A level set methodology for predicting the effect of mask wear on surface evolution of features in abrasive jet micro-machining

Burzynski, T.; Papini, M.

doi:10.1088/0960-1317/22/7/075001

Cited by 8 publications

(7 citation statements)

References 29 publications

(171 reference statements)

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“…For example, Wensink et al [29] used electroplated copper masks with AJM in order to create channels as small as 50 μm wide on glass, and observed them to be highly erosion resistant. Ghobeity et al [31] and Burzynski et al [32] used steel shims to machine and model the surface evolution of AJM features in glass and PMMA with aspect ratios (depth to width) greater than one.…”

Section: Mask Materials Used In Abrasive Jet Micro-machiningmentioning

confidence: 99%

“…Despite these advantages, they were found to not be suitable for making high aspect ratio features, since they are relatively thin, erode quickly, and can deform elastically [34]. Burzynski et al [32] modeled the effect of their wear on the surface evolution of features made using AJM, reported that the mask wear resulted in undesirable widening of the machined feature profiles in both brittle targets and ductile targets. In Chapter 6, elastomeric masks are used in a novel rotating mask configuration that extends their lifetime, whilst also increasing their flexibility to create a wider variety of features.…”

Section: Mask Materials Used In Abrasive Jet Micro-machiningmentioning

confidence: 99%

“…Papini [32] used narrow band level set methods (LSM) to predict the shape of inclined channels machined at oblique incidence using AJM on glass and PMMA. AJM has also made it possible to machine a variety of suspended structures such as accelerometers in glass, millimeter size cantilever beams, complex micro-structures and monolithic micro-structures [44,58].…”

Section: Introductionmentioning

confidence: 99%

“…AJM has also made it possible to machine a variety of suspended structures such as accelerometers in glass, millimeter size cantilever beams, complex micro-structures and monolithic micro-structures [44,58]. With the exception of Burzynski and Papini [32], none of these processes were rigorously modelled, and in all cases, models for predicting the process parameters leading to a particular desired shape were not presented.…”

Section: Introductionmentioning

confidence: 99%

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Sculpting Desired Topographies Using Abrasive Jet Micro-Machining

Sookhaklari¹

2021

Preprint

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Abrasive jet micromachining (AJM) uses a jet of high-speed particles to erode a wide variety of materials. Given a set of process parameters, surface evolution models capable of predicting the shape of straight, constant-depth channels in a wide variety of materials are well-established. This dissertation presents novel methods for solving the unaddressed more challenging and industrially relevant inverse problem of determining the process parameters required to machine a particular user-specified feature topography. Since the air driven jet used in AJM is divergent, the edges of the desired features are usually defined using a mask which is attached to the surface of the target material. This dissertation presents alternate techniques using stationary or moving shadow masks that can be moved over the surface and maskless techniques, in order to allow direct writing of desired features on the surface. A mathematical framework is then introduced to determine the direct writing source velocity function and path required to create a desired shallow topography. It is also shown how the methodology can be used with existing surface evolution models to predict the feature shape at any depth. The methodologies are demonstrated to work well for the AJM of constant depth micro-channels with user-specified cross-sectional shape, gradient etched micro-channels with specified texture along their length, and pockets with texture in two perpendicular directions. Finally, a new technique is introduced that utilizes a rotating patterned mask in order to control the AJM erosive footprint size and shape. Models for predicting the rotating mask pattern required to create virtually any desired footprint are presented, and experimentally verified for symmetric and asymmetric W-shaped, trapezoidal and wedge shaped footprints.

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Section: Mask Materials Used In Abrasive Jet Micro-machiningmentioning

confidence: 99%

Section: Mask Materials Used In Abrasive Jet Micro-machiningmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sculpting Desired Topographies Using Abrasive Jet Micro-Machining

Sookhaklari¹

2021

Preprint

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“…The predicted channel and eroded mask shapes were directly compared against measurements on channels machined in both glass and PMMA targets, using two different masks, thus verifying the predictive capability of the methodology. The majority of the material in this chapter has been submitted for publication and is currently under review [50].…”

Section: Motivationmentioning

confidence: 99%

Modelling surface evolution in abrasive jet micromachining using level set methods

Burzynski¹

2021

Preprint

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The time dependent surface evolution in abrasive jet micromachining (AJM) is described by a partial differential equation which is difficult to solve using analytical or traditional numerical techniques. These techniques can yield incorrect predicted profile evolution or fail altogether under certain conditions. More recently developed particle tracking cellular automaton simulations can address some of these limitations but are difficult to implement and are computationally expensive. In this work, level set methods (LSM) were introduced to develop novel surface evolution models to predict resulting feature shapes in AJM. Initially, a LSM-based numerical model was developed to predict the surface evolution of unmasked channels machined at normal and oblique jet impact angles (incidence), as well as masked micro-channels and micro-holes at normal incidence, in both brittle and ductile targets. This model was then extended to allow the prediction of: surface evolution of inclined masked micro-channels made using AJM at oblique incidence, where the developing profiles rapidly become multi-valued necessitating a more complex formulation; mask erosive wear by permitting surface evolution of both the mask and target micro-channels simultaneously at any jet incidence; and surface damage due to secondary particle strikes in brittle target micro-channels resulting from particle mask-to-target and target-to-target ricochets at any jet incidence. For all the models, a general ‘masking’ function was developed by applying previous concepts to model the adjustment to abrasive mass flux incident to the target or mask surfaces to reflect the range of particle sizes that are ‘visible’ to these surfaces. The models were also optimized for computational efficiency using an adaptive Narrow Band LSM scheme. All models were experimentally verified and, where possible, compared against existing models. Generally, good predictive capabilities and improvements over previous attempts in terms of feature prediction or execution time, were observed. The time dependent surface evolution in abrasive jet micromachining (AJM) is described by a partial differential equation which is difficult to solve using analytical or traditional numerical techniques. These techniques can yield incorrect predicted profile evolution or fail altogether under certain conditions. More recently developed particle tracking cellular automaton simulations can address some of these limitations but are difficult to implement and are computationally expensive.In this work, level set methods (LSM) were introduced to develop novel surface evolution models to predict resulting feature shapes in AJM. Initially, a LSM-based numerical model was developed to predict the surface evolution of unmasked channels machined at normal and oblique jet impact angles (incidence), as well as masked micro-channels and micro-holes at normal incidence, in both brittle and ductile targets.This model was then extended to allow the prediction of: surface evolution of inclined masked micro-channels made using AJM at oblique incidence, where the developing profiles rapidly become multi-valued necessitating a more complex formulation; mask erosive wear by permitting surface evolution of both the mask and target micro-channels simultaneously at any jet incidence; and surface damage due to secondary particle strikes in brittle target micro-channels resulting from particle mask-to-target and target-to-target ricochets at any jet incidence. For all the models, a general ‘masking’ functionwas developed by applying previous concepts to model the adjustment to abrasive mass flux incident to the target or mask surfaces to reflect the range of particle sizes that are ‘visible’ to these surfaces. The models were also optimized for computational efficiency using an adaptive Narrow Band LSM scheme.All models were experimentally verified and, where possible, compared against existing models. Generally, good predictive capabilities and improvements over previous attempts in terms of feature prediction or execution time, were observed.The proposed LSM-based models can be practical assistive tools during the micro-fabrication of complex MEMS and microfluidic devices using AJM.

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