Registered trade markStevens Industrial Services (SIS) Ltd

HIGH PERFORMANCE FLUIDS

WATER-SOLUBLEMETALWORKING FLUIDS

general information booklet

Preface

Unfortunately, it is a fact of life that metal working fluids are accorded a position of minor importance.The importance of these fluids only occurs when there are problems: the productionprocess is suffering !Though, problems can be easily prevented if you know what you are doing.

With this booklet we want to give you a little information about what a soluble metal working fluid actually is and how to realise a healthy, clean and trouble free production minimum of waste.

A very important factor for trouble-free working is the correct choice of the fluid.Important parameters for a correct choice concerning fluids are material, product,machine and the nature of the industry.The wide range of chlorine-free THE WORKS

products can help you to make the rightchoice.

Our sales team are ready to give you any assistance you require.

We hope that this booklet will help contribute to the optimisation of cutting fluid usage in your company.

Contents

1. General page 1

2. Main purpose of cutting fluids page 2

3. Structure of cutting fluids page 3

4. Maintanance and control of coolants page 5

1. General

Cutting fluids are preparations/mixtures used in the cutting and forming metalworking industry for cooling, lubrication and swarf transport.

CLASSIFICATION CUTTING FLUIDS:

1. Products, mostly based on vegetable or mineral oil, non-water soluble such as: -- Tapping fluids;- Stamping and deep drawing fluids.

2. Oil in water emulsion.

If a mineral oil is introduced into water it will separate. To get a stableemulsion we have to add an emulsifier, so that water and any other additives do not separate.

Other classifications of emulsion are:

Synthetic emulsion : contains 0% min. oil; Semi synthetic emulsion : contains up to 40% min. oil; Mineral oil based emulsion : more than 40% min. oil.

Production speed and price (£/m³) mostly dictates the choice of the cutting fluid and given a choice of neat or water-soluble the choice will often be water-soluble coolants.

The economics involve not only the purchase of coolant but also the costs of wastefluids and by machine stoppage because of fluid change. Since the costs for waste disposaland machine stoppage become more important every year it is essential to keep thesecosts as low as possible.

Crucial factors to maintain the costs as low as possible are:

Right choice of the coolant, other oils and accessories. Setting up an efficient control and maintenance system.

The right choice of the coolant must be made together with the supplier becauseonly they can judge if their coolant is suitable for your application.

1.NEAT FLUIDS

2.WATER-SOLUBLE

FLUIDS

CUTTING FLUIDS

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2. Main purpose of cutting fluids

During a metal cutting process temperatures of more than 1000°C will occur (seedrawing). This heat transmission is 75% into the swarf, 18% into the tool tip and 7%into the product/component.

It is therefore very important to keep the heat development as low as possiblethrough lubrication and dissipation of the heat through cooling.

Main tasks for cutting fluids are: lubrication and coolinglubrication and cooling..

CoolingCooling: Can be done best by water because water has excellent heatexchange properties. Further, water is a “thin” fluid whichcan remove the swarf easily

LubricationLubrication: Mostly done with a mineral oil containing extreme pressure(EP) properties, to keep friction as low as possible leadingto less tool wear and prevention of swarf build-up and theopportunity for metals welding together.

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A cutting fluid is necessarily very complex to be able to fulfill the many demands, such as:

-Cooling;-Lubrication;-Universal application;-Long li fe;-Noise reduction;-Prevention of metal welding and swarf built up;-Reduction of dimensional instabil i ty;-No foaming;-No st icking;-No dangerous vapours;-Skin fr iendly;-Friendly for machine paint;-Rust protection;-Surface optimisation-etc…-Nowadays, increasingly, a cutting fluid must also be

health and environment friendly.

3. STRUCTURE OF CUTTING FLUIDS

To enable the fluids to meet all these requirements, a large number of differentsubstances are required. An inventory of substances, which may be used in cuttingfluids, showed that there are a total of over 300 different individual substances.

Today, cutting fluids should (must) be free of many of the substances that were used as additives in the past, such as:

1. Chlorine;2. Nitrite;3. Di-ethanolamine;4. Aromatic hydrocarbons;

1. When using chlorine-containing additives, harmful by-products occur atincreased temperatures. These are very poisonous and irritating for the skin.(chlorine-containing vapours can penetrate our body and give severe healthproblems).Further, the disposal of chlorine-containing waste is more expensive than non-chlorine waste. These are excellent reasons to use chlorine-free metalworking fluids. Chlorine-containing fluids were previously used because of there excellent EPproperties in the temperature range of 200 – 500 °C. and because chlorinecontributed to the stability of the coolants.

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2. Nitrites had, in the past, a good record as anti rust inhibitors.

3. Nitrite however, forms nitrosamine, which is proven to cause cancer. The process for forming nitrosamine occurs more rapidly if there are amines inthe fluid, especially di-ethanol amine (= emulsifier and corrosion inhibitor).The use of nitrite-free coolants only is no guarantee that nitrosamine can notbe formed, because nitrite can get into the fluid over a period of time through: - Micro-organisms transforming nitrate in drinking water (used for diluting the

coolant) into nitrite;- Absorption of nitrogen oxide from the air (exhaust gases);- Nitrite containing hardening salt, cleaners and/or corrosion inhibitors.

So, a coolant must not only be free of nitrite, but it also must be free of di-ethanolamine to prevent the forming of nitrosamine, which can cause cancer.One should try to keep the nitrite content in the coolant below 50 ppm( determined by analytical test strips), because amine-containing substancescan always enter the fluid and nitrosamine can still be formed.

4. The use of basic oils with a high percentage of aromatic hydrocarbons (oftencheap) can form, if heated below 1000 °C, polycyclic aromatic hydrocarbons(PAH’s). These polycyclic aromatic hydrocarbons can cause cancer.So it is important to use oils with an extreme low percentage of aromatichydrocarbons. This is possible by using modern, more expensive refinerytechniques.

The Works products are completely chlorine free, nitrite free and di-ethanol aminefree. The mineral oils have an extremely low percentage of aromatic hydrocarbons(<<0.5%) !

Environment- and health friendly metal working fluids are costly and need good

maintenance and 'house-keeping'

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4. MAINTANANCE AND CONTROL OF COOLANTS

Soluble cutting fluids typically consist of 95% water. The remaining 5% has to doalmost all the work. Therefore, you need to control and maintain the fluid.

What you can easily do yourself:

A. CLEANING

Start with a clean machine.If there is any doubt, clean and disinfect thoroughly with a fluid advised bythe supplier of the coolant. Also, use a cleaning- and disinfectant fluid if youchange the coolant for any reason. The function of the cleaning is to softendirt and to kill bacteria in the machine, especially on difficult places such aspipes and pumps. Also it is advised, 8 to 12 hours before cleaning out the machine, to adddisinfectant cleaning fluid to the dirty coolant according the directions for use.

There are two types of water-soluble system cleaners in The WORKSprogram which provide this disinfectant and cleaning process.

CLEANING OUT THE MACHINE WILL GIVE A POSSITIVE INFLUENCE TO THE LONG LIFE AND STABILITY

OF THE NEW COOLANT

B. TO MIX AN EMULSION

An emulsion should always be mixed in such a way that water is poured intothe mixing tank and the coolant concentrate is then stirred into the waterwhilst mixing forcefully. This is the only way to ensure that a perfect oil-in-water emulsion is produced.

MIXING RULE: FIRST WATER - THEN OIL.

Do not use cleaners like detergents, petroleum, degreasers etc….

The residues of these products have andestructive influence on the coolant.

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undesirable effect on new coolants

C. SLIDEWAY OIL

Use a slideway oil which can be combined with the coolant and which has de-mulsifying properties so that the oil can be skimmed off.The Works has first class slideway oils in its program that have excellenttolerance to The Works coolants.

D. REFRACTOMETER

Measure, with a regular frequency, the dilution of the water-soluble cutting fluid witha refractometer. This is because water evaporates and the coolant concentrate staysin the machine, resulting in increasing dilution.

A high concentration gives:- Poor heat dissipation;- Poor swarf removal;- Higher alkaline value, creating an unpleasant fluid for the skin- Higher concentrate consumption.

A low concentration gives:- Poor lubrication, which means extra tool wear and poor product surface;- Corrosion;- No resistance against bacterial growth.

NOTE: Use the right refractometer factor and dilution chart of the coolant.Ask for the correct dilution chart for each of The Work water-soluble coolants.

Refractometer reading x factor = % mixing ratio.

Reading scale

6

8

9

10

11

7, neutral

Up to 14

Skin damage

Alkaline

Corrosion

Acid

65,6 skin

5

4

Steel

Aluminium

E. pH VALUE AND NITRITE MEASUREMENT

Frequently measure the pH value of the coolant with a pH- indicating test strip or witha pH-meter (note that the pH meter has to be calibrated frequently). The pH value of the mixing water should be neutral, in other words around 7. The pHvalue of the mixed emulsion should be between 8,4 and 9,5. If the pH value is too low the corrosion protection will be reduced as well as the longlife stability. If the emulsion is too high, (alkaline) it will tend to degrease the skin and remove thenatural skin protection.

Some materials, like aluminium, are very sensible for strong alkaline coolants

pH value

E. pH VALUE AND NITRITE MEASUREMENT 7

pH measurement with indicating test strips

Frequently measure the nitrite value in the coolant with nitrite indicating test strips.When the nitrite value is more than 50 ppm, you should consider changing the fluidfor health reasons (clean out the machine thoroughly).

Nitrite measurement with indicating test strips

Other measurements like testing the oil- and dirt-content of the fluid can be done bythe supplier of the coolant.

E. WATER HARDNESS

The hardness of the water depends on its content of water-soluble calcium andmagnesium compounds. In very hard water the calcium and magnesium ions reactwith components of the emulsifying oil. This reaction forms compounds which are notsoluble in water and may be precipitated in the circulation system. Since these reactions use up part of the emulsifier, it reduces the stability of theemulsion. This may lead to de-mulsification and oil separation.Soft water will increase the risk of foam.The ideal water hardness is 8 and 15 °DH

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The Works has a control case in its sales program, consisting:hand refractometer, pH-, nitrite-, and waterhardness testing strips and dipslides

for bacterial and fungicide test.

F. MAINTANANCE

Frequently remove tramp oils from the coolant such as: slideway oilshydraulic oils and cutting oils.This can easily be done by:

- Vacuum;- Absorption;- Skimmer (Jokisch® chain-skimmer).

Filter the coolant frequently. An important accessory is a coolant and swarfvacuum cleaner with oil-water separation abilities (see photo below) or aprofessional emulsion cleaning system.

Coolant and swarf vacuum cleaner, with filter and separation abilities

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Emulsion cleaning system for tramp oil removal (ca. 98,5%) andfiltering of particles, capacity 480 ltr./ h (possible also for hire)

The contaminared coolant is Skimmed from the surface

More expensive methods, like separating the tramp oils and particles by centrifuge(see photo above), give an even better coolant cleaning and therefore a longer lifestability.A regular costs calculation is therefore important

It is clear that the long life stability also depends on the product material.E.g. cast iron and cast aluminium cause additional pollution and the coolanttherefore needs extra attention.

To record the measurements taken, it is advised to list in writing, the results in aweekly machine report. The advantage is that the machine operator can takeremedial action in time if something is not ok.

Further:Ask the supplier for the safety data sheet(s) according the directive 91/155/EEC.This safety data sheet mentions all the relevant information about the product, suchas: storage, transport, health and safety regulations, etc..

All metal working fluids are subject to the European chemical waste law. Thisincludes the waste from the so-called biodegradable coolants.

Water soluble coolants need to be checked frequently and the results must

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analysed and corrective measures taken.