller. The elastic deformation of the tensioned web is described by the large-deflection bending of thin plates equations, considering its non-negligible bending stiffness. A Fischer–Burmeister complementarity condition captures the contact mechanics between the tensioned web and the roller. The governing equations combine in a coupled elastohydrodynamic lubrication model, which is fully described by a set of non-dimensional numbers. These are used in a parameter study to investigate the effect on the pressure and film height distributions. It is shown that the bending stiffness of the tensioned web results in an additional hydrodynamic pressure peak and corresponding minimum in the film height, near the inlet of the roller contact. An increase of the bending stiffness corresponds to a decrease in film height. The numerical results are compared with benchmarks from literature and experimentally validated with layer height measurements from flat layer imprints. Good agreement is found between the numerical and experimental results.

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“…The result is a strong coupling between the hydrodynamic and elastic effects, which is described by elastohydrodynamic lubrication (EHL) theory. The working principle behind roller-based imprint systems is analogous to roller-based coating and printing processes [ 27 , 28 , 29 , 30 ]. These studies also use EHL theory for the prediction of the coating or printing layer height.…”

Section: Introductionmentioning

confidence: 99%

“…These studies also use EHL theory for the prediction of the coating or printing layer height. When the thickness of the elastomeric layer is relatively small, it influences the elastic deformation and its finite thickness needs to be taken into account [ 28 , 31 , 32 , 33 ]. Cochrane also employs EHL theory to predict the RLT in a roll-to-roll set-up to imprint deformable substrates [ 34 ].…”

Section: Introductionmentioning

confidence: 99%

Simulating the Residual Layer Thickness in Roll-to-Plate Nanoimprinting with Tensioned Webs

Snieder

Dielen²,

Ostayen

2022

Micromachines

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Roll-to-plate nanoimprinting with flexible stamps is a fabrication method to pattern large-area substrates with micro- and nanotextures. The imprint consists of the preferred texture on top of a residual layer, of which the thickness and uniformity is critical for many applications. In this work, a numerical model is developed to predict the residual layer thickness (RLT) as a function of the imprint parameters. The model is based on elastohydrodynamic lubrication (EHL) theory, which combines lubrication theory for the pressure build-up in the resin film, with linear elasticity theory for the elastic deformation of the roller material. The model is extended with inextensible cylindrical shell theory to capture the effect of the flexible stamp, which is treated as a tensioned web. The results show that an increase in the tension of the web increases the effective stiffness of the roller, resulting in a reduction in the RLT. The numerical results are validated with layer height measurements from flat layer imprints. It is shown that the simulated minimum layer height corresponds very well with the experimental results for a wide range of resin viscosities, imprint velocities, and imprint loads.

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Numerical Modelling of the Contact between Lithographic Printing Press Rollers by Soft EHL Theory

Cited by 5 publications

References 18 publications

A model for deformable roll coating with negative gaps and incompressible compliant layers

A model for deformable roll coating with negative gaps and incompressible compliant layers

Elastohydrodynamic lubrication of soft-layered rollers and tensioned webs in roll-to-plate nanoimprinting

Simulating the Residual Layer Thickness in Roll-to-Plate Nanoimprinting with Tensioned Webs

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