Thermal Welding Research Articles

Post-tonsillectomy morbidities: randomised, prospective controlled clinical trial of cold dissection versus thermal welding tonsillectomy

New surgical techniques and devices have been described that decrease post-tonsillectomy morbidities. This study aimed to compare the two most popular tonsillectomy techniques. Forty children underwent tonsillectomies using both the thermal welding and cold dissection techniques. In each patient, one side was removed with thermal welding and the other was removed with cold dissection. There was a significant decrease in intra-operative blood loss, and the mean operation time was significantly lower on the thermal welding side compared with the cold dissection side. On the cold dissection side, tissue healing (i.e. the rate of complete tissue healing) was better and less pain was reported compared with the thermal welding side. However, there were no significant differences between the two techniques in terms of throat pain scores on the 1st, 3rd or 14th day post-operatively, or tissue healing scores on any of the post-operative days assessed. Cold dissection resulted in better tissue healing and lower pain scores than thermal welding, but thermal welding was associated with less intra-operative blood loss and lower mean operation time than cold dissection.

Joining phenomena of stainless steel/aluminium alloy joint welded by thermal compensation resistance spot welding

Aluminium alloy and austenitic stainless steel were welded using a thermal compensation resistance spot welding technology. The interface region was observed using electron microscopy, and the temperature distribution on the welding zone was investigated as well. The results reveal that higher heat can be obtained in thermal compensation resistance spot welding in comparison with conventional one, and that the morphology and thickness of the reaction layer vary with the position at the welding interface.

The Response of the Heat Affected Zone to Natural Aging in Friction Welded Al-Mg-Si-T6 Alloy

In this work, it is aimed to study the e ect of welding parameters on the response of the fully reverted zone of the heat a ected zone in Al Mg Si T6 alloy to natural aging. The study takes in consideration the e ect of welding time which usually receives less attention than other parameters. Rods of 25 mm diameter were friction welded at varying welding times and forge pressures. The highest hardness recovery in the fully reverted zone was obtained by a combination of a high heat input with a short welding time. These welding conditions produced a thermal welding cycle with higher cooling rate with a relatively longer time at the peak temperature. The high cooling rate is important to avoid the formation of the non-hardening Mg2Si precipitates which do not contribute to the hardness. The longer hold time at peak temperature permits more precipitate dissolution to increase the solute concentration in the solution before the rapid cooling.

Reduction of Welding Distortion for an Improved Assembly Process for Hatch Coaming Production

The alignment between the hatch coaming top surface and hatch cover is essential to maintain hatch cover water tightness and smooth mechanical operation. An improved assembly process for hatch coaming production is proposed, in which the complete hatch coaming is assembled on the shop floor and then lifted as one part, fitted, and welded to the deck. When this complete hatch coaming is assembled to a ship deck, an irregularly distributed gap is usually found between the lower side of the hatch coaming and the deck. Fitting and welding distortion, in particular longitudinal and transverse shrinkage, influence the dimensional accuracy and consequently the production schedule. In this research, welding pass sequence of a fillet welded joint is improved using thermal elastic plastic analysis and welding distortion of the hatch coaming top surface is predicted using elastic analysis. First, three specimens with different gaps that model the welded joint between the hatch coaming and deck were welded and the changed distance between the measuring equipment and the flange was measured. A three-dimensional thermal elastic plastic finite element analysis was carried out for the same specimens and the computed welding distortion was shown to have good agreement with the measurements. As a result of the possible significant influence of welding pass sequence on transverse shrinkage of a fillet welded joint, the influence of welding pass sequence is studied using the computational approach and improved welding pass sequences are proposed to reduce transverse shrinkage. Finally, elastic analysis using inherent longitudinal and transverse shrinkage deformations evaluated by thermal elastic plastic analysis is used to predict welding distortion of the hatch coaming. In this elastic analysis, the influence of different gaps at different locations between the hatch coaming and the deck is considered.

Reduction of Welding Distortion for an Improved Assembly Process for Hatch Coaming Production

The alignment between the hatch coaming top surface and hatch cover is essential to maintain hatch cover water tightness and smooth mechanical operation. An improved assembly process for hatch coaming production is proposed, in which the complete hatch coaming is assembled on the shop floor and then lifted as one part, fitted, and welded to the deck. When this complete hatch coaming is assembled to a ship deck, an irregularly distributed gap is usually found between the lower side of the hatch coaming and the deck. Fitting and welding distortion, in particular longitudinal and transverse shrinkage, influence the dimensional accuracy and consequently the production schedule. In this research, welding pass sequence of a fillet welded joint is improved using thermal elastic plastic analysis and welding distortion of the hatch coaming top surface is predicted using elastic analysis. First, three specimens with different gaps that model the welded joint between the hatch coaming and deck were welded and the changed distance between the measuring equipment and the flange was measured. A three-dimensional thermal elastic plastic finite element analysis was carried out for the same specimens and the computed welding distortion was shown to have good agreement with the measurements. As a result of the possible significant influence of welding pass sequence on transverse shrinkage of a fillet welded joint, the influence of welding pass sequence is studied using the computational approach and improved welding pass sequences are proposed to reduce transverse shrinkage. Finally, elastic analysis using inherent longitudinal and transverse shrinkage deformations evaluated by thermal elastic plastic analysis is used to predict welding distortion of the hatch coaming. In this elastic analysis, the influence of different gaps at different locations between the hatch coaming and the deck is considered.

Structure and Strength at Immiscible Polymer Interfaces.

Thermal welding of polymer-polymer interfaces is important for integrating polymeric elements into devices. When two different polymers are joined, the strength of the weld depends critically on the degree of immiscibility. We perform large-scale molecular dynamics simulations of the structure-strength relation at immiscible polymer interfaces. Our simulations show that immiscibility arrests interdiffusion and limits the equilibrium interfacial width. Even for weakly immiscible films, the narrow interface is unable to transfer stress upon deformation as effectively as the bulk material, and chain pullout at the interface becomes the dominant failure mechanism. This greatly reduces the interfacial strength. The weak response of immiscible interfaces is shown to arise from an insufficient density of entanglements across the interface. We demonstrate that there is a threshold interfacial width below which no significant entanglements can form between opposite sides to strengthen the interface.

Surgical advantages of laparoscopic pelvic and para-aortic lymph node dissection using the thermal welding instrument compared with conventional laparotomy for lymph node dissection

We sought to evaluate the feasibility of laparoscopic pelvic lymph node dissection (PLND) and para-aortic lymph node dissection (PALND) using a thermal ligating shears (TLS) thermal welding instrument comparing with the conventional laparotomic PLND and PALND in the management of endometrial cancer. The current study retrospectively reviewed 100 patients who underwent TLS laparoscopic PLND and PALND and 20 patients who underwent abdominal PLND and PALND as a control group between July 2003 and December 2008. The surgical parameters were compared between the groups. In the TLS laparoscopic group, 73 patients underwent PLND and 27 patients underwent PLND and PALND; in the conventional laparotomic group, nine patients underwent PLND and 11 patients underwent PLND and PALND. Compared to the laparotomic group, the surgical parameters of the laparoscopic group including mean operating time (52 minutes vs. 76 minutes, p < 0.005), mean blood loss (64 mL vs. 162 mL, p = 0.0001), and mean hospital stay (3.96 days vs. 8.92 days, p = 0.001) were all decreased significantly. A significant difference was also found between groups in total number of pelvic (47.6 vs. 35.7, p < 0.05) and aortic (8.4 vs. 6.5, p < 0.05) lymph nodes dissected. The data demonstrate that lymph node dissection could be performed effectively by laparoscopy with the thermal welding instruments with a greater number of retrieved lymph nodes, less blood loss, and shorter hospital stay.

Effect of Thermal Welding Tonsillectomy on Emergence Agitation

: This study sought to examine the effect of thermal welding tonsillectomy that reduces pain and length of anesthesia on emergence agitation. A total of 60 patients (age range, 3–6 years) with chronic recurrent tonsillitis with an indication for tonsillectomy were included. Patients were randomly assigned to 2 groups. The control group (the CD group) was composed of patients undergoing cold dissection (CD) tonsillectomy. The study group (TW group) included patients undergoing thermal welding (TW) tonsillectomy. All patients were given sevoflurane as an anesthetic agent. For all patients, anesthesia time, operation time, extubation time, Pediatric Anesthesia Emergence Delirium scale, pain scale, nausea/vomiting score, and delivery time were recorded. The duration of anesthesia, operation, and delivery was significantly lower in the TW group as compared with the CD group (P = 0.000 < 0001). The pain and agitation scores were significantly lower in the TW group as compared with the CD group (P = 0.000 < 0001). We assume that, besides reducing pain and allowing surgery without bleeding, the TW tonsillectomy method diminishes emergence agitation induced by anesthetic agents, such as sevoflurane.

Automatic Meshing Method for Optimisation of the Fusion Zone Dimensions in Finite Element Models of Welds

A new method has been designed to automatically adapt the geometry of the fusion zone of a weld according to the temperature calculations when the thermal welding heat source parameters are known. In the material definition in a Finite Element code for welding stress calculations, the fusion zone material has different properties than the base material since, among others, the temperature at which the material is stress free is the melting temperature instead of room temperature. In this work, the fusion zone has been determined by postprocessing the thermal model results. The calculated dimensions of the fusion zone have been used as an input for a user subroutine which automatically creates a Finite Element mesh that separates fusion zone elements and base material elements according to the physical reality. It has been shown that the method allows a more accurate stress prediction in the fusion zone and the heat affected zone close to the fusion line, where residual stresses can be important. Neutron diffraction measurements have been used as a validation of the model.

Efficacy of Sucralfate in the Early Postoperative Improvement of Pediatric Thermal Welding Adenotonsillectomy Morbidity

Methods: We investigated the efficacy of sucralfate together with the TW technique on post-tonsillectomy morbidity in children. Our hypothesis was that the advantages of the TW technique might be improved by the protective coating effect of sucralfate on post-tonsillectomy morbidity. Patients were examined and scored clinically by their parents on the day of the operation and at the end of the day for the next 7 days. Throat pain was estimated by parents using the Faces Pain Scale-Revised from 0 to 10 with 0 representing the absence of pain and 10 maximal pain on postoperative days 1 to 7 while swallowing, speaking and resting.

Building Molecular Models Using Screw-On Bottle Caps

Chemical models can be built using screw-on bottle caps. Two identical caps can be joined together by thermal welding to form atoms, and the resulting atoms can be joined together by welding or by hot polymer glue to form molecules. The method is easy, can be applied at every level of chemical education, and gives access to an unlimited number of models at almost no cost. It inspires hands-on activity of pupils and can be used to show the dependence between the three-dimensional structure of molecules and their chemical, physical, and biological features.

Efficacy of Dexpanthenol for Pediatric Post-Tonsillectomy Pain and Wound Healing

We evaluated the efficacy of dexpanthenol in managing pediatric post-tonsillectomy pain and wound healing and sought to discover which of two surgical tonsillectomy techniques provides better healing and less postoperative pain. One hundred twenty patients who underwent tonsillectomy were equally randomized to thermal welding and cold dissection groups. Dexpanthenol pastilles were given to half of each group. Postoperative throat pain was determined with a visual analog scale on the 1st, 3th, 7th, and 14th days, and mucosal healing patterns were assessed on the 7th and 14th days. Regardless of surgical technique, post-tonsillectomy throat pain was significantly less in the dexpanthenol groups than in the placebo groups (p < 0.05), and tonsillar wound healing was significantly better in the dexpanthenol groups than in the placebo groups (p < 0.05). When a comparison was made with regard to surgical technique, wound healing was significantly better in the cold dissection group (p < 0.05), whereas postoperative throat pain was less in the thermal welding group (p < 0.05). Postoperative administration of dexpanthenol significantly accelerates the wound healing process and decreases tonsillectomy-related pain complaints.

Special Topic: Welded Metal/CFRP‐Structures

In autumn 2004 the research unit for 524 entitled “Joining, properties, and simulation of welded metal/CFRP lightweight structures” was established by the German Research Foundation (DFG) to enable alternative joining methods for future multi-material design concepts by understanding the basics of mechanical and microstructural performance. In this joint research different aluminum alloys, steels, and carbon fiber reinforced thermoplastic composites were studied. To realize metal to composite joints three different welding techniques were investigated: ultrasonic welding, induction welding, and thermal impact welding. Different characterization and experimental techniques were combined in order to establish a thorough understanding of the microstructure–property relationships in welded hybrid joints. Their mechanical, physical, and technological properties were investigated with respect to the specific characteristics of the different joining zones by high resolution microscopy and surface analysis. The results provide essential input parameters for modeling and simulation of the welding processes themselves as well as the mechanical behavior of metal/CFRP-structures. By the crosslink of experiment, modeling, and simulation microstructure-based as well as property-based models were developed for prediction of the performance of future multi-material components. Finally the synergy of all FOR 524 projects led from a scientific view on coupon level to advanced welded hybrid structures. A closed hybrid Al/CFRP demonstrator shows the potential of the alternative joining techniques for future applications in structural automotive and aircraft design concepts. Parts of the results were presented during the FOR 524 colloquium at the University of Kaiserslautern in summer 2012 as well as during an international symposium at the TMS 2013 annual meeting in San Antonio (TX, USA). This issue of Advanced Engineering Materials presents full papers, which address different aspects relevant for welded metal/CFRP-joints. Two reviews on ultrasonic and induction welding provide a basic overview about alternative joining techniques for dissimilar materials, especially of metals to thermoplastics. Further communications cover all remaining aspects of the research unit 524: Joining, properties, and simulation of welded metal/CFRP-structures. Finally we would like to thank DFG, in particular Dr. Xenia Molodova and Dr. Burkhard Jahnen, for their on-going interest and financial support of our work. Without the financial support of DFG these unique joint research projects would not have been possible. Last but not least we hope that the selected contributions will stimulate future research activities and we wish enjoyable reading. Frank Balle Dietmar Eifler Frank Balle and Dietmar Eifler Institute of Materials Science and Engineering (WKK) University of Kaiserslautern (Germany)

Assessment of postoperative pain scores in thermal welding and conventional tonsillectomy techniques: A randomized control study

ObjectivesTo assess postoperative pain of the thermal welding system tonsillectomy compared to the conventional tonsillectomy. Design342 Patients aged from 8 through 39years were enrolled in a randomized prospective controlled study. Extracapsular tonsillectomy with thermal welding system and conventional system was performed randomly in each patient. Patients with chronic tonsillitis were included. Patients undergoing adenoidectomy, suspected or confirmed tonsillar malignancy or any other procedure together with tonsillectomy were excluded from this study. Postoperative pain was measured by means of Faces Pain Scale and Numerical Pain Score for each patient in three occasions (6–8h post operative, 24h and 6days later during the first postoperative visit) for each side. ResultsThere was a statistically significant difference between the pain scores of both procedures, in all three occasions (P>0.001). Patients treated with Thermal welding had the least postoperative pain score regardless of the occasion. Patients treated with the conventional technique had a significantly higher postoperative pain score in all three occasions. ConclusionsThermal welding tonsillectomy is superior to the conventional technique, with less postoperative pain scores, compared to the conventional technique.

Micro-structural geometry of thin films intended for the inner lumen of nerve conduits affects nerve repair

Damage to peripheral nerves can cause significant motor or sensory injuries. In serious cases, a nerve is sacrificed from another part of the body to repair a damaged nerve (autograft). The development of biodegradable polymer conduits may offer an alternative to autografts. This study investigated the surface topography and mechanical properties of smooth, pitted and grooved structures of ultra-thin poly (ε-caprolactone)/poly lactic acid blended, solvent-cast films. We have investigated the effect of the groove shape on cell morphology and alignment. Photolithography and dry/wet etching was used to develop patterned silicon substrates with grooves with accurate geometries (V shaped, sloped walls and square shaped). Using a neural cell line (NG108-15), in vitro experiments confirmed good cell attachment and proliferation on all the polymer scaffolds. Imaging techniques demonstrated that there was different cellular responses and morphology according to the shape of the groove. Studies showed that the geometry, particularly the angle of the slope and the space between grooves, affected cellular responses. In addition, biomechanical studies showed that the patterned films had excellent mechanical properties and were stronger than the natural nerve. The conduit tubes were made by rolling the films around a mandrel and using a thermal welding technique to join the edges. The promising biomechanical and in vitro results demonstrate that nerve cell responses are affected by the shape of longitudinal grooves, and particularly by the angle of the slope of the groove walls.

The effects of thermal welding tonsillectomy on postoperative pain

This study aims to compare the effects of the thermal welding tonsillectomy and conventional cold dissection tonsillectomy on the postoperative pain. Between November 2009 and May 2011, 60 pediatric patients (38 boys, 22 girls; mean age 8.4 years; range 5 to 15 years) who underwent tonsillectomy due to chronic tonsillitis or obstructive sleep apnea were included. Tonsillectomy with thermal welding was performed on 30 patients and conventional cold dissection tonsillectomy was performed on the 30 patients. Postoperative pain was assessed by visual analog scale. Postoperative first day pain score was accepted as 10 and the patients were asked to score between 0-10 for other nine days. Student t-test was used for the statistical evaluation of pain scores in the first five days, while Mann-Whitney-U test was used for the other days. In the first five day evaluation, the mean pain score was 35.83 for cold dissection tonsillectomy and 31.90 for thermal welding tonsillectomy. The mean pain value for the last five days was 15.6 for cold dissection tonsillectomy and 10.33 for thermal welding tonsillectomy. The mean pain scores of cold dissection tonsillectomy were statistically significantly higher, compared to thermal welding tonsillectomy for first five day, last five day and total 10 days (p<0.05). We consider that thermal welding tonsillectomy results in lower postoperative pain, compared to the conventional cold dissection tonsillectomy.

Molecular Dynamics Simulations of Polymer Welding: Strength from Interfacial Entanglements

Large-scale simulations of thermal welding of polymers are performed to investigate the rise of mechanical strength at the polymer-polymer interface with the welding time t(w). The welding process is at the core of integrating polymeric elements into devices as well as in the thermal induced healing of polymers, processes that require the development of interfacial strength equal to that of the bulk. Our simulations show that the interfacial strength saturates at the bulk shear strength long before polymers diffuse by their radius of gyration. Along with the strength increase, the dominant failure mode changes from chain pullout at the interface to chain scission as in the bulk. The formation of sufficient entanglements across the interface, which we track using a primitive path analysis, is required to arrest catastrophic chain pullout at the interface. The bulk response is not fully recovered until the density of entanglements at the interface reaches the bulk value. Moreover, the increase of interfacial strength before saturation is proportional to the number of interfacial entanglements between chains from opposite sides.

An investigation of thermochemical changes in Canadian hardwood species during wood welding

Thermochemical changes during wood-dowel welding were investigated in two Canadian hardwood species commonly used for indoor appearance applications: sugar maple (Acer saccharum) and yellow birch (Betula alleghaniensis). The original reference wood sample and the welded interface between two bonded wood pieces, a dowel and a substrate, were compared to explain differences in mechanical properties between species. Pyrolysis gas chromatography–mass spectrometry (Py-GC/MS), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS) were used. The gases emitted during wood welding were determined by Py-GC/MS and gas chromatography coupled with a thermal conductivity detector and a flame ionization detector (GC-TCD/FID). Results showed that thermal welding of birch and maple woods degrades hemicelluloses and affects lignin polymer through depolymerisation. Welding effectiveness is therefore directly associated with the properties of the original wood constituents, primarily lignin and carbohydrates. The lignin-related changes at the welded interface were greater for sugar maple than for yellow birch, corroborating mechanical property differences observed between the two species. The gases proportions were similar for both species and no harmful gases were detected in the smoke released during welding process.

평판형 광생물반응기 케이스 접합 기술

Adhesive bonding and plastic welding have been widely used to join two plastic materials together. The goal of this paper is to determine a proper joining technology of a pair of flat panel (FP) photobioreactor (PBR) case. The material of the FP PBR case is polycarbonate (PC) plate. Two types of adhesion, including acryl adhesive and two-part epoxy adhesive, as well as two types of plastic welding technology, including ultrasonic welding and thermal welding, are employed for joining of PC plates. In order to influence of the adhesion and welding conditions on the joining characteristics of the PC plates in operational conditions of the FP PBR case, the morphology in the vicinity of the joined region as well as the water and pressure resistance characteristic are investigated. In addition, the variation of the bonding strength of the joined region and deformation behaviors in the vicinity of the joined region according to the adhesion and welding conditions is examined via the lap-shear test. From the results of basic experiments, proper joining technologies are chosen. Using the chosen joining technologies, the FP PBR case are fabricated to perform full-scale durability experiment. The results of the full-scale durability experiment have been shown that the chosen joining technologies can be applicable to fabricate the FP PBR case.

Grain boundary segregation of antimony in heat affected zones during welding thermal cycles for a Cr–Mo low alloysteel

Grain boundary segregation of Sb in heat affected zones during welding thermal cycles is examined using field emission gun scanning transmission electron microscopy (FEGSTEM) for an Sb-doped Cr–Mo low alloy steel. A Gleeble-1500 thermomechanical simulator is used to simulate the welding heat affected zone with a peak temperature of 1320°C for heat inputs of 36, 60 and 100kJ/cm. The results show that non-equilibrium segregation of Sb occurs during thermal cycles and critical welding heat input is found to be between 36kJ/cm and 100kJ/cm, at which the maximum segregation of Sb may be obtained during corresponding thermal cycling. If possible, this critical heat input should be avoided in engineering practice.