Abrasive jet micromachining of polymethylmethacrylate

A level set methodology for predicting the surface evolution of inclined masked micro-channels resulting from abrasive jet micro-machining at oblique incidence

“…The model was further extended to the AJM of ductile materials, such as PMMA and polycarbonate [2,10], by using a semi-empirical function to describe the dependence of the erosion rate on the angle of attack [2]. In another work, Ghobeity et al [11] developed an analytical model to approximate the spatial distribution of 'erosive efficacy', i.e.…”

“…mass of material removed per unit mass of erodent particle launched, at normal incidence (a¼901) [18]. PMMA, on the other hand, behaves in a ductile erosive manner, with a maximum erosion rate at shallow angles of attack [2,18]. The AJM process models that will be developed for these two materials are thus applicable to a wider class of ductile and brittle erosive systems by simply specifying different erosive system parameters.…”

“…The AJM process models that will be developed for these two materials are thus applicable to a wider class of ductile and brittle erosive systems by simply specifying different erosive system parameters. In all machining experiments, aluminum oxide particles of 25 mm nominal diameter were blasted using a microblaster (MB 1005 Microblaster, Comco Inc., Burbank, CA, USA) into which a mixing device was incorporated to prevent particle bed compaction [2]. The use of a constant blasting pressure of 200 kPa and a round 0.76 mm inner diameter nozzle placed at a standoff distance, h, of 20 mm ( Fig.…”

“…Scanning speeds of 1 and 0.5 mm s À 1 were used in machining the glass and PMMA channels, respectively, over a 15 mm length. These scanning speeds ensured that particle embedding and temperature effects in PMMA were minimized [2]. The average abrasive particle mass flow rate was measured before and after each channel was machined, by weighing with a micro-mass balance (accuracy¼0.01 mg) the amount of powder blasted for a minute into a special container that was covered with filter material which prevented the particles escaping, while also preventing back pressure.…”

“…AJM has been used to machine a wide array of microcomponents for use in the electronics, Micro-Electro Mechanical Systems (MEMS), microfluidic, and opto-electronic industries [2]. For example, AJM has been used to micro-machine glass to produce three-dimensional (3D) suspended micro-cantilever beams for inertial sensors [3], microfluidic channels [4] and high aspect ratio (AR), i.e.…”