Plastic Workpieces Research Articles

Practical Approaches for Acoustic Emission Attenuation Modelling to Enable the Process Monitoring of CFRP Machining

Acoustic emission-based monitoring of the milling process holds the potential to detect undesired damages of fibre-reinforced plastic workpieces, such as delamination or matrix cracking. In addition, abrasive tool wear, tool breakage, or coating failures can be detected. As measurements of the acoustic emission are impacted by attenuation, dispersion, and reflection as it propagates from source to sensor, the waveforms, amplitudes, and frequency content of a wave packet differ depending on the propagation length in the workpiece. Since the distance between acoustic emission sources and a stationary sensor attached to the workpiece changes continually in circumferential milling, the extraction of meaningful information from the raw measurement data is challenging and requires appropriate signal processing and frequency-dependent amplification. In this paper, practical and robust approaches, namely experimentally identified transfer functions and frequency gain parameter tables for attenuation modelling, which in reverse enable the reconstruction of frequency spectra emitted at the acoustic emission source, are presented and discussed. From the results, it is concluded that linear signal processing can largely compensate for the influence of attenuation, dispersion, and reflection on the frequency spectra and can therefore enable acoustic emission based process monitoring.

Utilization of 3D Printing in Replacement of Basic Plastic Workpieces

In the experiment, a 3D printed cogwheel is made using the FDM technology to replace a broken part in a sewing machine. The aim of the project is to examine if a 3D model can be created and manufactured using only entry-level technical knowledge and tools. By the end of the article, it will be apparent that creating functioning plastic parts with a hobby 3D printer and basic CAD experience is very much possible.

Pengaruh Parameter Pemesinan terhadap Kualitas Hasil Potong Mesin Bubut Maximat V13 pada Benda Kerja Poros PVC

Metal cutting process (cutting process) is to cut metal to get the shape and size and quality of the planned cutting surface. The metal cutting process is carried out with special tools, according to the type of cutting process. So the tools for one process cannot be used in another process, even for similar processes, the tools cannot be exchanged if the cutting plans are not the same. Lathe process is a machining process to produce cylindrical machine parts which are carried out using a Lathe. Its basic form can be defined as the machining process of the outer surface of cylindrical or flat lathe objects. Polyvinyl Chloride, commonly abbreviated as PVC, is the third-order thermoplastic polymer in terms of total usage in the world, after Polyethylene (PE) and Polypropylene (PP). Worldwide, more than 50% of PVC produced is used in construction. PVC is produced by polymerizing vinyl chloride monomers (CH2 = CHCl). Because 57% of its mass is chlorine, PVC is the polymer that uses the lowest petroleum feedstock among other polymers. This research follows up the selection of configuration of the lathe machining process using plastic work pieces. In this study, Maximat V13 lathe and PVC type plastic were used. The variation of machining processes are spindle rotation (320, 540, and 900 rpm), feeding speed (0.07, 0.14, and 0.28), the use of tool types (carbide and HSS) and cooling (without cooling, coolant, and oil). So, with this research, it is expected that the optimal parameters in determining the configuration of the lathe machining process on a PVC work piece to produce a good turning surface can be achieved

Experimental study of fiber-glass plastic work pieces contour milling

The article represents the results of study of cut and feed speed influence on wear of monolithic hard alloy end milling cutter during cutting of foiled fiber-glass plastic sheets, used for printed-circuit boards’ production. The peculiarities and problems of cutting layered materials are described. The most effective feed and cut speed values are determined by cutter wear analysis.

Investigation of the geometric change of plastic articles made by polyamide

The following paper includes an investigation of the geometric variation of plastic workpieces in a simulated environment of normal climate by 21° / 50% relative humidity. In the industrial manufacturing, the daily quality checks are required to determine, if the plastic workpieces can be released. Due to the humidity or water absorption, the plastic workpiece grows so far that the dimensional accuracy is not given. In this investigation, the results of 12 weeks are determined and presented.

Surface Quality of Staggered PCD End Mill in Milling of Carbon Fiber Reinforced Plastics

Machined surface quality determines the reliability, wear resistance and service life of carbon fiber reinforced plastic (CFRP) workpieces. In this work, the formation mechanism of the surface topography and the machining defects of CFRPs are proposed, and the influence of milling parameters and fiber cutting angles on the surface quality of CFRPs is obtained, which can provide a reference for extended tool life and good surface quality. Trimming and slot milling tests of unidirectional CFRP laminates are performed. The surface roughness of the machined surface is measured, and the influence of milling parameters on the surface roughness is analyzed. A regression model for the surface roughness of CFRP milling is established. A significance test of the regression model is conducted. The machined surface topography of milling CFRP unidirectional laminates with different fiber orientations is analyzed, and the effect of fiber cutting angle on the surface topography of the machined surface is presented by using a digital super depth-of-field microscope and scanning electron microscope (SEM). To study the influence of fiber cutting angle on machining defects, the machined topography under different fiber orientations is analyzed. The slot milling defects and their formation mechanism under different fiber cutting angles are investigated.

Study on Application of Taguchi Method to Ultrasonic-Aided Spin Welding of Heterogeneous Plastic Materials

The Taguchi Method was applied in this study to discuss the mechanical strength of heterogeneous plastic materials by ultrasonic-aided spin welding. Two heterogeneous plastic workpieces were rotated by a high speed motor, to make the top of conducting energy angle generate the high temperature due to friction. When the thermoplastic material reached the heat distortion temperature, a proper pressure was exerted on another material, the surface would be welded in a semi-melted state. Then the process conditions of ultrasonic welding were arranged by using the standard orthogonal table of Taguchi Method, and the temperature of the contact friction surface could be increased by the excitation of ultrasonic transducers as well as magnified and displaced by sound wave welding head. The optimal value of tensile strength was obtained by using the Large-the-Best characteristic of the Taguchi Method to obtain the important control factors of this experiment; a validation experiment was carried out by using the adjusted factors.

Proposal of a New Ultrasonic Welding Technique for Thermoplastic Polymer

This paper proposes an alternative ultrasonic welding technique capable of welding plastic parts with different shapes and sizes. In this method, a thin plastic sheet of less than 0.5 mm in thickness is fixed to the ultrasonic vibration body called the horn, and two plastic workpieces to be welded are pressed upon the sheet from both sides at a constant normal pressure. Once the horn starts to ultrasonically vibrate, frictional heat is momentarily generated between the sheet and the plastic workpieces, increasing the frictional temperature to a high level. When the temperature increases to over the melting point of all the materials, the materials melt and eventually are welded after the ultrasonic vibration stops. In the current work, an experimental apparatus was designed and constructed. A series of experiments was subsequently carried out on the apparatus to investigate how the surface roughness of the workpieces, the welding time, and the normal welding pressure affect the actual welding area and the tensile strength of the welded workpieces. The experimental results showed that a bigger welding area and a higher tensile strength can be obtained under the appropriate welding conditions, providing validation of the new welding method.

Input electrical impedance as signature for nondestructive evaluation of weld quality during ultrasonic welding of plastics

As a wide applied joining process of plastics with long history, ultrasonic welding of plastics could be helped by newer technologies in sensing, pattern recognition, etc. to improve production rate and weld quality. This paper introduces a new concept which allows in situ monitoring of an ultrasonic welding process in real time and assessing the resulted weld quality right after the completion of the process. In the method, the input voltage and current of a welding machine are first probed and processed to obtain the input electrical impedance during the whole welding period. Because there are no changes of the dynamic properties of the welding machine and fixtures during the process, the detected waveforms of the real and imaginary part of the impedance directly reflect the thermo-mechanical behavior of the plastic work-pieces at the joining point. By recognizing the patterns of these waveforms, the joining quality could then be properly evaluated. This new concept and the accordingly derived nondestructive evaluation method were investigated experimentally. The results show that the input electrical impedance is an effective signature and that the built system evaluates bonding quality of welds effectively and efficiently.