Piston-Based Material Extrusion of Ti-6Al-4V Feedstock for Complementary Use in Metal Injection Molding

Piston-based material extrusion enables cost savings for metal injection molding users when it is utilized as a complementary shaping process for green parts in small batch sizes. This, however, requires the use of series feedstock and the production of sufficiently dense green parts in order to ensure metal injection molding-like material properties. In this paper, a methodological approach is presented to identify material-specific process parameters for an industrially used Ti-6Al-4V metal injection molding feedstock based on the extrusion force. It was found that for an optimum extrusion temperature of 95 °C and printing speed of 8 mm/s an extrusion force of 1300 N ensures high-density green parts without under-extrusion. The resulting sintered part properties exhibit values comparable to metal injection molding in terms of part density (max. 99.1%) and tensile properties (max. yield strength: 933 MPa, max. ultimate tensile strength: 1000 MPa, max. elongation at break: 18.5%) depending on the selected build orientation. Thus, a complementary use could be demonstrated in principle for the Ti-6Al-4V feedstock.

MULTIPLE PROCESS PARAMETER OPTIMIZATION OF FORWARD EXTRUSION PROCESS ON AA 2024

Extrusion is a simple metal forming process in which a block of metal is forced through a die orifice with a certain shape under high pressure. This extrusion process is influenced by many process parameters such as die angle (DA), ram speed (RS), coefficient of friction (COF), Extrusion ratio, Die land height, work piece diameter and length, material properties etc. In extrusion process, extrusion force is crucial parameter, the flow of metal and hence the extrusion force is significantly influenced by the above parameters which results in quality of the product. The present study numerically investigates the influence of major process parameters such as die angle, ram speed, coefficient of friction on the extrusion process. The AA2024 material is chosen as work piece material and the extrusion force and damage is considered as the output responses. The input process parameters are varied in three levels (Level - 1: 10° DA, 1.6mm/min RS, 0.06 COF; Level - 2: 20° DA, 3.2mm/min RS, 0.08 COF; Level - 3: 30° DA, 4.8mm/min RS, 0.01 COF). Numerical simulations are performed by using DEFORM 3D software. The simulations are conducted as per L27 orthogonal array. From the results it is observed that Increase of die angle, ram speed and coefficient of friction increases the extrusion force. The die angle has highest (86.45%) influence on the extrusion force, then after ram speed (6.60%). The coefficient of friction has insignificant influence (0.55%). It is also noticed that the damage is considerable after the 20° die angle. A multi parameter optimization is also done by using the Grey relation analysis by considering the equal weightage of extrusion force and damage. The optimum levels of input process parameters for the minimum extrusion force and damage is DA level 1, RS level 1, and COF level 3.

Selection of Die Material and Its Impact on the Multi-Material Extrusion of Bimetallic AZ31B–Ti6Al4V Components for Aeronautical Applications

This paper investigates the effect that the selection of the die material generates on the extrusion process of bimetallic cylindrical billets combining a magnesium alloy core (AZ31B) and a titanium alloy sleeve (Ti6Al4V) of interest in aeronautical applications. A robust finite element model is developed to analyze the variation in the extrusion force, damage distribution, and wear using different die materials. The results show that die material is a key factor to be taken into account in multi-material extrusion processes. The die material selection can cause variations in the extrusion force from 8% up to 15%, changing the effect of the extrusion parameters, for example, optimum die semi-angle. Damage distribution in the extrudate is also affected by die material, mainly in the core. Lastly, die wear is the most affected parameter due to the different hardness of the materials, as well as due to the variations in the normal pressure and sliding velocity, finding critical values in the friction coefficient for which the die cannot be used for more than one forming stage because of the heavy wear suffered. These results can potentially be used to improve the efficiency of this kind of extrusion process and the quality of the extruded part that, along with the use of lightweight materials, can contribute to sustainable production approaches.

Numerical Simulation and Experimental Study on Rotary Cold Extrusion Forming of Screw Rod

The rotary cold extrusion forming process is a plastic forming process with very low material loss, especially in the production of hollow screw rods with equal wall thickness. In this work, the rotary cold extrusion forming process of a hollow T2 copper screw rod with a wall thickness of 4 mm and solid T2 copper screw rod was verified by experimental method. The finite element simulation software Deform-3D was also used to simulate the rotary cold extrusion forming process of the screw rod. The effects of the die with different heights of the working belt and the different wall thickness of the billet on the eccentricity, extrusion force, and forming torque in the forming process of the screw rod were studied. The results show that it is feasible to process hollow and solid T2 copper screw rods with equal wall thickness by rotary cold extrusion. With the increase of die working belt height, the eccentricity of the screw rod becomes smaller and closer to the ideal eccentricity. With the increase of the wall thickness of the billet, the amplitude fluctuation range of the eccentricity of the screw rod gradually decreases. The higher the height of the die working belt, the greater the extrusion force and torque required in the extrusion process, and the more intense the change of torque. These results also provide theoretical guidance for the production practice and lightweight transformation of the screw pump rotor.

Research on the key design and application of the device of opening cover and ring cutting and digging flesh of Mandari

Aiming at the problems of low efficiency and poor sanitation of manual cover opening and meat digging in the production of common orange tea, a multi station full-automatic meat digging machine for common orange tea is designed to realize the automatic cover opening and pulp separation device of green orange, so as to meet the production of common orange tea in Xinhui District of Jiangmen. The mechanism of peel stress and pulp separation damage of green citrus in the process of mechanical meat digging was studied. The state of peel contact deformation area of green Citrus under the extrusion of meat digging knife was analyzed by simulation, and the structural and operating parameters of de jacking and opening mechanism and meat digging mechanism were optimized. When the extrusion force was less than 35.6n, the peel damage rate could be minimized. Compared with manual operation, it reduces labor cost and production cost, saves processing time, and realizes automatic and rapid production.

Comprehensive assessment of the production of a pipe billet with a flange by forging at various temperature conditions

With the help of QForm simulation software, a comprehensive assessment of the production of a pipe billet with a flange is carried out. The paper studies the influence of the temperature of the die tooling on the technological extrusion force, the stress-strain state in the workpiece, as well as the change in the temperature of the semi-finished product, die and punch in the process of hot forging. The article presents the force graphs, the maximum values of the intensity of stresses and the intensity of deformations in the part, as well as the highest values of temperatures.

Meshfree simulation and experimental validation of extreme thermomechanical conditions in friction stir extrusion

Friction stir extrusion (FSE) is a novel solid-phase processing technique that consolidates and extrudes metal powders, flakes, chips, or billets into high-performance parts by plastic deformation, which has the potential to save substantial processing time and energy. Currently, most studies on FSE are experimental and only a few numerical models have been developed to explain and predict the complex physics of the process. In this work, a meshfree simulation framework based on smoothed particle hydrodynamics (SPH) was developed for FSE. Unlike traditional grid-based methods, SPH is a Lagrangian particle-based method that can handle severe material deformations, capture moving interfaces and surfaces, and monitor the field variable histories explicitly without complicated tracking schemes. These aspects of SPH make it attractive for the FSE process, where in situ evolution of field variables is difficult to observe experimentally. To this end, a 3-D, fully thermomechanically coupled SPH model was developed to simulate the FSE of aluminum wires. The developed model was thoroughly validated by comparing the numerically predicted material flow, strain, temperature history, and extrusion force with experimental results for a certain set of process parameters. The validated SPH model can serve as an effective tool to predict and better understand the extreme thermomechanical conditions during the FSE process.

Effect of Punch Surface Grooves on Microformability of AA6063 Backward Microextrusion

In order to apply conventional forming processes at the micro scale, the size effects caused by material properties and frictional effects must be taken into account. In this research, the effects of tool surface properties such as punch surface grooves on microextrudability, assessed using extrusion force, shape of the extrusion, and Vickers hardness, were investigated using an AA6063 billet. Microscale grooves of 5 to 10 µm were fabricated on the punch surface. The extrusion force increased rapidly as the stroke progressed for all the grooves. Comparing the product geometries showed that, the smaller the groove size, the lower the adhesion and the longer the backward extrusion length. The results of material analysis using EBSD showed that a 5 µm groove depth punch improved the material flowability and uniformly introduced more strain. On the other hand, material flowability was reduced and strain was applied nonuniformly when a mirror-finish tool was used. Therefore, the tribology between the tool and the material was controlled by changing the surface properties of the punch to improve formability.

Optimization Design of Extrusion Roller of RP1814 Roller Press Based on ANSYS Workbench

Firstly, the force of an extrusion roller under actual working condition was analyzed while the contact stress between the roller shaft and the roller sleeve and the extrusion force between the roller sleeve and the material were calculated. Secondly, static analysis of the extrusion roller was carried out using ANSYS software, and conclusively, the stress concentration appears at the roller sleeve’s inner ring step. Furthermore, an optimization scheme of the setting transition arc at the step of the contact surface between roller shaft and roller sleeve was proposed, and a simulation test was carried out., Finally, the maximum equivalent stress of the extrusion roller was set at the minimum value of the objective function; the extrusion roller was further optimized by using the direct optimization module in ANSYS Workbench. The results from optimization show that the maximum equivalent stress is reduced by 29% and the maximum deformation is decreased by 28%. It can be seen that the optimization scheme meets the strength and deformation requirements of the extrusion roller design. The optimization scheme can effectively improve the bearing capacity of the extrusion roller and reduce its production cost. This can provide a reference for the design of the roller press.

Influence of rheological characteristics on the quality of 3D printing of food pastes

In extrusion 3D printing, the rheological properties of food are critical to achieving quality printing. The aim of this study is to investigate potential correlations between the printability of food pastes and rheological characteristics. Potato and tomato puree were used as a model system. The rheological properties of mashed potatoes with the addition of potato starch and their behavior during 3D printing have been investigated. A correlation has been established between the formulation and manufacturability in 3D printing. Potato mass without starch had a low yield point, which affected the deformation and subsidence of the mass later. At the same time, the addition of 2% starch showed excellent extrudability and printability, that is, the ability to flow. Under these conditions, the printed objects had a smooth shape, good resolution, and could withstand shape over time. The object with the addition of 4% starch represented good shape retention but poor extrudability due to its high consistency index and toughness. The results obtained using tomato puree showed a linear correlation between ingredient flow stress, zero shear viscosity and corresponding print stability. The extrusion pressure required to extrude tomato paste increases linearly with increasing flow voltage. Modules of viscosity, elasticity, and zero shear rate turned out to be not linearly correlated with the extrusion force, which can be explained by the fact that these parameters reflect the rheological properties of the non-deforming state of the material, in contrast to the flow stresses.