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Metal Working Fluids


Concentration and PH
Many problems experienced by companies who use metalworking fluids are caused by the poor control of the metalworking fluid concentration and PH. More than 70% of the times a company experiences problems with metalworking fluids, it is down to this.

It is vitally important that metalworking fluid maintenance is performed regularly and by trained staff . Some MWF suppliers will provide this service in part or in full.

It is important that these responsible people are properly trained to perform concentration and pH testing and adjustment,  but they should not be allowed to add bactericides, emulsifiers or other materials.

Water alone should NEVER be added to a metalworking fluid to adjust concentration. A small quantity of fresh fluid should always be pre-mixed with the water.

Metalworking fluid mixing is best achieved using one of several  automatic mixing systems available which control the concentration, mix more efficiently and help eliminate any errors. It is also more economical with the metalworking fluid and can save up o 10% of the fluid.

Metalworking fluid concentration can be determined by the use of a refractometer.

Metalworking fluid PH can be determined by using PH papers or electronic devices.

The metalworking fluid PH should normally be between 8.5 and 9.8.
Bacteria growth increases when the pH is lower than 8.3 and carbon steel can rust with pH lower than 7.5.  A high pH must be avoided because skin can react to the alkalinity of the MWF.

MWF concentration and pH should be checked daily, or more regularly in very special cases.

Prevent or remove MWF contamination
Bacteria and Funghi  can grow exponentially if the right conditions are present.  Food for this bacteria is available from organic components  and can lead to generation of  organic acids and aldehydes which can generate bad smells, lower the PH and be harmful to the operator.

Tramp oils are a problem, but other contributors can be  dust, debris, human contact or contaminants in the water source.  Additive in the fluid can also b e source of nutrient for the bacteria, particularly phosphorous or sulphurized additives. This is why it is vital to get advice from Gulf to ensure you are using the best suited fluid for your application

Swarf from cutting or grinding operations can also contribute to an increase microbial growth. All machines should be equipped with filters and conveyors for removal of swarf from the fluid. This can be done using filters, skimmers, seperators and centrifuges.

The storage of metalworking fluids is critical. They should be stored indoors (between 10°C and 40°C). 

Use of Bacteriocides
Bactericides kill bacteria but they can also be harmful so they should only be used when deemed necessary to control bacterial growth. Over use of biocides can result in the used metalworking fluid being considered hazardous waste, therefore limiting the disposal options and increasing its cost.

Documenting  your Metalworking fluids
Metalworking fluids are often costed purely on a pence per litre basis, but the correct fluid  can influence many other costs in the production process

In order  to monitor this it is important to keep the relevant records.

For each machine the following should be recorded:-

Sump capacity, metalworking fluid being used, mix ratio, concentration, PH readings and visual observations.

Additions  and adjustments that have been made to the fluid, frequency of testing, frequency of cleanouts  and documenting of any problems that occur.

The correct metalworking fluid can influence the life of the tools and the frequency of resharpening of the tools. The correct fluid can double or triple  the life of the tool.

The surface finish of the component can be improved by the correct metalworking fluid being used

A proper metalworking fluid  management program from selection through to  maintenance and disposal will result in significant cost  savings for the company. 

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For England & Wales (Gulf & Shell) call 0345 609 9002 or for England & Wales (Castrol & Valvoline) call The Race Group 01384 263614 or for Scotland (all brands) 0345 609 9156