Tackling Foam in Metalworking Fluids.

Foam is more than just an aesthetic or visual problem in MWF. It can seriously impair function, reduce equipment lifespan, and increase maintenance costs. In high-speed, high-pressure systems when mechanical agitation and air entrainment are common, formulators must proactively design with foam control in mind.

Why does foam form?
Foam typically occurs in two stages:

  1. Primary (dynamic) foam. This forms during agitation or circulation of MWF through pumps, valves, or turbulent areas.
  2. Secondary (static) foam. This is the lingering after-effect after agitation stops. Secondary foam can affect fluid levels and pressure control.
The main causes of foam formation are surface-active agents, entrained air, or contaminants such as water, dust or oxidation products. If left unchecked, foam can wreak havoc on mechanical equipment and impair the function of formulated products.
Foam interferes with accurate fluid level detection and hydraulic response. Increased oxidation rates and overflow and leakage are other negative effects caused by foaming in systems. Not only that, but foam can interfere with system filters and impede the function of anti-wear additives and corrosion inhibitors. Poor foam control “accelerates wear and shortens the service life of both the lubricant and the equipment.”1

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The need for foam control components.
While many base oils possess intrinsic resistance to foaming, modern lubricants often require performance additives that can destabilize foam rapidly without affecting other formulation properties. Excessive foam is not just a physical nuisance but will eventually lead to mechanical wear and premature system failure.2

Solutions for foam control
Foam can easily be controlled by incorporating additives from Additiv-Chemie Luers like Antifoam ASI 200, ASI 400 that suppress foam formation and AC-16101- M1 that is inherently low foaming.

  • Antifoam ASI 200 is a silicone-free foam suppressant that offers consistent foam control across a wide range of applications, including hMWF. It provides excellent dynamic and static foam reduction. Incorporating ASI 200 will not impact demulsibility or oxidation stability.
  • Antifoam ASI 400 is an advanced, long-lasting component that builds on the performance of ASI 200 with enhanced persistence and stability, especially under high-temperature and high-shear conditions. It’s an ideal option for extreme environments or where silicone-based foam control is required. It provides superior, long-term foam knockdown and excellent compatibility with Group I-III base oils and PAOs.
  • AC-16101-M1 is a low foaming, multi-functional corrosion inhibitor designed as a replacement for CorFree® M1. It delivers rust and corrosion protection without contributing to excessive foam formation. Its performance makes it ideal for water-extended or soluble lubricant systems where air release and system stability are critical.
All three products demonstrate favorable results in standardized foam and air release testing protocols, including ASTM D892, ASTM D6082, and relevant corrosion tests such as ASTM D665.

 

Selecting the right solution.
Formulators should choose foam control agents based on the formulation’s base oil, additive system, application conditions, and performance targets. ASI 200 and ASI 400 can be easily blended into existing additive packages and finished formulations with minimal disruption.
Without proper foam control, your lubricant system risks efficiency loss, increased wear on equipment, and early equipment failure.

Need help finding the right foam control solutions? ASI 200 and ASI 400 can help you deliver stable, high-performing lubricants that meet modern application demands without compromise. Contact a Barentz Technical Team Member for technical data, formulation advice, or to request a sample.

Sources:

  1. NLGI. (2015). Lubricating Grease Guide (5th ed.). National Lubricating Grease Institute.
  2. Totten, G. E., & Westbrook, S. R. (Eds.). (2003). Handbook of Hydraulic Fluid Technology. CRC Press.

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