The reclamation of crankshafts (and many other components) by plasma spraying can produce considerable savings over the replacement cost. 50% savings are common and on large components, as much as 90% may be saved.
Note: Crankshafts having the following defects are not recommended for treatment by plasma spray: Cracks, distortion, wear below final re-grind tolerance. All traces of nitriding should be removed during pre-machining refer to a) and b).
It is recommended that crankshafts be finish ground. Wet grinding using a soluble cutting fluid and wheels of medium hardness with vitrified bond are normally recommended. Silicon carbide or bauxite grit with a grit size of 30-50 are also acceptable.
Favoured for components that are subjected to heavy loading, nitriding imparts a high surface hardness which promotes high resistance to wear, scuffing, galling and seizure. Fatigue strength is increased mainly by the development of surface compressive stresses. The wide range of possible temperatures and case depths, which allow adjustment of different properties of the treated parts, give gas nitriding a broad field of applications.
Typical applications include gears, crankshafts, camshafts, cam followers, valve parts, springs, extrusion screws, die-cast tooling, forging dies, aluminium-extrusion dies, injectors and plastic-moulds.
Nitriding is most effective when applied to the range of steels containing nitride-forming elements such as chromium, molybdenum, vanadium and aluminium. The process is also applicable to tool steels such as hot-work, cold-work and mould steels. A low temperature application is nitriding of spring steels to prolong the fatigue life of springs for automotive use. In general, all ferrous materials can be gas nitrided up to 5% chromium. For higher contents of alloying elements and for gas nitriding of stainless steel, plasma nitriding might be considered. Gas nitriding of sintered steels with low density is not recommended.
Crankshaft is most important and a critical component in an Internal Combustion Engine. In this study plays a dual role of multi cylinder petrol engine crankshaft was made up of EN-19 steel and Nitriding coated EN-19 steel. It has been shaped by using modelling software (PRO-E) and Analysed by using analysis software (ANSYS). Finite element Analysis (FEA) is a method was used to conduct the dynamic Analysis on crank shafts, which are applied Load spectrum on crank pin bearings. The various Analyses on crank shaft also conducted such as Von misses stress, Yield, Tensile, hardness and thermal expansion. The analysis is done for finding critical location in crank shaft. Stress variation over the engine cycle and the effect of torsional and bending load in the analysis are investigated.
Liquid nitriding may be performed at temperatures as low as 500°C (932°F), and as high as 630°C (1166°F). Typically, however, the temperature range is between 540°C - 590°C (1000°F -1090°F). TS USA uses specially formulated nitriding chemistries whereby nitriding can be performed at 510°C (950°F) for certain types of steels, without compromising compound layer depth or quality and without any reduction in process productivity.
Typical time cycles in the actual nitrocarburizing step are 60-90 minutes, at temperature. However, this can be as low as 10 minutes or as high as 4 hours, depending on the material and specific customer requirements. Pre- and post- nitriding steps may add 3-4 hours, for a total time of 5-6 hours, approximately. Typical gas nitriding times are between 24-30 hours, excluding pre and post nitriding times.
The crankshaft consists of the shaft parts which revolve in the main bearings, the crankpins to which the big ends of the connecting rod are connected, the crank arms or webs (also called cheeks) which connect the crankpins and the shaft parts. The crankshaft, depending upon the position of the crank, may be divided into the following two types :
The crankshaft, depending upon the number of cranks in the shaft, may also be classified as a single throw or multi-throw crankshafts. A crankshaft with only one side crank or the center crank is called a single-throw crankshaft whereas the crankshaft with two side cranks, one on each end or with two or more centers cranks is known as the multi-throw crankshaft.
The bearing pressures are very important in the design of crankshafts. The maximum permissible bearing pressure depends upon the maximum gas pressure, journal velocity, amount, and method of lubrication and change of direction of bearing pressure.
Most crankshaft failures are caused by a progressive fracture due to repeated bending or reversed torsional stresses. Thus the crankshaft is under fatigue loading and, therefore, its design should be based upon endurance limit. Since the failure of a crankshaft is likely to cause serious engine destruction and neither all the forces nor all the stresses acting on the crankshaft can be determined accurately, therefore a high factor of safety from 3 to 4, based on the endurance limit, is used.
The crankshaft must be designed or checked for at least two crank positions. Firstly, when the crankshaft is subjected to maximum bending moment and secondly when the crankshaft is subjected to maximum twisting moment or torque.
1. The crankshaft must be designed or checked for at least two crank positions. Firstly, when the crankshaft is subjected to maximum bending moment and secondly when the crankshaft is subjected to maximum twisting moment or torque. 2b1af7f3a8