Study on Joint strength of UltrasonicallyWelded Dissimilar Plastics VigneshA1, Rajamani R2Graduate student1, Department of Production Engineering, PSG college of Technology,Coimbatore-641004, IndiaAssistant Professor2, Department ofProduction Engineering, PSG college of Technology, Coimbatore-641004, India AbsractPlastics being welded ultrasonically iswidely used everywhere under the applications of industries , commercial andmedical. The Purpose of the project is to analyse the joint strength ofdifferent combinations of dissimilar materials being welded ultrasonically andalso to reduce the weight factor and economic factors. Three input parametersnamely holding time, weld time , weld pressure and one output parameter namelyjoint strength is chosen. The input parameters are set in Ultrasonic weldingmachine and the output parameter is determined by Universal testing machine.The joint strength is determined by means of Universal testing machine. Designof experiments is applied to conduct the experiments based on the input andoutput parameter.
Plastics chosen to weld are HDPE, LDPE, ABS and Nylon.Experiment is conducted to check the feasibility of the joint strength bycomparing with theoretical values from literatures for reference. Thetheoretical values are those for the combination of LDPE with LDPE and HDPEwith HDPE. This experiment helps in analyzing the proper combination ofplastics. The experiments conducted will help in selecting the proper materialat low cost with high strength.keywords- plastics, holding time, weldpressure, weld time, combinations I. INTRODUCTIONUltrasonic welding uses high-frequency vibrations to weld the workpieces.
It is widely used forplastics, and for joining dissimilarmaterials. In ultrasonic welding, there is no use of extra adhesives to weldthe materials together. For joining workpieces, ultrasonic welding used to fitthe parts. The parts to be welded are held between a anvil and a horn connected to the transducer, where 20 kHz low-amplitudeacoustic vibration is emitted. When welding plastics, the interface between two parts to melt the plastics. The ultrasonic vibrations melts the plastics where the joint of theplastics meets at the point. Ultrasonics is also used for metal welding but areapplicable only to little extent. Ultrasonic welding in thermoplastics creates melting of the plastic by vibrational energyalong the joint to be welded.
Ultrasonic welding is used for both hard and softplastics. Many criteria of ultrasonic welding still require more study, relatedto process parameters of weld quality. II. LITERATUREREVIEW Umang Parmar et al.1, experimentally investigated the ultrasonic welding of thermoplastics isone of the joining methods which is based on application of high-frequencyvibratory energy in that workpieces are held together under pressure withoutmelting. This study involves the experimental data of joint strength ofacrylonitrile butadiene styrene (ABS) material for ultrasonic welding onwelding parameters (welding pressure, welding time and amplitude) and criticalstates of the welding parameters has been analysed by analysis of variance.Mantra Prasad satpathy et al.
2, research work explored the joints of various dissimilar metals producedby ultrasonic spot welding and the weld strength, interface temperature ,weldarea ,micro hardness were measured as well as the quality of the weld revealedfor different weld times. Further increase in weld time, the interfacialtemperature was far above than the recrystallization temperature, showing asubstantial loss in joint strength.Benatar 3 , studied the theory of ultrasonic welding including viscoelastic heating and the difference between near field and far field ultrasonicwelding and it discussed about the joint and part design and thermoplasticmaterial weldability.Yeh 4 , key factors affecting the welding process and weld qualityare discussed based on industrial applications and selection of medical plasticsand impact of material structure for ultrasonic welding applications arestudied and also covered optimization and troubleshooting.
Jiromaru tsujino5, experimentally studied that at high frequencywelding charcteristics can be improved due to larger vibration of plasticmaterials. For welding of rather thin or small specimens , as the fundamentalfrequency of these welding systems is higher and the number of driven higherfrequencies are driven simultaneously. Larger welded area and weld strength wereobtained.Kim et al. 6, stated about a process robustness study ofultrasonic welding of thin metal sheets and quality of the welded joints isevaluated based on mechanical tests and the quality criterion is then appliedto evaluate the weldability.
These results were used to determine both theoptimal weld parameters and the robust operating range. Shakil et al. 7, stated aboutthe optimizisation of ultrasonic spot welding parameters forjoining 3003 Aluminum alloy with 304 Stainless steel. Welding was performed atvarious clamping pressures and energy levels for investigating its effect onmicrostructure, mechanical properties and bond quality of the weld. The maximumtensile strength is achieved once a reasonable amount of bond density and materialthinning (required for the formation of metallurgical bonds) is attained.Francesca Lionetto et al.
8, applied ultrasonic metal weldinghas been applied for joining aluminum AA5754 sheets to a thermoset matrixcomposite consisting in a carbon fiber reinforced epoxy resin (CF/epoxy). Thesurface created on the thermoset matrix composite provides a fast welding witha metallic sheet. By selecting the proper welding energy and force, an averageadhesion strength of 34.8 MPa has been obtained on CF/epoxy-PA6- AA5754.Balle et al. 9, focused onstatistical test planning methods to increase process stability by means ofreproducibility in comparison to a stepwise empirical variation of each processparameter during solid state joining as well as the significant reduction ofexperimental time and costs.
Ren-Yu Yeh et al. 10, stated that both shear strength and normal tensile strength were affected by changesin the grid structures and welding parameters, and the experimental resultsshow that the micro-structure geometry of the metal plate is a major factor inthe joining strength. Successful welds required that process cycle times beless than 1s. Shih-Fu Ling et al. 11, research work explored a newconcept which allows in monitoring of an ultrasonic welding process in realtime and assessing the resulted weld quality right after the completion of theprocess.
In the method, the input voltage and current of a welding machine arefirst probed and processed to obtain the input electrical impedance during thewhole welding period. and the results show that the input electrical impedanceis an effective signature and that the built system evaluates bonding qualityof welds effectively and efficiently.Ng et al. 12, attempted ultrasonic welding as a technique for thebonding of connectors to microfluidic devices. Different schemes of the methodwere explored based on different designs of the connectors to achieve a strong,minimal dead-volume connection. Results showed that without the use of inserts,there would be unwanted flow of melt material into the conduit of the connectorcausing blockage. It was found out that the width of the welding zone islimited by the width of the sleeve (application of ultrasonic energy to theconnector).
Hence, the welding zone would proceed no further towards theconduit and causing blockage.Xin Wu et al. 13, investigated experimentally the microstructures ofthe ultrasonic welds between three layers of lithium-ion battery tabs (eitherAl or Cu) and bus bars were studiedIt was found that the metal inter-mix is themain weld formation mechanism among Al tabs, while constrained surfacedeformation bonding is the main mechanism for Cu-Cu or Al-CuWei Xuan Chan et al. 14, research work reveals that the difference indynamic modulus between the matrix material and PMMA is the most significantcontribution to the viability of this composite ultrasonic welding film. Theexperiment is conducted with PDMS as the matrix material to determine effect ofthe concentration of PMMA microspheres as micro energy directors on the weldingstrength and quality of the proposed methodology with the chosen composite. FaridHaddadi 15, investigated that forming effective welds in lessfor difficult dissimilar material combinations such as aluminium to steeljoint. However, in dissimilar joint the inter diffusion and thus intermetallicformation was accelerated due to high strain rate dynamic deformation inultrasonic spot welding which deteriorates mechanical performance.Ninggang Shen et al.
16, experimentally investigated that duringultrasonic welding, intensive material interactions occur due to the severeplastic deformation (SPD) and frictional heat generation, which leads to themicrostructural change. Dynamic recrystallization and grain growth kineticslaws were applied to simulate the microstructural evolution under differentwelding time durations. Jianhui Qiu et al. 17, experimentally investigated excessively long welding time has broughtIPS cracking and air bubbles at local part of interfaces.
. Therefore, enlargingwelding areas and reducing the air bubbles are very important to improve thewelding strengths. The effective welding conditions are the shorter weldingtime and higher welding stressPrakasan et al.18, experimentally studied amodel for the temperature distribution during welding and stress distributionin the horn and welded joints are presented. With the the forces that act atthe interface it is possible for controlling the weld strength and avoidsonotrode welding .
The finite element model presented is capable of finding out the interface temperature ,stressdistribution during welding and their influences in the work piece, sonotrode, anvil and coefficient of friction during heatgeneration at the weld interface.Bongsu Kang et al. 19, experimentally investigated thatsufficient energy is required to produce proper bonding, while excessive energycan cause such quality issues as weld fracture and perforation. Tiziana Segreto et al. 20, experimentally investigated an advancedultrasonic non-destructive evaluation technique is applied for the qualitycontrol of brazed copper cells in order to realize an accelerometer prototypefor cancer proton therapy. From the literature it is clearthat there is enough scope to carry out the project and to determine the properparameter combination of plastics by weight factor. III. OBJECTIVEAND METHODOLOGY A.
ObjectivesThe objectives of the study isa) to studythe strength of various materials by means of ultrasonic welding.b) toreduce the weight factor. c) toselect the proper material at low costwith high strength.d) toreplace complex situations B.
MethodologyFrom the literature survey , it is understood that the parameters suchas weld pressure, weld time and holding time influencing the weld strength ofthe plastics. By applying DOE, L9 orthogonal array is selected . After theexperiment is completed, the tensile strength is calculated and it is comparedwith the values from the literature survey. The figure 1 represents themethodology. Not satisfactory Satisfactory Fig 1. Methodology IV. EXPERIMENTAL WORKA. Material modelExperimentalmaterial model has been designed.
Thesize of the model is dia 35mm × length 30 mm. Figure 2 represents the 3D modeldesign and figure.3 represents the detailed dimensions of the model design(male component). Fig.
2 3D Model design Fig 3. Detailed dimensions ofmale componentThe figure 4 represents the detailed dimensions offemale component. Fig4. Detailed dimensions of female component B. ExperimentationTheexperiments to be conducted on the plastic ultrasonic welding machine . Thespecification of the ultrasonic welding machine is shown in the table 3. Inultrasonic welding machine used here,the horn is made of stepped aluminium and anvil is made of steel material.
The plastic materials to be welded in the form of cylindrical shape, namelymale part and female part are placed in the fixture. Parts are welded by meansof applying the pressure by fixing the holding time and welding time. After theworkpieces are being welded , the joint strength value is calculated byUniversal testing machine.
The specifications of the universal testing machineis shown in table 4.After the joint strength is being calculated , the bestcombination of parameters are identified by using ANOVA. C. Design of Experiments Thelevels are chosen between the ranges for HDPE-HDPE combinations are given intable 1. Table 1.
Levels chosen for HDPE-HDPE S.No Parameters Level 1 Level 2 Level 3 1 Weld pressure (bar) 3 3..25 3.
5 2 Weld time (sec) 2.5 2.75 3 3 Holding time (sec) 2.5 3 3.5 Basedon the L9 orthogonal array , the design of experiments for HDPE-HDPEcombination is designed by MINITAB software and it is shown in table 2. Table 2. Design of experiments byMINITAB S.No Parameters Holding time(in sec) Weld time(in sec) Weld pressure(bar) 1 3.
5 3 3.5 2 3.5 2.75 3.25 3 3.5 2.5 3 4 3 3 3.5 5 3 2.
75 3 6 3 2.5 3.25 7 2.5 3 3.25 8 2.5 2.75 3 9 2.5 2.
5 3.5 a) Experimental set up:Figure 5 represents theexperimental set up of ultrasonic welding while the HDPE-HDPE combination isdone. Fig.5 Experimental set up (i)Specifications of ultrasonicwelding machine: Table 3. Specifications of ultrasonic welding machine S.No Description Value 1 Make Ultra weld, National Indosonic, Pune 2 Input power 230 V, 50Hz,Single phase 3 Output power 1500 W 4 Output frequency 20 KHz 5 Max .
Amplitude 60 Microns 6 Max. Pressure 10 bar 7 Stroke length 100 mm (ii) Specifications of Universal testing machine Table 4. Specifications of Universal testingmachine S.No Description Value 1 Maximum capacity 10 KN 2 Least count displacement 0.1 mm 3 Accuracy of load 1% indicated load from 4% to 100% of load cell capacity 4 Grip separation 25 to 75 mm 5 Straining rate 1mm/min to 100mm/min 6 Power Single phase, 220V,50Hz, AC 7 Motor 0.
5 HP b) HDPE-HDPE welded component: HDPE-HDPEcombinations are being made and welded under the levels through design ofexperiments and figure 6 represents the welded combination of HDPE-HDPE. Fig.6 HDPE-HDPE welded combination V. SUMMARYThis experimentation results will help incarrying out the proper selection of combinations of dissimilar materials in future and also ingood tensile strength at proper levels are known . This will state theselection of plastics to be chosen in order to reduce the weight factor. VI. REFERENCES1.
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