Influence of the Different Combination of Diameters of Two Tool Heads on Forming Quality in Double Sided Incremental Forming

The existing double sided incremental forming (DSIF) mostly uses two tools with the same diameter as the upper/lower tools, which is not conducive to improve the forming quality and forming efficiency. In this paper, the influence of the different combination of the upper and lower tool head diameters on the thickness distribution and the contour dimension accuracy of the formed part is studied by using ANSYS / LS-DYNA software and by taking the model with bidirectional convex features as the research object. It is found that the reasonable combination of different diameters of the upper/lower tools based on the characteristics of the parts to be formed can improve the forming quality and forming efficiency.

An Experimental Study on Processing TC4 with Nano Particle Surfactant Mixed Micro EDM

Micro electrical discharge machining (micro EDM) is able to remove conductive material by non-contact instantaneous high temperature, which is more suitable for machining titanium and its alloys compared with traditional machining methods. To further improve the machining efficiency and machined surface quality of micro EDM, the nano particle surfactant mixed micro EDM method is put forward in this paper. Experiments were conducted to explore the effect of nano particle surfactant on the micro EDM performance of titanium alloy. The results show that the material removal rate of micro EDM in dielectric mixed with TiO2 is the highest when open-circuit voltage is 100 V, followed by Al2O3 and ZrO2. Lower tool wear rate can be produced by using dielectric mixed with nano particle surfactant. The taper ratio of micro EDM in dielectric mixed with nano particle surfactant is higher than that in deionized water. The surface roughness Ra of micro EDM in dielectric mixed with TiO2 can be 50% lower than that in deionized water. It is helpful to improve the machining performance by adding surface surfactant in the dielectric of micro EDM.

Part-optimized forming by spatially distributed vaporizing foil actuators

Electrically vaporizing foil actuators are employed as an innovative high speed sheet metal forming technology, which has the potential to lower tool costs. To reduce experimental try-outs, a predictive physics-based process design procedure is developed for the first time. It consists of a mathematical optimization utilizing numerical forming simulations followed by analytical computations for the forming-impulse generation through the rapid Joule heating of the foils. The proposed method is demonstrated for an exemplary steel sheet part. The resulting process design provides a part-specific impulse distribution, corresponding parallel actuator geometries, and the pulse generator’s charging energy, so that all process parameters are available before the first experiment. The experimental validation is then performed for the example part. Formed parts indicate that the introduced method yields a good starting point for actual testing, as it only requires adjustments in the form of a minor charging energy augmentation. This was expectable due to the conservative nature of the underlying modeling. The part geometry obtained with the most suitable charging energy is finally compared to the target geometry.

Analysis of tool wear and deformation in friction stir welding of unequal thickness dissimilar Al alloys

Friction stir welding between plates of unequal thickness, which are made from similar or dissimilar materials, finds wide range of applications in the aerospace and automotive sectors. Friction stir welding of plates made from dissimilar materials having unequal thicknesses is challenging. One of the major challenges is the control of rapid tool degradation which occurs during welding. This work reports a maiden study on tool degradation of high thickness ratio unequal thickness dissimilar material joints made between 6.3 mm thick AA2024-T3 and 2.5 mm thick AA7475-T7 plates. The degradation of friction stir welding tool made of T4 tool steel having tapered cylindrical pin and scrolled shoulder was analyzed. The geometry of tool (before and after welding) was compared; the degradation was categorized, characterized, and analyzed in the light of measured welding temperature, process forces, and process parameters. It was found that the pin undergoes significant degradation in the form of wear and deformation compared to the tool shoulder. The experimental results demonstrated that lower flow stresses caused by higher process temperature leads to lower tool wear and deformation, and vice versa. In addition to temperature and process forces, the surface tilt angle was found to significantly affect the pin deformation. The higher surface tilt angle caused an increase in tool wear and deformation.

Influence of physical properties on boring operations of AISI 1050 steel bars

The main reason for vibration and tool deflection in boring processes are the geometrical, mechanical, and physical properties of the boring bar employed. The diameter of the boring bar is rather small when compared with its length due to the nature of the mechanism in the boring process., In the present study, the influence of the physical properties of boring bars on the deflection amplitudes, natural, and circular natural frequencies were investigated both theoretically and experimentally. For that purpose, seven kinds of boring bars were used. The influence of the characters of boring bars on the amplitudes of tool deflection was investigated both theoretically and experimentally. By contrast, this influence on the natural and the circular natural frequencies were investigated only theoretically. It was found that boring bars filled with rubber and silicon recorded the smallest deflection amplitudes. Particularly, bars filled with silicon manifested the lower tool deflection amplitudes under the selected conditions. It should be added that lower feed rates and cutting depths caused severe tool deflection amplitudes. Moreover, the optimum compatibility between the theoretical and experimental results of tool deflection amplitudes was observed in bars filled with silicon ∅ 16 mm.

Major Developments in EDM Surface Alloying using Composite Material Tool Electrode

Electric Discharge alloying/Coating (EDC) is an emerging field for the surface modification of advanced engineering materials like tool steel, high heat resistance alloy, titanium alloy etc. The advanced engineering materials have good mechanical properties and are used for the engineering applications like dies, aerospace, and automotives. To treat these difficult-to-machine advanced engineering materials with new challenges, numerous advancements in electrical discharge machining (EDM) processes have been carried out. Electrode materials for EDM are usually made up of copper, and its alloys. Proper selection with composition of electrode materials are required to avoid cracks, residual stresses etc during or after Electrical Discharge Machining and at the same time to have better surface finish and material removal rate and lower tool wear rate of the electrode. Further electrodes can be prepared by different methods like powder metallurgy, stir casting technique etc. This paper presents the brief details of effect of different electrodes on the surface and machining characteristics.

Study of Sheared Edge Formability of Ultra-High Strength DP980 Sheet Metal Blanks

Advanced high strength steels (AHSS) and ultra-high strength steels (UHSS) have been increasingly implemented by the automotive industry for better crashworthiness and fuel economy. However, these steels are often sensitive to the trimmed edge cracking. The objective of the present paper is to study the sheared edge of ultra-high strength dual-phase steel, DP980, in mechanical trimming and hole punching by sheared edge quality assessment, stretchability, and hole expansion tests as well as finite element analysis. Furthermore, the mechanism of fracture propagation in trimming and hole punching processes of DP980 was discussed. Rather a unique fracture mechanism was observed for trimming of DP980 steel leading to the burr removal at the final stage of the trimming process. Finite element analysis revealed that, under very large clearances, a secondary crack initiates from the edge of the lower tool, and the primary propagated crack turns toward it simultaneously. Intersecting of these two cracks leads to the total separation and leaves the edge of the trimmed part with a broken burr. Fracture observation of trimmed specimens revealed that crack initiation sites under tension moved from the middle of the trimmed surface toward the burr tip with increasing the clearance. This study demonstrates the importance of stretchability tests for designing the stamping dies as well as a reliable finite element simulation for characterizing the material behavior during the shearing process.

A Review of Assisted / Augmented Manufacturing Processes

Manufacturing has a history almost as long as the humankind, but as materials get more and more complex due to material science technology, manufacturing them becomes increasingly difficult. Using processes in combination has been a common practice. Similarly, using a simple process to aid a more complex process has often been employed. However, more advanced technologies have been developed to manufacture difficult-to-manufacture materials, as well as advanced auxiliary techniques to aid the main manufacturing process. In most of these processes, the aim is to improve the manufacturability of the part. Initial considerations to improve manufacturability were focused on being able to produce the part in ways aligning with the design. For example, in hot forging, it was not possible to achieve the right product without the aid of the secondary process (heating). As the manufacturing field evolved, needs of the industry changed to improving part quality and lowering manufacturing costs. Modern methods of assisting main manufacturing processes focus on ensuring (1) an extended use of the tool quantified by lower tool wear and higher tool life, (2) improved machine capabilities quantified by lower maintenance times and higher automation, (3) improved final product quality quantified by dimensional accuracy and surface, subsurface, and bulk material quality, and (4) increased sustainability of the process quantified by lower resource use such as machine power and lubrication. In this study, an overview of the use of assistance in manufacturing processes is provided. The review is focused on more modern techniques such as laser, electrical, magnetic field, and ultrasonic assistance, more modern materials that are difficult-to-manufacture such as hardened steels and titanium and nickel-based alloys, and on machining processes that are more imminent for the critical industries such as automotive, aerospace, energy production, and biomedical industries.

Additive Manufacturing Technologies: An Overview about 3D Printing Methods and Future Prospects

The use of conventional manufacturing methods is mainly limited by the size of the production run and the geometrical complexity of the component, and as a result we are occasionally forced to use processes and tools that increase the final cost of the element being produced. Additive manufacturing techniques provide major competitive advantages due to the fact that they adapt to the geometrical complexity and customised design of the part to be manufactured. The following may also be achieved according to field of application: lighter weight products, multimaterial products, ergonomic products, efficient short production runs, fewer assembly errors and, therefore, lower associated costs, lower tool investment costs, a combination of different manufacturing processes, an optimised use of materials, and a more sustainable manufacturing process. Additive manufacturing is seen as being one of the major revolutionary industrial processes of the next few years. Additive manufacturing has several alternatives ranging from simple RepRap machines to complex fused metal deposition systems. This paper will expand upon the structural design of the machines, their history, classification, the alternatives existing today, materials used and their characteristics, the technology limitations, and also the prospects that are opening up for different technologies both in the professional field of innovation and the academic field of research. It is important to say that the choice of technology is directly dependent on the particular application being planned: first the application and then the technology.

Overcoming Difficult to Inspect Multi-Diameter, Low Pressure Gas Transmission Pipeline Challenges

Pacific Gas and Electric Company owns and operates an extensive network of over 10,700 km (6,700 miles) of gas transmission pipelines, much of which is under 16″ diameter and operates at less than 27.5 bar (400 psig), making them difficult to inspect with free swimming in-line inspection (ILI) tools. Additionally, many piggable pipeline sections are multi-diameter and have numerous 1.5D fittings, some of these in back to back configuration, requiring tools that are not currently available. Following several failed attempts to inspect PG&E’s 12″ × 16″ pipelines in 2015 using existing ILI tools, and after working to modify a 12″ × 18″ tool for lower pressure service in 2016, PG&E and ROSEN decided to collaboratively develop new, specially designed, 12″ × 16″ geometry and axial MFL tools. The goal of this project was to develop tools that could meet both the PG&E pipeline passage requirements and allow for an acceptable speed profile. The need to inspect a total of 16 pipeline sections in the long-term ILI Upgrade Plan, in this size range, justified the investment in these new tools. The service provider embarked on a new ILI tool design process including design, manufacturing, fabrication and testing at their facilities in Germany. Through this process, a number of unique ILI tool design features to lower tool drag and improve ease of collapsibility were implemented, resulting in a tool that far exceeds existing industry capabilities. To confirm the tools’ capabilities before their first use in a live gas transmission pipeline, pump testing in water, as well as in compressed air, was performed. In late 2017, using these tools, PG&E inspected two previously unpiggable 12″ × 16″ low-pressure pipelines successfully. In this paper, the process of developing these tools will be discussed. The test program will be reviewed comparing findings under controlled conditions in water and compressed air with pig run behavior in the live pipelines. The analysis also provides an assessment of the operating conditions that are deemed necessary for the inspection tool to gather a good quality data set.