• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.842-845
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• 2000

The purpose of this paper is to investigate the influences on mechanical properties of motor pistons manufactured by casting, conventional forging and powder forging, using the comparison of characteristics like microstructure, hardness, tensile strength, and elongation. To form conventional forging piston, the experiment of visioplasticity was performed. As the model material, plasticine was used. To form powder forging piston, the shape of piston was simplified as simple cup shape. Material properties like workability, density variation before and after forging, and strain loci of material during forging were investigated. Powder forging and conventional forging technologies were effective to gain dense microstructure. In powder forging, distribution of such dense microstructuer was uniform. For hardness, pistons from powder forging and conventional forging technologies were much better than that from casting. For tensile strength and elongation, powder forging and conventional forging technologies were also advantageous.

• Transactions of Materials Processing
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• v.24 no.6
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• pp.411-417
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• 2015

The piston engine is an essential component in automobiles. Since the piston is used in a high temperature and high pressure environment, the piston needs to be manufactured to achieve high strength and high durability. In addition, cost reduction is also an important consideration. In conventional forging, an additional heat treatment after hot forging is necessary to ensure proper mechanical properties for heavy-duty engine pistons. The newly developed manufacturing method lowers production costs by saving manufacturing time and reduces energy consumption. The current paper describes the hot forging of an engine piston made from 38MnSiVS5 micro-alloyed steel using controlled cooling. The finite element analysis was used to check for possible problems and suitable press capacity. Hot forging experiments were then conducted on a 2500tons crank press to evaluate feasibility of the proposed material and process. To check the mechanical properties after hot forging, the forged specimens were tensile tested, and the microstructures were examined in order to compare the results with the conventionally forged material. The skirt region of the as-forged 38MnSiVS5 piston showed better material properties compared to the conventional material. In addition, the total production time was reduced by about 80% as compared to conventional forging.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.4
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• pp.69-74
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• 2001

Powder forging technology has been introduced to manufacture the parts for vehicles. This paper describes the process conditions for the powder forging of aluminium also piston for vehicles including the determination of composition of aluminum alloy by experiment, preform design by FEM simulation, coed compaction of aluminum alloy powder, sintering of preform, and the experiment of powder forging. The mechanical properties such as hardness, tensile strength, and elongation of the farmed piston were invested and compared with casted piston and forged piston. The tensile strength and hardness of the piston formed by powder forging technology were much more excellent than other pistons.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.5
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• pp.25-31
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• 2004

In order to prepare for the large power diesel vehicle, the current trend of advanced nations is to shift from the aluminum alloy piston to the steel piston. In this research, a steel forging piston which replaces the aluminum alloy piston is developed to improve the power performance of the diesel engine. The three dimensional flow and combustion analysis of the target engine is conducted. Using the result of the analysis, the piston is optimized, and a prototype of the articulated steel forging piston is built. The reliability of the piston has been evaluated through durability test using a Hydropuls Test Machine for 300,000 km.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.177-181
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• 1996

A fundamental study for the production of an internal combustion engine piston by forging is performed through UBET(Upper Bound Elemental Technique) analysis and experiments. In UBET analysis, an optimal preform of the aluminum piston is predicted and the results are compared with the experimental results. The internal flow pattern and and the forging loads according to the different friction condition are investigated.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.87-93
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• 2000

Powder Forging technology is being developed rapidly because of its economic merits and the possibility of lightening parts by replacing steel parts with aluminum ones especially in automotive parts manufacturing. Recently Powder Forging process is widely used for manufacturing primary mechanical parts as a combined technology of P/M and precision hot forging. This paper describes the process conditions for the powder forging of Aluminium alloy piston. For example powder alloy design preform design by FEM simulation cold of compaction of specimens and preform sintering of preform powder forging process. The characteristics of sintered compaction of specimens and preform sintering of preform powder forging process. The characteristics of sintered products and final forged piston ones are investigated with tensile strength hardness ductility and so on. Eventually its results prove the improve mechanical properties of the piston produced by powder forging.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.9
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• pp.30-36
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• 1997

In this study, the development of an aluminum forged piston was tried to substitute the cast piston, in which there were internal defects such as blow hole and shrink pipe. A gasoline engine piston was chosen as an example for developing the forged piston. Before aluminum forging, model, material (plasticine) test was carried out to investigate the forgeability and internal flow pattern of the forged piston at room temperature. From the result of model material test, an aluminum piston to be forged was redesigned. The aluminum pistion was forged in hot process. The quality of a forged piston was compared with that of a cast piston in the point of mechanical properties, internal defect and microstructure. It was proved that the forged piston was superior to the cast piston.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.54-59
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• 2004

The goal of this research is to confirm reliable durability and evaluate the engine performance of the current aluminum alloy piston and the newly developed steel forging piston. For such purpose, the test environment was built with 2.91 target engine mounted on the engine dynamometer and additional exhaust gas analysis system. Using the test environment, engine performance test was conducted, and durability test was also conducted using a dedicated piston durability test equipment for 400,000 km. As a result of the experiment, similar durability was appeared for both aluminum piston and steel piston, and the engine output power and torque are slightly reduced because of $158\%$ heavier weight of the steel piston compare to the aluminum alloy piston.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.25-28
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• 2003

The articulated piston that was used to more powerful diesel engine was composed by Al casted skirt part and steel forged crown part. this paper has the target to design the forging process of crown part. The parameters of piston design and forging process design were gotten based on work experience, experimental data, approximately calculated data and finite element analysis. Preform design parameter decided using the Taguchi method. Through this research, could design optimal shape of preform and produce prototype of the articulated piston

• Transactions of Materials Processing
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• v.23 no.2
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• pp.88-94
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• 2014

The under-drive brake piston is an essential part in the automatic transmissions of automobiles. This component is manufactured by forging after blanking from S55C plate with a thickness of 6mm. It is difficult to design the plate forging process using a thick plate approach since there will be limited material flow as well as large press loads. Furthermore, the under-drive brake piston has a complex shape with a right angle step, which often results in die unfill and abrupt increase in press load. To overcome these obstacles, a separate die for filling material sufficiently to the corner of the right angle step is proposed. However, this approach induces an uncontrolled workpiece surface between the dies, resulting in flash. This excess flash degrades the tool life in the final machining after cold forging as well as increases the cycle time to obtain the net-shape of the part. In the current study, we propose an optimum process design using a conventional die shaped with the benefit of finite element analysis. This approach enhanced the process efficiency without sacrificing the dimensional accuracy in the forged part. As the result, the optimum plate forging process was done with a two stage die, which reduces weight of by 6% compared with previous process for the under-drive brake piston.