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Metalworking Fluid Operations: Why the Metalworking Fluid is Important

July 01, 2012
John C. Steigerwald
Online Only Articles

Metalworking Fluids have been involved in the world of metalworking operations for as long as we've been able to remove metal from a workpiece. Metalworking fluid technology has changed over time and will continue to change to keep up with the continued evolution of equipment and process technology.

The primary reasons metalworking fluids are used in the metal removal process have not changed when we consider basic functionality and expectation. Those reasons include:

  • Improve tool life and productivity
  • Flush away chips
  • Prevent in-process corrosion on parts, equipment and fixturing where water dilutable products are used
  • Provide the needed lubrication type based on the application.

In addition to the above primary requirements for a metalworking fluid, there are numerous secondary characteristics that are fulfilled by the metalworking fluid, particularly with water-dilutable metalworking fluids. Those characteristics include:

  • Control of biological growth and odors
  • Foaming characteristics
  • Residue formations
  • Operator acceptance
  • Environmentally acceptable
  • Ease of disposal.

In the metal deformation process when a chip is formed, the immediate need of the process is to control the heat being generated. This remains the same whether we're talking about a machining operation or grinding operation. The heat generation management has an immediate impact on the workpiece from a tool life and part geometry perspective. A primary requirement of the metalworking fluid is to control the tool/workpiece temperature and reduce the friction of the tool on the workpiece and the chip on the tool while controlling the formation of the built-up edge on the tool (BUE). Once there is BUE, all elements in the process will be negatively impacted including the friction forces, heat, surface finish and part quality.

Given this point, it is always important to choose the metalworking fluid that best fits the application, process environment, and the needed conditions after the metal removal steps. At times, it is a choice of compromises.

The metal removal process can be divided into two main general categories: machining, which is the largest; and grinding. In an more simplistic view, it can be definedby the size of the chips created in the process. Machining creates large chips and grinding produces small chips.

There are a host of operations that fall into the general category of machining. As noted below, along with taking into consideration the workpiece and tooling type, this must be balanced to the overall process expectation. Machining operations include:

  • Turning
  • Broaching
  • Milling
  • Gear Hobbing and Shaping
  • Drilling
  • Reaming
  • Threading
  • Tapping
  • Others.

There are also a host of operations in the general category of grinding. These operations will also be influenced by metal, tooling and process output expectations in regards to the choice of metalworking fluid. Grinding operations include:

  • Centerless Grinding
  • Cylindrical Grinding
  • Internal Grinding
  • Surface Grinding
  • Lapping
  • Honing
  • Others.

In each of the general categories noted above, it is important to understand the output conditions that are expected of the process whether it is machining or grinding.

One can easily start to see the complexities of the needs of today's processes and as a result, the needs being fulfilled by a metalworking fluid(s) used in this dynamic environment. Choosing a metalworking fluid for an application goes far beyond the needs of the actual application. The overall process needs to be clearly understood prior to making a solid recommendation. The overall process needs to include the needs for filtration and post-cleaning of the workpiece. In addition, the metalworking fluid will need to be disposed of after its useful life in a system or an individual sump, and this aspect needs to be dealt with at the beginning of the product recommendation process, since it's one of the secondary points noted about metalworking fluids.

Metalworking operations today and in the future will continue to challenge the metalworking fluid on the ability of the fluid to provide the primary and secondary benefits needed in the process. It goes beyond just reducing friction.

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