Weld Load Research Articles

Synthesis of 10-undecenoic acid based C22-dimer acid esters and their evaluation as potential lubricant basestocks

A new class of C22-dimer acid esters was synthesized from 10-undecenoic acid by montmorillonite K10 clay catalyzed polymerization to dimer acid followed by their esterification using straight and branched chain alcohols (C1 to C10). All the newly synthesized products were characterized by IR, 1H NMR, 13C NMR, ESI–MS and HPLC, and evaluated for their physicochemical and lubricant properties such as density, specific gravity, viscosity, pour point, flash point, thermal and oxidation stability, weld load, wear and copper corrosion. Structural features like chain length and branching of alcohols influence the physicochemical and lubricants properties of the C22-dimer acid esters. It was observed that the esters synthesized using branched chain alcohols showed lower pour point and higher oxidation stability than their counterparts synthesized using straight chain alcohols. Overall, the physicochemical and lubricants properties of all the synthesized C22-dimer acid esters indicate that they can be potential base oils for hydraulic, metal working fluids and low-temperature lubricant applications.

Tribological Studies of Transmission Oil Dispersed With Molybdenum Disulfide and Tungsten Disulfide Nanoparticles

This paper compares the tribological properties of transmission oil dispersed with molybdenum disulfide (MoS2) and tungsten disulfide (WS2) nanoparticles. Lubricant samples are prepared by dispersing MoS2 and WS2 nanoparticles in 0.5 wt.% in transmission oil. The nanoparticles are stabilized in the lubricant by surface modification with surfactant SPAN 80. The stability of the lubricant in terms of size variation of dispersed nanoparticles is evaluated using particle size analyzer. The antiwear, antifriction, and extreme pressure (EP) properties are tested on a four-ball wear tester and a comparison is made to assess the relative performance of MoS2 and WS2 nanoparticles. The friction and wear characteristics of lubricant dispersed with nanoparticles are strongly dependent upon the load taken into consideration. The lubricant dispersed with WS2 nanoparticles gave higher weld load and load wear index (LWI) than that of lubricant dispersed with MoS2 nanoparticles. The metallographic studies show that under high load conditions, the WS2 nanoparticles deposit more than MoS2 nanoparticles, thereby giving better performance at higher load conditions.

Development of a Biodegradable/Ecofriendly Turbine Lubricant from a Novel Polyalkylene Glycol Ester

A biodegradable/ecofriendly polyalkylene glycol ester 1,2-PTHC6 (polyglycol containing 1:2 mol fraction of propylene oxide (PO) and tetrahydrofuran (THF)) esterified with n-hexanoic acid (C6 fatty acid) was synthesized following the two step reaction. At first, propylene oxide and tetrahydrofuran were polymerized in 1, 2-dichloroethane to obtain a polymer 1,2-PTH (polyglycol containing 1:2 mol fraction of PO and THF) with molecular weight ( $$\overline{{{\text{M}}_{{\text{n}}} }}$$ ) 838.6. In the second step, esterification of 1,2-PTH was done with C6 fatty acid catalyzed by p-toluenesulfonic acid and toluene as solvent to obtain final product 1,2-PTHC6 having the molecular weight ( $$\overline{{{\text{M}}_{{\text{n}}} }}$$ ) 982.7. The crystallinity and molecular structure of the synthesized poly(propyleneoxide-co-tetrahydrofuran) ester was studied by FT-IR, X-ray diffraction and DSC. The physicochemical properties like; pour point (ASTM 97), kinematic viscosity (ASTM 445), viscosity index (ASTM 2270), refractive index, density, thermal stability, autoignition temperature (IS 7895), corrosion stability and oxidation stability (IP 48) were evaluated. The extreme pressure (IP 239) and antiwear properties (ASTM D 4172) were also evaluated in terms of weld load and average wear scar diameter respectively. All the properties so determined were compared with the specifications of lube oils and it was revealed that this poly(propyleneoxide-co-tetrahydrofuran) ester i.e. 1,2-PTHC6 had suitable physical and tribological properties to be used as base stock for turbine lubricant.

Research on New Lifting Technology of Gantry Crane

In order to improve the safety, efficiency and economy of hoisting operation for gantry crane, the overall lifting scheme of hydraulic lifting device of double upright door frame cluster with multiple anchors is optimized in the process of hoisting operation. According to the ‘carrying method’ ascension process principle, the innovative design for the hinge structure of gantry crane is conducted. The allowable stress method and limit state design method are applied to make the design and checking calculation of the bearing capacity of crossbeam structure caused by installed load, hinge structure and strength of weld and pin to make sure the safety of hoisting hinge structure. The proposed lifting scheme is more secure, efficient and economic and it has extensive application value.

Effect of ultrasonic vibration on welding load, temperature and material flow in friction stir welding

The main process variables were measured, characterized and compared in friction stir welding with/without ultrasonic vibration. The exerted ultrasonic vibration causes reduction in traverse force, tool torque and axial force of welding. Based on the measurement of thermal cycles in friction stir welding process, the thermal effect of ultrasonic vibration is negligible, and the mechanical coupling between ultrasonic vibration and tool action plays a more important role in affecting both the welding process effectiveness and the joint quality. Ultrasonic vibrations improved weld formation by either reducing or eliminating the weld defects, and the suitable process-parameter window is expanded. Dissimilar welding of AA6061-T6 to AA2024-T3 with ultrasonic vibration was used to characterize the enhanced material flow which results in the better weld formation.

Antiwear, Antifriction, and Extreme Pressure Properties of Motor Bike Engine Oil Dispersed with Molybdenum Disulfide Nanoparticles

ABSTRACTThis work presents studies on the antiwear, antifriction, and extreme pressure properties of motor oil dispersed with MoS2 nanoparticles. Commercial oil (SAE 20W-40 grade) is dispersed with stabilized MoS2 nanoparticles in 0.25, 0.5, 0.75, and 1 wt%. The test oils are tested for antiwear, antifriction, and extreme pressure properties on a four-ball wear tester. The wear and friction offered by nanolubricants has decreased remarkably compared to the commercial base oil. The weld load and load wear index of oils dispersed with nanoparticles were improved substantially compared to the commercial base oil. Metallographic studies conducted on the wear balls from the extreme pressure test show that nanoparticles are deposited on the worn area along with additives in the oil, thereby preventing welding of the surfaces. An optimum weight fraction is arrived at for best performance. A synergy between the additives in the oil and dispersed nanoparticles has been observed, resulting in less dispersion for best results. It is found that beyond an optimum weight percentage of nanoparticles, the trends tend to reverse, resulting in greater wear and friction.

Tribological properties of dispersed carbon nanotubes in lubricant

ABSTRACTThis study examined the tribological properties of two lubricating oils, mobil gear 627 and paraffinic mineral oils, with multi-walled carbon nanotubes (MWCNTs) nanoparticles used as additives with various concentrations (0.1, 0.5, 1, and 2 wt.%). The friction and wear experiments were performed using a four ball tribotester. The samples were tested for their anti-wear, load carrying capacity, and friction coefficients according to ASTM D-2783, ASTM D-2596, and ASTM D-5183 standards. The experimental results show that the addition of MWCNTs to base oils exhibit good friction reduction and anti-wear properties. The wear test results show a decreased wear by 68% and 39% in the case of MWCNTs-based mineral oil as compared with base mobil gear 627 and paraffinic mineral oils, respectively. Furthermore, the friction reduction results show a decrease of friction about 57% and 49% in the case of MWCNTs-based mineral oil as compared with base mobil gear 627 and paraffinic mineral oils, respectively. The weld load of the base oil containing 1% MWCNTs was found to be 400 kgf and 125 kgf as compared with base mobil gear 627 and paraffinic mineral oils, respectively, which got welded at 200 kgf and 100 kgf. The morphologies and typical element distribution of the worn surfaces were characterized by scanning electron microscope (SEM) and energy-dispersive X-ray (EDX). The SEM micrographs and EDX chemical analysis confirm the formation of a tribolayer composed of the elements from the nanoparticles.

Analysis of heat transfer and material flow in reverse dual-rotation friction stir welding

Reverse dual-rotation friction stir welding (RDR-FSW) is a novel variant of conventional FSW process. The key feature is that the tool pin and the assisted shoulder rotate reversely and independently during the process; thus, it has great potential to improve the weld quality and lower the welding loads through adjusting the rotating speeds of the tool pin and the assisted shoulder independently. In this study, a 3D model of RDR-FSW process is developed to conduct the numerical simulation of heat generation, material flow, and temperature profile during the process. Heat generated due to plastic deformation and friction at the tool-workpiece contact interfaces are both considered. Streamlines show that there are two material flows with reverse direction, which is beneficial to the uniformity of both the temperature and the microstructure at the advancing side and retreating side. The simulation results show that rotating speeds of the assisted shoulder and the tool pin have great effects on the shape and size of the thermo-mechanically affected zone (TMAZ). The calculated peak temperatures at typical locations match with the experimentally measured ones. It lays solid foundation to optimize the process parameters in RDR-FSW.

Nano-PTFE: New entrant as a very promising EP additive

The paper highlights the effect of varying nano-PTFE concentrations (0–6%) in 150N API Group II oil on physical and tribological properties (based on Four-ball testers and SRV Optimol). The results showed that nano-PTFE particles at 3wt% can significantly improve the weld load (5 times), as well as anti-wear and friction reduction properties of the virgin oil. The topography and surface chemistry of the specimens were examined using scanning electron microscopy and Energy dispersive X-ray analysis. A possible mechanism was proposed to explain the deterioration in performance beyond 3% of PTFE nano-particles.

The effect of the welding parameters and tool size on the thermal process and tool torque in reverse dual-rotation friction stir welding

Reverse dual-rotation friction stir welding (RDR-FSW) is a novel variant of conventional friction stir welding (FSW) process. The key feature is that the tool pin and the assisted shoulder are separated and rotate reversely and independently during welding process, thus it has great potential to improve the weld quality and lower the welding loads through adjusting the rotation speeds of the tool pin and the assisted shoulder independently. A 3D model of RDR-FSW process is developed to analyze the effect of welding parameters and tool size on the thermal process and the tool torque quantitatively. The model considers the effect of the welding parameters on the dimensionless slip rate and the friction coefficient between the tool-workpiece contact interfaces. It is found that with an increase of the radial distance, the locations of peak and valley values of heat generation rate at the shoulder-workpiece contact interfaces vary from the retreating side (RS) to the advancing side (AS) and from the AS to the RS, respectively. Although the reverse rotation of the tool pin and the assisted shoulder has little effect on the total heat generation, the corresponding material flow pattern and the distribution of heat generation rate lead to a more homogeneous temperature distribution and a much lower torque exerted on the workpiece in RDR-FSW process. The model is experimentally validated by comparing the measured thermal cycles with the calculated data.

Influence of Tensile Speeds on the Failure Loads of the DP590 Spot Weld under Various Combined Loading Conditions

This paper is concerned with the evaluation of the dynamic failure load of the spot weld under combined axial and shear loading conditions. The testing fixture is designed to impose the combined axial and shear load on the spot weld. Using the proposed testing fixtures and specimens, quasi-static and dynamic failure tests of the spot weld are conducted with seven different combined loading conditions. The failure load and failure behavior of the spot weld are investigated with different loading conditions. Effect of tensile speeds on the failure load of the spot weld, which is critical for structural crashworthiness, is also examined based on the experimental data. The failure loads measured from the experiment are decomposed into the two components along the axial and shear directions and failure contours are plotted with different loading speeds. Dynamic sensitivities of failure loads with various combined loading conditions were also analyzed. Experimental results indicate that the failure contour is expanded with increasing loading speeds and failure loads show similar dynamic sensitivity with respect to the loading angles.

A Novel Methodology for the Synthesis of Acyloxy Castor Polyol Esters: Low Pour Point Lubricant Base Stocks.

Castor oil, a non-edible oil containing hydroxyl fatty acid, ricinoleic acid (89.3 %) was chemically modified employing a two step procedure. The first step involved acylation (C(2)-C(6) alkanoic anhydrides) of -OH functionality employing a green catalyst, Kieselguhr-G and solvent free medium. The catalyst after reaction was filtered and reused several times without loss in activity. The second step is esterification of acylated castor fatty acids with branched mono alcohol, 2-ethylhexanol and polyols namely neopentyl glycol (NPG), trimethylolpropane (TMP) and pentaerythritol (PE) to obtain 16 novel base stocks. The base stocks when evaluated for different lubricant properties have shown very low pour points (-30 to -45°C) and broad viscosity ranges 20.27 cSt to 370.73 cSt, higher viscosity indices (144-171), good thermal and oxidative stabilities, and high weld load capacities suitable for multi-range industrial applications such as hydraulic fluids, metal working fluids, gear oil, forging and aviation applications. The study revealed that acylated branched mono- and polyol esters rich in monounsaturation is desirable for developing low pour point base stocks.

THE AFTERMARKET ADDITIVES USED IN LUBRICATING OILS

The paper presents literature review concerning the aftermarket additives used in lubricating oils. Classification, principle of operation and scientific research of aftermarket additive operational effectiveness was presented. In majority of cases lubricating oils modified by aftermarket, additives are tested by means of a four-ball extreme pressure tester T-02 or friction machine T-05. Tester T-02 is used to determine lubricating oil parameters like weld load Pz, maximum non-seizure load Pn, seizure load Pt, load wear index Ih and load limit of wear Goz according to Polish Norm (PN-76/C-04147). Investigation of the tribological properties (friction force, wear of the matching elements) is executed by means of friction machine T-05. Until now, scientific research does not result in unequivocal assessment of the aftermarket additives. It come from big variety of aftermarket additives (chemical interaction aftermarket additives, additives that contain molecules of solid lubricants, additives that are able to form conditions for selective transfer lubrication) and their various principles of operation. Now the chemical interaction aftermarket additives have the widest application. These additives join permanently with lubricating oil, so they do not precipitate on the filters and do not create heat-insulating layers unlike the additives which contain molecules of solid lubricants (for example PTFE). Chemical interaction aftermarket additives improve antiwear (AW) and antiseizue (EP) properties of lube oils, decrease temperature in friction area and consequently minimize wear of the machines metal elements. Their functioning efficiency is usually the highest in hard working conditions (high loads, polluted environment, deteriorating technical condition of friction node elements) and in case of oils worse equipped with AW and EP additives (machine and hydraulic oils). In case of polymers, the influence of aftermarket additives is ambiguous.

Temperature and Material Flow Prediction in Friction-Stir Spot Welding of Advanced High-Strength Steel

Friction-stir spot welding (FSSW) has been shown to be capable of joining advanced high-strength steel, with its flexibility in controlling the heat of welding and the resulting microstructure of the joint. This makes FSSW a potential alternative to resistance spot welding if tool life is sufficiently high, and if machine spindle loads are sufficiently low that the process can be implemented on an industrial robot. Robots for spot welding can typically sustain vertical loads of about 8 kN, but FSSW at tool speeds of less than 3000 rpm cause loads that are too high, in the range of 11–14 kN. Therefore, in the current work, tool speeds of 5000 rpm were employed to generate heat more quickly and to reduce welding loads to acceptable levels. Si3N4 tools were used for the welding experiments on 1.2-mm DP 980 steel. The FSSW process was modeled with a finite element approach using the Forge® software. An updated Lagrangian scheme with explicit time integration was employed to predict the flow of the sheet material, subjected to boundary conditions of a rotating tool and a fixed backing plate. Material flow was calculated from a velocity field that is two-dimensional, but heat generated by friction was computed by a novel approach, where the rotational velocity component imparted to the sheet by the tool surface was included in the thermal boundary conditions. An isotropic, viscoplastic Norton-Hoff law was used to compute the material flow stress as a function of strain, strain rate, and temperature. The model predicted welding temperatures to within 4%, and the position of the joint interface to within 10%, of the experimental results.

Experimental Investigation of Friction Stir Seal Welding of Tube–Tubesheet Joints

To ensure heat exchanger tube–tubesheet joints tightness, industrial standards may recommend performing a combination of roller expansion and seal welding, using conventional fusion welding processes. Solid state friction stir welding (FSW) has several advantages over the conventional fusion welding but has not yet proven its usefulness in seal and strength welding of heat exchanger tube–tubesheet joints where the available space is very limited and weld pass is of a relatively complex contour. In this work, a newly designed tool and procedure have been developed to friction stir seal weld tube–tubesheet joints. The effects of process conditions such as welding speed and tool offset on dependent process parameters including welding loads and joint quality have been investigated on a 6xxx-series aluminum three-tube test cell. The results of the investigation revealed that the quality of the seal weld of tube–tubesheet joints is affected by the above parameters. Lower weld speeds increase the size of the heat-affected zone while higher speeds lead to larger weld defects. Better weld quality is obtained when the center of the pin tool is offset from the tube–tubesheet interface by an amount lower than 40% of the pin diameter.

Extreme Pressure Properties of 600 N Base Oil Dispersed With Molybdenum Disulphide Nano Particles

This work presents the extreme-pressure behavior of 600 N base oil dispersed with MoS2 Nano particles with 1 volume percent of polyisobutylenesuccinamide as dispersant. MoS2 Nano particles were dispersed in 0.05, 1.0 wt. % and tested for Extreme pressure behavior on a 4 ball wear tester using the test method ASTM D 2783. The weld load and load wear index of base oil and oil dispersed with Nano particles are evaluated and compared for improvement. Prior to dispersion, the MoS2 Nano particles are suitably surface modified to make them uniformly disperse in oils. The seizure load, weld load and load wear index of Nano particles dispersed oils have improved remarkably compared to Base oil. Metallographic studies done on the wear balls show that Nano particles get deposited on the worn area preventing the welding of the surfaces and hence higher weld load. The wear scar of bottom there balls are also found to be less for Nano dispersed oils compared to base oil and hence lower load-wear index. reduced by applying extreme pressure (EP) and anti-wear (AW) additives. These tend to be sulphur-chlorine and phosphorous containing compounds designed to react chemically with the metal surfaces, forming easily sheared layers of sulphides, chlorines or phosphide and thereby preventing severe wear and seizure. The advantage of using nano materials in lubricants are 2 fold: one they form a barrier between two mating surfaces thereby preventing wear and secondly the spherical nano particles cat as rollers thereby reducing friction.

The optimisation of process parameters for friction stir spot-welded AA3003-H12 aluminium alloy using a Taguchi orthogonal array

The aim of the present work is to optimise the welding parameters for friction stir spot welded non-heat-treatable AA3003-H12 aluminium alloy sheets using a Taguchi orthogonal array. The welding parameters, such as the tool rotational speed, tool plunge depth and dwell time, were determined according to the Taguchi orthogonal table L9 using a randomised approach. The optimum welding parameters for the peak tensile shear load of the joints were predicted, and the individual importance of each parameter on the tensile shear load of the friction stir spot weld was evaluated by examining the signal-to-noise ratio and analysis of variance (ANOVA) results. The optimum levels of the plunge depth, dwell time and tool rotational speed were found to be 4.8mm, 2s and 1500rpm, respectively. The ANOVA results indicated that the tool plunge depth has the higher statistical effect with 69.26% on the tensile shear load, followed by the dwell time and rotational speed. The tensile shear load of the friction stir spot welding (FSSW) joints increased with increasing plunge depth. Additionally, examination of the weld cross-sections, microhardness tests and fracture characterisation of the selected friction spot welded joints were conducted to understand the better performance of the joints. All the fractures of the joints during tensile testing occurred at stir zone (SZ), where the bonded section was minimum. The tensile shear load and tensile deformation of the FSSW joints increased linearly with increasing the bonded size. The finer grain size in the SZ led to the higher hardness, which resulted in higher fracture strength. When the tensile shear load of the joints increased approximately 3-fold, the failure energy absorption of the joints increased approximately 15-fold.

Evaluation of Mechanical Properties of Hastelloy C-276 Weld by Small Punch Test

Mechanical properties of the electron beam weld zone, which are different from the base metal, of Hastelloy C-276 were studied by small punch test (SPT) technology. Load–displacement curves and material properties were obtained by using miniaturized plate-type specimens (3mm diameter×(0.15-0.4) mm thick) from the weld and base metal respectively. The result shows that the maximum load of weld is larger than that of the base metal under the same thickness, meaning the higher strength of the weld. Furthermore, finite element method analysis was performed to investigate the effects of specimen thickness, the diameter of loading ball and the diameter of center hole in holder on the plastic damage of Hastelloy C-276.

Synthetic Base Stock Based on Guerbet Alcohols

AbstractGuerbet (β branched) alcohols of varying chain length of even carbon numbers were synthesized by using single linear fatty alcohols ranging from 1‐octanol to 1‐dodecanol. All Guerbet alcohols having fewer than 28 carbon atoms and are liquid at 0 °C due to β branching. Synthetic base oils were prepared by reacting commonly available unsaturated fatty acids and dicarboxylic acids with Guerbet alcohols using p‐toluenesulfonic acid as a catalyst. These base oils were characterized by physical and tribological properties like viscosity, viscosity index, pour point, flash point, wear scar, weld load, coefficient of friction etc. and compared with commercially available 150 and 500 N base oils.

Joint strength in high speed friction stir spot welded DP 980 steel

High speed friction stir spot welding was applied to 1.2 mm thick DP 980 steel sheets under different welding conditions, using PCBN tools. The range of vertical feed rates used during welding was 2.5∼102 mm per minute, while the range of spindle speeds was 2500∼6000 rpm. Extended testing was carried out for five different sets of welding conditions, until tool failure. These welding conditions resulted in vertical welding loads of 3.6∼8.2 kN and lap shear tension failure loads of 8.9∼11.1 kN. PCBN tools were shown, in the best case, to provide lap shear tension failure loads at or above 9 kN for 900 spot welds, after which tool failure caused a rapid drop in joint strength. Joint strength was shown to be strongly correlated to bond area, which was measured from weld cross sections. Failure modes of the tested joints were a function of bond area and softening that occurred in the heat-affected zone.