An Evaluation of Quality Parameters for High Pressure Die Castings

Lumley, Roger; Deeva, Natalia; Gershenzon, M.

doi:10.1007/bf03355517

Cited by 22 publications

(9 citation statements)

References 9 publications

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“…Nevertheless, the sole investigation of the first stage neglects the positive effects due to the forces exerted by the plunger on the melt in the second stage, which allow for air bubble collapse and oxide fragmentation with a consequent enhancement of the mechanical properties. The focus on the second stage is consistent with the results proposed in [6] and [7], which show that the tensile properties improve by increasing the gate velocity. In particular, in [6], the analysis of Al-Si alloy specimens manufactured with different melt velocities (in the range 26-82 m/s) demonstrated that increasing melt velocity results in a finer microstructure and a lower porosity percentage and, consequently, in better mechanical properties.…”

supporting

confidence: 78%

“…Hence, the research of tools for controlling the process and optimizing its parameters is widely recognized as a challenge for the HPDC industry [5]. Several works in the literature attempt to investigate this relevant issue, by studying the effect on the final outcome of different types of process parameters, such as kinematic parameters of the plunger (speed or position) [6][7][8], pressure parameters (e.g., intensification pressure) [8] and thermal characteristics of the melt and the die cavity (e.g., pouring temperature, thermoregulation and lubrication systems of the die) [9][10][11]. Particular attention has been paid to the first type of process parameters, i.e.…”

mentioning

confidence: 99%

“…In particular, in [6], the analysis of Al-Si alloy specimens manufactured with different melt velocities (in the range 26-82 m/s) demonstrated that increasing melt velocity results in a finer microstructure and a lower porosity percentage and, consequently, in better mechanical properties. A similar study was proposed in [7], which investigated the influence of the second stage velocity in die cast Al9Si3Cu alloy. The experimental results revealed that the probability of failure decreases by increasing the melt velocity at the gate, due to less amount of pores and oxides on the fracture surfaces of the tensile specimens.…”

mentioning

confidence: 99%

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Improving the quality of die castings through optimal plunger motion planning: analytical computation and experimental validation

Fiorese

Richiedei

Bonollo

2016

Int J Adv Manuf Technol

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High-pressure die casting is a process widely used to manufacture components with high productivity and dimensional accuracy. Its main disadvantage is the high percentage of scraps, due to a high amount of defects. Thus, the identification of the parameters affecting quality of castings is the current challenge towards an efficient and effective production. In their previous work, the authors have found and statistically validated a novel parameter explaining and forecasting both static mechanical properties and porosity of castings. Such a parameter, defined as the root mean square value of the plunger acceleration in the fast shot stage, represents a measure of the average force transmitted by the plunger to the melt and has been proved to be very effective in predicting casting quality. In order to provide a practical tool for the use of this parameter, this work proposes an analytical method for its computation, starting from the plunger displacement curve or just some notable points. The method formulation takes advantage of the analytical development of the typical motion primitives adopted and also accounts for limitations due to the machine. Hence, the optimization of the process can be achieved by selecting in advance the most suitable plunger motion profile, among those feasible, that allows to improve the casting quality. Besides the theoretical formulation, a meaningful experimental validation is provided to demonstrate the correctness of the proposed parameter and of the analytical approach, as well as its ease of implementation that makes it suitable for industrial applications.

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confidence: 78%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Improving the quality of die castings through optimal plunger motion planning: analytical computation and experimental validation

Fiorese

Richiedei

Bonollo

2016

Int J Adv Manuf Technol

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“…3 If parameters are not carefully controlled, the castings will turn out defective. The most typical defect in HPDC components is porosity, [4][5][6][7][8] which substantially degrades properties. Adamane et al 6 reviewed the effects of the injection parameters on the porosity and tensile properties of the die castings and suggested optimal values for the gate velocity and intensification pressure for an aluminum alloy.…”

Section: Introductionmentioning

confidence: 99%

Effect of Process Parameters on Distortion and Residual Stress of High-Pressure Die-Cast AZ91D Components

2017

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This paper presents a study of distortion and residual stress within a high-pressure die-cast AZ91D component, cast under different processing conditions. The influence of process parameters, i.e., die temperature, cooling time, intensification pressure and first-phase injection speeds, was examined. Distortions were measured using the inhouse standard analog quality control fixture. Residual stress depth profiles were measured using a prism holedrilling method. It was found that the most important process parameter affecting the distortion was intensification pressure and the second most important was temperature difference between the two die halves (fixed and moving side). Tensile residual stresses were found very near the surface. Increasing the intensification pressure resulted in an increased level of tensile residual stresses.

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“…The objective of developing corrective actions for a wide range of situations has led several researchers to thoroughly investigate the formation and the control of defects. Most of the focus has been on the structural defects and the surface defects from die wear, which are beyond the scope of this report; citing only a few references from a broad range of literatures, they include gas and shrinkage porosity [9], degradation of mechanical properties [10,11], and soldering, heat checking and erosion [12,13].…”

Section: Background and Literaturementioning

confidence: 99%

Cold flow defects in zinc die casting: prevention criteria using simulation and experimental investigations

Armillotta

Fasoli²,

Guarinoni

2015

Int J Adv Manuf Technol

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High-pressure die casting of zinc alloys is increasingly used in the manufacturing of parts with high aesthetic value. These parts must comply with strict requirements on surface quality, which are generally overlooked in traditional mechanical applications. Cold flow defects, which are a primary concern for surface quality, originate from several different causes that have not yet been fully understood. This report investigates the factors that influence cold flow defects and the choices that can lead to an improvement in surface quality. The research method is based on a case study performed at a die casting company. First, an existing process has been analyzed using simulation to explain the causes of cold flow defects observed in production samples. The temperature at the end of the cavity fill has emerged as a key index for the occurrence of defects, which can be controlled by three primary process parameters: injection velocity, temperature of the cooling medium, and lubricant spraying time. These same factors are then assessed using experimental tests on an existing die, where the number of defects in the selected regions of the casting has been evaluated by image processing. The results suggest that the surface quality can be particularly improved by increasing the flow rate of the molten metal through the gates and avoiding excessive flow turbulence in the wide cavity sections. Consequently, the increase in the gate area has been identified as a specific criterion for the die design. These findings have been validated in the redesign of the die and the selection of the process parameters, which have resulted in a significant reduction in the surface defects.

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An Evaluation of Quality Parameters for High Pressure Die Castings

Cited by 22 publications

References 9 publications

Improving the quality of die castings through optimal plunger motion planning: analytical computation and experimental validation

Improving the quality of die castings through optimal plunger motion planning: analytical computation and experimental validation

Effect of Process Parameters on Distortion and Residual Stress of High-Pressure Die-Cast AZ91D Components

Cold flow defects in zinc die casting: prevention criteria using simulation and experimental investigations

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