Cylinder honing is an advanced grinding process which is an integral part of our manufacturing and repair process. We use honing to produce cylinders that have a finely finished surface with highly accurate dimensions. We hone cylinders in a wide range of different materials including all steels and non ferrous metals.
Largest honing machine in the UK
Cylinder have invested in one of the largest honing machines in the UK, capable of honing tubes up to 650mm in diameter and up to 14m in length. We can manufacture cylinder tubes with special dimensions, reducing lead times and costs for our customers.
We can manufacture of repair unusual cylinder profiles including:-
- out of round bores
- tapered bores
- bores with keyways and ports
- bowed bores
- tandem bores
Honing is similar to grinding as the aim of both processes is to achieve dimensional accuracy and a fine surface finish. Grinding involves an abrasive wheel moving at relatively high speeds normally in a side-to-side motion. This can result in a high impact shock to the metal, not always ideal for some types of surface finish. Honing uses a different approach making it more suitable for finer surface finishes, providing greater dimensional accuracy.
The advantages of honing over a more conventional grinding process are:
- fineness of the finish
- configuration of the surface finish
- roundness of the cylinder
The fineness of the finish is achieved because the honing process is more gentle than grinding. The process can be up to 40 times slower than grinding (15 -76 metres/min v 762 – 2900 metres/min for grinding). Honing does not have the risk of impact damage, however, that can occur with grinding. This is because the honing process maintains a constant contact between the tool and the cutting surface of the cylinder. The constant contact is achieved by a tool that holds stones that move in a helical motion. The honing tool moves up or down the cylinder as it turns. The honing tool also presses outwards and is spring-loaded to tolerate eccentricities in the circular motion. This also means that unusual cylinders can be easily accommodated.
The constant change in the direction of movement means that any imperfections on the cutting surface of the tool are not transferred to to the surface of the cylinder. This makes it easier to achieve a fine finish.
The Configuration of the Surface Finish
Honing stones are mixtures of aluminium oxide or silicon carbide abrasive grits assembled into an abrasive block. The stones are bonded together with an agent that can be baked to create a solid tool.
The size of the tool depends upon the size of bore to be cut. The movement of this stone within the cylinder provides a fine finish. At a microscopic level this appears with cross hatch type pattern. The cross hatch pattern on the surface finish is ideal for holding microscopic levels of lubricant. This makes it perfect for use in hydraulic cylinder applications.
The Roundness of the Cylinder
The honing tool assembly is less rigid than a grinding tool. The circular motion of the tool even has a degree of eccentricity. The honing process uses this eccentricity in the circular motion to good advantage.
The complex circular and side to side movement of the honing stones means that the final circle of the bore hole is a sort of average. This creates a cylinder that is as close to perfect as can be realistically achieved. The near perfect end result allows the honed cylinder to be used as a reference point for other machining processes. For this reason honing is usually the first part of the machining for a cylinder repair.