Honing of cylinders: what it is?

Honing of cylinders (application of hon, honing of cylinders) - abrasive surface treatment with hons (honing heads). Such heads should be understood as the head of a special tool, on which abrasive bars are fixed. Honing is most often used for this, to process the inner cylindrical holes. The honing process involves a combination of rotational and reciprocating movements of the hon with fixed sliding abrasive bars. Also honing is accompanied by constant drawing on the processed surface of special liquid for greasing and cooling..

We also recommend reading the article about it, how to choose the right piston rings. In this article you will learn about the features of the selection of repair piston rings by size and other parameters.

The final hon on the walls of the cylinders is a kind of rough mesh, which helps to retain the required amount of engine oil on the walls of the cylinders and improves the performance and lubrication of friction parts. This procedure is aimed at ensuring high-quality running-in of parts of the CHP (in particular, piston rings and cylinder walls). Also honing is able to increase the life of the engine after assembly, increase the efficiency of the engine lubrication system. In the latter case, the hon on the cylinder walls allows you to hold the grease stably, resulting in a sufficient thickness of the oil film, improves lubrication and cooling of loaded parts, friction losses are minimized.

Which is better, honing or grinding of engine cylinders

Any motor is subject to wear during operation. The engine cylinders gradually change their original shape, becoming elliptical, oval, acquire the shape of a cone, etc.. d. Burrs appear on the walls of the cylinders, scratches, in some cases cracks and other defects. Major repairs are required for the normal operation of such motors.

The so-called "capital" (overhaul) engine often involves the replacement of pistons and piston rings for repair, restoration work or replacement of the crankshaft, as well as boring the engine cylinders to the repair size. For normal running-in of details and more effective work of the internal combustion engine after repair of a wall of cylinders should have certain roughnesses before final assemblage.. Honing is used for this purpose.

Also during repair it is possible to honing other internal cylindrical surfaces. We are talking about the bushings of the upper head of the connecting rod, holes in the lower head of the connecting rod, bushings of rocker arms of the valve mechanism, crankshaft beds and other holes. Honing of the cylinder differs favorably from other methods of grinding, such as polishing or grinding the cylinder walls. Let's start with that, A common concept for engine repair is the so-called cylinder mirror.

This "mirror" is understood as a completely smooth surface of the walls of the engine cylinder. Such a smooth surface is created as a result of processing (grinding) cylinder walls before assembling the engine after repair. Also the mirror of the cylinder is stuffed (rubbed) during further operation of the engine.

We also recommend reading the article about it, What shall I do, if the cylinder block has cracked or a crack has been detected in the cylinder head. In this article you will learn about the signs of malfunction and available ways to repair cracks in the block or head of the engine block.

In other words, the mirror on the walls of the cylinder is created as a result of contact of the walls with the piston rings. For this reason, many representatives of the "garage" repair ignore the procedure of applying hon. The reason for this is the idea, that hon will still be erased after several thousand kilometers, and a mirror is loaded on the walls of the cylinders. It should be noted, that in some cases after honing (honing) mesh on the cylinder walls recommended quick replacement of piston rings. This fact is another reason, on which "garage" masters do not aspire to carry out procedure of honing and incline to polishing of the cylinder for immediate reception of a mirror.

Now about Hone. Honing is a thorough treatment of the cylinder surface with a special tool. The result of professional honing of the motor is fast and high-quality production of piston rings, higher compression, reduction of wear of details, increase in motor resource, etc.. d. At the same time after the application of hon reduces the consumption of engine oil for soot, the combustion chamber becomes more airtight, which minimizes the breakthrough of crankcase gases and their entry into the crankcase. Let's look at this process and answer the questions, what is cylinder honing and why it is necessary to apply hon.

How to properly apply hon on the walls of the cylinders

Let's start with that, that the process of proper honing in the factory is quite complex. We'll talk about that later. As for the repair of internal combustion engines in car repair shops or specialized workshops, honing of cylinders occurs in two main stages:

  • initial processing by means of the bars with a big abrasive fixed on hongolovke;
  • final honing, which involves finishing the cylinder with fine-grained abrasive. This abrasive allows to achieve high-precision surface treatment;

Completion of the process of honing of cylinders can be considered as finishing cleaning of surfaces by means of special abrasive paste. This procedure allows you to remove sharp corners, transitions, depressions and other microdefects. The result is a smooth and evenly applied honing grid on the walls of the engine cylinders. Note, that in some cases the use of abrasive pastes for fine finishing is omitted, performing only two main stages of applying hon.

The complete end of the process of honing the cylinders is the washing of the cylinder block (BC) to remove metal shavings, as well as the remnants of polishing pastes. Then in the process of assembling the engine you can count on the correct landing of the piston rings, fast grinding and high-quality sealing of the combustion chamber. Let's add, that the abrasive for honing cylinders is like ceramic, and diamond bars. Ceramic bar has certain advantages over diamond abrasives, as tak4oy honbrusok more durable, which ultimately determines the lower cost of ceramic honing compared to diamond solutions.

Now let's talk about professional honing, which involves the presence of complex expensive equipment. Such honing is used in the manufacture of new internal combustion engines, as well as to restore engines in the conditions, as close as possible to the factory. Honing should be understood as creating on the wall of the cylinder is not just a chaotic grid, and a certain microprofile on the surface. In other words, hon in the cylinder is a set of strokes, which intersect with each other. The depth of these lines also plays an important role, their location relative to each other. Compression in the cylinders directly depends on these factors, engine power, fuel and engine oil consumption, as well as the resource of the entire LPG and the engine itself.

The special tool for honing provides exact, instead of chaotic drawing of the specified lines by means of a honing head, on which honbruski are mounted. As already mentioned, the tool performs not only rotation, but also reciprocating movements. Due to this, in the process of applying hon manages to withstand a given angle, under which the intersection of the lines on the surface of the walls of the cylinder.

This angle is called the honing angle. There is also a dependence on the type of abrasive and its grain size, which affects the final quality and structure of the hon. The degree of surface roughness depends on the type of honbrusk, the depth and dimensions of the applied lines. The whole process of honing is divided into starting and finishing. Different bars are used at each stage. Accurate control of surface roughness becomes possible due to further visualization of chen microprofile diagrams. The honing angle is set using special film templates.

  1. To form the surface at the initial stage of honing, which is quite rough, has deep risks and increased roughness, requires the use of a large-grain abrasive. Diamond honbrusks are used for this purpose, which are made on a copper basis. The whole process of rough honing is accompanied by an abundant supply of lubricating and cooling fluid. This is necessary for effective removal of mechanical particles from the application area, abrasive residues, etc.. d.
  2. After diamond honing, the rough surface does not allow you to immediately begin installation of other elements of the internal combustion engine, as rings and the piston in such cylinder will not be able to work. Sometimes diamond honing is an alternative power method for boring engine cylinders. Then the rough surface is again treated with an abrasive with a smaller grain. This treatment allows the formation of a new microprofile on the walls of the cylinders. The final stage of the honing process is re-treatment with fine-grained abrasive, that allows to reach the planned repair size of the cylinder.
  3. Upon completion of the formation of the "finished" surface is additionally carried out the so-called additional honing crawling. This procedure is not aimed at further boring of the cylinder, the main task is to clean the previously obtained microprofile from the remnants of honing abrasives. Also cutting of the pig-iron cylinder allows to open graphite grains. In the case of cast iron, this further reduces friction and reduces mechanical losses, as well as slow down wear. Brushes are used for trimming, which are based on nylon threads, and silicon crystals are present.

Let's add, that honing also allows the application of an additional layer of special antifriction coatings. Honing can be like cast iron cylinder blocks, and some BC, made of aluminum alloys. Flat-top honing is very popular today, which is actually similar to the classical method. Differences of flat-top honing from a usual method of drawing hon consist in materials and bars, which are used in flat-topped processing.

As a result: mirror or hon

Given the above, it is fair to say so, that the best maintenance of motor oil is capable to provide only a wall with a rough surface. As for the perfectly smooth wall (mirrors) cylinder, such a surface cannot ensure proper lubricant retention in the amount, which will be enough to effectively lubricate the piston rings.

On the mirror polished surface of the cylinder engine oil is removed almost completely, leftovers will be spent on waste, and the collection of new oil will not happen. In this case, we can talk about partial or completely dry friction, resulting in accelerated wear of the rings and walls of the cylinder.

On the honing surface, which is rough, the oil is retained much better, which allows to withstand high mechanical loads. Let's add, that the lack of roughness of the hon automatically means the worst retention of oil on the walls. Also pay attention to the honing angle. This angle affects the oil consumption of soot. The greater the angle, the rougher the surface, but the surface of the cylinder becomes more wavy and the engine consumes oil more intensively. Reducing the hon angle reduces oil consumption, at the same time the roughness of the walls deteriorates. Taking into account these laws when honing cylinders, it is necessary to carefully select certain modes of application of hon and abrasives in relation to the materials of a particular BC. This approach allows you to achieve the best results.

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