Formulations of Metalworking Fluids (MWFs)
Metalworking fluids are specialized lubricants and coolants used in machining, grinding, and metal forming processes to reduce heat, friction, and wear.
There are four main types of MWFs, each with unique formulations:
🧪 1. Straight Oils (Neat Oils)
Form: 100% oil-based (no water)
Use: Heavy-duty cutting, deep drilling, tapping, threading
🔬 Typical Formulation:
| Component | Dosage (%) | Function |
|---|---|---|
| Mineral oil / synthetic base oil | 85–98 | Base fluid, lubrication |
| EP additives (sulfurized, chlorinated, or phosphorus compounds) | 1–10 | Reduce wear under high pressure |
| Fatty oils (lard, esters) | 1–5 | Boundary lubrication, film strength |
| Antioxidants | 0.1–1 | Prevent oxidation during use/storage |
| Corrosion inhibitors | 0.1–1 | Protect workpiece and machine from rust |
💧 2. Soluble Oils (Emulsifiable Oils)
Form: Oil concentrate diluted with water (5–20%)
Use: General machining, turning, milling, grinding
🔬 Typical Formulation (Concentrate):
| Component | Dosage (%) | Function |
|---|---|---|
| Mineral oil / base oil | 40–80 | Lubrication |
| Emulsifier (nonionic/anionic surfactants) | 5–15 | Helps oil mix with water |
| Corrosion inhibitors (amines, borates) | 5–15 | Rust prevention |
| EP/AW additives (sulfurized, esters) | 1–10 | Load-bearing protection |
| Biocides / Fungicides | 0.1–1 | Prevent microbial growth |
| Antifoam agents | 0.05–0.5 | Minimize foaming in systems |
💧 3. Semi-Synthetic Fluids
Form: Lower oil content (5–30%) + synthetic additives
Use: Precision machining, grinding, moderate loads
🔬 Typical Formulation:
| Component | Dosage (%) | Function |
|---|---|---|
| Mineral oil / synthetic oil | 10–30 | Lubrication |
| Water (in use) | 70–90 | Cooling medium |
| Emulsifiers / solubilizers | 5–15 | Maintain stable emulsion |
| Corrosion inhibitors | 5–15 | Protect parts and tools |
| EP/AW agents | 1–5 | Surface protection under pressure |
| Biocides | 0.1–0.5 | Inhibit microbial contamination |
| pH adjusters / buffers | 0.5–2 | Maintain stable pH (8.5–9.5) |
💧 4. Synthetic Fluids (Full Synthetics)
Form: 100% water-soluble, no mineral oil
Use: High-speed grinding, CNC, aerospace, cleanliness-critical work
🔬 Typical Formulation:
| Component | Dosage (%) | Function |
|---|---|---|
| Water-soluble polymers / glycols | 10–30 | Lubrication, cooling |
| Corrosion inhibitors (amines, borates) | 10–30 | Protect machinery and workpiece |
| EP/AW additives (phosphate esters, esters) | 1–5 | Improve load-carrying performance |
| Chelating agents (EDTA, NTA) | 0.5–2 | Control water hardness |
| Surfactants | 1–5 | Wetting, cleaning, foam control |
| Biocides | 0.1–0.3 | Bacteria and fungus control |
🧰 Additives Used Across All Types
| Additive | Function |
|---|---|
| Sulfurized EP agents | Reduce tool wear |
| Chlorinated paraffins (phased out in some regions) | High EP performance |
| Polyalkylene glycols (PAGs) | Lubricity, water solubility |
| Amine-based buffers | Maintain alkaline pH |
| Boric acid derivatives | Dual role: antiwear + corrosion inhibition |
| Esters (synthetic or natural) | Lubricity enhancement |
| Triazoles / molybdenum compounds | Anti-corrosion or friction modifiers |
🧪 Sample Soluble Oil Concentrate (for Dilution 1:20)
| Ingredient | % |
|---|---|
| Mineral oil | 60 |
| Nonionic emulsifier | 10 |
| Fatty ester (lubricity agent) | 8 |
| Borated corrosion inhibitor | 10 |
| Biocide (isothiazolinone) | 0.5 |
| Foam control agent | 0.2 |
| Water | Balance |
Metalworking fluid formulations vary widely depending on process type, machine design, and environmental requirements. Choosing the right base oil, emulsifier, corrosion inhibitor, and biocide is key to maximizing lubricity, cooling, tool life, and surface finish.
Metalworking Fluids: Discover Their Formulations and Functions
Metalworking fluids play a vital role in industrial production, and their performance directly affects the quality and efficiency of metal processing. Metalworking fluids can be divided into two categories: oil-based cutting fluids and water-based cutting fluids according to their composition.
First, let’s look at oil-based cutting fluids. Oil-based cutting fluids are famous for their good lubricity and anti-rust properties, but they also have problems such as poor cooling, easy generation of smoke and workpiece deformation. However, in some specific applications, such as high temperature and high-speed cutting, oil-based cutting fluids still have irreplaceable advantages.
Next, let’s look at water-based cutting fluids. Water-based cutting fluids can be divided into emulsified oils (about 50-80% oil content), semi-synthetic cutting fluids/microemulsions (oil content <30%) and fully synthetic cutting fluids (oil-free) according to the content of mineral oil. Fully synthetic cutting fluid is favored for its good cooling and cleaning properties, but its rust resistance and lubricity are relatively poor, and it is mainly suitable for easy-to-machine materials. Emulsified oil and micro-emulsion cutting fluids combine the advantages of oil-based cutting fluids and water-based fully synthetic cutting fluids, and have a wide range of applications.
So, what exactly does the formula of metal working fluid contain? Generally speaking, the main components of metalworking fluids include cutting fluid, cutting oil, emulsion, stamping oil, quenching oil, quenching agent, high temperature oil, extreme pressure cutting fluid, grinding fluid, anti-rust oil, cleaning agent, blackening agent Agent, drawing oil, thickener, etc. The selection and proportions of these ingredients are tailored to the specific application needs.
For example, a formula to improve the protective ability of aluminum alloys in metal working fluids contains ingredients such as salicylic acid, boric acid, octanoic acid, sodium metasilicate, isopropanolamine, diglycolamine, and triethanolamine. This formula uses the neutralization reaction of salicylic acid and boric acid with polyamines so that the boron element can be firmly adsorbed on the surface of aluminum, while the benzene ring structure of salicylic acid can form a hydrophobic layer, thereby forming a hydrophobic layer on the metal surface. Anti-rust film. This kind of film is not only more uniform and dense, but also provides better protection to the metal.
In addition, there are other metal working fluid formulas, such as one composed of sodium naphthenate, cotton oleic acid, triethanolamine, alkanolamide, extreme pressure additives, alkylphenol polyoxyethylene ether, sodium tripolyphosphate, antifungal agent , dimethyl silicone oil, etc. This formula also has good anti-rust, lubrication and cooling properties and is suitable for a variety of metal processing processes.
The formulations of metalworking fluids (MWFs) can be quite complex, but they generally consist of a base fluid mixed with various additives to achieve specific properties. Here’s a breakdown of the key components:
Base Fluid:
- Mineral Oil: The most common base fluid, offering good lubrication and cooling properties. However, it can be less environmentally friendly and may require additional additives for enhanced performance.
- Synthetic Fluids: Engineered fluids offering superior performance in specific areas like extreme pressure or biodegradability. Examples include polyalphaolefins (PAOs) and esters.
- Semi-Synthetic Fluids: Blends of mineral oil and synthetic fluids, providing a balance between cost and performance.
- Water: Used in water-based (or emulsion) MWFs, offering good cooling properties and lower environmental impact. However, water alone lacks lubrication, so additives are crucial.
Additives:
A wide range of additives are used in MWFs to target specific needs. Here are some common ones:
- Extreme Pressure (EP) Additives: Enhance lubrication under high pressure and load, preventing metal-to-metal contact and wear. They often contain sulfur or phosphorus compounds.
- Anti-Wear Additives: Form a protective film on metal surfaces to reduce wear during machining processes. Examples include fatty acids, chlorinated paraffins.
- Emulsifiers: Allow oil and water to mix and form a stable emulsion in water-based MWFs.
- Corrosion Inhibitors: Protect metal surfaces from corrosion caused by the MWF or the machining process.
- Biocides: Prevent bacterial and fungal growth in the MWF, extending its lifespan and reducing foul odors.
- Cooling and Antifoaming Agents: Enhance heat transfer and prevent excessive foaming, which can disrupt the machining process.
The specific formulation of an MWF depends on several factors, including:
- Machining operation: Different operations (e.g., drilling, milling, grinding) have different lubrication and cooling requirements.
- Material being machined: Different materials require different lubrication properties to avoid wear or reactions.
- Environmental regulations: Some regions have regulations on the use of certain chemicals in MWFs, promoting environmentally friendly formulations.
It’s important to note that the exact formulations of commercial MWFs are often proprietary information. However, understanding the general types of base fluids and additives used can help you choose the most appropriate MWF for your specific machining needs.
Here are some additional points to consider:
- Safety: MWFs can contain hazardous chemicals. Always follow safety data sheets (SDS) and proper handling procedures.
- Disposal: MWFs require proper disposal to minimize environmental impact. Consult regulations and waste management companies for proper disposal methods.
By understanding the composition of MWFs and their impact on performance and safety, you can make informed decisions when selecting and using them in your metalworking operations.
In general, the formula design of metal working fluid is a complex and delicate process, which requires comprehensive consideration of various factors, such as the properties of metal materials, processing conditions, environmental protection requirements, etc. In the future, with the development of science and technology and the improvement of environmental protection requirements, the research and application of metal working fluids will be more in-depth and extensive.