Special note: This article stems from the Chinese machine tool business network http://www.jc35.com/news/detail/52986.html, only from an academic point of view of the industry trends, no intention to copy. If there is any objection, please let us know by letter (81887515@qq.com). We will delete it in the first time. Please forgive me for the inconvenience caused!
Solid lubricant friction due to excellent performance, high bearing capacity, good wear resistance and the characteristics of wide temperature characteristics and timeliness, and can be used in place can not use lubricating grease, bad environment and no maintenance occasions, lubrication during machining is also widely used in solid lubricating agent to improve friction.
There are three main ways to lubricate the cutting process. One is cutting fluid with lubricating function; the other is lubricating coating on the surface of cutting tool; the third is using self lubricating cutter.
In the cutting fluid, solid lubricant acts as an additive to improve the performance of the cutting fluid. In the latter two lubrication methods, the solid lubricant is the main factor of its lubrication.
Applied to coated cutting tools
At present, the commonly used tool coating material is mainly all kinds of hard nitrides, oxides, carbides or boride ceramic, all have high hardness, excellent heat resistance, oxidation resistance and corrosion resistance.
Because the coating material has the advantages of low free energy, stable chemical property and small chemical affinity to the workpiece material, it can effectively resist adhesion between the knife chip and the tool - work interface. Under the condition of high temperature in the cutting zone, the coating materials such as TiC and TiN can also be oxidized to produce some softer TiO2 films. Al2O3 is more than 800 DEG C and has considerable fluidity. It can act as extreme pressure lubrication. From the point of view of tribology, the two aspects of the coating material plays a very good solid lubricant role, not only the cutting ability of anti adhesive wear increased, to reduce the cutting force, cutting temperature and improve processing quality benefit.
The solid lubricant is bonded to the tool surface by coating and coating methods to form a solid lubricant film, which can serve as a lubricant. With solid lubricant and friction surface layer structure has strong bonding ability, have lower shear strength between the layers of itself, in the cutting process, solid lubricating film exists in the surface of the cutter will be transferred to the workpiece surface, the formation of transfer film, so that the cutting friction occurs between the transfer film and the film too in the process of. Even if friction occurs inside the solid lubricant film, the friction coefficient and tool wear can also be reduced.
Applied to self-lubricating cutters
Self lubricating tool means that tool material itself has the functions of antifriction, anti-wear and lubrication, and it can be applied to self lubrication cutting without any additional lubricant or lubricant. Due to the application of self lubricating cutter can reduce friction and wear, eliminating the cooling and lubricating system, reduce equipment investment, avoid cutting fluid caused by environmental pollution, to achieve clean production, reduce production costs, so the self lubricating cutter is a kind of efficient and clean green tool, has broad application prospects in modern machining.
At present, the realization method of self lubrication tool in cutting process mainly has two kinds: using the cutting friction chemical reaction under high temperature, with the reaction film self lubrication in situ surface tool material generation; direct solid lubricant is added to the tool material, tool to realize self lubrication. Adding solid lubricant is an important way to prepare self-lubricating materials. Commonly used solid lubricants are MoS2, hBN, H3BO3, TaS2, WS2, and some of the soft metal (Ni, W, Al, Ti, Co, etc.), and their friction coefficient of metal materials can be reduced to 0.1-0.2.
The solid lubricant additives for composite tool materials forming tool material matrix, can be used as solid lubricant, friction coefficient of drag to compress small, the formation of solid lubricating layer continuous on the tool surface, so that the tool material obtained from the lubrication characteristics. This kind of self lubricating tool materials with high temperature friction and good performance, can adapt to the cutting temperature range of 1200 DEG and a wide range of cutting speeds, and can withstand high loads, it can meet the strict requirements of high-speed cutting, dry cutting, hard cutting and machining difficult materials such as advanced manufacturing technology of cutting tool materials.
Adding solid lubricant will produce two effects on the material properties: on the one hand, the solid lubricant can be deposited on the surface of friction drag form a lubricating film, so as to improve contact conditions of friction, reduce friction and wear; on the other hand, dispersion solid lubricants in tool materials may lead to the decrease of mechanical properties of materials. Therefore, in order to ensure adequate content of solid lubricant to form continuous lubricating film lubrication, achieve stability, and to ensure the physical and mechanical properties of tool material will not significantly decreased, it must be in the physical and mechanical properties and self-lubricating properties between comprehensive balance.
Because this kind of self lubricating tool materials always contain internal solid lubricant, so the tool in the entire life cycle has the self lubrication function, and tool materials in a wide temperature range (low to high speed cutting) are self lubricating ability.
The application of solid lubricants in cutting fluid, greatly improves the bearing lubrication, cutting ability and temperature adaptability, improve the quality of the machined surface, the cutting fluid performance in harsh processing conditions greatly improved.