Honing is the finishing process for machining parts with holes and is performed exclusively on honing machines. In some cases, this process can be equated to grinding. The only difference between the procedures is that when honing, only holes can be machined with the final removal of the stock balls.
Machine design
As mentioned earlier, for this type of processing, a honing machine is used, which in its design is very similar to the second group metal cutting machines (drilling). The machine consists of a bed (base), a spindle rotation drive, a device for controlling the machine and setting the part.
During the process, the workpiece remains stationary, and only the spindle rotates, in which the honing head is fixed - a tool for processing holes. The spindle is made in such a way as to enable the tool to perform both translational (up and down) and rotational motion (around its axis). This design feature allows you to process the surface evenly to achieve the necessary roughness and accuracy of the manufactured holes.
Types of machines
Depending on the design and other technical characteristics, a honing machine can be:
- with horizontal and vertical spindle placement;
- single or double spindle, as well as with multiple spindles;
- for external and internal processing, as well as complex (for external and internal processing at the same time);
- with mechanical (manual), semi-automatic and automatic control (CNC machines).
The most common models are: 3G833, 3A833 (vertical honing machines), SS 740V, SS 743 (CNC honing machines), 3K833 (semi-automatic).
Specifications
In order to choose a honing machine for a particular treatment, it is necessary to take into account the main characteristics of each of them. These include:
- Accuracy classes. There are five of them - from H (normal accuracy) to C (ultra-high accuracy). Many models of honing machines produce H and B (normal and high) accuracy.
- Processing Sizes. In this case, this is the maximum and minimum diameter of the hole being machined.
- Processing length. This characteristic is only taken into account if the intended machined holes are too long.
- The maximum stroke of the spindle. As in the previous case, it is taken into account only when the length of the hole being machined is too long.
- The dimensions of the working surface of the table. This characteristic is taken into account only if the workpiece is large.
- Spindle speed This characteristic should be taken into account when it is necessary to process a hole with high technological requirements. Indeed, the final surface accuracy will depend on the spindle speed.
- Engine power. For stronger workpiece materials, a honing machine with high engine power is required.
- Other specifications. For example, the distance from the tool (hone) to the surface of the table and the workpiece, the power of the cooling system, the presence of numerical control.