Cutting Fluid selection criteria

Choosing the right metalworking fluid for your operation can be confusing and time consuming. To select a fluid for your application, advantages and disadvantages of metalworking fluid products should be compared through review of product literature, supplier information, and usage history. Product performance information shared by other machine shops is another means of narrowing choices. Ultimately, the best indicator of fluid performance is through actual use.

In addition to the fluid properties discussed earlier , the following factors should be considered when selecting a fluid:

• Cost and life expectancy
•   Fluid compatibility with work materials and machine components
•   Speed, feed and depth of the cutting operation
•   Type, hardness and microstructure of the metal being machined
•   Ease of fluid maintenance and quality control
•   Ability to separate fluid from the work and cuttings
•   The product’s applicable temperature operating range
•   Optimal concentration and pH ranges
•   Storage practices
•   Ease of fluid recycling or disposal

One thing must be remembered when choosing fluids – you generally get what you pay for. Don’t choose a fluid just on its initial cost but on the cost per gallon divided by its life expectancy. Although purchase of a premium product is initially more expensive, the long-term cost of the fluid will likely be lower than products of inferior quality because of its superior fluid life.

During fluid selection, the benefits of a fluid’s versatility should be weighed against its performance in each metalworking application . Because of significant improvements in fluid formulations, today’s fluids are capable of handling a wide variety of machining applications . Machine shops that once required several types of fluids may now find that one or two fluid types meet their needs. Consolidating the number of fluids used in the shop simplifies fluid management.

The most common metalworking fluids used today belong to one of two categories based on their oil

content:

Oil-Based Fluids – including straight oils, soluble oils and ag-based oils

Chemical Fluids – including synthetics and semisynthetics

Fluids vary in suitability for metalworking operations. For example, petroleum-based cutting oils are frequently used for drilling and tapping operations due to their excellent lubricity while water-miscible fluids provide the cooling properties required for most turning and grinding operations.