Attacking Aluminum: a Machining Guide - In The Loupe

Attacking Aluminum: A Machining Guide - In The Loupe

When machining aluminum, achieving optimal performance hinges on understanding key factors, such as material properties, tool geometry, and running parameters. Approaching aluminum machining with the right strategies can greatly enhance productivity and ensure high-quality results.

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Material Properties

Aluminum is a highly formable, workable, lightweight material. Parts made from this versatile material can be found in virtually every industry. Additionally, aluminum is particularly popular for prototypes due to its affordability and flexibility.

Aluminum is available in two basic forms: Cast and Wrought. Wrought Aluminum is typically stronger, more expensive, and has a lower percentage of outside elements in its alloys. Additionally, Wrought Aluminum is more heat-resistant and has higher machinability compared to Cast Aluminum.

Cast Aluminum, on the other hand, offers less tensile strength but greater flexibility. It costs less and contains higher percentages of external elements in its alloys, making it more abrasive than Wrought Aluminum.

Tool Geometry

When selecting tools for aluminum machining, several coating options are available, including the widely-used ZrN (Zirconium Nitride) and highly effective TiB2 (Titanium Diboride). Uncoated tools can also perform well, but the key to high performance is understanding the correct flute count and helix angle for your specific operation.

Flute Count

End mills for aluminum typically come in either 2-flute or 3-flute designs. Higher flute counts can impede effective chip evacuation at high speeds due to smaller chip valleys. Traditionally, 2-flute end mills were preferred, but 3-flute end mills have proved successful in many finishing and even roughing operations. The choice between 2 and 3 flutes often depends on personal preference and specific machining requirements.

Helix Angles

The helix angle measures the angle formed between the centerline of the tool and a line tangent to the cutting edge. Tools designed for aluminum often feature higher helix angles, typically 35°, 40°, or 45°. A 35° or 40° helix angle is suitable for roughing and slotting, while a 45° angle is ideal for finishing and high-efficiency milling (HEM) toolpaths due to its aggressive cutting action.

Tooling Options

Standard 2-flute or 3-flute tools are usually sufficient for machining aluminum, but specific applications may benefit from specialized tooling options for enhanced performance.

Chipbreaker Tooling

Effective chip evacuation is crucial in aluminum machining. Standard 2-3 flute end mills handle this well, but 3-flute chipbreaker tools offer improved performance at higher speeds and feed rates. Their unique geometry creates smaller chips for optimal evacuation while leaving a semi-finished surface. These tools are perfect for advanced toolpaths like High Efficiency Milling.

High Balance End Mills

High balance end mills are engineered for high-performance in balanced machining centers operating at elevated RPMs and feed rates. These tools are precisely balanced for high-velocity aluminum machining, reaching up to 33,000 RPM. Available in standard 2-flute and coolant-through 3-flute designs, they enhance chip evacuation and material removal rates, making them suitable for HEM toolpaths.

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Running Parameters

Setting the right parameters is crucial for optimizing aluminum machining. Pushing your machine to its limits is essential for staying competitive. For cast aluminum alloys such as 308, 356, and 380, a surface footage of 500-1000 SFM is recommended. For wrought aluminum alloys like 2024, 6061, and 7075, 800-1500 SFM is ideal. Calculate the RPM starting point by (3.82 x SFM) / Diameter.

High Efficiency Milling

High Efficiency Milling (HEM) is gaining popularity in the manufacturing industry and is frequently included in CAM programs. HEM employs a low Radial Depth of Cut (RDOC) and high Axial Depth of Cut (ADOC) to maximize tool efficiency. This roughing technique is beneficial for extending tool life and improving performance, especially in aluminum machining.

Summary

Aluminum offers excellent machinability, but it requires the right approach to achieve top-notch results. Optimizing your tools, machine setups, and toolpaths is key to remaining competitive and boosting efficiency in your shop.

Harvey Performance Company’s team of engineers collaborates to address all your machining challenges, from tool selection and application support to custom tool design for your next job, ensuring a thorough and comprehensive solution.

8 Keys to Success When Machining Aluminum

Aluminum, a non-ferrous metal and chemical element with the symbol Al, is widely used due to its low weight, high electrical conductivity, and excellent thermal behavior.

Compared to other metals, aluminum is soft and light, yet also tough. It has a lower melting point (660.4°C) and is significantly less dense (2.70 g/cm³) than steel. Its tensile strength varies based on purity, and its thermal conductivity surpasses other base metals except for silver, copper, and gold. These physical properties make aluminum highly suitable for electrical engineering and energy technology applications.

Aluminum naturally forms a protective oxide layer when exposed to air, giving it a corrosion-resistant silver-grey finish. Depending on the application, aluminum may be used in its pure form or as an alloy, with various metals enhancing or reducing specific properties.

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