Knurling is a post-finishing technique that gives a workpiece’s surface a rough pattern.
Although knurling was done by hand in the past, the invention of turning and milling machines has allowed for the creation of increasingly intricate and accurate patterns.
What’s Knurling?
To create a rough, patterned surface, a workpiece or a portion of it is deformed during the knurling manufacturing process. Though it is sometimes done on flat surfaces as well, it is mostly done on round or cylindrical elements.
The surface material is sliced or formed to produce the patterns. To get the right look for the material and application, different patterns call for different knurling tools.
Vertical, horizontal, and angled lines can all be seen in knurling designs. Among the most prevalent patterns are:
Straight: made up of either vertical or horizontal lines.
Straight lines that slope to the right or left (often at a 30° angle) are called diagonals.
A diamond is made up of lines that slope left and right toward the workpiece.
Concave, convex, beveled, and square knurls are more knurl designs.
Additionally, there are sorts of knurls according on their location:
Band: over a certain section of the workpiece.
Complete: the entire surface is knurled.
Internal: the internal diameter is knurled.
Face/Milling: on the workpiece’s flat surface.
The tapper is a conical knurl at the workpiece’s end.
Applications for Knurling: When Is It Used?
For instance, most individuals have come across knurled surfaces when playing darts or on weightlifting bars in gyms.
Beyond these examples, however, there are innumerable uses for knurling in a variety of fields, including jewelry, electronics, manufacturing, maintenance, and the arts.
Knurling components increase the material’s surface friction by adding ridges. These parts’ ridges make it possible to improve assembly coupling. Tool handles, pistons, nuts, and bolts are a few examples of uses.
Consumer electronics: Commonly seen in household appliances, small knobs and dials improve grip, usefulness, and appearance.
Jewelry in the arts: Beautiful knurling patterns have been used into bands, wedding rings, ornamental motifs, and even everyday household items.
Repair: The raised sections around the depressed areas of the rolled-in knurled surface can compensate for wear on the component. As a result, knurling is occasionally employed as a repair technique, but it is less popular these days because finding replacement components may be a more affordable choice. In order to continue operating, worn-out piston cylinders were frequently knurled.
What Kinds of Materials Are Knurled?
Metal: typical metals include brass, stainless steel, mild steel, and aluminum. Harder metals are often machine knurled since they are more challenging to imprint.
Plastic: Because the material is more prone to failure and has a lower heat resistance, knurling plastics calls for a more sensitive technique.
Wood: Although wood may be knurled, the procedure is more complicated than it is for other metals. Checkering is the most popular approach, while knurling is actually only effective on hard woods and is restricted to basic patterns.
Knurling Method
The knurling wheels or dies are used to create a knurled pattern on the surface material. In order to produce complex patterns, these tools are forced against the workpiece and cause deformation.
Pitch, angle, hole diameter (internal knurling), knurl and blank diameter, face width, and grade (teeth per inch) are some of the criteria to consider before beginning the procedure.
There are two methods for doing the knurling process : manually and using a machine.
Knurling of the Hand
To generate certain patterns and distort the metal, hand tools are pushed against the workpiece. These indentations are made on the workpiece using a tiny roller tool. Depending on their use, these instruments have a variety of patterns and designs.
Because a knurling tool is more cost-effective than a lathe machine, hand knurling is a fantastic choice for smaller tasks. Since it needs little accuracy, knurling a tiny metal pin to bite into a plastic molding’s diameter is an example.
Knurling of machines
The knurling technique was made better by lathe machines, but CNC-controlled turning machines have increased the precision and degree of control even further.
A cutter or knurling wheel is forced against the workpiece’s surface after it has been secured onto the lathe. It is possible to generate patterns with different dimensions by adjusting the machine feed and RPMs. As the workpiece moves around the lathe, the tool chips away material to create a rough pattern. Compared to hand knurling, this technique is quicker and more accurate, especially for repetitive tasks.
For an accurate output, the workpiece must be positioned in the middle of the lathe. However, this process produces a lot of heat since the workpiece is constantly rotating as its surface comes into contact with the roller. To stop the workpieces from galling, flaking, and accidentally welding to the knurling tool, lubricants such as oil are utilized.
Although they are essentially designed to function like lathes with the help of Computer-Aided Manufacturing (CAM) software, milling machines may also be used for knurling. On the other hand, flat surfaces may be patterned using milling machines.
