Blow Holes Research Articles

Gray relational analysis for parametric optimization of micro-EDM of thermo-mechanically processed AA7075 and AA7075/SiC/Gr composite

The AA7075 alloy and AA7075/SiC/Gr hybrid composite prepared by the stir-casting method have been further thermo-mechanically processed through unidirectional hot rolling and hot cross-rolling routes to eliminate casting defects like voids, blow holes etc. Three initial sample temperatures, that is, 350℃, 400℃, and 450℃, have been considered for the hot cross-rolling. The Al alloy and its hybrid composite prepared at different rolling temperatures are studied to investigate their micro-machining behavior through micro-electric discharge machining (µ-EDM). The micro-holes are made on the rolled samples along the rolling direction of the final rolling pass using a tool with twist drill bit geometry. Further, multi-objective optimization of the µ-EDM process parameters considering the response parameters viz. material removal rate (MRR) and tool wear rate (TWR) has been carried out using the gray relational analysis (GRA) technique. The µ-EDM parameters chosen to optimize in this study are voltage, pulse on time, and tool rotation. The obtained GRA results are further analyzed through normality and equal variance tests. The R-squared values of 95.02% and 95.53% for AA7075 alloy and hybrid composite, respectively, indicate that the data fit well with the statistical model. In material removal, the different electrical and thermal characteristics of the Al matrix and the reinforcements possibly generate sparks with a different characteristic that ultimately affects the MRR of the composite. Through scanning electron microscopy (SEM), the morphological study confirmed the presence of globules and voids on the machined surface. The formation of globules and voids is more significant in the AA7075 alloy than in the composite.

The Technique of Inorganic Core Sand Shooting with Reduced Pressure in Venting System

The publication presents a new shooting technique with reduced pressure in venting system for manufacturing foundry cores using inorganic sand mixture with Cordis binder. Traditional technologies for producing casting cores using blowing methods, despite their undeniable advantages, including the ability to produce cores in series, also come with some disadvantages. The primary drawbacks of the process involve uneven compaction structure of the cores, with denser areas primarily located under the blow holes, and under-shooting defects, which often occur in regions away from the blow hole or in increased core cross-sectional areas. In an effort to improve core quality, a concept was developed that involves incorporating a reduced pressure in the core box venting system to support the basic overpressure process. The solutions proposed in the publication with a vacuum method of filling the cavities of multi-chamber core boxes solve a number of technical problems occurring in conventional blowing technologies. It eliminates difficulties associated with evacuating the sand from the chamber to the shooting head and into technological cavity and increases the uniform distribution and initial degree of compacting of grains in the cavity. The additive role of this “underpressure” support is to enhance corebox venting by eliminating 'air cushions' in crevices and structural elements that obstruct the flow of evacuated air. The publication presents the results of studies on core manufacturing using blowing methods conducted in three variants: classic overpressure, utilizing the core box filling phenomenon by reducing pressure, and an integrated approach combining both these methods.

Effect of pulse time (Ton), pause time (Toff), peak current (Ip) on MRR and surface roughness of Cu–Al–Mn ternary shape memory alloy using wire EDM

Shape memory and super elasticity are two outstanding properties of Cu–Al–Mn SMAs together with additional copper-based shape memory alloys that make them superior to NiTi alloys. It's quite hard to machine Cu–Al–Mn SMA. The machinability properties of Cu–Al–Mn SMAs during Wire Electrical Discharge Machining (WEDM) were experimentally investigated using molybdenum wire as the electrode material. Material Removal Rate (MRR) and Surface Roughness (SR) are two machining qualities that are studied in relation to the combinational values of pulse time (Ton), pause time (Toff), and peak current (Ip), which are selected as the changeable input process factors. From the experimental investigation, it was found that both MRR and Ra values were increased with an increase in pulse on time(Ton), pulse off time(Toff), and peak current (IP)values. Because the wire electrode contains maximum current under these conditions, it is easy to remove more material at the tool and work material interface, resulting in moderate surface finish. Surface quality was higher on samples machined at low energy input than it was on samples machined at high energy input. This SEM micrograph clearly shows that a lower pulse on time produces a superior surface quality.SEM images and the analysis of the machined surface morphology on the surface of the CAM7 alloy clearly showed that the machined surface of the alloy had a lower surface roughness value at a lower Ip-2A and was associated with a higher surface roughness value at a higher Ip-6A, as well as a lot of uncleared debris and blow holes.

Emergent Bedside Cesarean Section for COVID-19 Patient on Veno-venous Extracorporeal Membrane Oxygenation: A Case Report

Background & Case: A 38-year-old Spanish-speaking, pregnant woman at 26.1 weeks’ gestation with two previous Cesarean sections (C-section) presented with acute respiratory distress syndrome secondary to COVID-19 pneumonia. She was intubated and ventilated, complicated by bilateral pneumothoraces and emphysema requiring bilateral chest tubes and blow holes. She had worsening hypoxic respiratory failure ultimately requiring cannulation for venovenous extracorporeal membrane oxygenation (VV-ECMO). She was started on cefazolin for Methicillin-susceptible Staphylococcus aureus bacteremia. On day three of VV-ECMO, there was non-reassuring fetal heart tone necessitating emergent bedside non-sterile Cesarean section at 27.2 weeks’ gestational age in the surgical intensive care unit. Post-Cesarean section, her respiratory failure improved, and she was decannulated from VV-ECMO 13 days later. This case report highlights that VV-ECMO can be a life-saving treatment option for pregnant women with cardiopulmonary failure who are unresponsive to conventional therapy. Literature describing Caesarean section on VV-ECMO is limited. Specifically, there have been only a handful of case reports of C-sections on patients put on VV-ECMO due to respiratory failure. Results: The obvious benefit of proceeding with this emergent bedside C-section was to save the fetus. However, this had to be weighed against the risks of hemorrhage in this high-risk patient since she had two previous C-sections and was on a therapeutic heparin drip while on VV-ECMO. Additionally, there is the risk of infection due to having the C-section done in a non-sterile manner, especially in a patient who is bacteremic. This was mitigated by using additional prophylactic antibiotics post-operatively. The patient’s respiratory status improved significantly after the fetus was delivered, likely due to improvements in respiratory mechanics post-partum. The successful outcome of this patient and her baby required the timely coordination of a multidisciplinary team. Conclusions: Emergent C-section on a pregnant woman with respiratory failure on VV-ECMO can be life-saving for the fetus and the mother. However, the inherent risks associated with it requires close monitoring of the patient and the fetus in order to determine when this is truly necessary. Keywords: Acute respiratory distress syndrome, Cesarean-section, COVID-19, Pregnancy, Veno-venous extracorporeal membrane oxygenation

Management of Extensive Subcutaneous Emphysema with Blow Hole Infraclavicular Incision and Continuous Suction Installation

Background: Subcutaneous emphysema often occurs in cases of implanted pneumothorax chest tubes and must always be evaluated. Subcutaneous emphysema is a condition where air or gas is found in the tissue under the skin.
 Case presentation: A 49-year-old man was treated for sudden shortness of breath that occurred after a violent cough accompanied by pain and heaviness in the chest area 1 day before admission to the hospital. The patient had previously received anti-tuberculosis drug treatment for 6 months based on chest X-ray results in 2022, and the patient had undergone a rapid molecular test (TCM) examination, mycobacterium tuberculosis (Mtb), and obtained Mtb results not detected. Lung auscultation obtains sound intensity breath weakness until it disappears in both lung fields. Palpation of the skin revealed widespread crepitus on the face, neck, upper extremities, back, chest, and abdomen. The range of motion areas of the neck, shoulders, and hands are limited due to pain with movement. Evaluation of the chest tube obtained: the chest tube was installed in the anterior axillary line on the right at the level of the 5th intercostal space with number 10 attached to the chest wall and the chest tube well fixed to the chest wall. The end chest tube has been connected to the WSD bottle, and evaluation of the WSD shows that there are undulations and bubbles.
 Conclusion: The patient was admitted with spontaneous pneumothorax secondary to tuberculosis and was implanted with a chest tube.

Parametric Optimizing Green Sand-Casting Process Parameters using hybrid Taguchi Grey Relational Analyses and Principal Component Analyses

The Green Sand-casting technique is a very ancient method of casting that has many different uses. The increased rate of errors and rejection in this process is a key drawback that reduces output and profits. It’s challenging to develop a good link between the many different parameters and defects since the process is so complicated. This article describes a hybrid approach to find the co-relation for sand casting process’s variables. This approach mixes the Taguchi method (TM) with Grey Relational Analysis (GRA) paired with Principal Component Analysis (PCA). Moisture content, Permeability, Loss of Ignition, Pouring Time & Pouring Temperature selected as input parameters while types of defects (Shrinkage, Blow holes, Cracks, Porosity) as responses for proposed study. The L27 OA from Taguchi is used to plan the tests. TM implemented to analyse individual responses. GRA is applied to find optimal solutions for a set of replies, whereas PCA is used to determine how much weight each response should be given. Using proposed methodology, 4% moisture content, 160% permeability, 5% loss of ignition, 60 seconds of pouring time, and 1400°C found as optimum set of parameters. The findings demonstrate that the hybrid approach, which makes use of both a cost-effective and efficient experimental design strategy, was successful in resolving the complexity trade-off experienced throughout the judgment process of multi-response optimization.

Investigation of the heat flux reduction scheme on a V-shaped blunt leading edge based on secondary recirculation jets

Complex shock interactions on the lips of hypersonic vehicles typically induce severe aerodynamic thermal loads. Considering a V-shaped blunt leading edge as the simplified model of the lip, the design, optimization, and performance of secondary recirculation jets for reducing aerodynamic thermal loads are investigated. The secondary recirculation jet scheme is crucial in reshaping the shock interaction structures, allowing the high-pressure gas downstream of the main shock structures to be transported back into the upstream flow field. Numerical results show that setting the bleed hole of the secondary recirculation jet scheme upstream of the shock wave/boundary layer interaction region yields the greatest reduction in heat flux. The combined effect of the oblique shock upstream of the blow hole and the bow shock at the windward edge of the bleed hole weakens the shock wave/boundary layer interaction structure, thereby reducing the associated heat flux peak. Prior to optimization, the scheme reduces the heat flux peak by approximately 25%. Once the critical design parameters have been optimized and a stagnation bulge has been introduced, the scheme achieves excellent heat flux peak reduction ability of approximately 43%. Simulations under a wide range of freestream conditions show that the optimal scheme has strong applicability to nonzero attack and sideslip angles and is suitable for hypersonic flows below Mach 9.0. In general, the secondary recirculation jet scheme designed in this work exhibits excellent ability to reduce the peak and average values of the heat flux.

Casting Product Image Data for Quality Inspection with Xception and Data Augmentation

Casting defects encompass a broad spectrum of imperfections, such as blow holes, pinholes, burrs, shrinkage defects, and various metallurgical anomalies. Detecting these defects manually requires a trained eye, and even the most diligent inspectors can inadvertently overlook subtle irregularities. To address these challenges, there is a growing movement toward automation in quality control. Deep learning models, including the Xception model, are being harnessed to create a robust classification system. Such models have the capacity to analyze thousands of product images with precision, identifying defects that may elude human inspectors. Furthermore, data augmentation techniques are applied to enhance the dataset, allowing the model to generalize more effectively and improve its defect recognition capabilities.

Defect detection for industrial neutron radiographic images based on modified YOLO network

Neutron radiography (NR) has been widely used in non-destructive investigations. Since the industrial neutron radiographic images (NRIs) usually suffer from unclear defect features, insufficient data volume, and low efficiency of manual detection, we propose a proof-of-concept defect-detection method based on the modified YOLO network for the degraded NRIs in this paper. Firstly, 6336 radiographic images including crack, inclusion, blow hole, and residual core are built as the defect-detection dataset. Secondly, the types and the relative coordinates of defects are labeled by a graphical image annotation tool (i.e., Labelimg). Finally, the adaptive spatial feature fusion (ASFF) and convolutional block attention module (CBAM) are introduced to the modified YOLO network to enhance its ability of small-size defect detection. Experimental results demonstrate that the proposed method can achieve the average accuracy of 98.1% and detection rate of 85.985 frames per second (FPS) with a single NVIDIA GeForce RTX 4090 GPU on the built radiographic image dataset. In addition, the proposed method shows a good potential in detecting the above defects contained in the real NRIs.

Research on Optimization of Profile Parameters in Screw Compressor Based on BP Neural Network and Genetic Algorithm

In order to accurately calculate the geometric characteristics of the twin-screw compressor and obtain the optimal profile parameters, a calculation method for the geometric characteristics of twin-screw compressors was proposed to simplify the profile parameter design in this paper. In this method, the database of geometric characteristics is established by back-propagation (BP) neural network, and the genetic algorithm is used to find the optimal profile design parameters. The effects of training methods and hidden layers on the calculation accuracy of neural network are discussed. The effects of profile parameters, including inner radius of the male rotor, protection angle, radius of the elliptic arc, outer radius of the female rotor on the comprehensive evaluation value composed of length of the contact line, blow hole area and area utilization rate, are analyzed. The results show that the time consumed for the database established by BP neural network is 92.8% shorter than that of the traditional method and the error is within 1.5% of the traditional method. Based on the genetic algorithm, compared with the original profile, the blow hole area of the screw compressor profile optimized by genetic algorithm is reduced by 54.8%, the length of contact line is increased by 1.57% and the area utilization rate is increased by 0.32%. The CFD numerical model is used to verify the optimization method, and it can be observed that the leakage through the blow hole of the optimized model is reduced, which makes the average mass flow rate increase by 5.2%, indicating the effectiveness of the rotor profile parameter optimization method.

Performance evaluation of metal mould for casting aluminium alloy (AA6063) of scientific products in National agency for science and engineering infrastructure

The study investigated the major Causes of inconsistency in the cast results of the aluminium cast products from the metal moulds supplied by the then Hungarian Technical Partners to Scientific Equipment Development Institute, Minna. The metal moulds for different scientific products for Schools Scientific Laboratories were to achieve mass production of these products. The aluminium alloy A6063 ingot used were likewise imported. However, another consignment of the ingot used is produced in Nigeria by Nigerian Aluminium Extrusion Company, Lagos. Result of the products defects including shrinkage, blow holes, etc. remained the same, hence the need for this investigation work to ascertain the causes traceable to either moulds or the class or group of alloys.The outcome as shown could be that pouring speed or melting temperature etcetera are responsible for the inconsistency in obtaining acceptable cast products at different operations and with these moulds. A particular product mould gives inconsistent cast products and varying defects. This is applicable to all the available moulds supplied to the Institute at the same time.

Numerical simulation of mould filling process using ansys

ABSTRACT Filling of moulds with molten metal and solidifying it affects the cycle time, casting’s interior quality and the amount of material required throughout the process. Blow holes, slag inclusions, cold shut, shrinkage, and other casting faults are all linked to the mould filling process. Industry demands the simulation of filling and solidification process before the actual operation begins. The simulation helps to examine the molten metal’s free surface variations, temperature distribution, and gas pouring problems to reduce filling-related defects and benefited to the industrial sector by eliminating the wastage of raw resources, money, labour and time. CFD analysis was carried out to investigate the impact of VOF and air entrapment in the casting part at subjected velocities to uncover pouring flaws of the casting part generated in response to the applied velocities.

Study on the leakage in water-injected twin-screw steam compressor

Steam compressor shows great energy-saving potential in mechanical vapor compression and high-temperature heat pump systems. However, leakage remains a huge problem for compressor performance improvement and design optimization. In this article, a thermodynamic model with detailed leakage flow model was developed for the working process in water-injected twin-screw compressor. Altogether, leakage in different paths and heat and mass transfer between injected liquid and compressed vapor were considered. Compared with experimental results, the accuracy of predicted efficiency is within ± 5% for all tested operating conditions. In the validated model, leakage flow in five leakage paths and their effects on compressor efficiency was investigated. Results indicate that leakage can reduce volumetric efficiency by up to 50.2%, while the injected water liquid vaporization can improve volumetric efficiency by 7.9% at 5000 r·min−1. The leakage through contact line (CL), tip sealing (TS) line, and discharge end face (DE) show the most important impact on compressor efficiency, while the leakage through blow hole (BH) and suction end face (SE) has little impact on compressor efficiency. Compared with zero leakage under certain conditions, the reduction of volumetric efficiency caused by CL, TS line, and DE can reach up to 22.4%, 20.4%, and 12.7%, respectively. Reducing clearances of the above three leakage paths can efficiently improve the performance of steam compressor, especially for CL.

Serdam Sebagai Alat Musik Tiup Bambu Lampung Barat: Kajian Organologi

Serdam is an artistic product in the form of a wind instrument, the only one in West Lampung and made of bamboo. Serdam is usually used to accompany oral literary vocals such as muayak, hahadoh, hahiwang and dance music along with other traditional Lampung musical instruments. The bamboo used for the manufacture of Serdam is bamboo of the type of bamban and is often found in the plantations of the people of West Lampung. The purpose of this study is to describe the physical form, tools and materials, the process of making Serdam, sound source and tone system and how to play the Serdam. Serdam has many physical similarities to bamboo wind instruments from other regions, but Serdam has a distinctive blowing technique and tone. The research method used is the descriptive qualitative research method. The data obtained from this study with data collection methods by observation, interviews and documentation studies. The results of this study indicate that the Serdam wind instrument is made of bamboo bamban which is often found in the plantations of the people of West Lampung. Serdam has a shape like a long tube that has four melody holes and one blow hole. This musical instrument still uses a traditional manufacturing process to this day. Serdam as the only wind instrument originating from West Lampung has many organological peculiarities that are not yet known by the supporting community.

Investigation on Different Compositions of Clay and Water to the Permeability of the Silica Sand Used in Greensand Casting Mould

Greensand casting is a casting process that uses mixture of silica sand with addition of control additions which are bentonite clay and the presence of water. Control additions influence the mechanical properties of greensand casting mould, for this study focuses on the permeability. Bentonite clay acts as a binder and activated by water to develop strength and plasticity thus the greensand casting mould can be formed. Permeability is ability of gas to pass through the moulding mixture aggregates in order to reduce the defects due to trapped gasses in mould cavity such as blow holes or pin holes. The objective of this study is to investigate the effect of control addition (water and clay) on the permeability number of silica sand sample (tailing sand) from former tin mine site in Tronoh, Perak. Experiments are conducted according to American Foundrymen Society (AFS) standard of procedures. Sand sample is sieved using mechanical sieve shaker to size of 425 µm. Cylindrical test pieces dimensioning of Ø50 mm×50 mm in height from various mixtures of sand-clay–water ratios are compacted by applying three ramming blows of 6666 grams using Ridsdale-Dietert metric standard rammer. The test pieces are tested for permeability with Ridsdale-Dietert permeability meter. The results show that clay and water have affected the permeability of silica sand sample and when more water and clay added, into the moulding mixture, the permeability is found decreased. The appropriate allowable water and clay content are crucial for permeability number of greensand casting mould.

Rejection Analysis of Casting Defect Using Statical Quality Tools

Abstract: In the industry different type of casting component are produced, nowadays increasing demand of high-quality casting component at right time. For the quality casting component required skill and knowledge. In small industry use trial and error technique defect analysis it is used for reduced rejection percentage of casting compound but this process is time consuming and economical and also this process has less control on rejection of casting components the main aim is produced defect free components at right time and increase the quality of casting components, in this paper used statistical quality tools and Auto-cast simulation software for finding root cause of casting defect. Ishikawa diagram, why-why analysis and brain storming this are statistical quality tool used for rejection analysis casting. Using statistical quality tools cover defect like sand drop, sand fusion, blow hole cold shut etc. but leakage defect root cause not found using statistical quality tool. For minimize leakage defect use auto-cast simulation software find out the root cause. Taking the corrective action and reduced rejection percentage of casting defect of RDP Carrier.

Study on practical application for in-process blowholes detection technology

For the development of in-process blowholes detection and prediction technology, a welding system with an infrared camera and welding robot was integrated and the authors verified the detection of welding phenomena directly associated with the occurrence of blowholes. In addition, an image analysis index for welding defect detection and prediction was considered. It was clarified that it is possible to observe the bubbling phenomena just under the arc due to the blow hole generation by the welding system. In addition, it was considered possible to detect and predict the occurrence of blowholes with high accuracy by analyzing the observation frequency of the bubble generation phenomenon directly under the arc with an appropriate index.

Metode Pembelajaran Suling Laras Slendro Gaya Yogyakarta

This research is motivated by the fact that many flute players, artists, musical practitioners and students do not recognize the characteristics of the Yogyakarta style flute, so there is a tendency to abandon it. On the other hand, the Yogyakarta style flute instrument has specifications that lead to special characteristics. This study aims to provide an understanding of the Yogyakarta style flute as well as produce teaching materials for the Yogyakarta style flute as a guide for learning. This study uses two methods, namely data collection and analysis and design methods. Yogyakarta Style flute learning techniques include: knowledge of the flute, basic techniques, intermediate techniques, and advanced techniques. Knowledge of the flute includes the characteristics of the shape, blow hole, tone hole, closing tone, cengkok seleh, and the application of cengkok seleh flute Yogyakarta style. Basic techniques include mastery of blowing and closing types in finding the tone of both the slendro barrels. Intermediate techniques include basic mastery of crooked selh, slendro barrel and pelog barrel. Advanced techniques include the application of seleh bends on the gending and lagon.

Metode Pembelajaran Suling Laras Slendro Gaya Yogyakarta

This research is motivated by the fact that many flute players, artists, musical practitioners and students do not recognize the characteristics of the Yogyakarta style flute, so there is a tendency to abandon it. On the other hand, the Yogyakarta style flute instrument has specifications that lead to special characteristics. This study aims to provide an understanding of the Yogyakarta style flute as well as produce teaching materials for the Yogyakarta style flute as a guide for learning. This study uses two methods, namely data collection and analysis and design methods. Yogyakarta Style flute learning techniques include: knowledge of the flute, basic techniques, intermediate techniques, and advanced techniques. Knowledge of the flute includes the characteristics of the shape, blow hole, tone hole, closing tone, cengkok seleh, and the application of cengkok seleh flute Yogyakarta style. Basic techniques include mastery of blowing and closing types in finding the tone of both the slendro barrels. Intermediate techniques include basic mastery of crooked selh, slendro barrel and pelog barrel. Advanced techniques include the application of seleh bends on the gending and lagon.

EFFECT OF PARTICLE LOADING ON THE BURNING CHARACTERISTICS OF BORON-LADEN GEL FUEL DROPLET

Droplet combustion of pure and boron-loaded gel fuels is studied to understand the combustion behavior of gel fuel under atmospheric conditions. Here, Jet A-1 is taken as a base fuel, Thixatrol ST as gellant, and boron as energetic particles. Four kinds of gel fuels are taken for this study with varying boron loadings of 0%, 10%, 20%, and 30% (by weight). Before combustion studies, the rheological properties of all gel fuels were determined. The results show a linear variation of viscosity with an increasing shear rate and with increasing boron content. Combustion characteristics of all these fuels were studied and analyzed. The droplet combustion process was captured using a time-resolved high-speed imaging system. The evolution of droplet profile shows that droplet regresses smoothly for pure gel (PG) sample (0% boron), whereas for the GB10 and GB20 cases with 10% and 20% boron, respectively, the droplet regresses with puffing, disruption, and is followed by micro-explosions. For the GB30 case with 30% boron, the phenomena of micro-explosion occur immediately after the ignition of the droplet. Flame standoff distance decreases with the higher boron-loaded gel fuel. Analysis of secondary droplets explains that: (1) puffing induces a smaller diameter, while micro-explosion ejects daughter droplets of larger diameter. (2) Average secondary flame length increases with the increase of boron loading. As a result, the boron component in gel fuel appears to have a good impact on the whole combustion process. Scanning electron microscopy (SEM) image shows numerous micropores (blow holes) on particle surface in case of GB30 sample while no such pores were present on other counterparts. The micrograph also reveals eroded, flaky, and ashy-like structures in the residue of the GB30 case.