Effects of processing parameters on the performance of carbon fiber reinforced polyphenylene sulfide laminates manufactured by laser-assisted automated fiber placement

In situ consolidation of thermoplastic composites can be realized through laser-assisted automated fiber placement (AFP) technology, and the properties of composites were significant affected by the process parameters. In this work, the effects of process parameters on the properties of continuous carbon fiber–reinforced polyphenylene sulfide (CF/PPS) composites manufactured by laser-assisted AFP were investigated. Four-plies CF/PPS prepreg was laid under the combination of different process parameters and the morphology, void content, crystallinity, and inter-laminar shear strength (ILSS) of the composites were characterized. It turned out that the resin distribution on the surface of the composites could be significantly improved by increasing the laser temperature and compaction pressure. The highest crystallinity of the composites reached 46% at tool temperature of 120°C while the value was only 18% when the tool temperature was 40°C. Meanwhile, with the increasing compaction force ranging of 500–2000 N, the void content of the composites decreased obviously. The ILSS was evaluated through double notch tensile shear test. The results indicated that the mechanical properties of the composites were dominated by void content rather than crystallinity.

Effects of Submerged Convective Cooling In The Turning of AZ31 Magnesium Alloy For Tool Temperature And Wear Improvement

Low melting point and material adhesion attributed by the magnesium alloy led to extreme built-up edge (BUE) and built-up layer (BUL) formations. Dry machining is favourable for machining magnesium alloy; however, this strategy inflicts excessive adhesive wear on the cutting tool. Therefore, this current work focuses on innovative cooling technique known as submerged convective cooling (SCC) for the turning of the AZ31 magnesium alloy. Prior to cutting experiment, a computational fluid dynamics (CFD) simulation was conducted to evaluate internal structure of cooling module. Based on the CFD simulation, small inlet/outlet diameter significantly contribute to reduction of tool temperature because of effective heat transfer coefficient of cooling fluid in the SCC. Experimental results revealed that SCC has effectively reduced the tool temperature by 50% and contributed to 37% improvement in surface roughness when compared to dry cutting. Finally, both BUE and BUL were observed in dry and SCC conditions, but the severity of these wear mechanisms improved or decreased remarkably under SCC conditions.

MODELING THE COOLING EFFECT OF THE CUTTING FLUID IN MACHINING USING A COUPLED FE-CFD SIMULATION

The cooling with cutting fluids is a complex process in manufacturing, since chemical, mechanical and thermal phenomena occur simultaneously. The experimental methods developed so far do not allow for a direct observation of the coolant flow during machining, which limits the understanding of the cooling mechanism. The main aim of this paper is the investigation of convective heat transfer between cutting fluid and the cutting zone as well as the heat flow distribution on the tool surface during the cutting process by means of a coupled FE-CFD simulation. The FE model calculates the heat generation under consideration of the experimentally validated punctual, transient tool temperature during the machining processes. Based on the result of the FE, the subsequent CFD simulation performs the calculation of the flow behavior and convective heat transfer. This method allows a detailed investigation of the temperature field in the cutting zone under consideration of the cutting fluid. The simulation returns spatially resolved heat transfer coefficients along the tool surface and provides first findings for an improvement of heat removal efficiency by changing the coolant supply parameters and the physical properties of the cutting fluid. The model parameters were validated by comparing the simulation results and the measured punctual tool temperature.

Numerical and Experimental Investigation of the Temperature Rise of Cutting Tools Caused by the Tool Deflection Energy

Tool temperature variation in flank milling usually causes excessive tool wear, shortens tool life, and reduces machining accuracy. The heat source is the primary factor of the machine thermal error in the process of cutting components. Moreover, the accuracy of the thermal error modeling is greatly influenced by the formation mechanism of the heat source. However, the tool heat caused by the potential energy of the tool bending and twisting has essentially not been taken into consideration in previous research. In this paper, a new heat source that causes the thermal error of the cutting tools is proposed. The potential energy of the tools’ bending and twisting is calculated using experimental data, and how tool potential energy is transformed into heat via friction is explored based on the energy conservation. The temperature rise of the cutting tool is simulated by a lattice-centered finite volume method. To verify the model, the temperature separation of a tool edge is measured experimentally under the given cutting load. The results of the numerical analysis show that the rise in tool temperature caused by the tool’s potential energy is related to the time and position of the cutting edge involved in milling. For the same conditions, the predicted results are consistent with the experimental results. The proportion of temperature rise due to tool potential energy is up to 6.57% of the total tool temperature rise. The results obtained lay the foundation for accurate thermal error modeling, and also provide a theoretical basis for the force–thermal coupling process.

Effects of press-forming parameters on the dimensional stability of paperboard trays

The dimensional stability of press-formed paperboard trays was investigated during heating and cooling of trays packed with oatmeal. Female mold tool temperature, dwell time, pressing force, and blank holding force were altered in the press-forming of the trays to observe their impacts on the dimensional stability. Dimensional measurements of the trays showed reduced tray width, and the trays exhibited distortions on the tray flange and outer wall. The results showed smaller effects on the tray length, parallel to the machine direction of the material. Improved dimensional stability of the trays was found with a 180 °C female mold tool temperature, a 600-ms dwell time, a 150-kN pressing force, and a 1.44-kN blank holding force. The optimal press-forming parameters were concluded to enhance bonding of the paperboard fibers during the press-forming. The optimization of the press-forming parameters was found necessary to reduce the observed negative response of the material to the challenging environmental conditions in the production of prepared food.