Thus, the ‘ideal’ cutting fluid would not cause the typical problems of: foaming in soft waters; or forming insoluble soaps in hard waters, • Freedom from tacky, or gummy deposits – as
Trang 1may have a susceptibility to staining, so here, it is
prudent to discuss the problem with the cutting
fluid manufacturer,
•
Water-supply compatibility – a water-soluble cut-ting fluid should ‘ideally’ be capable of being diluted
with any water supply. Geographical locations can
create variations in water supply and its condition,
this latter factor is especially true for water hardness
(i.e see Fig. 199b), where its hardness can vary quite
considerably. Thus, the ‘ideal’ cutting fluid would
not cause the typical problems of: foaming in soft
waters; or forming insoluble soaps in hard waters,
• Freedom from tacky, or gummy deposits – as water
soluble fluids dry out on a machine, or component’s
surface, the water content evaporates to leave a resi-due which is basically the product concentrate. This
residue should ideally be light and wet, allowing
it to be easily wiped-off. However, any gummy, or
tacky deposits collect swarf and debris, necessitat-ing increased machine and component cleaning,
• ‘Tramp oil’ tolerance – is a lubricating, or hydraulic
oil which leaks from the machine tool and contam-inates the cutting fluid. Most modern machines are
equipped with ‘total-loss’
slideway lubricating sys-tems which can contaminate the cutting fluid with
up to a litre of oil per day – on a large machine tool.
The ‘ideal’ cutting fluid would be capable of toler-ating this contamination without any detrimental
effects on its operating performance. Some cutting
fluids are formulated to emulsify the ‘tramp-oil’ ,
while other fluid formulations reject it, allowing
‘Total-loss’ fluid systems, are as their name implies in that they
purposely leak oil to the machine’s bearing surface, requiring
periodic tank replenishment. When this oil leaks-out of the
machine tool it is termed: ‘tramp-oil’ , therefore the oil will
eventually end up in the machine tool’s coolant tank, where it
is either tolerated by the coolant product, or is separated-out,
requiring periodic ‘tramp-oil skimming’.
NB ‘Tramp-oil’ losses are invariably not accounted for in
many production shops, which invariably means their
‘eco-nomic model’ for such losses are habitually not considered,
or not even thought about by the company. It has been
re-
ported that on a quite ‘large-sized’ horizontal machining cen-tre, it can lose up to 365 litres of ‘tramp-oil’ per annum, which
is an on-going cost that needs to be addressed. Multiply this
individual machine tool loss by the number of machines in
the manufacturing facility and this will represent considerable
unaccounted for expenditure!
the residual ‘tramp-oil’ to float to the surface for re-moval by physical ‘skimming’ ,
• Cost-effectiveness – but what does this term mean?
There was a time when the cost-effectiveness was simply judged in terms of the price per litre of the product concentrate. Fortunately, there are only few engineering companies who still take this view, with most recognising that there are many inter-related factors that contribute to cost-efficiency. Some of these factors might be the: dilution ratio; sump-life; material versatility; tool life; machined component quality; health and safety aspects; plus many others.
Having identified the ‘ideal’ cutting fluid features, one
must unfortunately face reality, as there is no such product that encompasses all of these desirable charac-teristics – at the optimum level in just one cutting fluid product. However, all cutting fluids are not equal and
even apparently similar products may well perform in quite different ways! Therefore, it is for the machine-shop supervisors/managers – in conjunction with other interested parties: purchasing; health and safety; unions; etc., to select a reputable supplier who is pre- pared to undertake the necessary survey and ‘trouble-shooting’ exercise to recommend the best fluid(s) for a particular manufacturing environment.
Today, there are many different types of cutting fluids available they can be classified according to widely varying criteria, although some unified system
of terminology exists in various countries guidelines and Standards. This commonality of ‘language’ reflects both the chemical and technical requirements of the users. On the basis of the various countries publicised cutting fluid literature, the following classification
is perhaps the most useful – from the user’s point of view. Broadly speaking, it was previously shown in Fig.
197, that cutting fluid groups are of two main types,
either ‘oil-’ , or ‘aqueous-based’. The ‘aqueous’ cutting fluids can be divided into ‘emulsifiable’ and ‘water-sol-uble’ types. As has already been mentioned, the former
‘oil-based’ cutting fluids are supplied as ready-for-use products, while ‘aqueous’ types are normally found in the form of a concentrate, which must be mixed with
water, prior to use. Once mixed with water, the ‘emulsi-fiable’ cutting fluids form an emulsion, conversely, the
‘soluble’ variety forms a solution. In both of these cases, the resultant cutting fluid product is termed: ‘water-mixed’. In the following section, the various types of
cutting fluids currently available will be briefly men-tioned
Trang 28.4.1 Mineral Oil, Synthetic,
or Semi-Synthetic Lubricant?
Mineral Oil
In order to manufacture cutting fluids the raw materi-als are naturally occurring oils, such as: mineral oils;
animal and vegetable oils; or fats. Of these oils, the for-mer mineral oils are probably most commonly utilised
by the manufacturing industry. These mineral oils, in
a similar fashion to naturally occurring oils, tend to
be complex mixtures of widely varying compounds.
Such compounds consist of carbon and hydrogen and as
such, are usually referred to a ‘hydrocarbons’. In addi-tion, they will contain: sulphur; nitrogen; plus various
trace elements.
So that the mineral oil can be separated out to form
a ‘stock oil’
– with natural lubricating properties, ther-mal processes are employed by the fluid manufacturer.
These partly-refined ‘stock-oils’ are still chemically
complex mixtures of hydrocarbons, with widely vary-ing characteristics. By way of an example of the
di-verse nature of ‘crude oil’ , it is a mixture of more than
one thousand hydrocarbons, with different chemical
structures. Such widely varying characteristics make
it impossible to supply mineral oil to closely defined
specifications, which limits its uses and performance
as a cutting fluid. The complex structure of a cutting
fluid made up entirely from naturally occurring oils, is
schematically illustrated in Fig. 198a.
Synthetic Lubricants
The use of Synthetic lubricants cannot be compared
with those lubricants that are extracted from
natu-rally occurring oils, since the properties of the latter
are always an aggregate of the properties of their many
different components, as such, cannot be exactly pre-dicted. While the former synthetic lubricants are made
from two types of raw material:
1 Mineral oil – normally from: polyalpha olefin and
alkali aromatics,
2 Polybutenes.
At present (i.e. from around the late 1980’s, until
now), synthetic hydrocarbons predominate, as they
are not derived from mineral oils, they have become
of increased importance. In particular, they include
derivatives from ‘fractioning’ of plant oils. The most significant classes of compounds are the esters and polyglycols. These synthetic lubricants being a solution
of chemicals, which usually contain: corrosion inhibi- tors; biocides; dyes; in water. Moreover, they may con-tain such additions as synthetic lubricity additives and
wetting agents. Synthetic lubricants form transparent solutions and as a result, provide good visibility of the
cutting operation.
In use, synthetic fluids require special attention in their application, because they contain no mineral oil, they tend not to leave a corrosion-protective oily film
on machine surfaces. As a result, it is essential to lubri- cate exposed machine tool surfaces carefully. In addi-tion to this lack of protection, there may be some effect
on certain paint finishes and even degradation of the machine’s seals, as a result of this synthetic fluid enter-ing the machine tool’s lubrication system. Normally, these problems of practical usage, limit these synthetic lubricants in the main, to grinding operations
Semi-Synthetic Lubricants
Today, the use of Semi-synthetic lubricants, or ‘Micro-emulsions’ – as they are sometimes known, has become
much more widespread, because of certain advantages they have over mineral-soluble oils
By increasing the ratio of: emulsifier-to-oil in the formulation, either by reducing the oil content, or
by increasing the level of emulsifiers, the product takes on different characteristics from those of min-eral-soluble oils. Due to this increased ‘ratio’ , the oil particles formed, are significantly smaller than those found with the mineral-soluble oil types (i.e. see Fig.
201a). Hence, these ‘micro-emulsions’ , visually appear
to be translucent, or even transparent, owing to the fact that the oil particles are smaller than the wavelength of light
(i.e. <0.5 µm). This translucency is an obvious ad-vantage where workpiece visibility is important to the machine setter/operator. In addition, the high level of emulsifiers in the product leaves some ‘spare capacity’ , which enables the ‘micro-emulsion’ to emulsify any oil-leakage from the machine. This emulsification of
‘Fractionation’ , is the breakdown of crude oil into its constit-uents (i.e. fractions), by distillation.
Trang 3Figure 198 The basic structure of an oil-based cutting fluid and an ‘oil-in-water’ emulsifying molecule [Courtesy of
Cimcool]
.
Trang 4Figure 199 The principle of polar and passivating corrosion protection and the minimum requirements for water
quality [Courtesy of Cimcool]
.
Trang 5the formation of a layer of ‘tramp-oil’ on the surface –
which might otherwise encourage unwanted bacterial
growth. The definition of Semi-synthetic cutting fluids
can cause some difficulty, but generally the oil content
is much lower than with the mineral-soluble oils, rang-ing from approximately 10 to 40%.
Additives for: corrosion inhibition; bacterial
con-trol; lubricity0; EP; are employed in the same manner
as for mineral-soluble oils, also, there is often an addi-
tion of a blue, or pink dye, as these translucent micro-
emulsions can appear to look somewhat ‘watery’ oth-erwise. Although translucent micro-emulsions are
initially formed, Semi-synthetics do not go cloudy in
use. They contain excess emulsifiers to ensure that fine
micro-emulsion of oil particles are formed in water. As
previously mentioned, these ‘spare’ emulsifiers enable
the micro-emulsion to absorb tramp oil. Hence, as
these ‘spare’ emulsifiers are consumed by suspending
the ‘tramp-oil’ , both the amount of oil in the emulsion
and the oil particle size increases. This increase in oil
particle size causes more incident light to be reflected
and results in the visual ‘clouding effect’
within the lu-bricant. In particular, this ‘cloudiness’ of the lubricant
is not necessarily an indication that there is anything
wrong with the fluid, it is merely an suggestion of the
oil absorbed by the cutting fluid.
All cutting fluids, whether ‘aqueous-’ , or ‘oil-based’ ,
may contain some: mineral oils; synthetic products; or
a combination of both. The choice of raw material and
composition depends on certain parameters and their
actual composition (i.e its formulation) will depend
‘Emulsification of tramp-oil’ when using Semi-synthetic oils,
will only occur, until all of the ‘spare’ emulsifiers are used up!
Therefore, after this time, the excess ‘tramp-oil’ will float on
the cutting fluid’s surface.
NB Some Semi-synthetic formulations will emulsify only
small quantities of ‘tramp-oil’ , while others can emulsify
much larger concentrations.
Perhaps the easiest and best fluid definition is this: ‘A
semi-synthetic cutting fluid forms a translucent emulsion and
con-tains mineral oil’
0 ‘Lubricity’ , or ‘Oiliness’
as it is often known, is difficult to de-
fine with any precision. One reasonable definition is that Lu-bricity is: ‘[The significant] differences in friction greater than
can be accounted for on the basis of viscosity, when comparing
different lubricants under identical test conditions.’ [Source:
American Society of Automotive Engineers]
upon many factors, which is closely-guarded secret by any lubricant manufacturer.
8.4.2 Aqueous-Based Cutting Fluids
A large proportion of cutting fluids used for machin-ing operations are still of the aqueous-based types (Fig. 197), as they combine the excellent heat-absorbing ca-pacity of water, with the lubricating power of chemical substances. Such cutting fluids offer excellent cooling, lubricating and wetting properties. Machine tools re-quire protection from the lubricant ingress and should
be compatible with lubricating and hydraulic systems
on the machine, making it possible to apply water-mixed cutting fluids to the manufacturing environ-ment. The aqueous-based lubricants can be utilised across quite a diverse range of workpiece materials, ranging from steels, to non-ferrous metals.
An aqueous cutting fluid can consist of naturally occurring oils such as: mineral oil; synthetic mater-ial; or a combination of both, but generally they are present in the form of an emulsion, or solution – as previously discussed. Other forms of cutting fluids, such as: suspensions; gels; pastes; are rarely used in the production process. Hence, the commonest form
in which aqueous cutting fluids are used is as an emul-sion. Much of this cutting fluid terminology has al-ready been discussed, but is worth restating, to ensure that its significance is sufficiently comprehended. An emulsion is a disperse system formed by mixing two fluids which are not soluble in each other. In the emul-sion, one of the fluids forms the internal phase, which
is dispersed in the form of droplets suspended in the external phase, or ‘medium’ – as its is often known. Such corresponding cutting fluids are of two types:
‘emulsive’ , or ‘emulsifiable’ – of which the former type
is normally the most commonly used. The ‘emulsive’ cutting fluid consists of an oil-in-water emulsion, in which the oil forms the internal phase. While its coun-terpart, the ‘emulsive’ type is the ‘emulsifiable’ solu-tion, consisting of a water-in-oil emulsion, but here, the water is the internal phase – lately this cutting fluid has become less important
An aqueous ‘emulsive’ cutting fluid always contains
a stock oil, usually having a: mineral oil; synthetic hydrocarbon; synthetic ester; or fatty oil, etc.; together with certain additives to the formulation. The most important additives tend to be: ‘emulsifiers’; corro-sion inhibitors; stabilisers and solubilisers; anti-foam
Trang 6see Fig. 197). Consideration will now be given to each
of these ‘additives’ in turn:
‘Emulsifiers’
The ‘emulsifiers’ are necessary to help form a stable
emulsion and as such, are very important for the tech-nical characteristics of the cutting fluid. ‘Emulsifiers’
make it possible for the oil droplets to form and re-
main suspended in water, preventing them from merg-ing and floating upwards to form a surface layer in the
fluid’s tank. ‘Emulsifiers’ reduce the surface tension and
form a lubricating film at the boundary surface. These
‘emulsifier’ molecules are bipolar in characteristic and
as a result ‘line-up’ like the bristles on a brush, with
one end toward the oil and the other end facing the
water, as shown in Fig. 198b. In this way, the ‘emulsi-fier’ forms a film which is one molecule thick at the
boundary surface
Corrosion Inhibitors
The main task of a corrosion inhibitor in any aqueous
cutting fluid is to prevent the water in the fluid from
corroding the exposed portions of the machine tool,
such as its: slideways; spindle nose; ballscrews; etc. The
mechanism by which different corrosion inhibitors
operate, will vary widely and one commonly used ver-sion of ‘inhibitor’ , consists of an additive which forms
a protective film on the exposed metal’s surface.
‘Galvanic corrosion’ , for two metals in contact
in the ‘electro-chemical series’ the further apart they are in this ‘series’ , the
greater their electro-potential and the faster the rate of
corro-sion. For example, in this ‘series’ gold (i.e. being a ‘noble metal’)
is at one extreme, thus having a potential difference of +1.70
v – being cathodic, while at the other end of the galvanic table,
calcium (i.e. being a ‘base metal’) has a potential difference
of –2.87 v – being anodic. Hence, the anodic metal will cor-rode, while the cathode remains unchanged, hence in gold’s
case, the term ‘noble’ metal is used.Thus, water-miscible flu-ids can penetrate between bolt threads, setscrews and fixtures
and as water is an electrolyte – a liquid that can conduct an
electrical current, the presence of water produces a galvanic
electrical current flow between these mating parts. So, say on
a lightweight workpiece fixture – perhaps made from alumin-ium (–1.67 v) with this being located onto a machine tool’s
table – normally produced from cast iron (–0.44 v). Thus, the
potential difference here being 1.23 v, which is not too acute,
as both these metals are in fact, relatively close-together in the
‘electro-chemical series’.
These corrosion inhibitors consist of long, narrow molecules which are negatively-charged and as such, are attached to the metal in contact (Fig. 199a – top
schematic diagram, shows: rust protection by polari-sation, whereas the lower schematic diagram depicts; rust protection by a passifying film). These ‘films’ that
are subsequently formed, are no thicker than just a few molecules and as such, are invisible. Nevertheless, such ‘films’ can effectively prevent the electro-chemi-cal process of corrosion, such as passivation by means
of nitride, but the latter type is now being effectively phased-out.
Stabilisers and Solubilisers
Stabilisers considerably extend the life of the concen- trate, while solubilisers act to increase the oil’s solubil-
ity. Various alcohols and glycols can be used as stabi-lisers, or solubilisers
Anti-Foaming Agents
Anti-foaming agents are often known by the alter-native names of: ‘anti-froth-’; or ‘defrothing-agents’; being utilised to prevent the formation of foam. Sili-cones, while being subject to certain restrictions have proved in the past to be very popular anti-foaming agents. A typical restriction to that of using silicones additives in machining operations, might be because afterward it may prove difficult to either: paint; coat;
or adhesively-bond to the machined parts. In the past when both the coolant pressures and flow rates were low, foaming did not present too great a prob-lem, but nowadays, the pressures and flow rates are much greater and severe coolant agigtation can re-sult, creating potential foaming conditions. Foaming
is at its most prevalent when a newly-charged clean and fresh cutting fluid is employed and as this coolant
is contaminated with: ‘tramp-oil’; metal fines; abra-sive grains; from the subsequent machining process, these contaminants will tend to suppress foaming tendencies.
NB Galvanic corrosion occurs between contact of dissimilar
metals – in the presence of an electrolyte. This electrolytic con- tact might at the least cause either: surface staining; mild corro-sion; or pitting, with its severity depending upon how long the two metallic surfaces are in contact in the presence of water.
Trang 7Today, anti-foaming agents tend to be
‘branch-chained’ higher alcohols – being insoluble in
wa-ter, or as mentioned above, silicones. Both alcohols
and silicones evidently disrupt the foam-producing
surface film with that of an alternative
gas-perme-able surface film, causing the surface-active liquid
surrounding each bubble to drain away, causing the
foam layer to collapse. If severe foaming occurs, anti-foaming agents are not the answer, as eventually these
‘anti-foams’ get carried away, or filtered-out of the
coolant on the resultant machined: chips and swarf;
workpieces; or on coolant filters. The problem to
foaming may not be due to the lack of ‘anti-foams’ ,
but may be the result of air leaks that are sucking air
into the coolant stream. These air leaks often arise
around the pipe unions, or at pipe-connectors to
either the valves and pumps in the coolant delivery
system
Microbiocides
Microbiocides are often added to the aqueous-based
cutting fluid as they help prevent the dramatic and un-
controlled growth of microbes in the coolant. Micro-
biocides uses are normally limited, owing to the po-tential skin-care consideration – more will be said
concerning this very important topic later in the chap-ter, when ‘health-issues’ will be discussed.
8.4.3 Water Quality
The main constituent of any aqueous-based cutting
fluid is obviously water and by nature, it is impure. The
impurity depends on the source: rain-; river-; spring-;
ground-water; etc. The water may also contain: dust
particles; oxygen; nitrogen; calcium and magnesium
salts; often with smaller quantities of: ammonia;
bo-ron; flourine; ibo-ron; nitrate; strontium; aluminium;
arsenic; barium; phosphate; copper and zinc.
Addi-tionally, the water has in its presence
micro-organ-isms, such as: algae; bacteria; fungi and viruses (i.e.
see Fig. 203); although in different orders of
magni-tude. So, depending on its composition, water can
affect the aqueous-based cutting fluid in many ways
and since the composition varies throughout the
year, these seasonal variations will have an effect on
its use. By far the greatest effect on the properties of
the cutting fluid is caused by the hardness of the water.
Water’s hardness depends on the concentration of ele-ments such as: calcium, magnesium and other heavy metals like iron and manganese. Hard water may cause
a soapy deposit, which will eventually block filters, or destabilise the emulsion and may have a detrimental effect on the fluid’s corrosion protection. Equally, soft water can be a problem, but for a different reason, in this case it can promote foaming under ‘abusive’ ma-chining conditions.
The degree of alkalinity of the water can be
ex-pressed as a pH-value (i.e. see the pH-scale shown in
Fig. 202b) and this is an important measurement, as
it affects its usage and can react to human skin caus-ing ‘serious complaints’ – more will be said concerning these health issues later in the chapter. Alkalinity in the main, affects the growth of microbes (i.e. see Fig. 203b) and the degree of corrosion protection afforded
‘Water hardness levels’ , are calculated based upon the quantity
of ‘grains’ of hardness minerals the water contains. By way
of example, one grain of calcium carbonate, constitutes 17.1 parts million– (ppm) per 3.785 litres (i.e. equivalent to a U.S.
gallon). ‘Salts’ such as sodium chloride and sodium sulphate are found in hard water, where they contribute to corrosion, or rust – if not ‘inhibited’. Moreover, the greater the cutting fluid’s solution salt content, the more coolant concentrate is required
to prevent subsequent corrosion. Further, coolant degradation occurs with time and usage. For example, a new charge of relatively soft water admixed with coolant concentrate, will initially have say, a 3-grain hardness, but after one month’s use its hardness will have increased to between 12–14 grains and, after two months this hardness will have increased still further,
to between 24–27 grains. This problem is exacerbated if the water content evaporates, needing periodic cutting fluid analy-sis to maintain optimum coolant performance.One method of significantly reducing water of its hardness minerals, is to run
it through a water softener, which removes the calcium and magnesium ions, replacing them with sodium ions, although residue build-up will be significantly reduced, corrosion may now be a problem, so for this reason softened water is not recommended when using water-miscible coolants. Other- wise, boil the water – ensuring that no softener, or anti-cor-rosion agents were present prior to using the condensed water product (i.e from the boiling process). Deionized water is the best source of pure water, as a deionizer removes all dissolved minerals, creating distilled water.
‘Human skin’ , varies from one body-region to another, but
generally, it has a pH-level slightly biased toward the acidic
region of the scale, at approximately 6.8 pH (e.g. a value of 7.0
pH is considered as ‘neutral’).
NB Skin also has a protective layer of natural oils, that act
to retard moisture evaporation, acting as a form of ‘defensive shield’ against some forms of biological attack.
Trang 8in improved protection, particularly when machining
ferrous workpieces. In view of the importance of water
composition for the effectiveness of a water-mixed
cutting fluid, it is essential to know the quality of the
water source available and to take account of this fac-
tor when selecting a concentrate. Cutting fluid manu-facturers undertake water analysis, as do local water
companies. In Fig. 199b, the minimum requirements
for water quality for aqueous-based cutting fluids is
shown.
8.5 Cutting Fluid
Classification – According
to Composition
Generally speaking, cutting fluids are purchased under
the following classifications, according to their com-position:
• Synthetic fluids – are those cutting fluids which
contain very little, or no natural oil. The various
components such as the actual cutting fluid are
finely distributed in water, as such, they form a
watery transparent solution – shown in a schematic
representation in Fig. 200a. The applications of
synthetic cutting fluids range from light-to-heavy
cutting, together with usage in grinding
applica-tions. In order to ensure the necessary lubricating
power desirable for heavy cutting operations, some
of these products contain synthetic lubricants (Fig.
200b). The major properties of synthetic cutting
fluids can be summarised as follows:
– A very clean and transparent fluid,
– Excellent corrosion protection,
– A long life cutting fluid,
– Outstanding cooling capabilities,
– Easy to mix,
– Does not burn, or smoke
• Semi-synthetic fluids – can contain up to 41% oil
and when mixed with water they have a translucent
property (Fig. 200c). Extreme pressure (EP) addi-tives and synthetic lubricant can be added, in order
to widen the range of potential workpiece materials
and applications. The properties of semi-synthetic
cutting fluids can be summarised in the following
manner:
– Very clean in appearance, – Excellent corrosion protection, – Long life of cutting fluid, – Outstanding cooling capabilities, – Good wetting properties, – Easy to mix,
– Does not burn, or smoke
• Emulsion fluids – contain a high proportion of oil
and when the concentrate is mixed with water it has a ‘milky appearance’ (Fig. 201a). Cutting fluid products intended for very heavy cutting operations additionally contain EP additives (Fig. 201b). The properties of an emulsion cutting fluid, are sum-marised below:
– Clean, – Offer good corrosion resistance, – Long life of emulsion,
– Outstanding cooling capabilities, – Easy to mix,
– Do not burn, or smoke
Finally, for all of these various cutting fluid types and compositions, the differences in the range of applica- tion of: synthetic; semi-synthetic; emulsion fluids; de-pends upon the respective machining requirements. In
general, the heavier the cutting operation, the higher the cutting forces produced and the greater the oil content required. This observation, means that synthetics are normally used for lighter cutting operations, whereas, emulsions are usually utilised for heavy-cutting appli-cations, while the semi-synthetics tend to be employed
as a general-purpose (i.e. alternative) cutting fluid.
8.6 Computer-Aided
Product Development
The latest cutting fluids are very complex products and
a considerable amount of research and development (R and D) is required to perfect them. The quantity of raw materials that have differing characteristics and the number of interactions between them, means that the possible combinations are potentially enormous. Even when most of the possible combinations are obviously unnecessary and hence could be disregarded, this still leaves the possibility of many thousands of coolant ad-ditive permutations and their respective interactions
to investigate, which would be a ‘Herculean task’ to
Trang 9Figure 200 Schematic representation of synthetic variaties of cutting fluids [Courtesy of Cimcool]
.
Trang 10further, this situation of determining the optimum
combination is analogous to that of: ‘looking for a
needle in a haystack’ , where the conventional empiri-cal methods become no better that in effect, searching
at random! Luckily a solution is at hand, by the evalu-ation using computer technology, when utilised with
specially-developed programs. Computer-aided prod-uct development will as a result, efficiently provide a
solution backed-up by statistical techniques, enabling
many thousands of combinations to be assessed,
re- ducing the final choices to just a few cutting fluid com- binations. In this way it is possible to rapidly and ac-curately optimise the solution, as depicted in Fig. 204, where a Computer-aided Design (CAD) application is used to select – in this case – a corrosion inhibitor for
a potentially-new cutting fluid. Such computer-based techniques have brought about a means of develop-ing cutting fluid products, using the CAD to not only
‘screen-out’ formulations which do not fit the present machining requirements, but can also uncover previ-
ously unsuspected properties – resulting form syner-Figure 201 Schematic representation of emulsion varieties of cutting fluids [Courtesy of Cimcool]
.