What Is Honing Machinery?
Honing machinery is a machine tool used to finish the inside surfaces of holes in hollow structures. It achieves the desired surface roughness with high accuracy, ensuring a high degree of roundness and cylindricity. A unique feature of honing is cross-hatching, which will be discussed later. The honing process requires a minimal grinding allowance, maintaining high accuracy of machined holes.
Applications of Honing Machinery
Honing machines are primarily used to grind cylindrical inner surfaces, such as cylinders in automobile and industrial machinery engines, as well as hydraulic and pneumatic equipment. They are also used to finish the inside diameters of gear parts, such as pinions in planetary gear mechanisms, which are crucial for gear-shifting mechanisms in automatic transmissions and forward/reverse switching in continuously variable transmissions (CVTs).
Honing Machinery Principle
Honing machinery grinds by pressing a bar-shaped grinding tool, known as a honing stone or horn, against the inner surface of a workpiece. Attached to a honing head, which is in turn attached to a core rod called a mandrel, the horns apply constant pressure to the workpiece. The grinding is performed with a combination of reciprocating and rotary motions, creating a cross-hatch pattern unique to the honing process. This pattern serves as oil reservoirs in engines and rolling surfaces for bearings.
Types of Honing Machinery
Honing machinery is classified into vertical and horizontal types, with vertical machines typically used for workpieces with large finishing diameters and horizontal machines for long workpieces. Other types include:
1. Parallel Plane Type
This type polishes workpieces by pressing them between two grinding wheels, aligning them at a uniform height. While it does not grind the inside diameter of a hole, it is considered honing machinery due to its polishing action.
2. CNC Multi-Axis Type
A computer-controlled machine that automatically performs machining with multiple grinding wheels. It can be programmed for operations requiring different roughness levels, enhancing efficiency and precision.
3. Liquid Honing
Also known as wet blasting, liquid honing uses a processing fluid containing abrasive grains instead of a grinding wheel. The fluid is sprayed onto the workpiece surface, producing a matte or even finish, and is also used for deburring.