Cast Iron Piston Research Articles

Research on Dynamic Evolution of Residual Stress Based on Simulation of Piston Manufacturing Process

Rather than focusing on the residual stress generated from casting, machining, or heat treatment unilaterally, a comprehensive research method to consider the whole dynamic evolution of residual stress is proposed. The cast iron piston is taken as the research object to establish a continuous simulation model for its manufacturing. Firstly, a simulation model of piston casting is established to analyze the stress change. Subsequently, through the machining and heat treatment simulation of the piston, the variation law of residual stress before and after machining is analyzed. Different process parameters are designed to study the redistribution mechanism of residual stress. Residual stress tests are further conducted on the processed piston products. The results indicate that shakeout can effectively remove 60% to 80% of the residual stress. The removal of materials results in overall residual stress release and redistribution for the piston, and the piston releases 10% to 40% of the residual stress after machining. The heat treatment of the machined piston can effectively reduce the residual stress with a maximum reduction of 27.1%. The good consistency between experimental results and simulation results further confirms the feasibility of the comprehensive research method. This study is beneficial for achieving low stress manufacturing of pistons and improving their working performance.

TRIBOLOGICAL PROPERTIES OF PISTON RINGS DESIGNEDFOR SLIDING AGAINST COMPOSITE MATERIALSIN LUBRICATED CONTACTS

The paper presents basic information on the production, structure and tribological properties of a compositechromium-ceramic coating deposited electrolytically on a cast-iron piston ring for a combustion enginedesigned for sliding against a composite cylinder liner. The results of comparative tests of two contacts,i.e. cast-iron GJL-250/AlMC and GJL250+Cr-Al2O3/AlMC, are described. The deposition of the Cr-Al2O3coating on the cast-iron piston ring reduces almost trifold the wear of the piston ring and about 20% thefriction resistance in the contact due to the presence of aluminium oxide particles and fibres. The reinforcingphase removed from the chromium layer polishes the chromium and composite sliding surfaces. The placesleft by the removed particles serve as depots for oil, which reduces the friction forces and minimises oilconsumption. The Al2O3 wear debris decreases the roughness of the surfaces in contact, which additionallyreduces the friction forces according to the friction hypothesis of Ernst and Merchant.

Topology Optimization in 3D Printed Piston

Abstract: Piston is the main alternating mass of a single cylinder 4 stroke engine and hence contain most of the inertial forces, also modern advancement in the automotive industry for the sake of pollution control and fuel economy many of the techniques such as Downsizing of engine (turbo charging), advance spark ignition, port injection, VVA and many more are adapted and hence results in high specific loading, including thermal and mechanical loads on the several parts of engine. This paper presents the re-designing of the piston, the topology optimization techniques have been used for increasing strength and decreasing mass of the piston which is our main objective. Traditionally pistons were manufactured by casting of aluminum and grey cast iron, aluminum was used in performance oriented vehicles as it was light in weight and have addition thermal properties and also it was easy to manage the inertial forces, whereas cast iron pistons were used in industrial purpose engine (heavy duty engine) today methods are replaced with 3-D printing, as a topology optimized piston cant be manufactured with traditional methods. The procedures in the paper are done for a generalized case and not for a particular so that the same methodology can be implemented in specific cases. Also it will cover a lot about the Material selection and additive manufacturing process used for this specific application.

Višekriterijumska optimizacija zasnovana na verovatnoći kao osnova za primenu novog robustnog dizajna na parametre mašinske obrade

Introduction/purpose: New robust design by means of probability-based multi-objective optimization takes the arithmetic mean value of the performance indicator and its deviation as twin independent responses of the performance indicator. The aim of this article is to check the applicability of new robust design in optimizing machining process parameters. To conduct the examination in detail, the robust design for optimal cutting parameters to minimize energy consumption during the turning of AISI 1018 steel at a constant material removal rate is applied as well as the concurrent optimization of the machining process parameters and the tolerance allocation of a spheroidal graphite cast iron piston. Methods: In the spirit of the probability-based method for multi-objective optimization, the arithmetic mean value of the performance indicator and its deviation are taken as two independent responses of the performance indicator to implement robust design. Each of the above twin responses contributes one part of the partial preferable probabilities to the performance indicator of the alternatives in the treatment. The arithmetic mean value of the performance indicator should be assessed as a representative of the performance indicator according to the function or the preference of the performance indicator, and the deviation is the other index of the performance indicator, which has the characteristic of the 99 smaller-the-better in general. Furthermore, the square root of the product of the above two parts of the partial preferable probability forms the actual preferable probability of the performance indicator. Moreover, the product of partial preferable probabilities gives the total preferable probability of each alternative, which is the overall and unique index of each alternative in the robust optimum. Results: The paper gives the rational optimum cutting parameters for minimizing energy consumption during the turning of AISI 1018 steel at a constant material removal rate and the concurrent optimization of the machining process parameters and the tolerance allocation of a spheroidal graphite cast iron piston. Conclusion: The application study indicates its rationality and convenience of new robust optimization in the optimization of machining process parameters.

INDUSTRIAL SCALING OF LOW-FRICTION HYBRID LAYER TECHNOLOGY ON PISTON RINGS

Technological trials of gas sulphonitriding processes for cast iron piston rings were carried out as an alternative to chromium electroplating for the production of low-friction layers. The effectiveness of different ways of packing heat treatment charges in minimising or eliminating deformation of the rings was compared, and the effectiveness of ring packing with restraining tooling was confirmed. The maximum duration of the gas sulphonitriding process was determined at 1 hour, both as a stand-alone process and as a component process in a multi-stage technology for the manufacture of low-friction hybrid layers, ensuring the maintenance of sufficient ring toughness for an opening during assembly.

MOS2/WS2/FINELPN COMPOSITE LAYERS – A NEW APPROACH TO LOW FRICTIONAL COATINGS FOR PISTON RINGS

In the search for alternative processes of technologically difficult and environmentally dangerous galvanic chromium coatings on cast iron piston rings, composite coatings of low-friction nanoparticles MoS2, WS2 and/or rGO embedded in a hard matrix of iron nitrides have been investigated. Laboratory tribological and operational tests on a real aircraft engine have been carried out to select the optimal technological parameters and microstructures of low frictional layers. A dry friction coefficient of 0.13 has been obtained for the best of the processes, i.e., four times lower than for raw reference samples (0.55). According to that technological option, the low-friction layers were produced for a set of rings for three cylinders of a Boxer aircraft engine and tested comparatively in an operational test with the rings in the other three cylinders. The experimental engine has passed the operational test obtaining the assumed power performance, fuel consumption and admission criteria of exhaust purity and oil purity.

A detailed review of the analysis of the different types of materials such as aluminum alloys and cast-iron piston by comparing the results we can say among these which one of the pistons had better results

A piston is a component of reciprocating engines, pumps and gas compressors. It is located in a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. The alloy from which a piston is made not only determines its strength and wears characteristics, but also its thermal expansion characteristics. Hotter engines require more stable alloys to maintain close tolerances without scuffing. The normal temperature of gasoline engine exhaust is approximately 650ºC (923ºK). This is also approximately the melting point of most aluminum alloys and it is only the constant influx of ambient air that prevents the piston from deforming and failing. For this purpose testing different types of materials such as aluminum alloys and cast iron piston. In this project we design the three models of pistons flat head, concave head & convex heads by using Pro-Engineer 5.0 software, and imported them to make analysis in ANSYS 11.0 soft ware. And find out the vonmisses stresses, total deformation, heat distribution, and heat flux. By comparing the results we can say among these which one of the piston had better results.

ТЕХНОЛОГИЧЕСКОЕ ПОВЫШЕНИЕ ДОЛГОВЕЧНОСТИ ПОРШНЕВЫХ КОЛЕЦ ДВИГАТЕЛЕЙ ВНУТРЕННЕГО СГОРАНИЯ

The ongoing improvement of internal combustion engines of various types involves the search for design and technological methods to improve their operational characteristics. In addition to the traditional requirements for reliability, durability and efficient performance, the requirement for environmental friendliness has recently taken one of the first places, since in many large cities both gasoline and diesel engines are the main sources of the unfavorable state of the environment. Intensive introduction of engines that are not related to the use of oil-based fuels will occur in the thirties of this century and, consequently, for at least another decade, urban residents will have to deal with air pollution problems. The paper considers the issues of increasing the reliability and durability of piston rings of internal combustion engines based on the improvement of their manufacturing technology and control methods based on comprehensive consideration and evaluation of elastic properties of this class, which determines the efficiency of the entire power plant. The analysis of existing technological processes of manufacturing cast-iron piston rings underlies the discovery of reserves for more reliable provision of a given diagram of the piston ring radial pressures on the cylinder liner. This positive effect was achieved through the use of modern edge cutting tools based on cubic boron nitride and a physical method for controlling the elastic state of the piston ring, based on defining the energy state of the surface layer of the product. Such studies are based on the use of the method of exoelectronic emission (EEE), capable of responding to changes in the physical and mechanical parameters of the surface layer of piston rings. The wear resistance tests carried out confirmed the possibility of making adjustments to the manufacturing technology and improving the performance characteristics of piston rings.

Femtosecond Pulsed Ti:Sapphire Laser-Assisted Surface Texturing on Piston Ring and Its Tribology Characterization

Abstract Femtosecond laser-assisted surface texturing of compression piston rings is proposed and demonstrated. A femtosecond pulsed Ti3+:sapphire laser is used to generate dimples of the same size but with different area density on a moly-chrome ceramic deposited cast iron piston ring. The influence of the surface morphology and tribology operating conditions, such as reciprocating frequency and temperature of the lubricant, on friction and wear characteristics of textured piston rings and plateau honed liner samples is investigated. A decrease in the friction coefficient is observed with the texturing of rings. The dimple area density, which is defined as the ratio of the total textured area and the total area of the surface, of 16% and 27% offered a reduced coefficient of friction and minimize wear on the liner surface.

SELECTION OF CYLINDER-PISTON CLEARANCES OF ROTOR-PISTON ENGINES

The effect of the clearance amount of the cylinder-piston connection of the new design RPD-4.4/17.5 rotary-piston pneumatic engine on its performance and reliability is considered and analyzed. The clearance analysis was carried out taking into account the material from which the connecting pairs (piston and working cylinder) are made, and their operating temperature. In the first case, AK12M2MgN aluminum casting alloy was selected as a material for the manufacture of pistons of a rotary-piston pneumatic engine, and in the second case, cast iron with spherical graphite VCh 50 was selected. In both cases cast iron with spherical graphite HF 50 was selected as a material for manufacturing the working cylinder (actually, the rotor) of a rotary-piston pneumatic engine. The temperature change range was selected based on previous experimental studies of a prototype RPD-4.4/17.5 rotary piston pneumatic engine. Thus, the selected temperature range is from -25 to 100° C. The minimum temperature is due to the low temperature of the exhaust air in the pneumatic engine exhaust receiver, and the maximum is the temperature of the possible heating of the compressed air at the inlet to the inlet receiver of the pneumatic engine. Practical recommendations have been developed for choosing the optimal clearance of the cylinder-piston connection of the RPD-4.4/17.5 rotary-piston pneumatic motor and it has been found that the nominal end clearance, which ensures normal operation in the temperature range from -25...100° С, for a cast-iron piston and a cast-iron working cylinder is 25 microns, and for a variant of manufacturing a piston from an aluminum alloy - 33 microns. The proposed end clearances do not exceed the recommended values for similar connecting parts of such units. The correctness of the selected end clearances of the connecting parts has also been confirmed by bench tests of a prototype rotary piston pneumatic engine with subsequent fault finding of parts. It has been determined that a temperature increase of 100° C for an aluminum alloy piston manufacturing option results in a scuffing on the working cylinder surface, jamming of the piston followed by breakage of the movable links and damage to the piston bosses.

Review of tribological behavior of graphene coatings on piston rings in engines

Purpose This study aims to find out friction and wear characteristics of graphene and graphene coating deposited by the Chemical Vapor Deposition (CVD) process on Honda GX270 engine (nodular cast iron) piston rings experimentally investigated under boundary lubricated conditions. Design/methodology/approach This study consists of two stages: tribotest and engine tests. First test was conducted through a reciprocating tribotest machine and second test was conducted through an engine bench with a duration of 75h. Engine piston ring was coated with graphene by two different methods: transfer method and direct CVD method. Findings Graphene has been demonstrated to be a potential and promising candidate for wear- and scratch-resistant coating because it is the thinnest, lightest and strongest known nanomaterial. In this case, the ability of a mono-layer graphene film to withstand high pressure differences (6 atm) indicates its mechanical robustness. It can effectively prevent or reduce mechanical failure by strengthening and toughening the loaded surface as well as by transferring the stress throughout the structure. The positive tribological outcomes of the graphene reinforced material under various dynamic loads revealed the potential of graphene-based coatings in macro - and micro-tribology. Originality/value This study fulfils an identified need to study for automotive industry a coating which is wear and scratch resistant.

Development of a system for organizing a modular design and technological preparation for the production of cast iron pistons for internal combustion engines

Modern engine building requires a significant increase in power, fuel efficiency and ensuring high environmental performance of internal combustion engines (ICE). When forcing the operating modes of diesel engines, one of the most loaded engine parts becomes a piston, due to a significant increase in mechanical and thermal stresses. With increasing load on the piston, the difficulty of meeting the high demands for them increases. When creating modern ICE and improving the quality of existing ones, special attention is paid to the design and technological preparation of the production of pistons, which is the object of research. Pistons determine the reliability and life of the engine as a whole.To solve this problem, all the main works related to the design and manufacture of cast-iron pistons are proposed to divide into separate modules, performed simultaneously in three areas: organizational, design and technological. These modules are integral sectors of a single modular system for organizing design and technological preparation for production of cast iron pistons. Modeling of the stressed-strain state of monolithic cast-iron pistons is considered for an example of implementation of one of the modules. The results of calculations of the stress-strain state and the temperature distribution field in the body of the piston are presented. The results show that the maximum temperature is 315 °C and concentrated on the edge of the combustion chamber. The stress does not exceed 617 MPa.

Quantitative comparison of tribological performance of chromium- and zinc-phosphate-coated piston rings in tribotest rig

The main purpose of this paper is to investigate the tribological performance of the zinc-phosphate- and chromium-coated spheroidal cast iron piston rings in reciprocating tribotest rig with conventional commercial lubricant. Results of the experiments showed that tribofilm was formed both on ring and liner surfaces. Zinc phosphate coating was removed from the ring surface after the experiments. Wear rate of liner-chromium-coated ring pair was lower than the liner-phosphate-coated ring. The friction coefficient of the liner-phosphate-coated ring pair ranged from 0.104 to 0.124, lower than the liner-chromium-coated ring, which ranged from 0.114 to 0.129. Change of average surface roughness was also lower in chromium-coated ring (31%) than the phosphate-coated ring (72%). Test results showed that hard chromium-coated ring had better tribological performance and coating efficiency than the phosphate-coated ring due to wear resistance and lower change of average surface roughness.

<b>Entropy-Based weighting applied to normal boundary intersection approach: the vertical turning of martensitic gray cast iron piston rings case

In practical situations, solving a given problem usually calls for the systematic and simultaneous analysis of more than one objective function. Hence, a worthwhile research question may be posed thus: In multiobjective optimization, what can facilitate the decision maker in choosing the best weighting? Thus, this study attempts to propose a method that can identify the optimal weights involved in a multiobjective formulation. Our method uses functions of Entropy and Global Percentage Error as selection criteria of optimal weights. To demonstrate its applicability, we employed this method to optimize the machining process for vertical turning martensitic gray cast iron piston rings, maximizing the productivity and the life of cutting tool and minimizing the cost, using feed rate and rotation of the cutting tool as the decision variables. The proposed optimization goals were achieved with feed rate = 0.35 mm rev-1 and rotation = 248 rpm. Thus, the main contributions of this study are the proposal of a structured method, differentiated in relation to the techniques found in the literature, of identifying optimal weights for multiobjective problems and the possibility of viewing the optimal result on the Pareto frontier of the problem. This viewing possibility is very relevant information for managing processes more efficiently.

Концепция модульного конструкторско-технологического проектирования чугунных поршней дизельных ДВС

Концепция модульного конструкторско-технологического проектирования чугунных поршней дизельных ДВС

Improving tribological behaviour of piston ring–cylinder liner frictional pair by liner surface texturing

Experiments were carried out on a reciprocating tester. The lubricant was supplied into the inlet side of the contact zone. The construction of tribological tester allows to measure the friction force between specimen and counter-specimen. Tribological behaviours of cylinder liners with and without oil pockets were compared. Specimens were cut from plateau honed cylinder liners made of grey cast iron. Counter-specimens were cut from grey cast iron piston rings. A special tool acted as a hammer to form additional dimples on the liner surfaces. The area density of oil pockets was about 13%. Specimen surfaces had dimples with average depths about 5μm and diameters in the range 0.15–0.2mm. Two batches of tribological tests were carried out, in regimes of full and starved lubrication. Friction tests were conducted at three mean sliding speeds: 0.44, 0.66 and 0.88m/s. Experiments were performed with normal load in the range 50–300N, starting from the lowest load. Normal load increased in a stepwise manner after 2min at each load, until the maximum load was reached. Areal surface topographies of specimens and counter-specimens were measured before and after two batches of tests by white light interferometer.

The influence of start–stop transient velocity on the friction and wear behaviour of a hyper-eutectic Al–Si automotive alloy

As worldwide automotive ownership is set to exceed 2 billion vehicles by 2030 (Dargay et al., 2007 [1]), environmental and economical pressures on the automotive industry mean there is a trend to reduce harmful greenhouse gas emissions whilst simultaneously improving fuel economy. The use of electrical hybrid, start–stop idling and materials light-weighting are some of the technological solutions which can offer efficiency savings, however their combined use in a tribological context is less well understood. Interruption of piston sliding as a result of start–stop technology will simultaneously interrupt fluid film lubrication at the ring/liner interface. This could have implications on the friction and wear behaviour of Al–Si cylinder blocks, where scuffing can be an issue. In order to determine the effect of a start–stop velocity cycles on the lubricated friction and wear behaviour of a hyper-eutectic Al–Si liner, an interrupted reciprocating laboratory tribometer test programme was developed based upon the European Urban Cycle standard. Refined cast iron piston ring segments were slid at 23Hz frequency, 4MPa nominal contact pressure and 25mm stroke length against a conformal honed Alusil cylinder liner segment. Regular velocity interruptions at 60s intervals did not significantly inhibit the dynamic friction behaviour between the liner and the cast-iron piston ring segment, indicating that lubricant additive function was not significantly inhibited. However contact potential and FIB–SIMS depth profiles indicated that anti-wear tribo-film thickness was reduced as a result of start–stop cycling. Mass loss from the piston ring was also notably higher as a result of the interruption of elasto-hydrodynamic lubrication causing boundary conditions at re-start and subsequent 2-body abrasion by harder protruding Si particles. Specific wear rates for the Al–Si liner as a result of start–stop velocities were surprisingly lower compared to uninterrupted tests and was believed to be due to faster running-in of the piston ring surface. These results are discussed in terms of the viability of Al–Si as engine materials running start–stop technology.

Friction Characteristics of Steel Pistons for Diesel Engines

The use of iron pistons is increasing due to the higher power requirements of diesel truck engines. Expansion of the iron piston is a common concern. The purpose of this study is to clarify the lubrication conditions of cast iron and steel pistons. Friction of steel and cast iron pistons were measured using the floating liner method. The friction of conventional aluminum pistons was also measured for comparison in this study. The measurement of the secondary motion of each piston was carried out to analyse piston friction, and the following findings were obtained. The cast iron piston showed boundary lubrication at compression top dead center (TDC). This is presumably caused by the larger tilting angle of the piston induced by the larger piston clearance. Steel pistons showed hydrodynamic lubrication conditions at TDC and BDC through each cycle, due to a good oil supply.

Nitriding effect on fatigue resistance of grey and nodular cast irons

AbstractThe influence of nitriding on the fatigue resistance of grey and nodular (ductile) cast iron piston rings was studied for six chemical compositions. The selected materials include three grey cast irons: one with a mixed initial microstructure (martensite plus bainite), the second martensitic and another martensitic alloyed with niobium; and three nodular cast irons: one common nodular cast iron, the second alloyed with Nb and another alloyed with Al and V. These materials were gas nitrided for 3 and 6 h. The relationship between the mechanical behaviour and the treatment time (depth of nitrided layer) was established. Samples were tested under a cyclical bending load. The stresses were determined in the cross-section, where the biggest moment was experienced. Results were statistically treated by means of Weibull analysis. Nitriding showed that fatigue resistance of grey cast iron with a martensitic structure is higher than that of a mixed structure. Fatigue resistance of nodular cast irons is red...

Development of a special geometry carbide tool for the optimization of vertical turning of martensitic gray cast iron piston rings

The machining process for vertical turning martensitic gray cast iron is of great importance to the automotive industry, mainly in the manufacturing process of piston rings. The aim of this paper is to demonstrate the process of development of coated carbide tools to maximize the productivity of the process, considering the maximum life of the cutting tool and the minimum machining cost per part. Using full-factorial design of experiments, we tested two different geometries: a square tool with special geometry—formed by two edges and two ends simultaneously cutting—and a hexagonal tool. Considering that the special square geometry provided maximum life, full quadratic models for responses of interest were constructed using a central composite design for feed (f) and rotation (n). Applying the generalized reduced gradient algorithm, the proposed optimization goals were achieved with feed f = 0.37 mm/v and rotation of 264 rpm for the use of the special square tool. Confirmation experiments prove the effectiveness of this solution.