Lubricants and Lubrication Part 9 pot

438 14 Metalworking Fluids oils. The use of zinc- and other heavy metal-based additives in cutting oils is declin- ing due to environmental and waste water considerations. Chlorinated paraffins are still used as universal EP agents throughout the world but combinations of sulfur additives and ester oils are being increasingly used in Germany and Western Europe as substitutes. The reasons for these developments are the considerably higher dis- posal costs for products containing chlorine in Germany (Fig. 14.16) [14.140]. 14.4.2.2 Significance of Viscosity on the Selection of Neat Products The viscosity of most metalworking oils is between 2 and 46 mm 2 s –1 at 40 C. The very low viscosities are used for spark erosion applications (EDM) and for honing and super-finishing while the higher viscosities are mostly used for difficult machining work at low cutting speeds such as broaching and gear cutting. In general, high cutting forces, continuous chips and large chip cross-sections require higher viscosities. These higher viscosities also have a positive effect on the evaporation and misting behavior of the oils. However, the disadvantages of higher viscosity oils are higher drag-out losses on chips and components and the resulting increased pollution of washing lines. For this reason, the current trend is towards low viscosity products. The disadvantages of low viscosities, i.e. lower flashpoints as well as greater evaporation and misting can be compensated for by new hydrocracked base oils or ester oils. Small components also normally require low viscosities because thicker oils can cause parts to stick together and thus cause transport and positioning problems. Thick oil films can also interfere with monitoring of routine manufacturing tolerance and here again, low viscosity oils are the only solution if component de-oiling is to be avoided. Low viscosity oils offer better heat dissipation and this is a clear benefit in processes which create high heat such as high-performance grinding. Also the better flushing properties of low viscosity oils make then ideal for honing, grinding and lapping operations which require the efficient removal of abraded material from the cutting zone for perfect results. Deep hole drilling also benefits Cutting oil AdditivesBase fluids Synthetic oil Mineral oil Additives to improve lubrication Anti wear additives Extreme pressure additives (Corrosion protection additives) Additives to improve wetting and flushing effect Anti mist additives Solvent raffinates Hydrocracked stocks White oils Synthetic ester (natural ester) Polyalphaolefins Fig. 14.16 Composition of neat metalworking oils. 43914.4 Neat Cutting Fluids from low-viscosity oils because chips are more rapidly flushed out of the hole. The other advantages of low viscosity oils relate to machinery peripherals. For example, the necessary size of belt filters falls exponentially with viscosity so that both costs and space can be saved. 14.4.3 Oil Mist and Oil Evaporation Behavior Hygiene and dermatological problems occur in the metalworking industry when machine personnel are subjected to repeated skin contact with metalworking oils. Chip-forming metalworking is particularly affected because of the regular and close contact between personnel and the machines. An overall reduction in the number of dermatological problems and a general reduction in the oil pollution of workshop atmospheres was achieved by mechanical barriers on machines as well as changes to manufacturing technologies, in particular, the automation of machining processes in transfer lines. The pollution of workshop air with oil mists and vapors is still a problem in many companies. Measures such as machine encapsulation, improved machining procedures, automation and above all, extraction at the machine or at a central point in the workshop have certainly improved the situation. However, extraction without de-oiling simply shifts the pollution outdoors and this is in conflict with general environmental protection measures. Many attempts have been made to reduce not only the misting properties of straight oils but also the misting of water-mixed coolants [14.141, 14.159]. Initial reduction of misting has been achieved but the effect could not be maintained over an 8-h working shift. Two effects must be mentioned–the mist-suppression effect gradually decreases as the molecular weight of the polymer is reduced and the polymer will be filtered out and is, therefore, no longer available for mist suppression. This means, in practice, that permanent addition of a suitable polymer is necessary to reduce the misting of a water-mixed coolant in workshops. Further studies show that total inhalable particulates can be used to estimate mineral oil mist exposure but cannot be used for water–mix MWF concentrate mist exposure [14.160]. 14.4.3.1 Evaporation Behavior The evaporation of cutting fluids on hot components, tool and chips and from the larger surface area of oil mist droplets leads to vapor pollution of workshops and even to condensed mists. As low-viscosity oils become more popular, the evaporation behavior of base oils is becoming increasingly important. This subject is covered in detail in Chapter 4. While a number of countries specify an oil mist threshold value in mg m –3 (particulates), Germany has in recent years moved over to evaluating the total hydrocarbon concentration in the air. In most metalworking factories, this is 5 to 20 times higher than the oil mist concentration. 440 14 Metalworking Fluids 14.4.3.2 Low-Misting Oils The development and application of low-misting neat cutting oils have significantly improved the oil mist pollution situation. Development work as well as the general acceptance of these oils in the metalworking industry was significantly influenced by new methods of measuring oil mists and of determining the misting characteristics of oils [14.56–14.58]. 14.4.3.3 The Creation of Oil Mist If an oil mist is analyzed, a variety of different factors are involved. lt is soon appar- ent that the whole process is highly complex in which mechanical, physical and phy- sico-chemical factors are intermixed. The causes of neat cutting oil mists can be roughly listed as follows: . As the fluid exits the nozzle, air friction acts on the jet in proportion to its exit velocity. Important factors are the geometry of the nozzle and the exit speed. The result is that droplets of oil are dispersed into the surrounding air. . If the oil jet rebounds off the machine bed, the component or tool, oil mist can be formed. This is greatly influenced by the oil pressure but also the quantity. The amount of oil mist with droplet sizes < 5 lm increases drama- tically with increasing pressure [14.59]. . Mechanical stress on the oil during the machining process also creates oil mist. Critical factors here include the machining speed, the geometry of the rotating machine parts and component, chip formation, the quantity of oil and the oil pressure. Oil misting is a major problem in machining processes which use geometrically non-defined cutting edges, i.e. particularly grinding. The porosity of the grinding face allows oil to be thrown-off at high periph- eral speeds and form a dispersion. . When the oil is returned to the tank, air can be trapped in the oil. As the air is released, it carries out oil in the form of a finely-dispersed mist. Important factors here are the geometry of the jet which impacts the surface of the fluid in the tank and the velocity of the jet. . Particularly if high oil pressures are used and depending on the pressure- related solubility equilibrium, larger volumes of air can be dissolved in the oil. When the pressure falls, the air is released from the oil. This escaping air can transport oil droplets to the workshop air. The decrease in the solubility of air in oil as the temperature of the oil increases causes air to be released from the oil as the temperature of the oil increases in the cutting zone. . Apart from the above-mentioned aerosols, metalworking and other processes can cause condensation aerosols to form. A largepart of the energyconsumed by the machining process is converted into heat and this can lead to very high tool and component temperatures. This, in turn, can cause a partial evaporation of the oil. This evaporation process can continue beyond the cutting zone insofar as oil can still evaporate on the hot machining chips. Shortly after this evaporation, the vapor cools somewhat and condenses. This sequence can create condensation aerosols with very fine droplet sizes. Apart from the surface temperature of 44114.4 Neat Cutting Fluids the wetted components, the surface itself, the thickness of the oil film and last but not least, oil-specific factors such as its vapor pressure also effect the creation of oil mist. Outside influences such as the amount of dust and moisture in the air influence condensation. In a simple laboratory misting test, an oil mist with a pronounced maximum droplet distribution at1.2 lm was examined [14.60]. 14.4.3.4 Sedimentation and Separation of Oil Mists All the above-mentioned possible causes of oil mist can create mists with a very large spectrum of droplet size distributions. Immediately after creation, oil mists begin to collapse. While droplets which are much larger than those in the mist itself normally precipitate in the immediate vicinity of the machine, smaller droplets can spread much farther if they have enough kinetic energy. A major factor in the precipitation of an oil mist is the droplet size. Suspended oil droplets agglomerate until they reach a maximum diameter of 3 lm when they begin to sink slowly (0.5 m h –1 at 2 lm diameter) [14.61]. Sedimentation can also be accelerated by coagulation. Air flow conditions and Brownian movement of smaller droplets can cause droplets to collide and thus grow by coagulation. And finally, small and large oil mist droplets can undergo an interchange caused by surface-activated evaporation and condensation. In plants in which chip-forming machining is performed with neat cutting oils, the oil mist in the workshop atmosphere can have droplet sizes up to a maximum of 3 lm [14.61]. The maximum numeric distribution is about 1 lm. The maximum mass distribution is naturally near to the upper droplet size limit if one assumes that the mass of a droplet increases by the third power of its radius. The average droplet size measured at various points on a centerless external grinding machine was about 95 % < 3 lm [14.61]. 14.4.3.5 Toxicity of Oil Mist An oil mist is a dispersed system with droplet sizes between 0.01 and 10 lm. This very wide range of sizes justifies the term, polydispersed system. The toxicological evaluation of oil in the air in the form of gas should be viewed totally differently to the evaluation of oil mists. Research on aerosols and dusts has shown that only particles or droplets smaller than 5 lm can reach the lung’s alveoles. Larger droplets are filtered out by the nose or are trapped in the bronchial tubes and made relatively harmless for the body’s organism [14.62]. Medical research on silicosis has shown that (as far as dust is con- cerned), particle sizes of 0.5 to 1.5 lm are efficiently retained, i.e. these particle sizes are effectively trapped by the alveoles in the respiratory system. Hydrocarbon oil mists tests on animals [14.63] have shown that this droplet size range is particularly important. Most oil mist tests have examined mineral oil hydrocarbons without additives. These are viewed chemically as relatively inert substances and this is mostly the case if one disregards the above-mentioned discussion about aromatic hydrocarbons or the tests performed on highly condensed aromatics. Nevertheless, toxicological evaluation of pure hydrocarbon mists is still extremely complicated. If lubricant additives are included in the evaluation, which are a much more reactive group of substances than hydrocarbons alone, generalized statements on the toxicity 442 14 Metalworking Fluids of neat cutting oils would be almost impossible. This proviso must however form the focus of the health hazards of oil mist. According to Reiter’s retention charts [14.64], the lung’s alveoles only retain about 10 % of oil droplets with a diameter of 0.1 lm but 70 % with a diameter of 1 lm. This should be noted when oil mists are evaluated even if the toxicological details are not available. As was the case with dust contamination, these medical considerations led to the creation of oil mist thresholds. The last time oil mists were mentioned in the Ger- man MAK (Maximum Workplace Concentration) list [14.65] was 1966. However, uncertainties regarding the toxicological evaluation of oil mists was the reason why MAK values were not established for oil mist. Some countries set the limit at 3 mg m –3 (and 5 mg m –3 for longer exposure). The American TLV list (Threshold Limit Values) contains a threshold of 5 mg m –3 oil mist (particulates) suggested by the 1973 Conference of Government Industrial Hygienists. This threshold was based on animal tests with a naphthenicwhite oil (molecular weight: 350 to 410) with no additives or aromatics [14.66]. lt is therefore particularly significant that the animal tests were oriented to oil mist droplet sizes found in practice. The maximum droplet size distribution was about 1.3 lm (90 % of the droplets were < 1.6 lm). This droplet size distribution roughly corresponds to that of mists found in metalworking shops and also to the type of mists which are toxicologically important. Without doubt, aromatic-free white oils are much less problematic than the mineral oil cuts normally used in cutting and grinding oils. Above all, the effect of additives was excluded. Two OSHA air contaminant permissible exposure limits currently apply to metalworking fluids. These are 5 mg m –3 for an 8-h time-weighted average (TWA) for mineral oil mist and 15 mg m –3 (8-h TWA) for particulates not otherwise classified (PNOC) (applicable to all other metalworking fluids) [14.142]. There are no other requirements. There are also other recommended exposure limits.In 1998 the National Institute for Occupational Safety and Health (NIOSH) published a criteria document which recommended an exposure limit(REL) for metalworking fluidaerosols of0.4 mg m –3 for thor - acic particulate mass as a time-weighted average(TWA) concentration for up to 10 h per day during a 40-h workingweek. Because of the limitedavailability of thoracic samplers, measurement of total particulate mass is an acceptable substitute. The 0.4 mg m –3 concentration of thoracic particulate mass approximately corresponds to 0.5 mg m –3 total particulate mass. The NIOSH REL is intended to prevent, or greatly reduce, respiratory disorders causally associated with exposure to metalworking fluid. It is NIOSH’s belief that in most metal-removal operations it is technologically feasible to limit metalworking fluid aerosol exposure to 0.4 mg m –3 or less [14.143]. The American Conference of Governmental Hygienists (ACGIH) threshold limit value (TLV) for mineral oils is 5 mg m –3 for an 8-h TWA and 10 mg m –3 for a 15- min short-term exposure limit (STEL). In 1999 the OSHA Metalworking Fluids Standards Advisory Committee also recommended a new 8-h time-weighted average permissible exposure limit (PEL) of 0.4 mg m –3 for thoracic particulates (0.5 mg m –3 total particulates). The committee based the recommended PEL on studies of asthma and reduced lung function. 44314.4 Neat Cutting Fluids In Germany, the toxicological evaluation has been based in recent years on the total hydrocarbon concentration in the atmosphere (which means the total of oil mists and vapor). The threshold value currently used (regulation officially not valid, February 2006) is set at 10 mg m –3 , which applies both to water-miscible and neat cutting fluids. Because of the diversity in measurement methods, many TLV (threshold limit values; MAK values) have been established; all are based on the same dimension of mg m –3 , but the results can never be compared with each other. As an example, if the method used in the USA gives a result of 0.5 mg m –3 the method applied in Germany under identical conditions leads to a result which is sometimes more than 30 mg m –3 . This is because the method used in the USA measures particulates in a specific size range only whereas the German method detects aerosols and hydrocarbon vapor of different droplet size [14.144]. 14.4.3.6 Oil Mist Measurement Determining the total hydrocarbon content of air is possible with good accuracy using carbon tetrachloride solvent washing with subsequent infrared spectroscopic examina- tion of the CH-valence shifts [14.67]. These measurements do not analyze oil mist concentration because the total hydrocarbon content in workshop atmospheres in the metalworking industry can be many times greater. Most suitable of all is a scattered light spectrometer which can be adjusted to measure the droplet sizes which are relevant to the retention characteristics of the lung’s alveoles. This method ensures that the toxicologically relevant oil mist is measured [14.56, 14.161]. This measuring method is simple and fast and can be used in all areas of a workshop. For comparative measurements of an oil’s misting behavior, a scattered light spectrometer is installed in a unit which isschematically described in Fig. 14.17 (Fuchs procedure) [14.68]. Air, at a given pressure, volume and temperature, is blown into the oil. This creates an oil mist which is measured by the scattered light spectrometer over time. Figure 14.18 illustrates the influence of viscosity on the oil mist characteristics of a series of neat cutting oils. Fig. 14.17 Measuring apparatus for determining the misting characteristics of cutting and grinding oils. 444 14 Metalworking Fluids 14.4.3.7 Oil Mist Index To give the oil misting characteristics of metalworking oils a figure, the oil mist concentration in mg m –3 is determined in line with defined machining conditions and this oil mist concentration set against that of a reference fluid. This ratio has no dimension but is multiplied by 100 to provide the Oil Mist Index. If the reference fluid is di-n-octyl phthalate or di-iso-octyl phthalate, whose misting behavior is simi- lar to that of a standard cutting fluid at a given viscosity, an Oil Mist Index as in Fig. 14.19 results. Figure 14.19 shows values for standard and low-misting oils and the viscosity of the oils. The oil mist index of medium viscosity standard oils (40 mm 2 s –1 at 40 C) is between 80 and 120 but between about 4 and 6 for low-misting versions. This provides a possible definition of low-misting oils. For low-misting oils with a viscosity > 30 mm 2 s –1 at 40 C, the index is < 10. According to Fig. 14.19, greater differentiation must be made for oils with lower viscosities [14.57]. 14.4.3.8 Oil Mist Concentration in Practice Back in 1978, Fuchs [14.69] performed a far-reaching study in Germany to deter- mine the oil mist concentrations near to machine tools using neat cutting oils. Table 14.15 shows values from 350 measuring points in 65 companies for standard and low-misting oils. The large deviation in values was mainly due to varying machine-specific counter-measures (encapsulation, extraction etc.). Figure 14.20 shows the oil-mist concentration in a machining shop over a period of 12 h (only neat cutting oils via a central system). Apart from the positive effect of low-misting oils, the extraction system’s effect on reducing the oil mist concentration can be seen. Fig. 14.21 shows the high sensitivity of the scattered light spectrometer and the effect of low-misting oils on a Gleason gear cutting machine. Each tooth cut by the machine can be identified by the pattern of oil mist concentration and the time scale. Such measurements also allow the cutting oil feed to be optimized in terms of oil mist pollution. Such measurements and mist concentration profiles are also of great assistance when extraction equipment is installed and/or monitored. 30 25 20 15 10 5 0 0 20406080100 Viscosity at 25°C [mm /s] 2 Fig. 14.18 Influence of viscosity on the oil mist characteristics of a series of neat cutting oils. 44514.4 Neat Cutting Fluids Tab. 14.15 Values from 350 measuring points in 65 companies for standard and low-misting oils. Type of oil Measuring point Standard oils, mg m –3 Low-misting oils, mg m –3 Range Average Range Average Workshop locations, various machining ops; points at some distance from machines; walkways between machines (> 1.50 m) 1.6 to 0.3 0.95 0.9 to 0.2 0.31 Hobbing; head-hight, < 1.5 m from the machinig point 40 to 3 18.1 21 to 0.2 7.9 Grinding; head-hight, < 1.5 m from the grinding point 99 to 2 19.4 21 to 0.2 6.9 Automatic lathe; Type I, head-hight, < 1.5 m from the machining point 95 to 2 13.3 24 to 0.8 5.2 Automatic lathe: Type II 72 to 1.5 6.3 7 to 1.2 3.1 Automatic lathe: Type III: head-hight, < 1.5 m from the machining point 34 to 10.8 10.1 9 to 0.3 2.9 0 20 40 60 80 100 120 140 160 180 200 220 1 5 10 50 100 500 1000 a c b V iscosit y at 20°C [ mm /s ] 2 Oil mist index Fig. 14.19 Dependence of theoil mist index (NI) on viscosity. (a) standard oils(not low-misting); (b) low-misting oils; (c) value for dioctyl phthalate (DOP,according to definition). NI = k p /k r 100;k p =mistconcentration of the oil under test, mg m –3 ; k r =mist concentration of the reference oil (DOP), mg m –3 . 446 14 Metalworking Fluids 0 5 10 15 0 20 40 60 80 Time [s] Oil mist [mg/g ] 3 1 2 Fig. 14.21 Gear cutting on Gleason machines. 1, conventional neat cutting oil; 2, equiviscous anti-mist neat cutting oil. Time of day [h] Oil mist concentration [mg/m ] 3 6 7 8 9 10 11 12 13 14 15 16 17 18 0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 0,3 a b c d e Fig. 14.20 Oil mist concentration in a machining shop over a period of 12 h. (a) conventional neat cutting oil without extraction; (b) conventional neat cutting oil with extraction; (c) anti-mist cutting oil with extraction; (d) basic extractor switched on; (e) complete extraction system switched on. 44714.5 Machining with Geometrically Defined Cutting Edges 14.5 Machining with Geometrically Defined Cutting Edges 14.5.1 Turning With a turning operation it is possible to produce parts which are round in shape. Cylindrical and conical surfaces are generated from a rough cylindrical blank which rotates about its longitudinal axis and against a cutting tool. Most turning operations use single-point tools. Normally, a tool holder contains an indexable insert with multiple cutting edges. The speed of the workpiece, the feed rate of the tool, and the depth of cut are main specifications for turning operations. Roughing cuts, which remove metal at the maximum rate, are followed by finishing cuts at a higher cutting speed, a lower feed rate, and a smaller depth of cut [14.70]. These machining conditions depend on the workpiece and tool materials, the surface finish, the dimensional accuracy, and the machine tool capacity. Each combination of workpiece and tool materials has an optimal set of tool angles. Tool geometry will affect the direction of chip flow. The objective is to avoid long continuous chips which can interfere with the machine tool operation or damage the partsurface. Chips will break when they hit the workpiece or tool holder. . The major turning processes performed on a lathe are straight or cylindrical turning, taper turning, facing, and boring. . Turning operations occur on the external surface of a part whereas facing is used to produce a flat surface. . Boring is an internal turning process and may be done to enlarge a hole made by a previous process, to enlarge the inside diameter of a hollow tube, or to machine internal grooves. . For turning operations, water-mixed metalworking fluids are used only when running automatic lathes; neat oils are often preferred. 14.5.2 Drilling The most common shape found in a manufactured part is a circular hole, and many of these holes are produced by drilling. Since the chips are formed within the part, the flutes or grooves normally serve two purposes. In addition to providing a conduit for the removal of chips, they also allow the cutting fluid to reach the tool–workpiece interface. Mostdrills are made from HSS which demands the application of a cutting fluid [14.71]. The coolant pressure recommended in drilling depends on several factors. The most important factors include the following: workpiece hardness, feed rate, hole diameter, depth, tolerance, and finish. As the coolant pressure is increased, recircu- lating the coolant could become a problem [14.72]. Drilling times can be reduced by using internally cooled drills with inserts. Tung- sten carbide inserts and inserts with PVD or CVD coatings are commonly used in these applications. An efficient coolant system supplies that coolant at the proper [...]... breathlessness Apart from bronchial fibrosis, influences have also been recorded on the heart, skin, thyroid glands and blood corpuscles Bronchial fibrosis was recognized as an occupational disease in the field of carbide manufacturing in 196 1 and in the field of carbide machining since 198 0 Health and safety studies show that the highest cobalt concentrations are found in ultra-fine dusts (1.4–3.8 lm) [14 .93 ]... plants and steam-turbine blades The Ni–Cr alloys Nimonics and Inconel are used to manufacture gas-turbine blades and disks, because of their high-temperature creep and oxidation resistance Nickel super alloys contain Ni, Cr, Fe, Mo, and W They are known under the name Hastalloy These alloys are resistant to reducing HCl and oxidizing acids at very high temperatures and are used in chemical plants and. .. hydrogen gas which can explode And even at low temperatures, there is a danger that chips will self-ignite In Germany, machining magnesium with water-based cutting fluids was prohibited by the TRGA 5 09 [14 .90 ] until 199 5 The reasons for this were not just the formation of hydrogen gas and the obvious danger of explosions but also the hazards connected with the storage and transportation of chips These... Karlsruhe, Germany [14 .92 ] have shown that the risks of magnesium dust explosions are eliminated if cutting oils are used Project SAMMI (Period: from 1st September 199 8 to 31st May 2001) [14.1 49] The objective of the project was to introduce safe and highly efficient processing of magnesium castings, using an adapted machining process with adapted tools, cooling lubricants, and a high-speed cutting... uncoated and diamond-coated inserts for milling tools, drills, and reamers have therefore been developed Coating conditions, especially, and also pretreatment of the substrates and geometry have been varied The tools have been evaluated in laboratory tests in which mainly machining forces, workpiece quality, and tool wear have been analyzed The tests have been performed both dry and with cooling lubricants. .. has an external cutting fluid supply and an internal chip flow The fluid is pumped between the drill tube and inner tube to the drill head Most of the fluid is forced through holes in the drill head and cools and lubricates the support pads and cutting tips The remainder is forced through the nozzle in the inner tube and diverted back to the outlet This creates a partial vacuum in the inner tube so... of particular significance to humans because particles smaller than 5 lm can enter the lungs Cobalt measurements on people have shown that 92 % of all measurements are below the TRK figure Cobalt concentration values of 0.005 and 14.7.4.1 4 69 470 14 Metalworking Fluids 0.77 mg Co m–3 were recorded No significant differences were recorded between dry and wet machining operations Another study [14 .93 ]... pressures and flow rates [14.75] External cylindrical grinding is used with symmetrical rotating workpiece contours We differentiate between centerless grinding and grinding between centers, depending on how the workpiece is mounted Industrial applications are, for examLubricants and Lubrication 2nd Ed Edited by Th Mang and W Dresel Copyright 2007 WILEY-VCH Verlag GmbH & Co KGaA, Weinheim ISBN: 97 8-3-527-31 497 -3... tool axis and the workpiece surface are vertical to each other A distinction can also be drawn between broad and fine lapping, depending on the fineness of the surface finish 14.6.1.8 Lapping Powder and Carrier Media Mainly silicon carbide (SiC), corundum (Al2O3), boron carbide (B4C) and diamond are used as abrasive grain Preference is given to corundum for soft steels, brass and bronze and castings,... cutting fluids [14 .94 , 14 .95 ] It is therefore absolutely necessary to use special water-miscible cutting fluids which prevents cobalt leaching when grinding carbides The visual signal for dissolved cobalt is when the cutting fluid turns reddish-pink Carbide-compatible cutting fluids have a pH between 8 and 9. 0 and contain inhibitors which limit the formation of cobalt complex compounds Apart from using . 0.3 0 .95 0 .9 to 0.2 0.31 Hobbing; head-hight, < 1.5 m from the machinig point 40 to 3 18.1 21 to 0.2 7 .9 Grinding; head-hight, < 1.5 m from the grinding point 99 to 2 19. 4 21 to 0.2 6 .9 Automatic. simi- lar to that of a standard cutting fluid at a given viscosity, an Oil Mist Index as in Fig. 14. 19 results. Figure 14. 19 shows values for standard and low-misting oils and the viscosity of the. applications are, for exam- Lubricants and Lubrication. 2nd Ed. Edited by Th. Mang and W. Dresel Copyright  2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN: 97 8-3-527-31 497 -3 45514.6 Machining

Định dạng
Số trang	60
Dung lượng	626,93 KB