Aluminum, a softer metal with a relatively lower melting point than other materials such as steel, poses a few specific challenges during cutting, grinding, and finishing. While some grades of aluminum cut smooth, others are gummy and can end up clogging tools. Intense heat coupled with friction generated during machining melt aluminum and make it stick to the tool surface, causing the cutting edge to foul. But the right cutting oil for aluminum machining cools down and lubricates the machining region, flushes chips away, improves the surface quality of the machined part, and decreases the tool wear rate.

Below, we discuss some common cutting oils for aluminum machining and why cut-to-order precision sawing services are ideal for fulfilling your aluminum machining requirements.

Types of Cutting Oils for Aluminum Machining

Before selecting a cutting oil for aluminum machining, consider the various properties of aluminum that can contribute to challenges during machining:

• Coefficient of thermal expansion (CTE): The high CTE of aluminum causes the cutting heat to quickly expand to the workpiece, resulting in thermal deformation and reduced machining accuracy.
• Oxidation: When exposed to strong acid or alkaline environments, aluminum develops an oxide layer. If the oxide layer is not removed before welding, it will lead to imperfections such as porosity or inclusions. The oxide layer can also cause material burn-through as the heat needed to remove the oxide layer is higher than required for the base material below.   
• Pitting: The corrosion of aluminum is characterized by small pits or holes on the surface. Pitting can pose a challenge for specific industrial applications where surface appearance is critical.
• Ductility: During aluminum cutting, long strip cracks may form and block the cutting area. The cutting debris needs to be removed to improve smoothness and accuracy.

Based on these unique challenges, a cutting oil for aluminum machining should meet the following criteria:

1. Excellent cooling performance: A cutting oil should address the heat buildup during milling, grinding, or turning while reducing temperatures on the workpiece and the cutting tool.
2. Excellent lubrication: A cutting oil for aluminum machining should provide excellent lubrication and have strong anti-friction properties to move chips away from the cutter—yielding a smooth surface finish to the workpiece.
3. Corrosion resistance: The cutting fluid should have outstanding corrosion resistance to prevent pitting on the surface of the aluminum.
4. pH level: The pH of an aluminum cutting oil should fall in the range of 8.0 – 8.5 to prevent oxidation.
5. Anti-rust agent: The cutting oil should contain anti-rust agents such as phosphate and sodium silicate to form an anti-corrosive film on the surface of the workpiece and maintain pH stability.

The major types of cutting oil used for aluminum machining include the following.

Straight Oil

Straight oils have exceptional lubricating properties and are used in heavy cutting operations that require high chip removal rates. For aluminum machining, straight oils with a base composition of petroleum or mineral oil in an undiluted form are best suited to keep the chips away from the milling tool and achieve a smooth surface finish. The viscosity of mineral oil-based cutting fluids can be further increased to let them flow more easily over the cutting zone. Lubricants such as vegetable oils, lard oil, kerosene, esters, and fats are all used for aluminum cutting.

Soluble Oil

Soluble oils are a preferred choice during the turning, milling, drilling, threading, tapping, and reaming of aluminum. Made by mixing mineral oil, water, and coupling agents, these oils are great for providing lubrication. Soluble oils mixed to a consistency of 1 part oil to 20-30 parts water can make for an effective cutting fluid for aluminum machining. Added emulsifiers and other additives can help disperse oil in water.

When it comes to successful aluminum machining outcomes, the concentration of cutting oil used is critical. Low quantities of cutting oil will lead to excessive heat and friction, resulting in the corrosion of the workpiece and cutting tool. Using more than required will lead to an  excessive amount of residue forming on machining tools, staining the workpiece. Choosing the best cutting oil for aluminum machining, the exact amount to be used for operations, and the right cutting tools for a smooth finish is a challenge. A cost-effective alternative is to outsource your aluminum machining requirements to a team of experienced professionals with industry-leading sawing resources.

Outsourcing Your Aluminum Machining Requirements

At Industrial Metal Service, we handle your sawing requirements to help you accelerate production processes and reduce material wastage. Using our proprietary MetlSaw NF12-T12 and Amada PCSAW 530 X band saw with pulse cutting technology, we conduct high-precision metal sawing to the fraction of an inch. Our cut-to-order precision sawing services can fulfill your aluminum needs whether you require a one-time order or regular deliveries for your projects.