What Are The Different Types of Knurling Patterns in CNC Machining?

Need a better grip on your parts? Or maybe a unique look? Smooth surfaces can be slippery or just plain boring, but there's a simple solution.

The main types of knurling patterns are straight, helical (or diagonal), and diamond (or cross) patterns. Each offers different grip characteristics and visual appeal for your CNC machined parts.

I've seen a lot of parts come through my shop, Worthy Hardware, and knurling is a feature many customers ask for. It's amazing how such a small detail can make a big difference. If you want to understand these patterns better, let's explore them. You'll see it's quite interesting.

What is the type of knurling pattern?

Confused about what a knurling "pattern" really means? It's more than just random marks on a surface. It's a carefully designed feature.、

A knurling pattern is a specific, repeated texture. It's pressed or cut into a material, usually metal. This is done to improve grip or for looks.

So, a knurling pattern is basically a set of uniform ridges or indentations on the surface of a part. We create these patterns for a few key reasons.

Why Use Knurling?

The most common reason is for grip. Think about tool handles, control knobs, or thumb screws. A knurled surface makes them much easier to hold and turn, especially if your hands are a bit greasy or wet. I remember working on a project for some custom tools, and the client was very specific about the knurl because it directly impacted how well users could operate the tool.

Another reason is aesthetics. A knurled pattern can give a part a more professional, industrial, or even decorative look. It just makes things look more finished sometimes.

Sometimes, it's also for minor wear resistance or to prepare a surface for press-fitting into another component. At Worthy Hardware, we often advise on the type of pattern based on how the part will be used. It's a functional detail that also looks good.

What are the different types of bar knurling?

Wondering what textures you can add to bars or round parts? Not all knurls are the same. There are several distinct patterns you can choose from.

The main types for bars are straight, helical (or diagonal), and diamond (or cross) patterns. Each gives a different kind of grip and visual style.

When we talk about knurling on bars or cylindrical parts, we usually see a few common styles. Each one offers a different feel and look. I've found that understanding these helps my customers, like Mark Chen from Canada, choose the best option for their CNC machined parts. He often needs a good balance between quality and cost for the components he sources from us in China.

Straight Knurling (Axial)

This pattern has ridges that run parallel to the axis of the part. Imagine lines going straight up and down if the bar is standing. It's great if you mostly need to prevent the part from twisting in your hand. It gives good axial grip.

Helical Knurling (Diagonal/Spiral)

Here, the ridges are at an angle, like a spiral. They can be left-hand or right-hand, or sometimes both crossing. This type gives good grip for both twisting and for pushing or pulling along the axis. We often see angles around 30 degrees for these.

Diamond Knurling (Cross)

This is probably the most common one I see. It's made by two sets of helical knurls, one left-hand and one right-hand, that cross each other. This creates a pattern of raised diamond shapes. Based on my experience and your insights, there are two main variations here:

• Rhombic (Diamond): Typically formed with 30° helical patterns crossing. This creates true diamond shapes and is very popular for general grip.

• Square (Male Diamond): Often formed with 45° helical patterns crossing. This creates more square-like raised points and can offer an even more aggressive grip.

Here's a quick comparison:

Choosing the right one depends on the application.

What is CNC knurling?

How is knurling done with modern machines these days? It's not just a manual task anymore. CNC machines offer much more control and precision.

CNC knurling is the process of creating knurled patterns on a workpiece. This is done using a Computer Numerical Control (CNC) machine, usually a lathe, for high precision.

CNC knurling is how we make these patterns with high accuracy at Worthy Hardware. "CNC" stands for Computer Numerical Control. So, instead of an operator manually controlling the machine, a computer program tells the CNC machine, often a CNC lathe for cylindrical parts, exactly what to do.

How CNC Knurling Works

A special knurling tool, which has one or more hardened wheels with the reverse of the desired pattern, is mounted on the CNC machine. The program controls the tool's feed rate (how fast it moves along the part), the pressure it applies (for form knurling), or the depth of cut (for cut knurling), and the spindle speed of the workpiece.

Advantages of CNC Knurling

The benefits are significant:

• Precision: The patterns are very accurate and consistent from one part to the next. This is crucial for our B2B clients who need wholesale orders with tight tolerances.

• Repeatability: We can make thousands of identical knurled parts.

• Complexity: More complex or fine knurling patterns can be achieved.

• Efficiency: It's faster for mass production, which helps keep costs competitive, something Mark, my customer, always appreciates.

It's a big step up from purely manual methods, ensuring the quality that my customers expect for their custom CNC parts. We can handle parts up to 62” in length on our lathes.

What are the methods of knurling?

Are there different ways to actually make these patterns? It's not a one-size-fits-all process. There are two main methods used to achieve knurling.

The two primary methods of knurling are cut knurling and form knurling. Cut knurling removes material, while form knurling displaces material to create the pattern.

When we decide to add a knurl to a part, there are generally two ways we can go about it. Both methods have their place, and the choice often depends on the material, the desired precision, and the part's design.

Form Knurling (Pressure Knurling)

This is probably the more common method.

• Process: With form knurling, one or more hardened wheels with the pattern are pressed hard against the workpiece. The material of the workpiece flows or deforms under this pressure, squeezing up to form the ridges of the knurl. No material is actually removed.

• Effects: Because material is displaced, the diameter of the knurled section will increase slightly.

• Pros: It's generally faster and puts less wear on the knurling tool itself.

• Cons: It can induce stress in the material. It might not be suitable for thin-walled tubes as it could distort them.

Cut Knurling

This method is different.

• Process: Cut knurling uses tools that have sharp cutting edges. As the tool engages with the workpiece, it actually cuts small chips away from the material to form the pattern.

• Effects: The diameter of the part doesn't really change, or changes very minimally.

• Pros: It often produces a cleaner, sharper pattern, especially on tougher materials. It also puts less stress on the workpiece and the machine's bearings.

• Cons: It's generally a slower process, and the cutting tools can wear out more quickly.

Here’s a simple table to compare:

At Worthy Hardware, we assess the project requirements, including material (we handle over 100 types, from aluminum to PEEK) and desired tolerances (we can hold +/- 0.005" or tighter), to choose the best knurling method for our clients.

Conclusion

Knurling adds grip and style. Straight, helical, and diamond are key patterns, made by forming or cutting, often with precise CNC machines. Worthy Hardware can help.