Metalworking Fluids

Metalworking Fluids

Uncontrolled contamination in metalworking fluids (MWF) not only affects the utility of the fluid, but can also expose workers to harmful contaminants. If one or more of the following occur, metalworking fluids should be evaluated as soon as possible.

Common spoilage signs include:

  • Worker complaints of skin irritation or dermatitis
  • Worker complaints of respiratory iritation
  • Foul odors (rancidity)
  • Floating Matter on the fluid
  • Low sump levels
  • Abnormal fluid appearance
  • Tramp oil floating on the surface
  • Excessive foam or changes in viscosity
  • Dirty machines or trenches
  • Changes in pH
  • Filters, screens or lines frequently clogged
  • Increased corrosion
  • Increased wear and tear on tools
  • Work pieces failing quality checks
  • Work pieces with blemished surfaces

Services Guide

Microbial Contamination

Bacteria and fungi are able to thrive in in typical metalworking fluids as they contain rich sources of nutrients for them to consume and multiply. Biocides may be incorporated into the fluids to help prevent or retard their growth.  Contamination may still occur if the biocide is not effective against a broad spectrum of microbes.

Microbes that have been isolated from MWF include:

  • Fusarium (EMSL Test Code:  M008)
  • Candida (EMSL Test Code: M008)
  • Cephalosporium (EMSL Test Code: M008)
  • Pseudomonas aeruginosa (EMSL Test Code:  M010)
  • Klebsiella pneumoniae (EMSL Test Code:  M010)
  • Proteus mirabilis (EMSL Test Code: M010)
  • Citribacter (EMSL Test Code: M010)
  • Bacillus (EMSL Test Code: M010)
  • Mycobacteria (EMSL Test Code: M031)
  • Legionella (EMSL Test Code: M341)
  • SRB- Sulfate reducing bacteria (EMSL Test Code: M122)

Samples of the MWF can be submitted for laboratory testing to confirm the presence and specific identification of the contaminant:

Sampling Instructions:

Collect 100 mL in a sterile container, place in a cooler with ice packs, and ship overnight to EMSL Analytical, Inc. We recommend our test code M008 as a general fungal contaminant screen, M010 for environmental bacteria, M031 specifically for Mycobacteria, M341 for Legionella, and M122 for sulfate reducing bacteria.

Interpretation Guidelines:

When interpreting microbial counts, a general rule of thumb follows (from Health and Safety Executive, UK):

<103 CFU/mL Good control. Bacteria are being maintained at low levels. No further action is required

103 to <106 CFU/mL Reasonable control. Review control measures to ensure levels of bacteria remain under control. Risk assessment should specify action to be taken. Biocides and or cleaning may be indicated. If biocides are used, expert advice should be obtained, and the concentration of biocides should be monitored

>106 CFU/mL Poor control. Immediate action should be taken in line with the risk assessment. Normally at very high levels draining and cleaning, should take place.

Contamination other than Microbial


Other problems that might be fluid-related that should be investigated as soon as possible are:

  • Premature tool & part failure due to loss of performance
  • Staining of the metal machine or machine tools and dies
  • Rust or corrosion of the machine tool or the part produced
  • Dirt and grit suspended in the fluid excessive wear and filtration requirements
  • Thermal cyclic failure at tool or die interface (malformation, scoring, micro cracking)

Modern manufacturing of complex parts or raw goods is a challenge with the ever changing application of technological development towards established manufacturing processes. In a full scale manufacturing environment, it is often the quality of the tooling and assembly equipment that can make the difference between profitability and an operating loss. Complex tooling for precision products, as well as the increasing number of products with micro-surface details that are critical to device functionality, can be problematic when often extremely tiny variations in tooling can impact the final product greatly. Being able to determine the quality of new tooling as well as monitor the condition and tolerances of deployed machining is crucial to maintaining the quality of your final product.  Microbial contamination of the machining fluid can lead to excesses in other types of contaminants.

EMSL’s team of analysts and scientists have decades of experience working with manufacturing companies and their raw material suppliers. Our wide-ranging variety of analytical expertise and services provide solutions to a range of potential problem sources. We can assist you with analysis of fracture or failure in your machinery through fractography and failure analysis inspection. Comparison of the contour and layout of the cutting and forming surfaces to planned CAD designs, in order to ensure that the die you ordered is the die you received. Surface inspection of the tooling can reveal nicks, breaks and defects before they become a problem, or manufactured goods can all be measured using advanced digital elevation mapping in order to fit defects in a part with the tooling changes their potential causative relationship. Finally, the microstructure and composition of portions of the tooling can be examined with SEM, EDS, XRD, XRF, and EBSD to ensure that surface hardness, brittleness, and wear characteristics are all as desired – rather than losing down time when a bit breaks or a blade dulls.

EMSL can offer a wide range of analytical services quickly and efficiently in order to keep up with the pressing demands of modern manufacturing environments. The comprehensive analysis we offer can be used to gain critical insight into the performance and quality of the machinery that makes up the backbone of many manufacturing industries.  Contact EMSL for your competitive quote today.

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