Cutting to the Point: Directly Machined Metal Molds for Directional Gecko-Inspired Adhesives

2021 ◽  
Author(s):  
Amar Hajj-Ahmad ◽  
Srinivasan A. Suresh ◽  
Mark R. Cutkosky
Keyword(s):  
Lower Bound ◽  
Material Removal ◽  
Process Efficiency ◽  
Tool Deflection ◽  
Orthogonal Machining ◽  
Dry Adhesives ◽  
Comparable Performance ◽  
Series Of Experiments ◽  
Removal Processes ◽  
Fea Analysis

Abstract Fabrication techniques for gecko-inspired adhesives generally target mold durability, adhesive performance, and process efficiency and simplicity. With these goals in mind, we present a micromachining process for creating reusable aluminum molds used to fabricate directional dry adhesives. The molds require deep, narrow and overhanging grooves to create sharp and angled adhesive features. This geometry precludes most traditional machining and lithographic material removal processes. The presented process is a hybrid of indenting and orthogonal machining, using a diamond-coated microtome blade as the tool. An FEA analysis reveals the local extent of work hardening as each groove is created, and helps to define a trajectory that reduces the effects of tool deflection and chip build up. The results of a series of experiments agree with predictions from the analysis and reveal a range of blade approach angles and a lower bound on groove spacing to achieve the desired geometry. This range is narrower than for molds machined from wax in previous work. Nonetheless, adhesive samples cast from the new metal molds achieve comparable performance to those previously cast from wax.

scholarly journals Effect of Water-Based Nanolubricants in Ultrasonic Vibration Assisted Grinding

2018 ◽  
Vol 2 (4) ◽  
pp. 80 ◽  
Author(s):  
Mir Molaie ◽  
Ali Zahedi ◽  
Javad Akbari
Keyword(s):  
Surface Roughness ◽  
Specific Energy ◽  
Material Removal ◽  
Normal Force ◽  
Tangential Force ◽  
Process Efficiency ◽  
Multiwall Carbon Nanotube ◽  
Ultrasonic Vibrations ◽  
Mql Grinding ◽  
Water Based

Currently, because of stricter environmental standards and highly competitive markets, machining operations, as the main part of the manufacturing cycle, need to be rigorously optimized. In order to simultaneously maximize the production quality and minimize the environmental issues related to the grinding process, this research study evaluates the performance of minimum quantity lubrication (MQL) grinding using water-based nanofluids in the presence of horizontal ultrasonic vibrations (UV). In spite of the positive impacts of MQL using nanofluids and UV which are extensively reported in the literature, there is only a handful of studies on concurrent utilization of these two techniques. To this end, for this paper, five kinds of water-based nanofluids including multiwall carbon nanotube (MWCNT), graphite, Al2O3, graphene oxide (GO) nanoparticles, and hybrid Al2O3/graphite were employed as MQL coolants, and the workpiece was oscillated along the feed direction with 21.9 kHz frequency and 10 µm amplitude. Machining forces, specific energy, and surface quality were measured for determining the process efficiency. As specified by experimental results, the variation in the material removal nature made by ultrasonic vibrations resulted in a drastic reduction of the grinding normal force and surface roughness. In addition, the type of nanoparticles dispersed in water had a strong effect on the grinding tangential force. Hybrid Al2O3/graphite nanofluid through two different kinds of lubrication mechanisms—third body and slider layers—generated better lubrication than the other coolants, thereby having the lowest grinding forces and specific energy (40.13 J/mm3). It was also found that chemically exfoliating the graphene layers via oxidation and then purification prior to dispersion in water promoted their effectiveness. In conclusion, UV assisted MQL grinding increases operation efficiency by facilitating the material removal and reducing the use of coolants, frictional losses, and energy consumption in the grinding zone. Improvements up to 52%, 47%, and 61%, respectively, can be achieved in grinding normal force, specific energy, and surface roughness compared with conventional dry grinding.

scholarly journals Insights on the Influence of Surface Chemistry and Rim Zone Microstructure of 42CrMo4 on the Efficiency of ECM

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2132
Author(s):  
Alexander Schupp ◽  
Oliver Beyss ◽  
Bob Rommes ◽  
Andreas Klink ◽  
Daniela Zander
Keyword(s):  
Mixed Oxide ◽  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Material Removal ◽  
Chemical Elements ◽  
Nitrate Solution ◽  
Electrochemical Machining ◽  
Process Efficiency ◽  
Negative Effect ◽  
Sodium Nitrate Solution

The electrochemical machining (ECM) of 42CrMo4 steel in sodium nitrate solution is mechanistically characterized by transpassive material dissolution and the formation of a Fe3−xO4 mixed oxide at the surface. It is assumed that the efficiency of material removal during ECM depends on the structure and composition of this oxide layer as well as on the microstructure of the material. Therefore, 42CrMo4 in different microstructures (ferritic–pearlitic and martensitic) was subjected to two ECM processes with current densities of about 20 A/cm2 and 34 A/cm2, respectively. The composition of the process electrolyte was analyzed via mass spectrometry with inductively coupled plasma in order to obtain information on the efficiency of material removal and the reaction mechanisms. This was followed by an X-ray photoelectron spectroscopy analysis to detect the chemical composition and the binding states of chemical elements in the oxide formed during ECM. In summary, it has been demonstrated that the efficiency of material removal in both ECM processes is about 5–10% higher for martensitic 42CrMo4 than for ferritic–pearlitic 42CrMo4. This is on one hand attributed to the presence of the cementite phase at ferritic–pearlitic 42CrMo4, which promotes oxygen evolution and therefore has a negative effect on the material removal efficiency. On the other hand, it is assumed that an increasing proportion of Fe2O3 in the mixed oxide leads to an increase in the process efficiency.

scholarly journals A molecular dynamics based digital twin for ultrafast laser material removal processes

2020 ◽  
Vol 108 (1-2) ◽  
pp. 413-426 ◽  
Author(s):  
Panagiotis Stavropoulos ◽  
Alexios Papacharalampopoulos ◽  
Lydia Athanasopoulou
Keyword(s):  
Molecular Dynamics ◽  
Material Removal ◽  
Ultrafast Laser ◽  
Laser Material ◽  
Digital Twin ◽  
Removal Processes

scholarly journals Improvement of Machining Processes: A Case Study

2019 ◽  
Vol 2 (3) ◽  
pp. 634-641
Author(s):  
Hakan Gökçe ◽  
Ramazan Yeşilay ◽  
Necati Uçak ◽  
Ali Teke ◽  
Adem Çiçek
Keyword(s):  
Material Removal ◽  
Current Practice ◽  
Complex Geometry ◽  
Vital Role ◽  
Machining Process ◽  
Machining Processes ◽  
Machining Time ◽  
Machining Strategy ◽  
Removal Processes

In material removal processes, determination of optimal machining strategy is a key factor to increase productivity. This situation is gaining more importance when machining components with complex geometry. The current practice in the determination of machining strategy mostly depends on the experience of the machine operator. However, poorly designed machining processes lead to time-consuming and costly solutions. Therefore, the improvement of machining processes plays a vital role in terms of machining costs. In this study, the machining process of a boom-body connector (GGG40) of a backhoe loader was improved. Improvements of toolpaths and cutting conditions of 22 different material removal processes were checked through a CAM software. According to the simulation results, the process plan was rearranged. Besides, some enhancements in casting model were conducted to decrease in the number of machining operations. When compared to current practice, a reduction of 55% in machining time was achieved.

scholarly journals Temperature sensor based on fiber optic pyrometer in material removal processes

2012 ◽  
Author(s):  
A. Tapetado ◽  
C. Vázquez ◽  
X. Soldani ◽  
H. Miguélez ◽  
D. S. Montero
Keyword(s):  
Temperature Sensor ◽  
Material Removal ◽  
Fiber Optic ◽  
Removal Processes

Experimental Investigation of Polymeric Material Removal by Low Diffraction Laser Beam

2002 ◽  
Vol 124 (2) ◽  
pp. 475-480
Author(s):  
Xuanhui Lu ◽  
Y. Lawrence Yao ◽  
Kai Chen
Keyword(s):  
Laser Beam ◽  
Polymeric Material ◽  
Material Removal ◽  
Beam Quality ◽  
Power Level ◽  
Average Power ◽  
Laser Material ◽  
Theoretical Predictions ◽  
Removal Processes

Effects of improved beam quality of a low diffraction laser beam on laser material removal processes are experimentally investigated in a polymeric material. The experimental results are in agreement with theoretical predictions. The results show that the low diffraction beam has marked advantages over the Gaussian beam in ablation-dominated material removal processes in terms of larger depth and smaller taper at the same average power level.

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