High-precision metalworking tools and machinery encounter significant stress during machining processes. As cutting tools engage with metal, the intense friction involved generates heat and accelerates wear, sometimes damaging both tools and workpieces.
To combat this, cutting fluids—often referred to as metalworking fluids—are essential components in the machining process. These fluids serve as lubricants, coolants, and corrosion inhibitors. In turn, they can improve tool life, part quality, and process efficiency.
From high-speed drilling to fine Swiss machining, choosing the right cutting fluid ensures your operation stays productive and cost-effective. In this article, our experts dive into the fundamentals of cutting fluids, their types, and the best products trusted by professionals.
Cutting fluids are specially engineered liquids used during metalworking operations like milling, drilling, grinding, and turning. Their primary purpose is to manage the friction and heat generated during metal cutting processes. By acting as a lubricant and coolant, they help maintain the integrity of both the cutting tool and the workpiece.
Depending on your machine configuration and the task at hand, there are several application methods for metal cutting fluids:
Cutting fluids provide several benefits that contribute to high-performance metal machining.
When cutting at elevated speeds, cutting fluids absorb and dissipate the significant amount of heat generated, preventing overheating and thermal deformation of workpieces.
In slower operations, such as tapping or reaming, cutting fluids act as a barrier between tool and material. In turn, they minimize friction and reduce tool wear.
Fluids help flush away chips and debris from the cutting zone, maintaining cutting accuracy and preventing chip re-welding onto the workpiece.
Cutting fluids create a protective layer over both the tool and workpiece, shielding them from oxidation and rust.
Hot parts are difficult to handle or measure. Cutting fluids cool surfaces post-cut, enabling quicker handling and inspection.
By controlling heat buildup, cutting fluids help avoid surface burning, micro-cracking, and structural changes to the metal.
Cutting fluids make it easier to manage and remove swarf, the tiny metal chips, fragments, or curls produced during machining processes. This reduces the need for frequent manual cleaning and improves automation potential.
By reducing tool chatter and material sticking, cutting fluids result in smoother, more consistent part surfaces.
Lower tool temperatures and reduced friction from cutting fluids directly translate into longer-lasting, more reliable tools.
Metal cutting fluids enable smoother cutting of hard-to-machine materials like titanium, stainless steel, and aerospace alloys, ultimately improving productivity.
There are multiple categories of cutting fluids, each tailored to specific applications.
These oils mix with water to create a milky emulsion, providing good lubrication and cooling. Best suited for nonferrous materials, they’re widely used in general machining applications.
Synthetic fluids contain no oil and are composed of chemical solutions, polymers, and additives. With superior cooling and extended shelf life, they are well-suited for high-speed machines and ferrous materials. However, some synthetic cutting oils may stain nonferrous metals like copper or brass.
Blending synthetic materials with oil, semi-synthetic fluids offer the best of both worlds. They provide lubrication, coolant properties, and resistance to contamination across a broad spectrum of ferrous and nonferrous applications.
Also known as neat oils, straight cutting fluids are undiluted mineral oils, often enhanced with Extreme Pressure (EP) additives like chlorine, sulfur, or phosphorus. They offer exceptional lubrication for demanding machining processes but have limited cooling capacity.
Keller-Heartt offers a wide range of premium cutting fluids to meet versatile metalworking needs. Here are the top recommendations to help you make the best choice for your shop:
Formulated with advanced polyesters, TRUEGARD SUPERCOOL #4086 delivers outstanding machining performance on both steel and aluminum. As part of the TRUEGARD SUPERCOOL #4000 series, this semi-synthetic coolant concentrate offers enhanced longevity and stability. It’s engineered without sulfur-containing emulsifiers, eliminating bacteria-feeding elements and extending coolant life. The product resists emulsification with hydraulic or way oil, maintaining emulsion integrity and allowing for easy tramp oil removal. TRUEGARD SUPERCOOL #4086 also boasts a high flash point and extremely low foaming, even under high-pressure conditions.
A multifunctional solution, TRUEGARD Tri-Purpose Cutting Oil serves as a cutting fluid, hydraulic oil, and machine lubricant. It helps reduce contamination between systems and is ideal for automatic screw machines. With a light, transparent color and chlorine-free composition, it’s a safe, versatile, and environmentally friendly option.
Designed for machining hard metals, this active cutting oil contains anti-mist and anti-weld agents, including active sulfur. It provides outstanding surface finishes and edge retention, making it ideal for operations where extreme pressure resistance is required.
This medium-duty, 100% virgin mineral oil is specially formulated for challenging machining tasks. Enriched with active sulfur and fat, it excels in operations like broaching, threading, and drilling. TRUEGARD #1290 enhances tool life and finish quality, even on exotic alloys.
Built for Swiss-style machining, this oil delivers superior lubricity and exceptional heat dissipation. It helps prevent discoloration, maintains dimensional accuracy, and supports long machine cleanliness cycles thanks to its advanced thermal stability.
An extremely heavy-duty option, HD-258 is built to handle stainless steel and nickel-based alloys. It can also be used as a performance booster when mixed with lighter oils. With superior load-carrying capability and wipe resistance, it’s ideal for slow, heavy-duty operations.
This dual-purpose oil is both a cutting fluid and machine lubricant. It contains a moderate level of chlorine, is sulfur-free, and is perfect for light to medium-duty tasks. Its clean, low-odor formula supports a healthy working environment.
Formulated for screw machines and lathes, this oil balances sulfur and fat content to offer great lubricity in moderately demanding tasks. Its mild detergency reduces swarf buildup, and its high flash point ensures safe, stable operation.
Check Out the Metalworking Product List →
Not all fluids are created equal—and the ideal fluid for one application might be a poor fit for another. Here’s a deeper look at the key factors you should consider when selecting metal cutting fluids for your shop:
Whether you're running a high-speed CNC machine or precision Swiss lathe, the right cutting fluid makes all the difference. At Keller-Heartt, we’re more than suppliers—we’re partners in your operation’s success.
We recommend starting with trusted solutions from our extensive TRUEGARD lineup to keep your tools sharp, your parts pristine, and your production moving forward. Simply place your order online or contact our team today to inquire about bulk pricing or personalized recommendations.