Knurling. The Knurling Process on a Lathe

Knurling

All knurls made in manufacturing shops are classified as fine, medium, coarse, straight, and diamond. The knurling tool consists of small hardened rollers with a knurled pattern on their surface.

Knurling: The process of adding indentations and ridges to a part’s surface using tools called knurls.
Parts that will be gripped by hand, turned, or adjusted, such as nuts, screws, or tool handles, are easier to work with if they are knurled. For example, like a fitness dumbbell bar.

We can provide a safer way to work by knurling tool handles that could otherwise cause accidents if held with sweaty or oily hands.
We can perform this knurling process on such cylindrical surfaces on lathes.

For this operation, we’ll need a knurling tool holder. A knurling tool holder is a piece of equipment with freely rotating knurl wheels mounted on it.

types of knurling tool holders single wheel 2-wheel adjustable

Knurling tool holders come in single-wheel, 2-wheel, or more-wheel adjustable types.

Knurl wheels also come in different types depending on preference: coarse, medium, fine tooth, straight tooth, and diamond tooth.

The principle of the knurling operation on a lathe is that the knurl wheels, in contact with a cylindrical part rotating on its own axis at low speed, advance slowly parallel to the part’s axis and form patterns on the part.

Knurling Operation on a Lathe

When starting the knurling process, care must be taken to ensure both wheels form the diamond pattern with matching, equal marks. When the knurling process begins, the wheels should be pressed firmly against the part; once you’re sure they’re making a mark, the pressure should be reduced.

The knurled section should be clean, sharp, and diamond-patterned as shown in the figure.

If it starts well, the knurling process usually goes well all the way to the end with a medium or fairly large feed. If the diamond pattern doesn’t start well, start from another section on the part; if the result is good this time, the defective section can be corrected by passing over it again.

Knurling process animation

Knurling Process Order

The workpiece is mounted as short as possible either between two centers or between the chuck and a center, and the length of the knurl is marked.
The knurling tool holder is mounted in the tool post at center height, at an angle of about 5 degrees toward the left.
The lathe spindle is set to a low, suitable speed.

4- The knurl is brought into contact with the surface of the workpiece and advanced by about 0.1 to 0.2 mm.

5- Once knurl marks are seen forming on the surface of the workpiece, the carriage is moved slowly. (Automatic feed should preferably be engaged)

6- When the end of the knurled section is reached, the machine is stopped and the spindle is reversed. This operation is similar to thread cutting on a lathe.

7- During the operation, oil should be continuously applied to the surface of the workpiece with a brush or oil can.