Optimization of Rheology Parameters for Feedstock by Powder Injection Molding (PIM) Via Taguchi Analysis

The most critical process in the powder injection molding method is determining the powder/binder rate and its properties. The most important feature that distinguishes the powder injection molding method from other powder metallurgy production methods is its advantage in producing high raw density and complex shaped parts. However, providing these advantages includes a multi-parameter process that directly affects the injection molding parameters and the final part's mechanical properties. In addition, the difficulty of experimental studies causes energy, time, and cost losses in determining the powder/binder rate and rheological properties of the feedstock so that the advantages of the method turn into a manageable disadvantage. This study performed rheology studies for three different feedstocks (PW/CW/SA, PW/PE/SA, and PEG8000/PP/SA). In this context, this paper determined the rheological properties of different feedstocks to take advantage of the Taguchi analysis. Flow behavior index, viscosity and optimum loading rates were determined separately for all feedstocks. The results exhibited the injection molding can be done with the determined best (58% steatite+PEG8000/PP/SA) F3 feedstock by volume. Based on it was found that viscosity and melt flow index were not a problem for injection molding in three different feedstocks used in the result, advantages and disadvantages were observed

Optimization of Rheology Parameters for Feedstock by Powder Injection Molding (PIM) Via Taguchi Analysis

The most critical process in the powder injection molding method is determining the powder/binder rate and its properties. The most important feature that distinguishes the powder injection molding method from other powder metallurgy production methods is its advantage in producing high raw density and complex shaped parts. However, providing these advantages includes a multi-parameter process that directly affects the injection molding parameters and the final part's mechanical properties. In addition, the difficulty of experimental studies causes energy, time, and cost losses in determining the powder/binder rate and rheological properties of the feedstock so that the advantages of the method turn into a manageable disadvantage. This study performed rheology studies for three different feedstocks (PW/CW/SA, PW/PE/SA, and PEG8000/PP/SA). In this context, this paper determined the rheological properties of different feedstocks to take advantage of the Taguchi analysis. Flow behavior index, viscosity and optimum loading rates were determined separately for all feedstocks. The results exhibited the injection molding can be done with the determined best (58% steatite+PEG8000/PP/SA) F3 feedstock by volume. Based on it was found that viscosity and melt flow index were not a problem for injection molding in three different feedstocks used in the result, advantages and disadvantages were observed

Investigation and Optimization of Cutting Performance of High Chrome White Cast Iron by Wire Erosion

Wire electric discharge machining (WEDM) is an emerging approach to producing more accurate and precise complex products in the unconventional machining process. The WEDM process is affected by several process factors. Therefore, the appropriate combination of process factors is required to achieve economical and quality machining. Machining is very difficult due to the presence of chromium carbide in the structure of high-Cr white cast irons (HCCIs) with 12–17% Cr content in machining processes. Therefore, the machinability of HCCIs has always been a disadvantage. In this study, specially molded HCCIs samples were subjected to softening, casting (not heat treated) and hardened heat treatment processes, respectively. We aimed to experimentally investigated the changes in HCCIs samples characteristics, pulse on time, pulse of time, wire speed, and cutting performance in the WEDM process in this study. The L18 orthogonal array was used using the Taguchi method, and an experimental study was prepared. Afterward, an optimization study was carried out using mathematical models for WEDM with the help of performance outputs via ANOVA analysis. The experimental performances examined in this study are material removal rate and surface roughness. The experimental study determined that the material removal rate and surface roughness increased when the pulse on time increased. Later, machined samples morphological and structures properties were analyzed X-ray spectroscopy (EDS), scanning electron microscopy, microhardness and surface roughness. Furthermore, electrical conductivity of them was measured. © 2023, King Fahd University of Petroleum & Minerals

ŞİRKET BİRLEŞMELERİ, BİRLEŞMELERDE TARİHSEL GELİŞİM SÜRECİ ve UYGULANAN ÖDEME YÖNTEMLERİ

Şirket birleşmeleri son yıllarda firmalar tarafından sıkça uygulanan bir dışsal büyüme şekli olarak karşımıza çıkmaktadır. Bununla birlikte, birleşmelerin yoğun bir şekilde yaşanması gerçekleşen tüm birleşmelerin başarılı olduğu anlamına gelmemelidir. Bu görüşlerden hareketle bu makale çalışmasında Şirket birleşmelerinde başarıya ulaşılabilmesi için Şirket birleşmelerinin tarihi gelişimine, birleşme şekillerine ve birleşme sürecinde uygulanan ödeme yöntemlerine değinilmiştir. Bu konuların anlaşılması sağlıklı birleşmelerin gerçekleşmesi açısından önem arz etmektedir

Experimental Investigation of Electro Erosion Machining Parameters of Boron Alloy Steels

In this study, the machinability of boron alloy steel by electro erosion method was investigated. Three different parameters were chosen as variables during the experiments (discharge current, pulse on-time, and pulse of time) and the effects of machining parameters on material removal rate (MRR), electrode wear rate (EWR), and average surface roughness (Ra) were investigated. According to the experimental results, MRR, EWR, and Ra increased with the increase of discharge current. It was determined that while the MRR and EWR values increased, electrode wear decreased with the increase of the stroke time. The ideal processing parameters for each processing level are at different levels has been specified. Ideal machining parameters for workpiece machining speed were found 12 A, 100 µs, and 50 µs for current, pulse duration, and pulse waiting time, respectively. Ideal processing parameters for EWR were found 24 A for current, 100 µs for pulse duration, and 6 µs for pulse waiting time. Ideal processing parameters for surface roughness were determined as 12 A, 50 µs, and 24 µs for current, pulse duration, and pulse waiting time, respectively. As a result of the experimental studies; material removal rate (MRR), electrode wear rate (EWR) increased with the increase of workpiece surface roughness and discharge current. It was also observed that MRR, workpiece surface roughness values increased with increasing stroke time. © 2022, TUBITAK. All rights reserved

Acil Pandemi Polikliniğine Başvuran ve COVID-19 Şüphesiyle Değerlendirilen Hastaların Retrospektif Analizi

Amaç: SARS-CoV-2 olarak adlandırılan yeni tip korona virüsün neden olduğu COVID-19 pandemisi halen tüm dünyada etkisini sürdürmektedir. COVID-19 etkeninin neden olduğu semptomlar diğer solunum yolu etkenlerine benzese de toplumsal etkileri oldukça şiddetli ve farklı seyretmektedir. Bu çalışma hastanemizin acil servis girişinde oluşturulan acil pandemi polikliniğine başvuran ve COVID-19 ön tanısıyla tetkik edilen hastaların analizinin yapılması amacıyla planlanmıştır.Gereç ve Yöntemler: Acil pandemi polikliniğine başvurmuş 16 yaş ve üzeri hastalardan, ateş, öksürük, nefes darlığı şikayetleri olup COVID-19 şüphesiyle polimeraz zincir reaksiyonu (PZR) testi için üst solunum yolundan sürüntü örneği alınmış ve Toraks bilgisayarlı tomografisi (TBT) yapılmış olanlar dahil edilmiştir. Bulgular: PZR testi pozitif ve negatif olan hastaların geliş şikayetleri karşılaştırıldığında, iki grubun da benzer şikayetlere sahip olduğu görülmüştür. PZR testi pozitif hastaların WBC sayıları (5748,39 ± 1547,01), nötrofil sayıları (3650,32 ± 1355,58), lenfosit sayıları (1467,74 ± 472,3) ve platelet sayıları (224,65 ± 76,01); PZR testi negatif olan hastalardan daha düşük bulunmuştur.Sonuç: COVID-19 PZR testi pozitif hastalarda daha düşük WBC, nötrofil ve lenfosit sayısı tespit edilmiştir. Toraks bilgisayarlı tomografi bulguları olan PZR pozitif vakalarda platelet sayısı daha düşük ve CRP değeri daha yüksek izlenmiştir. Bu verilerin özellikle ileri tanı testlerinin olmadığı veya geç sonuçlandığı sağlık kuruluşları için hastalıktan şüphelenme ve erken izolasyon için yol gösterici olabileceğini düşünmekteyiz.Aim: The COVID-19 pandemic caused by the new type of corona virus called SARS-CoV-2 is still effective all over the world. Although the symptoms caused by the COVID-19 agent are similar to other respiratory tract agents, their social effects are quite severe and different; we aimed to analyze the patients who applied to the emergency pandemic outpatient clinic created at the entrance of the emergency department in our hospital and who were examined with the pre-diagnosis of COVID-19. Material and Methods: Patients aged 16 and over who applied to the emergency pandemic outpatient clinic with complaints of fever, cough, and shortness of breath and those who received a swab sample from the upper respiratory tract for the polymerase chain reaction (PCR) test and had thorax computed tomography (TBT) were included. Results: When the complaints of the patients with positive and negative PCR tests were compared, it was seen that both groups had similar complaints. PCR positive patients WBC count (5748.39 ± 1547.01), neutrophil count (3650.32 ± 1355.58), lymphocyte count (1467.74 ± 472.3) and platelet count (224.65 ± 76.01); PCR was found lower than patients who were negative. Conclusion: Lower WBC, neutrophil and lymphocyte counts were detected in patients with positive COVID-19 PCR test. In PCR positive cases with TBT findings, the platelet count was lower and the CRP value was higher. We think that these data may be a guide for suspicion of disease and early isolation for healthcare institutions where there are no advanced diagnostic tests or late results

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide. Methods: A multimethods analysis was performed as part of the GlobalSurg 3 study—a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital. Findings: Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3·85 [95% CI 2·58–5·75]; p<0·0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63·0% vs 82·7%; OR 0·35 [0·23–0·53]; p<0·0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer. Interpretation: Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised. Funding: National Institute for Health and Care Research