TUV-95 Oil-Containing Water-Miscible Metalworking Fluid

What Is TUV-95

TUV-95 belongs to the traditional class of oil-containing emulsifiable metalworking fluids. The concentrate is mixed with water to prepare an emulsion at the required working concentration.
One of the main reasons TUV-95 remains relevant is its combination of high lubricating performance and low working-emulsion cost.
This means the product is not limited to light-duty machining. With the correct concentration, TUV-95 can also be used under higher loads, at high machining speeds and with intensive coolant delivery.
Water quality is a key consideration when using TUV-95. If the actual process water is suitable for the product, or its hardness is properly corrected, TUV-95 can effectively perform the functions of an oil-containing water-miscible MWF without switching to a more expensive product simply because it belongs to a newer generation.

Main Characteristics

Machining Operations

TUV-95 can be used for:

• turning;
• milling;
• drilling;
• deep-hole drilling;
• boring;
• honing;
• broaching;
• gear cutting;
• thread rolling and thread cutting;
• other machining operations.

TUV-95 should not be limited to low- and medium-speed machining. As machining speed and load increase, the working concentration should be adjusted to suit the specific operation.
For heavy-duty applications, TUV-95 concentration can be increased up to 10–15%, depending on the operation and operating conditions.

High-Pressure Coolant Delivery

TUV-95 can be used in systems where the working emulsion is delivered to the cutting zone under high pressure.
At higher concentrations, with intensive circulation or high-pressure delivery, foaming should be monitored.
If excessive foam develops, first check:

• actual working concentration;
• process water;
• correct emulsion preparation;
• circulation conditions;
• air entrainment;
• coolant delivery conditions and intensity.

If excessive foaming cannot be eliminated by correcting the operating conditions of the system, a defoamer for water-miscible MWFs can be used.
The defoamer can be added directly to the TUV-95 working emulsion at 0.1–0.5%. Before addition, it can be pre-diluted with water at a ratio between 1:1 and 1:10 to facilitate more uniform distribution throughout the system.
A defoamer should not be used as a substitute for correcting an obvious cause of excessive foaming when that cause can be eliminated by adjusting the system.

Typical Working Concentrations

For heavier-duty and higher-speed machining, concentration should be selected according to the actual machining load and performance. Where required, TUV-95 can be used at concentrations up to 10–15%.
Increasing concentration does not compensate for unsuitable water. Working concentration and water quality are separate factors and should be controlled independently.

Suitable Metals

The main applications include:
• carbon and structural steels;
• alloy steels;
• stainless steels;
• cast iron.

For aluminium alloys and non-ferrous metals, check performance on the specific material and machining operation before introducing the product for continuous use.

When TUV-95 Is a Good Choice

TUV-95 is worth considering when the application requires:

• high lubricating performance;
• low cost of the prepared working emulsion;
• adjustable concentration according to machining load;
• operation across different machining speeds;
• high-pressure coolant delivery;
• economical operation where large volumes of working emulsion are consumed.

Correct emulsion preparation and control of the actual process water remain important operating requirements.

TUV-95 vs. Modern Water-Miscible MWFs

The age of the formulation alone is not a reason to reject TUV-95.
With suitable water and the correct working concentration, TUV-95 can be effectively used in modern production, including high-speed machining, higher-load operations and systems with high-pressure coolant delivery.
Modern products such as Defender Pro should be considered as alternatives based on the overall requirements of the particular machine, system and operating conditions—not as an automatic replacement for TUV-95 simply because machining speed increases.

Cost Advantage of TUV-95

One of the main advantages of TUV-95 is the low cost of the prepared working emulsion combined with high lubricating performance.
For a meaningful cost comparison, do not compare only the price per kilogram of concentrate. Compare the cost of the actual prepared working fluid at the concentration required for the machining operation.
If water hardness correction is required, include the cost of soda ash. If foaming occurs at high concentration or with intensive coolant delivery, include the defoamer where required.
Even when water treatment and foam control are required, TUV-95 can remain more economical than modern oil-containing water-miscible MWFs.
Because concentrate and auxiliary-product prices change, the actual cost difference should be calculated using current prices at the time of purchase.
For a practical comparison, calculate the amount of concentrate required to prepare the same quantity of working emulsion and, where applicable, add the cost of soda ash and defoamer.

Water Quality Is a Key Factor for TUV-95 Stability

TUV-95 is sensitive to water hardness and composition.
At an industrial site, process-water characteristics may change because of:

• seasonal variations;
• significant rainfall;
• changes in the water source;
• switching within the water supply network;
• changes within the plant’s internal water distribution system.

For this reason, a practical TUV-95 compatibility test should be performed not only before initial use but regularly during operation.
Repeat the test particularly when the water source or supply conditions change, or when an emulsion that was previously stable begins to behave differently.

How to Test TUV-95 with Your Process Water

1. Take water directly from the source currently used to prepare the MWF.
2. Use a clean, transparent container.
3. Thoroughly mix the TUV-95 concentrate.
4. Prepare a small sample at the concentration you intend to use.
5. Add TUV-95 concentrate to the water while mixing. Do not add water to the concentrate.
6. Mix the prepared emulsion thoroughly.
7. Leave the sample until the next day.
8. The next day, visually inspect the emulsion through the transparent walls of the container.

If the emulsion remains homogeneous without visible separation, the water can be used to prepare the working volume based on this practical compatibility test.
If the sample separates, do not prepare a full machine tank with that water. Address the water-quality issue first and then prepare a new test sample.

What to Do with Hard Water

If TUV-95 loses stability because of the hardness of the actual process water, preliminary hardness correction may be required.
For this purpose, soda ash — sodium carbonate (Na₂CO₃) can be used.
Do Not Confuse Soda Ash with Baking Soda
For the water-hardness correction procedure described here, use:
Soda ash — sodium carbonate (Na₂CO₃).
Baking soda — sodium bicarbonate (NaHCO₃) — is a different substance.
Do not substitute baking soda for soda ash in this procedure.
Practical guidance on soda-ash quantities and water-treatment methods is provided in the separate article “Water Preparation for Metalworking Fluids.”

How to Prepare Water with Soda Ash

Soda ash is added to the water before preparing the TUV-95 emulsion.
After addition, the water must be mixed thoroughly.
Soda ash does not dissolve instantly. Simply adding it to the water and immediately starting to add TUV-95 is not sufficient. Allow adequate mixing of the treated water.
After water treatment, do not immediately prepare the full machine-tank volume.

First:

1. take the treated water;
2. prepare a new TUV-95 sample in a clean, transparent container;
3. leave it until the next day;
4. check that it remains homogeneous without separation;
5. only after a successful test should the required working volume be prepared.

The practical acceptance criterion is therefore a stable new TUV-95 test emulsion prepared with the treated water.
Important: Do Not Try to Restore a Separated TUV-95 Emulsion with Soda Ash
If a prepared TUV-95 working emulsion has already lost stability and separated because of unsuitable hard water, do not add soda ash to the working emulsion in an attempt to restore it.
Soda ash is used for pre-treatment of the water, not for restoring a TUV-95 emulsion that has already separated.

If TUV-95 has separated because of unsuitable hard water:

1. drain the unstable emulsion;
2. prepare or correct the water;
3. make a new TUV-95 test sample in a transparent container;
4. leave it until the next day;
5. confirm that the new sample remains stable;
6. then prepare a fresh working emulsion.

Mix the Concentrate Before Dilution

Before dispensing and dilution, thoroughly mix the TUV-95 concentrate until homogeneous.
For large containers, simply rolling a drum may not provide sufficient mixing. The drum may rotate while its contents move relatively little.
For a 200 kg drum, the concentrate can be mixed through the opening using a clean metal tube or another suitable clean tool. Make several circular movements in one direction and then in the opposite direction.
The purpose is to obtain homogeneous concentrate before dosing.

How to Prepare TUV-95 Working Emulsion

1. Make sure the tank and circulation system do not contain significant quantities of old sludge, chips or other contamination.
2. Thoroughly mix the TUV-95 concentrate.
3. Use water that has passed the practical TUV-95 compatibility test and, where necessary, has been pre-treated.
4. Determine the required working concentration.
5. While mixing, gradually add TUV-95 concentrate to the water.
6. Do not add water to the concentrate.
7. Ensure uniform mixing of the prepared emulsion.
8. Check the concentration after preparation.

Working concentration should also be monitored during operation. A refractometer for MWFs can be used, taking into account the product-specific data required for concentration measurement.

Operation and Maintenance

For stable TUV-95 operation, monitor:

• working concentration;
• actual process water;
• emulsion homogeneity;
• tank and system cleanliness;
• chip and sludge accumulation;
• circulation and filtration;
• foaming;
• appearance and odour of the working emulsion;
• MWF condition after extended shutdowns.

If an emulsion that was previously stable begins to behave differently, do not simply add more concentrate. Check the concentration, process water, system condition and circulation conditions first.

Limitations

1. Do not prepare a large volume of TUV-95 with untested water.
2. Do not attempt to compensate for unsuitable water simply by increasing the working concentration.
3. Do not use baking soda instead of soda ash for the water-hardness correction procedure described above.
4. Do not add soda ash to an already separated working emulsion in an attempt to restore it.
5. Do not use defoamer instead of correcting an obvious cause of excessive foaming when the system itself can be adjusted.
6. For aluminium alloys and non-ferrous metals, verify product performance in the specific machining operation before continuous use.

Storage and Safety

Store the concentrate in tightly closed containers according to the specified storage requirements for the product.
Prevent contamination of the concentrate with foreign substances.
When preparing and maintaining the working emulsion, use appropriate personal protective equipment and follow the site’s procedures for handling process fluids.

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FAQ

What is the main advantage of TUV-95?
Its key advantage is the combination of high lubricating performance and a low cost of the prepared working emulsion.
Can TUV-95 be used for high-speed machining?
Yes. TUV-95 should not be limited to low- and medium-speed machining. As speed and machining load increase, the working concentration should be selected for the specific operation. For heavy-duty applications, it can be increased up to 10–15%.
Can TUV-95 be delivered under high pressure?
Yes. TUV-95 can be used in systems with high-pressure coolant delivery. Foaming should be monitored under these operating conditions.
What should I do if TUV-95 foams?
First check concentration, process water, circulation, air entrainment and coolant-delivery conditions. If excessive foaming cannot be eliminated through system adjustments, a suitable defoamer can be added directly to the working emulsion.
How much defoamer should be added?
For the Novohim defoamer, the working guideline is 0.1–0.5%. Before addition, it can be diluted with water from 1:1 to 1:10 to facilitate more uniform distribution.
What is the typical TUV-95 concentration?
For many standard machining operations, 5% is a practical starting point. Higher concentrations are used for more demanding operations and can reach 10–15% depending on the application.
Why is water quality important for TUV-95?
TUV-95 is sensitive to water hardness and composition. Unsuitable water can cause loss of emulsion stability and separation.
How should process water be tested?
Prepare a small TUV-95 sample at the intended concentration using the actual process water in a clean, transparent container. Leave it until the next day and check for homogeneity and separation.
Is one water test enough?
No. Process-water characteristics can change because of season, rainfall, water-source changes or network switching. Repeat the test regularly and whenever a change in water quality is suspected.
Which type of soda should be used?
Use soda ash — sodium carbonate (Na₂CO₃). Do not confuse it with baking soda — sodium bicarbonate (NaHCO₃).
Does soda ash need thorough mixing?
Yes. Soda ash does not dissolve instantly. After adding it, thoroughly mix the water. Then prepare a new TUV-95 test sample and leave it until the next day before preparing the full working volume.
Can soda ash restore TUV-95 after the emulsion has separated?
No. Soda ash is used for water pre-treatment. If the emulsion has already separated because of unsuitable hard water, drain it and prepare a new emulsion using suitable or properly treated water.
How should TUV-95 be mixed with water?
First thoroughly mix the concentrate itself. Then add TUV-95 concentrate to water while mixing. Do not add water to the concentrate.

Ordering TUV-95

TUV-95 is worth considering when an oil-containing water-miscible MWF with high lubricating performance and a low working-emulsion cost is required.
The product can be adapted to different machining conditions by selecting the appropriate working concentration and can be used for high-speed machining and high-pressure coolant delivery. For stable operation, particular attention should be paid to the actual process water and correct emulsion preparation.