We see that word a lot in rearsets and other things. I don't know about this process, but it looks amazing. Yeah, well, well, I know something about it, you know? Do you mean like that? The one with the jagged edges. It's good, isn't it, the knurling process. Ahaha!
Anything with a serrated finishing isn't necessarily knurling.
WebiQ is here to bring you a little happiness and motorcycle knowledge. The file is serrated, but it's not knurled!
But actually ......
Any metal surface is knurled as long as it is machined to a geometric jagged edge. What's up with you, you mucker! You tricked me! I'm sure you'll say ......, but well, relax.
The term "knurling"
Knurling is not a technical term in the motorcycle industry, but a term commonly used to describe a form of metal surface processing. Of course, the vast majority of the general public is not involved in metalworking, so I don't care about that.
The term "knurling" is used to describe the process of knurling the metal surface to prevent slippage.
For example, it is used in a wide range of applications, such as the volume control dial for high-end audio equipment, the grip of a bench press shaft, the shaft of a precision screwdriver, and the grip of a high-end mechanical pencil.
As you may have noticed, there are not only jagged meshes like the footpeg bar, but also knurled vertical stripes only. The shaft of a precision screwdriver, for example, is this longitudinal knurling process.
This is knurling in the broadest sense of the word. So if a metal surface is knurled and non-slip, it is knurled, whether it is reticulated, striated, or blocky.
The Motorcycle Industry's "Knurling"
However, the situation is a little different when you focus on the narrower definition of the motorcycle industry. When you put a serrated edge on a metal surface to prevent slippage, it is generally called differently depending on the method of applying the serrated edge (the processing method to make the metal surface serrated).
High-grade rearsets are often machined with a machining center to prevent slippage, and this process is generally called "cutting" or "stone-cutting". It's not often referred to as knurling.
So what knurling in the motorcycle industry means is often a serrated non-slip surface that is not machined. In the broadest sense of the word, it's a knurling process, whether it's cutting or not.
But can you differentiate yourself by changing what you call it, and how is that non-slip process manufactured? I don't think it's okay to do so because it makes it easier to make the decision. There's no benefit to boasting of knowledge in the broadest sense of the word by pointing to a footpeg bar manufactured by cutting and saying, "This is also knurling!". The more easily the meaning is conveyed, the better, of course.
What is the knurling process that is not machined?
As mentioned above, the term "knurling" in the motorcycle industry generally refers to a form of machining that is not machined or cut.
The manufacturing method uses a rather surprisingly primitive method of pressing a super-hard roller, which is placed opposite to the pattern you want to knurled, against the area you want to knurled, to make an indentation.
For those of you who are having trouble visualizing it, if you remove the handle grips and roll them around on the dough, you'll see a pattern on the surface of the dough that is the opposite of the handle grips, right? This is so because the handle grip is stiffer than the bread dough, but the knurling process does the same thing.
By the way, it's not so easy to get a beautiful pattern, although I call it primitive. The super-hard roller to form serrated edges is rarely pressed against the material in one shot. In order to form a nice serrated edge, the ultra-hard roller must pass exactly through the same position every time. This is difficult.
If you work properly, you will always end up shifting and carving a knurled pattern with a sweet edge (such a condition is called "sleepy" or "sweet").
Each Characteristic
Thus, even though the knurling process is the same in the broadest sense, it turns out that in the motorcycle industry, there are two types of knurling: machined (cutting) and knurling. Of course, each has its own characteristics, so I'll zap them together.
In the case of so-called cutting
Since the process involves digging a groove in the area where you want to apply a non-slip finish, the edges of the groove are sharp and pointed. If the pattern looks like a row of fine pyramids, the tops of the pyramids will be sharply pointed, and if the pattern is a groove type, the difference between the groove and the material plane will be clicked! This will be the stage.
After all, it has a sharp edge, so the bite is excellent. It provides the best snagging performance when you consider the inherent effectiveness of anti-slip. If you have a footpeg bar, for example, that was originally designed to provide the best slip resistance when stepped on by the bottom of the boot, the edges are so sharp you can't help but bleed when you hold it in your hand.
The disadvantage is that each item must be machined one by one, which is very time-consuming. For this reason, the price increases.
In the case of the so-called knurling process
Depending on the pattern engraved on the ultra-hard roller, it's basically a matter of "pressing down to transfer the pattern". The part that is pressed tightly is depressed, and the part that is not pressed is depressed, and as a result, an uneven pattern is transferred.
However, the edges of the steps and other areas tend to be rounded because the extruded and raised areas are a collection of materials pushed from around them. In the case of a pattern that looks like a series of small pyramids, the top of the pyramid is not likely to be sharp because it is just a collection of materials pushed up from all sides. Rather, the apexes are usually not completely raised and the apexes are depressed.
In a pattern where a groove is dug, the difference between the groove and the material plane is not as sharp as in the cutting process. Rounded edges also mean that they do not bite as well, so the non-slip effect tends to be lower than with a machined pattern.
However, the price of the product is lower because the patterns can be mass-produced by simply rolling a super hard roller. This is fascinating.
Some people think that it doesn't have to be an expensive machined part, especially if it's supposed to wear out in a relatively short period of time (for example, a racing footpeg bar). Also, in many cases, aluminum handlebars are knurled to prevent the left side grip from slipping out, but the knurled handlebars are effective enough to prevent slippage in such areas, so there is practically no point in doing the expensive machining process.
Each of these has its own advantages and disadvantages, but if you can choose the right one for your application while balancing the performance you want with the price, you'll be satisfied.
Click here for the Footpegs on Webike!
Bonus: Speaking of which, isn't a file knurled?
The same pattern is repeated on the surface with uneven projections forming a rough surface ...... that is a file. This alone makes me think it's the equivalent of "knurling in the broadest sense of the word", doesn't it? However, this is completely different, and the file is made in a very special way.
Unfortunately, I'm not familiar enough with files to call myself a file fanatic, so maybe there are files that have been cut to form a file tooth, or maybe there are files that have been knurled to make them stand out. However, the majority of files are not made in that way.
So how does it form those rough edges? ...... and what a surprise, it makes each one of those rough edges by hammering in a tagline. Of course, you can buy a file at 1 USD shops because it's mechanized and can be used for continuous tagging, but it's a bit of a surprise.
Even mass-produced products with mechanized grindstone work require a great deal of special know-how in the manufacturing process, so they can't be mass-produced fully automatically.
Knurling is great, but so is filing!