Standard Cast Technique Research Articles

Role of Multiple Serial Casting beyond Standard Casting Technique in Managing Club Feet

Aim: To find the role of multiple serial casting beyond standard casting technique in managing club feet. Methodology: Cohort prospective study. Department of Orthopaedic, Chandka Medical College Hospital Larkana from July 1, 2021 to June 30, 2022. One hundred cases were enrolled. The Pirani scoring system was applied for detailed monitoring of the severity and treatment of clubfoot, and the Ponseti method technique was performed. Foot or feet were cast and fastened in an abduction brace at 95% of the correction rate being achieved. All children below two years of age who had one or both feet clubbed were included in this study. Results: The majority of the children visiting the hospital setting for treatment of clubfoot were within the age group of 0–5 months, followed by 6–12 months in 55% and 31% of the children, respectively. About 70% of the children with club feet were boys, with only 30% being girls. The baseline Pirani score was 3.47±0.523, while it decreased significantly to 0.0321±0.135 as the final Pirani score. The outcomes of the study showed that 68% of the children had excellent treatment, 10% had really good treatment, and 18% had fair treatment. Conclusion: Serial casting is a favourable technique for the treatment of clubfoot, wherein it assists in the maintenance of foot balance and proper development. Keywords: Multiple serial casting, Standard casting, Club feet

Strength calculation of aviation detail “reducer cover” obtained by additive growing

Purpose. Ensure the mechanical, technological and operational properties of parts made of structural aluminum alloys (AlSi5, AlMg5) for aviation purposes grown by the additive method using wire (WAAM).Research methods.To accomplish this goal, it was necessary to solve the following tasks: to obtain blanks of serial parts with the necessary geometry, operational and technological properties and to perform a calculation of the stress-deformable state of the obtained blanks of the part. As the first, experimental, product manufactured by this method was selected case detail “Gearbox cover”, due to the simplicity of the configuration of the workpiece. The cultivation of the workpiece was carried out using the Fronius MagicWave 1700 inverter c-welding machine and the FANUC robot. The short-term heat-resistant tests were carried out according to GOST 25.601-80 on the AIMA-5-2 machine. strength analysis of the stress-strain state was carried out using the licensed version of the software package ANSYS 18.1. To develop a finite element model, the SOLID 185 element having the shape of a tetrahedron was adopted.Obtained results. The result of the calculation of the stress-strain state showed that the safety factor for the AlSi5 and AlMg5 alloy is 2.6 and 3.4, respectively.Practical value. Despite the fact that the safety factor has decreased by 0.4, the use of additive technologies for manufacturing the “gearbox cover” from AlMg5 alloy will reduce the human factor when rejects occur, significantly reduce waste during production due to the absence of casting systems, etc. For alloy ML10-4.0. at the same time, the strength characteristics of alloys AlMg5 and ML10 are on the same level. This suggests that the product from the alloy AlMg5, made by additive technologies, can be used instead of the previously used products from the alloy ML10, which were made according to standard casting techniques.

Dimensional precision of implant-supported frameworks fabricated by 3D printing

Statement of problemSelective laser melting (SLM) is a promising additive technology for clinical practice, but data on dimensional precision assessed by marginal fit combined with stress and strain investigations of implant-supported fixed partial dentures (FPDs) are lacking. PurposeThe purpose of this in vitro study was to verify whether the SLM additive manufacturing technology provides better dimensional precision for 3-unit FPD frameworks than subtractive manufacturing with soft metal block (SMB) milling and the standard casting technique. Material and methodsThirty 3-unit implant-supported FPDs with Co-Cr frameworks were made by the casting, SMB milling, and SLM methods (n=10). The marginal fit between the framework and the implant abutment was evaluated with photoelastic (PH) and strain gauge (SG) models. Stress and strain in the implant-supported system were measured by quantitative PH and SG analyses after prosthetic screw tightening. Data were subjected to the Kruskal-Wallis test, Mann-Whitney U test, and Spearman correlation test (α=.05). ResultsThe framework manufacturing method affected the marginal fit (P<.001), stress, and strain values (P<.05). The SLM group showed the best mean ±standard deviation marginal fit (μm) (PH model: 8.4 ±3.2; SG model: 6.9 ±2.1) in comparison with SMB milling (PH model: 42.3 ±15.7; SG model: 41.3 ±15.3) and casting (PH model: 43.5 ±27.8; SG model: 41.3 ±24.6) (P<.05). SLM showed lower mean ±standard deviation stress and strain values (60.3 ±11.6 MPa; 91.4 ±11.1 μstrain) than casting (225.5 ±142.8 MPa; 226.95 ±55.4 μstrain) and SMB milling (218.6 ±101.7 MPa; 289.7 ±89.3 μstrain) (P<.05). A positive correlation was observed between fit and stress or strain for all groups (P<.05). ConclusionsThree-unit FPD frameworks made using the SLM technology showed better dimensional precision than those obtained with the casting or SMB milling methods.

Evaluation on Compression Properties of Different Shape and Perforated rHDPE in Concrete Structures

The purpose of this study was to develop a concrete structure by incorporating waste HDPE plastic as the main reinforcement material and cement as the matrix via standard casting technique. There are eight different shapes of rHDPE reinforcing structure were used to investigate the compression properties of produced concrete composites. Experimental result shown that the highest shape in compressive strength of rHDPE reinforcing structure were the concrete with the addition of X-perforated beam (18.22 MPa), followed by X-beam (17.7 MPa), square perforated tube (17.54 MPa), round tube (17.42 MPa) and round perforated tube (16.69 MPa). In terms of their compressive behavior, the average concrete containing rHDPE reinforcement was successfully improved by 6 % of the mechanical characteristic compared to control concrete. It is shown that the addition of waste plastic as reinforcement structure can provide better compressive strength based on their shape and pattern respectively.

Oxidation behaviour of Fe–40 at.-% Al intermetallics with Li or Cu additions at high temperature

ABSTRACTFe–40 at.-% Al intermetallics with the addition of Li (1 and 3 at.-%) and Cu (3 and 5 at.-%) were produced using standard casting techniques. The oxidation behaviour was obtained using thermogravimetric analyses in an atmosphere of 99.99% oxygen at 800, 900, 1000, and 1100°C. The oxidation product layers on the top and cross-sectional views were characterised using SEM and energy-dispersive X-ray spectroscopy mapping. The different alumina phases can produce a double layer with different mechanical and chemical properties. The results showed that the addition of 1% Li assisted the activation of the oxide production at 1000 and 1100°C, while the rest of the third element additions slightly modified the oxidation resistance.

Inference of optimal speed for sound centrifugal casting of Al-12Si alloys

True centrifugal casting is a standard casting technique for the manufacture of hollow, intricate and sound castings without the use of cores. The molten metal or alloy poured into the rotating mold forms a hollow casting as the centrifugal forces lift the liquid along the mold inner surface. When a mold is rotated at low and very high speeds defects are found in the final castings. Obtaining the critical speed for sound castings should not be a matter of guess or based on experience. The defects in the casting are mainly due to the behavior of the molten metal during the teeming and solidification process. Motion of molten metal at various speeds and its effect during casting are addressed in this paper. Eutectic Al-12Si alloy is taken as an experiment fluid and its performance during various rotational speeds is discussed.

Marginal accuracy of titanium copings fabricated by casting and CAD/CAM techniques

Advances in computer-aided design/computer-assisted manufacturing (CAD/CAM) technology purportedly enhance the marginal fit of dental restorations. However, little information is available on the marginal accuracy of restorations manufactured with various CAD/CAM systems. The purpose of this study was to evaluate and compare the marginal accuracy and refinement time of titanium copings fabricated by 3 different CAD/CAM systems relative to standard casting techniques. Sixty-four stone die duplicates of a human maxillary central incisor, prepared for a metal-ceramic crown, with a uniform chamfer design, were divided into 4 groups (n=16). The specimens were restored with titanium copings using CAD/CAM systems Pro 50 (PRO), DCS (DCS), and Everest (EVE). A conventional titanium casting technique, Biotan (BIO), served as a control. Vertical and horizontal discrepancies between restoration margins and the preparations were each measured before and after manual refinement. This refinement was completed using a disclosing agent and by removing the internal positive defects of the copings. The marginal discrepancies of the copings were evaluated at 4 standard areas using 10 measurements, for a total of 160 measurements of each margin. Repeated-measures ANOVA was used for analyzing marginal accuracy. The coping refinement time was analyzed with the Kruskal-Wallis and post hoc Wilcoxon rank sum tests (alpha=.05). The marginal discrepancies (microm) ranged from 32.9 to 127.8 before and from 3.4 to 58.4 after the manual refinement of copings. Manual refinement significantly improved the marginal accuracy (P<.0001) when compared with the initial fabrication. The relative (%) gain of marginal accuracy was PRO, 74.1%; DCS, 69.7%; EVE, 68.7%; and the control, BIO, 69.2%. The median duration of manual refinement time in minutes was 6.0 for PRO, 9.5 for DCS, 4.0 for EVE, and 4.0 for BIO (Kruskal-Wallis-test: P<.0001). Manual adjustment significantly improves the marginal accuracy of CAD/CAM system-fabricated titanium copings. The highest marginal accuracy was achieved with the DCS system, using a longer refinement time.

A novel process for membrane fabrication: thermally assisted evaporative phase separation (TAEPS)

Poly(vinylidene fluoride) (PVDF) membranes fabricated from conventional processes have a limited range of microstructures. For example, PVDF membranes with spherulitic and isotropic microstructures containing macrovoids are extremely difficult to avoid using standard casting techniques such as wet-casting and thermally induced phase-separation (TIPS) casting. In order to create novel PVDF membrane microstructures such as a spongy, open-celled structure, a new membrane-formation process with six independent process parameters has been developed. Because this new process, thermally assisted evaporative phase separation (TAEPS), has a large number of parameters, the membrane microstructures are easily changed. The TAEPS process can fabricate a PVDF membrane with a spongy, anisotropic microstructure without macrovoids using a simple ternary system with no additives. In addition to studying the novel and unique microstructures available with the TAEPS process, the relationship between final morphology, performance, and processing conditions has been investigated in this paper.

Low pressure permanent mould process simulation of a thin wall aluminium casting

The low pressure permanent mould process is a standard casting technique in current use to produce quality parts. The pressure-driven filling is quite steady and feeding of the casting during solidification is achieved by applying a pressure instead of using feeders. Applying this process to thin wall cast parts yields benefits in both economic and technical terms. However, specific problems such as misruns and oxide defects can arise. Using simulation can help in finding the optimum set of process parameters to produce sound casting. The simulation is consequently expected to reduce the development time of the cast part. SIMULOR, a filling and solidification simulation software, has been used for this study. Various configurations are simulated. For each of them, process parameters such as cycle time, preheat temperature, die coatings, etc. have been introduced in the software. Comparison of the various caasting configurations in terms of misruns and shrinkage defect is conducted. The influence of the heating device and pouring temperature can be clearly pointed out. Simulation is now powerful enough to be applied successfully in reducing development and prototyping time.

Toughness and fatigue of encapsulation-processed silicon carbide-polymer matrix particulate composites

A new process for composite fabrication was developed which improves distribution of the particulate reinforcing phase by polymer encapsulation of the particulate prior to consolidation. The effect of such processing on the fatigue-crack propagation and fracture toughness behaviour of particulate thermoplastic composites was investigated. Composites of several particulate size ranges were fabricated into disc-shaped, compact tension specimens and tested under cyclic and monotonie loading conditions. For comparison, a composite was also fabricated using a standard casting technique. The observed fatigue-crack growth rates spanned three orders of magnitude (10−11 to 10−9 m per cycle) over an applied stress intensity range, ΔK, of 0.3 to 1.1 MPa m1/2. The measured fracture toughness values ranged from 0.69 to 2.95 MPa m1/2. Comparison of the two processing techniques indicated that encapsulation processing increased the fracture toughness of the composite by approximately 33%; however, the fatigue-crack growth behaviour was unaffected. In addition, a trend of increasing crack growth resistance (toughness) with increasing reinforcement particle size was observed. These results are discussed in the light of crack shielding and bridging models for composite toughening.