scholarly journals High Aspect Ratio Thin-Walled Structures in D2 Steel through Wire Electric Discharge Machining (EDM)

Micromachines ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
Naveed Ahmed ◽  
Muhammad Ahmad Naeem ◽  
Ateekh Ur Rehman ◽  
Madiha Rafaqat ◽  
Usama Umer ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Structure Formation ◽  
High Aspect Ratio ◽  
Electrical Discharge Machining ◽  
Machining Processes ◽  
Thin Structures ◽  
Thin Sections ◽  
Thin Walled Structures ◽  
Machining Errors ◽  
D2 Steel

Thin structures are often required for several engineering applications. Although thick sections are relatively easy to produce, the cutting of thin sections poses greater challenges, particularly in the case of thermal machining processes. The level of difficulty is increased if the thin sections are of larger lengths and heights. In this study, high-aspect-ratio thin structures of micrometer thickness (117–500 µm) were fabricated from D2 steel through wire electrical discharge machining. Machining conditions were kept constant, whereas the structure (fins) sizes were varied in terms of fin thickness (FT), fin height (FH), and fin length (FL). The effects of variation in FT, FH, and FL were assessed over the machining errors (FT and FL errors) and structure formation and its quality. Experiments were conducted in a phased manner (four phases) to determine the minimum possible FT and maximum possible FL that could be achieved without compromising the shape of the structure (straight and uniform cross-section). Thin structures of smaller lengths (1–2 mm long) can be fabricated easily, but, as the length exceeds 2 mm, the structure formation loses its shape integrity and the structure becomes broken, deflected, or deflected and merged at the apex point of the fins.

A Study on the Characteristics of Micro Deep Hole Machining Processes

2007 ◽  
Vol 364-366 ◽  
pp. 566-571
Author(s):  
Tae Il Seo ◽  
Dong Woo Kim ◽  
Myeong Woo Cho ◽  
Eung Sug Lee
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
High Speed ◽  
Printed Circuit Boards ◽  
Hole Drilling ◽  
Deep Hole ◽  
Machining Processes ◽  
Deep Hole Drilling ◽  
Micro Drilling ◽  
Hole Machining

Recently, the trends of industrial products move towards more miniaturization, variety and mass production. Micro drilling which take high precision in cutting work is required to perform more micro hole and high speed working. Especially, Micro deep hole drilling is becoming more important in a wide spectrum of precision production industries, ranging from the production of automotive fuel injection nozzle, watch and camera parts, medical needles, and thick multilayered Printed Circuit Boards(PCB) that are demanded for very high density electric circuitry. The industries of precision production require smaller holes, high aspect ratio and high speed working for micro deep hole drilling. However the undesirable characteristics of micro drilling is the small signal to noise ratios, wandering motion of drill, high aspect ratio and the increase of cutting force as cutting depth increases. In order to optimize cutting conditions, an experimental study on the characteristics of micro deep hole machining processes using a tool dynamometer was carried out. And additionally, microscope with built-in an inspection monitor showed the relationship between burr in workpieces and chip form of micro drill machining.

Electrohydrodynamic Pressure Enhanced by Free Space Charge for Electrically Induced Structure Formation with High Aspect Ratio

Langmuir ◽  
2014 ◽  
Vol 30 (42) ◽  
pp. 12654-12663 ◽  
Author(s):  
Hongmiao Tian ◽  
Chunhui Wang ◽  
Jinyou Shao ◽  
Yucheng Ding ◽  
Xiangming Li
Keyword(s):  
Aspect Ratio ◽  
Space Charge ◽  
Structure Formation ◽  
High Aspect Ratio ◽  
Free Space ◽  
Induced Structure

scholarly journals Effect of Stiffness on Flutter of Composite Wings with High Aspect Ratio

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Shengjun Qiao ◽  
Jin Jiao ◽  
Yingge Ni ◽  
Han Chen ◽  
Xing Liu
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Bending Stiffness ◽  
Torsional Stiffness ◽  
Limit Cycle Oscillation ◽  
Spanwise Direction ◽  
Aerodynamic Loads ◽  
Thin Walled Structures ◽  
Computational Fluid Dynamics Cfd ◽  
Cycle Oscillation

High aspect ratio wing (HARW) structures will deform greatly under aerodynamic loads, and changes in the stiffness will have a great impact on the flutter characteristics of such wings. Based on this, this paper presents an effective method to determine the effect of the stiffness on the flutter characteristics of HARWs. Based on the calculation theory of the mechanical profile of thin-walled structures, the torsional stiffness and bending stiffness of the wing are obtained through calculation. We use the fluid-structure coupling method to analyze the flutter characteristics of the wing, and we use our research results based on the corotational (CR) method to perform structural calculations. The load is calculated using a computational fluid dynamics (CFD) solver. The results show that, compared with the original wing, when the bending stiffness and torsional stiffness of the wing along the spanwise direction increase by 8.28% and 5.22%, respectively, the amplitude of the flutter decreases by approximately 30%. Increasing the stiffness in the range of 0.4 to 0.6 Mach has a greater impact on the flutter critical velocity, which increases by 12.03%. The greater the aircraft’s flight speed is, the more severe the stiffness affects the wing limit cycle oscillation (LCO) amplitude.

The Plasma-Side Wall Interactions During Femtosecond Laser Drilling of High-Aspect-Ratio Microholes

2010 ◽  
Author(s):  
Benxin Wu ◽  
Sha Tao ◽  
Shuting Lei
Keyword(s):  
Aspect Ratio ◽  
Femtosecond Laser ◽  
High Aspect Ratio ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Side Wall ◽  
Femtosecond Laser Ablation ◽  
Laser Induced Plasma ◽  
Wall Interaction ◽  
Mechanical Machining

The drilling of high-aspect-ratio microholes has very important applications in automotive, aerospace, electronics and other areas. However, this is difficult to realize with conventional mechanical machining or electrical discharge machining approaches. Femtosecond laser ablation can potentially provide a good solution to this, but it also involves many technical difficulties. One of these is that the laser-induced plasma, as it expands out of the microhole, may transfer its energy to the side wall of the hole, which may affect the hole size and geometry. In this paper, the plasma – side wall interaction has been studied using a physics-based model, and the discovered characteristics of the interaction are discussed.

Micro Electro Discharge Milling of Freeform Micro-Features With High Aspect Ratio

2011 ◽  
Author(s):  
F. Modica ◽  
V. Marrocco ◽  
G. Trotta ◽  
I. Fassi
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Fill Factor ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
High Surface ◽  
Adjustment Factor ◽  
Machining Performance ◽  
Technological Parameters ◽  
Micro Features

Micro Electrical Discharge Machining (μEDM) technology is widely used to process conductive materials, regardless to their hardness and strength, and realize micro-sized feature components for industrial application. μEDM proves to be a very competitive fabrication technology since micro-sized features within 1 μm of accuracy and with high surface quality (<0.1 μm Ra) can be attained. When High Aspect Ratio (HAR) micro-features are machined via μEDM milling, the main problem is to identify the technological parameters and settings mainly affecting the process performance. In the present study the influence of the adjustment factor and flushing conditions are investigated and discussed for the machining of HAR cavities with different Fill Factor (FF). Material Removal Rate (MRR) and Tool Wear Ratio (TWR) are evaluated when deep cavities having variable square sections are machined on Ni-Cr-Mo steel workpiece. All tests are performed using a state of the art micro-EDM milling machine, with a Tungsten Carbide electrode tool and a dielectric oil for flushing. The experimental results presented here highlight different trends in the machining performance in dependence of AR and FF. In particular, MRR exhibits a decreasing trend where the curve slopes are strictly related to the FF and the initial adjustment factor. On the contrary, TWR, for higher FF, displays two distinct trends characterized by opposite slopes in each curve. Finally a nozzle for micro-injection with varying Aspect Ratio and Fill Factor is machined and presented as demonstrator.

High Aspect Ratio Machining of Carbon Fiber Reinforced Plastics by Electrical Discharge Machining Process

2020 ◽  
Author(s):  
Cibi Makudapathy ◽  
Murali Sundaram
Keyword(s):  
Carbon Fiber ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Machining Process ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Plastics ◽  
Reinforced Plastics ◽  
Fiber Reinforced Plastics

Abstract Micromachining of Carbon Fiber Reinforced Plastics (CFRPs) is essential for numerous applications in several industries such as aerospace, automotive, defense, shipping, sporting goods, and biomedical industries. The major challenge in machining CFRP by electrical discharge machining (EDM) is due to the non-conductivity of epoxy material which is used as a binder for manufacturing these CRFPs. This study attempts a novel, yet simple approach to ensure the conductivity of the work piece through the entire machining process. Experiments were carried out in this work to assess the feasibility of machining high aspect ratio micro-holes in CFRP by micro EDM. The effect of process parameters such as voltage and feed-rate on the hole quality was studied. Using optimal process conditions, micro hole of 2500 µm deep with an aspect ratio of over 11 was achieved.

Machining of High Aspect Ratio Micro-Holes on Titanium Alloy Using Silver Nano Powder Mixed Micro EDM Drilling

2019 ◽  
Author(s):  
Chong Liu ◽  
Asif Rashid ◽  
Muhammad P. Jahan ◽  
Jianfeng Ma
Keyword(s):  
Titanium Alloy ◽  
Aspect Ratio ◽  
Surface Finish ◽  
High Aspect Ratio ◽  
Electrical Discharge Machining ◽  
Turbine Blades ◽  
Weight Ratio ◽  
Recast Layer ◽  
Micro Edm ◽  
Micro Holes

Abstract Titanium alloy Ti-6Al-4V is used extensively in aerospace engines because of its high strength-to-weight ratio and corrosion resistance. Machining of cooling holes in turbine blades for aerospace engines is one of the major challenges faced in aerospace industries. Ti-6Al-4V is known as a difficult to be machined material by conventional machining processes, and machining of micro-through-holes with diameter less than 100 microns is even more challenging. Therefore, the objective of this study is to investigate the feasibility of machining high aspect ratio micro-through holes in Ti-6Al-4V using micro electrical discharge machining (micro-EDM) with the silver (Ag) nanopowder mixed dielectric. The machining time, overcut, recast layer, crater size, aspect ratio and surface finish of the micro-holes were evaluated. In order to minimize the positional inaccuracy and spindle runout, the microelectrodes were fabricated in-situ using block micro-EDM process. In this study, as received electrode of 300 microns diameter tungsten wire was reduced to about 50 microns diameter rod by micro block EDM using a tungsten carbide block. The effect of powder concentration, gap voltage, capacitance and electrode rotational speed was studied. It is found that high quality micro-holes of about 50 microns diameter can be achieved successfully and repeatedly using powder mixed micro-EDM (PM-μEDM). The micro-holes generated by PM-μEDM provides comparatively smoother surface finish and minimal recast layer around the rim of the micro-holes. In addition, PM-μEDM process improves machining stability, thus allowing to minimize the hole size and quality, thus enhancing the aspect ratio of micro-holes.

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