scholarly journals Fabrication of micro-structured tools for the production of curved metal surfaces by pulsed electrochemical machining

2021 ◽  
Author(s):  
Tejas Mankeekar ◽  
Dirk Bähre ◽  
Dan Durneata ◽  
Thomas Hall ◽  
Rainer Lilischkis ◽  
...  
Keyword(s):  
Electrochemical Machining ◽  
Wet Etching ◽  
Process Chain ◽  
Functional Area ◽  
Process Step ◽  
Tool Surface ◽  
Cost Efficient ◽  
Micro Structuring ◽  
Micro Structures ◽  
Lateral Structure

AbstractA new, scalable process chain for the fabrication of curved micro-structured metallic tools is developed and evaluated. Arrays of arrows, circles, semicircles and rings with final lateral dimensions of 124 to 819 µm are realised on the tools and successfully transmitted in one process step to stainless steel workpieces with a functional area of 6.5 cm2 using pulsed electrochemical machining. Photolithography-etching or micromilling are applied as initial micro-structuring processes, resulting in micro-structured master forms. These forms are copied into reusable silicon forms. This is followed by epoxy casting and electroforming to obtain the final tools. The tools are made of Nickel and have a diameter of 34 mm. Whilst micromilling, photolithography, silicon casting, epoxy casting and electroforming copy the structures very precisely, the wet etching process induces a widening of the dimensions due to the isotropic character of the process. The advantage of the process chain is the reusability of the master as well as of the silicone forms, which can be copied very precisely and easily with scalable processes to get precision tools with relatively large micro-structured areas. The reusability of the forms makes the fabrication of micro-structured tools relatively cost-efficient. The use of photolithography as the initial structuring process enables the generation of arbitrary, user-defined geometries for the micro-structures on the tool surface. The process chain described has the potential to fabricate lateral structure sizes on tools down to one micrometre.

scholarly journals An In-Depth Process Model for Fuel Production via Hydrothermal Liquefaction and Catalytic Hydrotreating

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1172
Author(s):  
Leonard Moser ◽  
Christina Penke ◽  
Valentin Batteiger
Keyword(s):  
Process Model ◽  
Reaction Network ◽  
Hydrothermal Liquefaction ◽  
Process Chain ◽  
Fuel Production ◽  
Model Compounds ◽  
Point Distribution ◽  
Process Step ◽  
Elemental Analyses ◽  
Made In

One of the more promising technologies for future renewable fuel production from biomass is hydrothermal liquefaction (HTL). Although enormous progress in the context of continuous experiments on demonstration plants has been made in the last years, still many research questions concerning the understanding of the HTL reaction network remain unanswered. In this study, a unique process model of an HTL process chain has been developed in Aspen Plus® for three feedstock, microalgae, sewage sludge and wheat straw. A process chain consisting of HTL, hydrotreatment (HT) and catalytic hydrothermal gasification (cHTG) build the core process steps of the model, which uses 51 model compounds representing the hydrolysis products of the different biochemical groups lipids, proteins, carbohydrates, lignin, extractives and ash for modeling the biomass. Two extensive reaction networks of 272 and 290 reactions for the HTL and HT process step, respectively, lead to the intermediate biocrude (~200 model compounds) and the final upgraded biocrude product (~130 model compounds). The model can reproduce important characteristics, such as yields, elemental analyses, boiling point distribution, product fractions, density and higher heating values of experimental results from continuous experiments as well as literature values. The model can be applied as basis for techno-economic and environmental assessments of HTL fuel production, and may be further developed into a predictive yield modeling tool.

scholarly journals Along the Process Chain to Probiotic Tablets: Evaluation of Mechanical Impacts on Microbial Viability

Pharmaceutics ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 66 ◽  
Author(s):  
Karl Vorländer ◽  
Ingo Kampen ◽  
Jan Henrik Finke ◽  
Arno Kwade
Keyword(s):  
Cell Survival ◽  
Survival Rates ◽  
Process Chain ◽  
Rapid Loss ◽  
Process Step ◽  
Colony Forming Units ◽  
Tablet Properties ◽  
Compaction Stress ◽  
Semi Solid ◽  
Initial Process

Today, probiotics are predominantly used in liquid or semi-solid functionalized foods, showing a rapid loss of cell viability. Due to the increasing spread of antibiotic resistance, probiotics are promising in pharmaceutical development because of their antimicrobial effects. This increases the formulation requirements, e.g., the need for an enhanced shelf life that is achieved by drying, mainly by lyophilization. For oral administration, the process chain for production of tablets containing microorganisms is of high interest and, thus, was investigated in this study. Lyophilization as an initial process step showed low cell survival of only 12.8%. However, the addition of cryoprotectants enabled survival rates up to 42.9%. Subsequently, the dried cells were gently milled. This powder was tableted directly or after mixing with excipients microcrystalline cellulose, dicalcium phosphate or lactose. Survival rates during tableting varied between 1.4% and 24.1%, depending on the formulation and the applied compaction stress. More detailed analysis of the tablet properties showed advantages of excipients in respect of cell survival and tablet mechanical strength. Maximum overall survival rate along the complete manufacturing process was >5%, enabling doses of 6   ×   10 8 colony forming units per gram ( CFU   g total − 1 ), including cryoprotectants and excipients.

Fabrication of Micro-Structures by Micro-ECM

2009 ◽  
Vol 69-70 ◽  
pp. 229-233
Author(s):  
Ming Huan Wang ◽  
Qiao Fang Zhang ◽  
C.Y. Yao ◽  
Wei Peng
Keyword(s):  
Mathematical Model ◽  
Electrochemical Etching ◽  
Electrochemical Machining ◽  
Pulse Power ◽  
Micro Machining ◽  
Slot Milling ◽  
Micro Ecm ◽  
Micro Holes ◽  
Machining System ◽  
Micro Structures

The machining of materials on microscopic scales is considered to be great importance to a wide variety of fields. Electrochemical Micro-machining (EMM) appears to be promising to machine the micro-structures in future due to the material is dissolved at the unit of ion. This paper is focused on developing a micro electrochemical machining system in which the micro-structures such as micro-cylinder, multiple micro-electrodes, micro-holes and micro-slot were processed. The micro-electrodes were prepared in a precisely controlling the electrochemical etching process. Mathematical model controlling the diameters of electrodes was built up. Furthermore, the obtained micro-electrodes were selected as the cathode tool for micro holes drilling and micro-slot milling using pulse power in Micro-ECM.

Fabrication of Micro Structures by Ultra Short Voltage Pulse Electrochemical Machining

2009 ◽  
Vol 419-420 ◽  
pp. 813-816 ◽  
Author(s):  
Hui Chen ◽  
Zhen Long Wang ◽  
Zi Long Peng ◽  
Wan Sheng Zhao
Keyword(s):  
Voltage Pulse ◽  
Electrochemical Machining ◽  
Pulse Frequency ◽  
Machining Accuracy ◽  
Machining Parameters ◽  
Stray Current ◽  
Micro Fabrication ◽  
Micro Hole ◽  
Micro Structures ◽  
Machining Localization

. The purpose of this paper is to study the application of electrochemical machining (ECM) technology for the fabrication of micro structures. The stray current corrosion, i.e. machining localization is a critical obstacle to micro fabrication for ECM. To machine micro structures by electrochemical machining ultra short voltage pulse is used. The effects of electrochemical machining parameters such as voltage, pulse duration, pulse frequency, and electrolyte composition on the machining accuracy were studied. In experiments, a micro hole was machined on stainless steel with cylindrical and square electrodes to investigate these effects.

Temple of Zeus: A Micro Replica

2009 ◽  
Author(s):  
Aditya N. Das ◽  
Rakesh Murthy
Keyword(s):  
Light Source ◽  
High Precision ◽  
Silicon Substrate ◽  
Epoxy Adhesive ◽  
Silicon On Insulator ◽  
Etching Process ◽  
Ion Etching ◽  
Cost Efficient ◽  
Micro Structures ◽  
Microassembly Robot

A miniature replica of “Temple of Zeus” has been built on a 1cm2 silicon die. The micro components have been fabricated on SOI (silicon-on-insulator) wafer using photolithography patterning and DRIE (deep-reaction-ion-etching) process. These micro components have been picked up and manipulated using a vacuum micro needle mounted on a high precision microassembly robot. After alignment the components are bonded to the silicon substrate using epoxy adhesive. A spherical sapphire lens has also been mounted on a micro tower made of silicon. This lens acts as a light source which illuminates the micro temple by diffusing a ray of light onto it. This micro replica of “Temple of Zeus” and other micro structures as well, have been built as a part of research on automated 3D microassembly at ARRI’s Texas Microfactory which demonstrates the versatility in developing robust, cost efficient and heterogeneous microsystems of future.

Statistical Analysis of Forming Processes as a First Step in a Process-Chain Analysis: Novel PRO-CHAIN Components

2012 ◽  
Vol 504-506 ◽  
pp. 631-636 ◽  
Author(s):  
Daniela Steffes-Lai ◽  
Tanja Clees
Keyword(s):  
Statistical Analysis ◽  
Statistical Information ◽  
Process Chain ◽  
Parameter Sensitivity Analysis ◽  
Forming Process ◽  
Process Step ◽  
New Approach ◽  
Chain Analysis ◽  
Process Chains ◽  
Metal Blank

This paper presents a new approach for statistical analysis of process chains, including a parameter sensitivity analysis of each process step as a basis for dimension reduction, and an efficient interpolatory metamodel in order to predict new designs. A Monte Carlo alike evaluation of this metamodel results in the requested statistical information, e.g. quantiles of the output functionals. Numerical results are presented for the forming process of a ZStE340 metal blank of a B-pillar. Additionally, a brief overview of results of the process chain forming to crash is given.

scholarly journals Fused Filament Fabrication of Small Ceramic Components

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1463 ◽  
Author(s):  
Dorit Nötzel ◽  
Ralf Eickhoff ◽  
Thomas Hanemann
Keyword(s):  
Low Cost ◽  
Geometric Feature ◽  
Process Chain ◽  
Post Processing ◽  
Fused Filament Fabrication ◽  
Ceramic Injection Molding ◽  
New Process ◽  
Ceramic Components ◽  
Cost Efficient ◽  
Binder Jetting

With respect to rapid prototyping of ceramic components, there are known only a few processes (stereo lithography, binder jetting). In this work, a new process chain is described in detail, showing that ceramics can be printed in a very cost-efficient way. We developed a ceramic–polymer composite as filament material that can be printed on a low-cost fused filament fabrication (FFF) desktop printer, even with very small nozzle sizes enabling very small geometric feature sizes. The thermal post-processing, with debinding and sintering, is very close to the ceramic injection molding (CIM) process chain.

scholarly journals Comparison of Different Manufacturing Processes of AISI 4140 Steel with Regard to Surface Modification and Its Influencing Depth

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 895 ◽  
Author(s):  
Florian Borchers ◽  
Brigitte Clausen ◽  
Sandro Eckert ◽  
Lisa Ehle ◽  
Jeremy Epp ◽  
...  
Keyword(s):  
Electrical Discharge Machining ◽  
Surface Condition ◽  
Electrochemical Machining ◽  
Manufacturing Processes ◽  
Initial State ◽  
Electron Microscopic ◽  
Dislocation Generation ◽  
Process Step ◽  
Aisi 4140 ◽  
Machining Operations

The surface and subsurface conditions of components are significant for their functional properties. Every manufacturing process step changes the surface condition due to its mechanical, chemical and/or thermal impact. The depth of the affected zone varies for different machining operations, and is predetermined by the process parameters and characteristics. Furthermore, the initial state has a decisive influence on the interactions that lead to the final surface conditions. The aim of the investigation presented here is to compare the influence of the load characteristics over the depth applied to manufactured components by several different machining operations and to determine the causing mechanisms. In order to ensure better comparability between the surface modifications caused by different machining operations, the same material was used (AISI 4140; German steel grade 42CrMo4 acc. to DIN EN 10083-3) and annealed to a ferritic-pearlitic microstructure. Based on interdisciplinary cooperation within the collaborative research center CRC/Transregio 136 “Process Signatures”, seven different manufacturing processes, i.e., grinding, turning, deep rolling, laser processing, inductive heat treatment, electrical discharge machining (EDM) and electrochemical machining (ECM), were used, and the resulting surface zones were investigated by highly specialized analysis techniques. This work presents the results of X-ray measurements, hardness measurements and electron microscopic investigations. As a result, the characteristics and depths of the material modifications, as well as their underlying mechanisms and causes, were studied. Mechanisms occurring within 42CrMo4 steel due to thermal, mechanical, chemical or mixed impacts were identified as phase transformation, solidification and strengthening due to dislocation generation and accumulation, continuum dynamic recrystallization and dynamic recovery, as well as chemical reactions.

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