Face Milling vs. Peripheral Milling: What Are the Key Differences?

Face milling and peripheral milling have fundamental distinctions and applications in precision machining. Each of these methods has specific benefits and applications, and they are essential in many different fields, including manufacturing and metalworking. While the milling cutter is oriented parallel to the workpiece during peripheral machining, the worker or machine operator aligns the lathe or machining center at a right angle to the workpiece while face milling. 

Choosing the best strategy for a given operation, maximizing efficiency, and attaining desired results all depend on an understanding of the differences between different strategies. Figure 1 displays a diagrammatic representation of peripheral (a) and face (b) cutters acting on a workpiece:

This article will examine the main differences between face milling and peripheral milling based on each technique's advantages and best applications.

What Is Face Milling in Machining?

Face milling in machining is a specialized CNC milling process in which excess material is removed from a workpiece using cutting tools. It is distinct from regular milling because of how the cutting tool is oriented. In this technique, the tool's rotational axis is positioned perpendicular to the workpiece, allowing for the effective removal of material from the surface and producing a smooth, perfectly machined finish. For fields in which flat, smooth surfaces are vital, this approach is widely used.

To learn more, see our guide on Face Milling.

How Does Face Milling Work?

Face milling is a methodical machining operation including four fundamental phases. To prevent any slippage during machining, the workpiece is firmly fastened to the machine table. The milling cutter is then positioned such that it is perpendicular to the workpiece, ensuring proper interaction of the cutter—typically a fly cutter—with the material's surface. If required, the proposed movement of the cutting tool is then fine-tuned by changing the feed rate and spindle speed. Finally, machining starts under the guidance of a CNC program, assuring accurate and consistent material removal and workpiece shape.

What Is the Purpose of Face Milling?

The purpose of face milling is to create a flat surface on the workpiece, achieved by cutting with the ends of the cutter rather than the sides. This process is essential for achieving precise, flat, and smooth surfaces on materials, such as plates or bars. Face mills, with their larger diameter compared to the workpiece width, commonly allow for efficient material removal in a single pass, making them ideal for tasks in which a flat, even face is required.

What Is Face Milling Used For?

Face milling serves as a versatile machining process with diverse applications. It levels surfaces, formats workpieces, and incorporates features like hole patterns and recesses. Edge processing is another key function. Despite a somewhat slower pace compared to planers, face milling machines are practical for smaller workshops. In woodworking, they're essential for crafting items like cutting boards and preparing wood-epoxy resin tabletops for further finishing. These machines can also efficiently drill rows of holes, enhancing their adaptability.

What Is Peripheral Milling in Machining?

Peripheral milling is a machining process defined by the employment of specialized tools having cutting teeth along their outside circumference. The workpiece's surface is kept parallel to the cutter's axis by performing this operation on a horizontal spindle machine. It is a procedure made to effectively remove material from a workpiece's exterior, enabling precision contouring and shaping. It is essential in industries that demand detailed and precise workpiece profiles.

How Does Peripheral Milling Work?

Peripheral milling is a systematic machining process that involves several key steps. It begins with securing the workpiece on a horizontal spindle machine, ensuring its alignment with the cutter's axis. A specialized cutter designed for peripheral milling, such as a slab mill cutter or staggered milling cutter, is selected and precisely positioned to engage the workpiece's outer edge. As the cutter rotates, it removes material from the workpiece's periphery, allowing for accurate shaping. This method is crucial for achieving precise external machining and intricate workpiece detailing. Quality checks are performed to ensure the workpiece meets the required specifications.

What Is the Purpose of Peripheral Milling?

Peripheral milling’s goal is the effective removal of large amounts of material from workpieces. This effectiveness comes from using the cutter's sides rather than its tip, which enables faster material removal rates. Peripheral milling maximizes the use of the cutter's whole periphery, unlike face milling, which just exposes the cutter's tip to the workpiece. It is the best option for applications requiring quick material removal and productivity benefits.

What Is Peripheral Milling Used For?

Peripheral milling boasts a broad range of applications, including: slabbing operations to cut large material slabs, profile milling for intricate shaping, slotting to create grooves or slots, straddle milling for simultaneous milling on two parallel surfaces, and slitting operations for precision cutting. Moreover, it's used in the milling of facades or slopes and finds a vital role in rough machining, particularly in mold making, in which material removal rates and productivity are essential considerations.

How To Choose Between Face and Peripheral Milling?

Choosing between face and peripheral milling depends on the specific machining requirements. Face milling makes use of the flat, toothed face of the cutter, which makes it perfect for finishing work to produce textured or smooth surface finishes. For roughing and machining formed surfaces, however, peripheral milling, which relies on cutter teeth near the edge, excels at removing considerable amounts of material. The choice is made based on the finish you want and how much material needs to be removed for your machining operation.

How Does the Main Cutting Direction Differ in Face Milling and Peripheral Milling?

In face milling, the cutting tool is positioned at a right angle to the spindle, resulting in a perpendicular orientation to the milling surface. In contrast, "peripheral milling" involves the cutter moving in a parallel direction to the workpiece's surface, maintaining a parallel alignment to the mill. This distinction is fundamental, impacting the types of cuts and finishes achieved in machining operations, with face milling providing flat surfaces and peripheral milling creating contoured or profiled edges.

How Do Face and Peripheral Milling Differ in Terms of Cutting Depth?

Face milling cutters primarily excel at removing material from the surface of a workpiece to create flat or planar surfaces. The cutting depth is typically quite shallow, often only a fraction of an inch. In contrast, peripheral milling cutters are designed for deeper cuts and can remove material from the edges or perimeters of the workpiece. They are suitable for applications in which greater cutting depths are required.

Do Face and Peripheral Milling Differ in Tool Engagement?

Yes, face and peripheral milling differ in tool engagement. Face milling involves full-width engagement, meaning the entire cutting edge of the tool contacts the workpiece simultaneously. This results in a smoother, more even surface finish since it minimizes tool vibrations and chatter. On the other hand, peripheral milling has partial-width engagement, in which only a portion of the tool's edge contacts the workpiece. This can lead to a less uniform surface finish due to the intermittent contact, which may result in more pronounced tool marks or scalloping.

How Does Face Milling Differ From Peripheral Milling in Surface Finish?

The two unique machining techniques of face milling and peripheral milling take different approaches to producing a surface finish. Face milling produces a finish that is smoother and more consistent since the cutting tool predominantly contacts the flat surface of the workpiece. A less consistent finish may result from changes in how the tool engages the material when peripheral milling, which involves cutting along the edge of the workpiece. Usually, face milling results in a better surface finish.

How Do Face Milling Tools Differ From Peripheral Milling Tools?

Face milling tools and peripheral milling tools are designed differently to suit their respective machining methods. Face milling tools have multiple inserts that engage the workpiece's flat surface, facilitating efficient material removal and a smoother surface finish. Common tools for face milling include face mills and fly cutters. Peripheral milling tools are intended for machining the edges of a workpiece. They typically have fewer inserts and are designed for cutting along the workpiece's periphery. Common peripheral milling tools include end mills and slot drills. These tools are more suitable for contouring and slotting operations.

Does Face Milling Remove Materials Faster Than Peripheral?

No, material removal during face milling is not always faster than during peripheral milling. The speed and effectiveness of the milling process depend on some variables, including: the particular application, machine configuration, tools, and workpiece material. While peripheral milling can excel when cutting along the periphery of the workpiece, optimizing tool contact, and face milling can be useful in other situations, such as attaining smooth surfaces. The particular project should determine which of these methods is best.

Are Face and Peripheral Milling Common Types of Milling in Machining?

Yes, face milling and peripheral milling are standard machine milling techniques. They are commonly used to shape, sculpt, and finish workpieces across a range of industries. While peripheral milling concentrates on the periphery, face milling entails cutting along the workpiece's face. These techniques are fundamental and adaptable, making them crucial in machining processes for tasks like: attaining exact profiles on workpieces, generating flat surfaces, and forming holes.

Summary

This article presented face and peripheral milling, explained each, and discussed their key differences. To learn more about face milling and peripheral milling, contact a Xometry representative.

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