Thermal analysis of cryogenically assisted abrasive jet micromachining of PDMS

Getu, H.; Spelt, J.K.; Papini, M.

doi:10.1016/j.ijmachtools.2011.05.003

Cited by 23 publications

(7 citation statements)

References 51 publications

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“…The finite element predictions were compared with experimental results. Much of the material in this chapter has been published in [101,102].…”

Section: Thermal Analysis Of Cryogenically Assisted Abrasive Jet Micro-machining Of Pdmsmentioning

confidence: 99%

Abrasive Jet Micro-Machining of Polymeric Materials

Hailu¹

2023

Preprint

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In the abrasive jet micro-machining (AJM) process, a jet of small particles is directed through an erosion resistant mask opening so that micro-sized features (i.e., micro-channels, holes, etc.) can be machined for the fabrication of micro-devices such as micro-fluidic and micro-electro-mechanical-systems (MEMS). Polymeric materials and elastomers have found applications in a wide variety of micro-devices. This thesis investigates the AJM of such materials, addressing the major challenges that must be overcome in order for the process to gain wider acceptance in industry. The thesis first presents a novel cryogenically assisted abrasive jet micro-machining (CAJM) technique that enables the micro-machining of elastomers such as polydimethylsiloxane (PDMS) that cannot be machined at room temperature. It was found that the erosion rate during CAJM is greatly increased, and the degree of particle embedment greatly decreased, compared to room temperature experiments. A finite element (FE) analysis was used to investigate the relationships between erosion, the heat transfer of the cooling jet and the resulting target temperature during the CAJM of channels in PDMS. The analysis illustrated the asymmetric nature of the cooling with much more cooling occurring towards the trailing edge of the jet. It was found that the predicted shape of the evolving machined surface profiles was improved significantly when a FE model was used to account for thermal distortion occurring during the CAJM process. An unwanted consequence of the AJM of polymeric materials was found to be particle embedding. Criteria leading to the embedding of spherical and angular particles in such materials were identified and modelled using rigid plastic analyses. It was found that the likelihood of embedding was proportional to the static coefficient of friction between the particle and the target for angular particles, and the depth of penetration for spherical particles. Scanning electron microscopy with EDX was used to measure the area coverage of embedded Al2O3 particles in polymers and elastomers, in order to evaluate various cleaning methods that were developed. It was found that glass bead blasting at 45˚ followed by the freezing technique was the best method to remove embedded particles, leading to 100% removal in some cases.

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“…The finite element predictions were compared with experimental results. Much of the material in this chapter has been published in [101,102].…”

Section: Thermal Analysis Of Cryogenically Assisted Abrasive Jet Micro-machining Of Pdmsmentioning

confidence: 99%

Abrasive Jet Micro-Machining of Polymeric Materials

Hailu¹

2023

Preprint

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“…Getu et al also published another paper [30] which investigated the temperature distribution beneath the abrasive jet for a stationary and moving substrate of PDMS using their CAJM setup. The authors found that the thermal front moved approximately 12 times faster than the material removal front.…”

Section: Cryogenic Erosion Of Polymers and Steelsmentioning

confidence: 99%

Cryogenic Abrasive Jet Machining of Polydimethylsiloxane and Polytetrafluoroethylene at Different Temperatures

Gradeen¹

2021

Preprint

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The temperature dependence of the solid particle erosion of polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE) and high carbon steel using aluminum oxide particles was investigated. The most efficient machining of PDMS occurred at approximately -178°C, at angles of attack between 30° and 60°. Although it was demonstrated that PDMS could be machined at temperatures above its glass transition, the erosion rate increased by a factor of more than 10 when the machining temperature was below this point. The maximum erosion in PTFE occurred at the coldest temperature of -177°C between the angles of 30 and 90°. This scenario improved the erosion rate by more than a factor of five. The erosion rate in high carbon steel was increased approximately twofold when lowering the temperature from 17°C to -177°C. The surface evolution results presented can be used to predict feature shapes both polymers while minimizing cooling costs, minimizing mask wear or maximizing substrate erosion.

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“…[1]. AJM can be used to machine glass [2][3][4][5], ceramics [6], metallic materials [7][8][9] and a variety of polymers [10][11][12][13][14].…”

Section: Motivationmentioning

confidence: 99%

The Effect Of Tangential Velocity Component In Abrasive Jet Micro-Machining Of Borosilicate Glass

Hasem¹

2021

Preprint

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Generally two types of erosion testers are used in solid particle erosion testing: air blast erosion testers and mechanically powered erosion testers. In the first portion of this thesis, the feasibility of implementing a mechanically powered erosion tester for abrasive jet micro-machining applications using very small particles was studied. It was found that, due to the ultrahigh vacuum requirement, such a device would not be practical. Therefore, in the second part of the thesis, the designed rotary mechanism was utilized as a rotary disc target holder apparatus and blasted with a typical air blast system. The apparatus could add or deduct a tangential velocity component into the system, allowing for detailed studies of the effect that the tangential velocity component has on the erosion of borosilicate glass using 25-150 μm aluminum oxide particles. Although the tangential velocity effect has been ignored for brittle materials by most researchers, the present results show that it can have an important role in erosion rate.Generally two types of erosion testers are used in solid particle erosion testing: air blast erosion testers and mechanically powered erosion testers. In the first portion of this thesis, the feasibility of implementing a mechanically powered erosion tester for abrasive jet micro-machining applications using very small particles was studied. It was found that, due to the ultrahigh vacuum requirement, such a device would not be practical. Therefore, in the second part of the thesis, the designed rotary mechanism was utilized as a rotary disc target holder apparatus and blasted with a typical air blast system. The apparatus could add or deduct a tangential velocity component into the system, allowing for detailed studies of the effect that the tangential velocity component has on the erosion of borosilicate glass using 25-150 μm aluminum oxide particles. Although the tangential velocity effect has been ignored for brittle materials by most researchers, the present results show that it can have an important role in erosion rate.

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Thermal analysis of cryogenically assisted abrasive jet micromachining of PDMS

Cited by 23 publications

References 51 publications

Abrasive Jet Micro-Machining of Polymeric Materials

Abrasive Jet Micro-Machining of Polymeric Materials

Cryogenic Abrasive Jet Machining of Polydimethylsiloxane and Polytetrafluoroethylene at Different Temperatures

The Effect Of Tangential Velocity Component In Abrasive Jet Micro-Machining Of Borosilicate Glass

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