Angle Milling: Definition, Process, Types, and Tips

Angle milling is a machining process that involves removing material from the edge or end of a workpiece at non-orthogonal angles to the workpiece's axis. This process is used to create beveled edges, chamfers, roughing complex curved surfaces, or creating angled features on the workpiece.

This article will discuss what angle milling is, its process, types, and tips.

What Is Angle Milling?

Angle milling is a machining process used to remove material from the edges or faces of a workpiece at an angle other than 90° to the machine axis. This process is performed using a milling machine with an adjustable quill, a rotary table, a fully orientable work clamping setup, and/or an angled cutting tool. Angle milling creates beveled edges, chamfers, and more complex angled features on the workpiece. In the most basic milling setup, where neither the workpiece holder nor the machine spindle axis can be adjusted, excellent angle milling results can still be achieved by the use of specialist angled cutters. The simplest of these is a countersink tool, that can be used to apply a bevel to the lip of a cylindrical hole. A stiffer version of the same cutter can be used in climb or conventional milling to cut on one side, for holes larger than the cutter diameter, or for irregular holes and straight edges.

Similar results can be achieved using a range of single and double-angle specialist side cutters that allow the selection of fixed and precise angles of surface to be extracted from the part.

Is Angle Milling and Angular Milling the Same?

Yes, angle milling and angular milling are essentially the same machining processes. Although some distinctions can apply. For example, angle milling typically refers to the process of milling at a specific angle relative to the workpiece's axis. Angular milling can have a slightly different interpretation and might refer to the milling of angular surfaces or contours, including angle milling, in a more generalized process description of the creation of complex and potentially multi-angled features.

What Is the Purpose of Angle Milling?

The purpose of angle milling is to machine workpieces by removing material at a specific angle or selecting non-orthogonal axes for the workpiece/machine. This process serves various purposes in machining and manufacturing such as: beveling, production of complex geometries, welding preparation, improving aesthetics, extracting features like angled grooves, slots, and undercuts that may be required for machine function or part engagement, providing clearance or preventing interference between moving parts within a machine, edge protection, and weight reduction by removing material that is less involved in strength/load bearing.

What Are the Features of the Angle Mill Machine?

Milling machines are versatile tools used for removing material from workpieces to create specific shapes or surfaces at various angles. The specific angled milling capabilities of a mill setup can vary extensively, depending on various machine features.

The spindle is the primary component that holds and rotates the cutting tool. It is responsible for material removal during milling. The machine table is where the work is secured. On basic machines, it can be moved on three axes but not rotated or angled. On more complex machines, the work-holding apparatus can include manual adjustment (a rotary table) or full rotational powered-axis motility (on a 5+ axis CNC machining center).

Milling machines use various cutting tools, such as end mills and face mills, which can be applied using an angular preset of the spindle axis, and an adjustment of the workpiece angle by various means. However, special angled cutters can also be employed to deliver angular offset cuts, alone or in combination with other machine capabilities. More advanced machines are equipped with computer numerical control (CNC) systems that allow for automated and programmable machining operations. Various degrees of freedom can be dynamically adjusted as cutting proceeds, allowing greater toolpath efficiency and fewer tool changes for complex outcomes. Various work-holding devices, such as: vises, clamps, and custom fixtures can be employed to hold workpieces in appropriately angled modes, to allow vertical cutters to extract angled faces.

How Much Does Angle Milling Cost?

The cost of angle milling varies based on several factors such as:

1. Material: The type and hardness of the workpiece material can influence tool wear and machining time, significantly altering costs.
2. Complexity: More intricate bevels and angles will require additional setup time and tool changes, resulting in higher costs.
3. Precision: Tighter tolerances and higher precision requirements may increase costs as they demand more careful tool selection and setup. Angle settings provide additional axes for error in setup or toolpath and angular tolerances can be harder and more costly to control because of this. 
4. Tooling: The choice of angular milling cutter can impact costs, as specialized cutters cost more due to the relatively small demand for them.

How Does Angle Milling Differ From Traditional Milling?

Angle milling and traditional milling share the same fundamental principle of material removal, but they differ in terms of the machining angle. In angle milling, the material is removed at specific angles other than 90 degrees relative to the workpiece's axis. This allows for the creation of beveled edges, chamfers, or angled features on the workpiece. Traditional milling, on the other hand, typically involves cutting at right angles to the workpiece's axis, resulting in flat surfaces or features. The key distinction is that angle milling focuses on machining at non-90-degree angles, enabling the creation of more complex geometric features and angled surfaces.

To learn more, see our What Is Milling: How It Works, Purpose, and Process article.

Is Angle Milling Better Than Angle Grinding?

It depends. Angle milling is a precision machining process that is used to extract non-orthogonal surfaces from a workpiece. This might involve light beveling of feature edges to remove sharp corners. It can also be used to apply a lead-in for holes that must receive a close-fit component.

An angle grinder, on the other hand, is a freehand grinding wheel that is used for freeform surface alteration and cutting, including approximate beveling. While some applications in which beveling is required may achieve satisfactory outcomes by use of a manual process such as angle grinding, these would be limited by differentials in the quality of the outcome.

The two processes have very little relationship to each other. Both find general applications in industrial applications, but there are few common applications in which a choice is made between them.

How Does the Angle Milling Process Work?

Angle milling is the machining of edges, surfaces, or internal features of a workpiece at specific angles with cutters or cutter axes set off 90° to the workpiece's axis. It is a versatile process that allows for the extraction of beveled edges, chamfers, and angled features on workpieces, making it a valuable technique in various industries. The complexity of angled features and surfaces that can be created depends heavily on the capabilities of the equipment, the availability of specialist cutters, and the ability to create custom fixtures to support/retain workpieces in non-right-angled positions.

What Are the Types of Angle Milling Cutters?

Angle milling cutters come in diverse types and sizes, tailored to specific machining needs and applications. Listed below are the two types of angle milling cutters:

1. Single Angle Milling Cutters

These are designed to create a single angle on the faces/edges of the workpiece. They come in various angles, such as 45 degrees or 60 degrees, or they can be custom-made to any required angle if the work value permits/requires this. They are disc cutters with cutting faces around the circumference.

2. Double Angle Milling Cutters

These are disk tools with differently angled cutting edges on each side of the circumference, allowing the extraction of two angles without a tool change.

How to Perform Angle Milling?

Angle milling has exactly the same setup and operational requirements as typical milling, with the addition of some angle settings that differentiate the process. The workpiece is securely clamped to the bed or worktable of the milling machine using appropriate work-holding devices like: clamps, vises, or fixtures. This can involve the use of a rotary fixture that is manual or CNC controlled, allowing the angle of presentation to be manually or dynamically set. The appropriate cutting tool, often an end mill or a special cutter designed for angle milling, is then selected based on the specific machining requirements. Where a specialist cutter that has the required angle integrated into it is used, this allows angle milling without any other setup specifically related to the cutter angle.

Set the spindle speed and feed rate based on the material type and machining requirements to ensure efficient material removal without causing tool wear or overheating. Angled tools can have some specialist requirements in this regard, as options in flute angle and number of flutes can be more limited than for general cutters. The milling proceeds as the cutting tool engages with the workpiece. The tool advances along the workpiece and the material is removed, extracting the angled surface or feature in a single plunge (Z-axis) cut or multiple X/Y cuts with Z steps. A coolant stream is used to cool the cutting tool and workpiece and to aid in chip evacuation.

When To Use Angle Milling?

Angle milling is used when beveled edges, chamfers, or angled features are required on workpieces. The process can do the following: remove sharp edges and burrs from workpieces, create beveled edges on parts for welding to ensure deep penetration and fusion, deliver improved aesthetics of components, prevent or reduce stress concentrations in components, create functional features requiring specific angles, reduce part weight, and act as roughing in preparation for complex and compound curvature surface cutting.

What Industries Use Angle Milling?

Any industry that uses milled components is a potential user of angled milling, to produce beveled, straight-angled, curved angled, and complex surfaces. Angle milling is particularly valuable in the following industries:

1. Aerospace applications, in which machining complexity is less important than final part weight. Angle milling is used to remove low-stress material for weight saving and improve stress distribution by easing sharp corners.
2. Furniture production, in which aesthetic considerations override basic cost concerns, allows complex surfaces to be used for visual appeal. Sports equipment, in which handling is expected, to remove sharp edges.
3. Machinery manufacture, in which both reliefs of sharps and reduction of weight in fast-moving parts require/allow complex surfaces and additional machining costs.

What Materials Are Suitable for Angle Milling?

Any material that is suited to milling is amenable to angle machining. Listed below are some materials:

1. Tool/alloy, stainless, high-, and medium-carbon steels.
2. All aluminum grades except pure aluminum.
3. Exotic metals such as: titanium, advanced nickel alloys, tungsten, niobium, and tantalum.
4. Engineering plastics.
5. Rigid composites.
6. Ceramics.
7. Stone.

Is Angle Milling Excellent for Cutting Metal Pipes?

Yes. There are two forms of angle milling that are applicable to metal pipes. It is common to bevel the cut edge of pipes, either internally or externally or both, to remove sharps, to ease engagement with close-fit components, and to prepare pipe ends for butt and lap joint welding. It is also common to angle-cut the ends of pipes to a non-orthogonal profile. In both cases, angle milling is an option for processing components from pipes.

Is It Possible To Use Angle Milling on Stainless Steel?

Yes, stainless steel responds well to angle milling. The best results are achieved by the use of carbide insert tips and liberal coolant application.

What Are the Tips for Angular Milling?

Angular milling requires attention to detail and precision to deliver useful and high-quality outcomes. Listed below are some tips to remember:

1. Ensure that the job is possible and that the workpiece is securely and accurately set up in the work-holding device or fixture.
2. Choose sharp and undamaged cutters suited to the angle and material type.
3. Use accurate measuring instruments to set the correct machining angle, if adjusting the machine is the right approach. If the angle is set by the cutter, ensure it meets your requirements.
4. Follow safety protocols including the use of PPE and machine guards.
5. Avoid irregular feeds to reduce tool wear and deliver a good surface finish.
6. Use appropriate coolant to reduce heat and air in chip evacuation.
7. Use effective workpiece clamping to minimize vibrations and ensure stability during machining.
8. Set appropriate spindle speed and feed rates according to the material and cutter type.
9. Check the alignment of the milling machine's worktable and/or head using a denial gauge or other suitable alignment system, to ensure accurate cutting.
10. Regularly check the cut angular and linear dimensions and make any necessary adjustments during machining.
11. Inspect the workpiece after angular milling to verify that linear and angular dimensions and surface finish meet specifications. Perform any required finishing or deburring.

What Is the Difference Between Angle Milling and Conventional Milling?

Angle milling and conventional milling are closely related but distinct machining methods. At its core, angular milling is simply one form of milling, and generally only an element of an otherwise conventional milling process, rather than a distinct process

Angle milling delivers cuts at specific angles other than 90° to create beveled edges, chamfers, or angled features. The process uses specialized angular cutters designed for bevels or chamfers, or angled machine setups, or a combination of the two. It is employed when beveled or chamfered edges are needed for aesthetics, weld preparation, or reducing stress concentrations.

Conventional milling, on the other hand, generally involves material removal perpendicular to the workpiece and machine axes. Standard end mills and milling cutters are used, although these can serve in angle milling when the spindle or workpiece is angled appropriately. Conventional milling is used for general milling operations, such as: facing, slotting, and contouring.

Summary

This article presented angle milling, explained it, and discussed its process and various types. To learn more about angle milling, contact a Xometry representative.

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