Form Milling: Types, Process, and Applications

Form milling is used to create custom forms, rounded edges, and detailed profiles that flat tools can’t handle.

In this article, you’ll learn what form milling is, understand how it works, the different types of cutters, and its applications.

What is Form Milling?

Form milling is a CNC machining process that uses a custom tool to cut curves, shapes, angles, and detailed parts in a single production. Unlike regular milling, it uses custom cutters that are shaped to match the final design, like a concave cutter for a rounded or convex edge.

How Does Form Milling Work?

The form milling process runs slower than standard milling, but it is still great for making precise and complex parts. Here’s how it works, step by step:

Tool Selection

Create a detailed part using CAD software. This includes every curve, angle, and size you need. Once that’s done, a custom form cutter is made to match the exact shape of your design.

CNC Programming

Convert the design into CNC code using CAM software. This code tells the machine exactly how to move, setting the tool path, cutting speed, and feed rate.

Workpiece Setup

Set up the machine by securing the workpiece, installing the cutter, and double-checking the machine settings, making sure everything’s in the right position before cutting.

Cutting Process

The CNC machine follows the programmed toolpath, moving the cutter to shape your part as designed. It removes material smoothly and precisely in one cut, reducing the need for extra passes or manual finishing. With advanced multi-axis systems, you can cut complex parts in one setup without moving the part.

Finishing and Inspection

After cutting, you inspect the part using tools like CMM or laser scanner to make sure it meets all the specs. If needed, you can do some light finishing, but most parts are nearly ready to use right after the form milling process.

Materials Used for Manufacturing the Form Milling Cutting Tools

Form milling cutting tools are made from strong materials, and these are the most commonly used:

High-Speed Steel (HSS)

HSS is tough, affordable, and works well for general form milling at high speeds without breaking.

Tungsten Carbide

Carbide is harder and lasts longer than HSS. It’s great for cutting tough materials like stainless steel and titanium, with less downtime.

Ceramic

Ceramic tools handle high temperatures and fast cutting, which is why they are ideal for hard metals in aerospace and automotive work.

Powdered Metal Alloys

Made from pressed metal powders, these tools balance cost and performance. Use them for custom form cutters needing both toughness and wear resistance.

Diamond-Tipped Tools

These are extremely hard and perfect for cutting ultra-hard materials like ceramics and composites while providing a smooth finish.

Coated Materials

Many cutters have coatings like titanium nitride (TiN), titanium carbonitride (TiCN), or aluminum titanium nitride (AlTiN) to reduce heat, lower friction, and extend tool life, especially with high speeds.

Different Types of Form Milling Cutters

Here are the most common types of milling cutters you’ll work with when doing form milling:

Concave Cutters

Produces inward curves, great for grooves, rounded slots, or indented features. These cutters help you create smooth, precise curves where the surface dips inward.

Convex Cutters

Produces outward curves, perfect for parts that need a bulging or raised shape. They’re great for adding rounded edges or raised features that stick out from the part.

Corner Rounding Cutters

In a form milling operation, you use corner rounding cutters for smooth, rounded edges on a part. They improve the appearance of your part and remove sharp edges, reducing friction and stress. These cutters come in different sizes.

Form Tools

These cutters are designed to create a variety of custom shapes for both external and internal surfaces. You can use them for machining splines, grooves, and other detailed parts

Advantages of Form Milling

Below are the benefits of using form milling:

High Precision: You can achieve extremely tight tolerances as small as 0.01mm.

Efficiency: You can create complex shapes in one pass. It saves time, especially for projects with large quantities.

Versatility: You can use form milling on many materials.

Complex Shapes: Form milling is perfect for complex features, curves, and detailed parts.

Cost-Effective for Big Projects: Using form milling when making a lot of the same part can cut down labor and machining time.

Disadvantages of Form Milling

Using form milling also comes with a few disadvantages. Here are some you should consider:

High Tool Cost: Custom-designed cutters usually cost more, making it a problem for small jobs and tough materials.

Skilled Workers Needed: It requires skilled operators to prevent errors and to maximize the use of the form milling tools.

Tool Wear and Maintenance: Working with hard materials or cutting at high speeds wears out tools too quickly. You’ll need to fix or replace them frequently, which adds to your costs.

Limited for Some Materials: It needs special cutters and machines for very hard materials like ceramics.

How to Choose a Form Milling Cutter?

When selecting a form milling cutter, you need to check a few important factors, like the following:

Material Compatibility

Use a cutter material that matches your workpiece. Use carbide for hard materials like stainless steel, HSS for softer ones like aluminum, and ceramic for high-temperature jobs.

Cutter Design

Choose a cutter shape that matches your profile. Whether it's concave, convex, corner rounding, or a custom form. Complex shapes may need custom cutters.

Machining Speed

Select a cutter that can handle your cutting speed. Carbide is great for high speeds, while tougher jobs might need slower feeds to protect the tool.

Quality and Durability

Go for high-quality cutters to reduce tool changes and downtime. Carbide and ceramic cost more upfront, but last longer and perform better.

Tool Coatings

Look for coatings like TiN, AlTiN to boost wear resistance, reduce friction, and extend tool life, which is ideal for hard materials and high-speed work.

Applications of Form Milling

Form milling is a flexible process you can use in many industries, such as the following:

Automotive Industry

You can use form milling to make detailed shapes for engine parts, transmission components, and custom interior pieces.

Medical Equipment Industry

You can use form milling to produce implants, prosthetics, surgical tools, and custom dental parts. Precision is important in this field, and it ensures a perfect fit and smooth finish for each piece.

Electronics Industry

You can use it to machine small, precise parts like casings, slots, and grooves for devices.

Industrial Machinery

It is great for making gears, cams, and brackets. A form milling diagram can help you plan tool paths for creating these complex shapes accurately.

Aerospace Industry

With form milling, you can make parts with curves and contours like turbine blades, brackets, and fuselage parts while meeting strict quality standards.

Tooling Industry

If you work with molds, dies, or special tools, form milling lets you shape detailed profiles quickly for stamping, casting, and molding.

Energy Sector

It’s used for parts in wind turbines, oil drilling machines, and power systems, making strong and high-performance parts for tough jobs.

Consumer Goods

You can also use form milling to create custom shapes for appliances, furniture parts, and sporting goods, like blenders, washing machines, bicycles, and golf clubs, adding function, style, and good performance.

Form Milling vs Other Milling Types

Now, let’s compare form milling with other common types of milling.

Form Milling vs Flat Milling

Flat milling handles small flat features. Form milling is capable of producing intricate, contoured shapes with greater precision.

Form Milling vs Slot Milling

Slot milling is limited to simple straight features. Form milling produces a variety of custom, complex features.

Form Milling vs Contour Milling

Contour milling may need multiple operations for complex shapes. Form milling produces precise profiles in a single operation

Form Milling vs Face Milling

Face milling is ideal for large flat, open surfaces. Form milling handles complex, detailed shapes.

Form Milling vs Gear Milling

Gear milling focuses on cutting gear teeth only. Form milling, including gear form milling, adapts to produce a variety of detailed profiles.

For Milling vs CNC Milling

CNC milling covers a range of machining processes. Form milling is a specialized operation for intricate profile cutting using custom cutters.

Conclusion

When you need precise, detailed, and customized shapes, form milling is the best option. Many industries rely on it to produce high-quality, complex parts quickly and accurately.

For your next project with complicated curves or profiles, partner with DEK. With advanced form milling machines and expert services, we deliver the precision, efficiency, and quality your production needs. Contact us today to get started!