Honing Manufacturing Review

Honing Manufacturing Review

Honing manufacturing is a low velocity abrasive machining technique. Honing consists of a tool with three or more abrasive stones which is rotated while in contact with the work feature. By controlling the pressure, velocity, the feature is ground to an accurate configuration and finish.

Typically, the stones are made from silicon carbide, aluminum oxide, cubic nitride, or diamonds. These materials are combined and bonded together. Honing will not affect the location of a cylindrical feature, but is rather used to refine a previously manufactured cylinder. Honing can be utilized to correct a cylinder that is out of round, wavy, or tapered.

Often, honing is utilized to create a crosshatched or multi-directional finish roughness. This type of surface is great for friction type cylinder applications, where seating of sealing rings is important.

Economics of Honing

Since honing is a high precision process, it is also relatively expensive. Therefore it is only used in components that demand the highest level of precision. It is typically the last manufacturing operation before the part is shipped to a customer. The dimensional size of the object is established by preceding operations, the last of which is usually grinding. Then the part is honed to improve a form characteristic such as roundness, flatness, cylindricity, or sphericity.

Performance advantages of honed surfaces

Since honing is a relatively expensive manufacturing process, it can only be economically justified for applications that require very good form accuracy. The improved shape after honing may result in a quieter running or higher precision component.

The flexible honing tool is a relatively inexpensive honing process. This tools produces a controlled surface condition unobtainable by any other method. It involves finish, geometry and metallurgical structure. A high percentage plateau free of cut, torn and folded metal is produced. The flexible hone is a resilient, flexible honing tool with a soft cutting action. The abrasive globules each have independent suspension that assures the tool to be self-centering, self-aligning to the bore, and self-compensating for wear.

Cross-hatch finish

A "cross-hatch" pattern is used to retain oil or grease to ensure proper lubrication and ring seal of pistons in cylinders. A smooth glazed cylinder wall can cause piston ring and cylinder scuffing. The "cross-hatch" pattern is used on brake rotors, and flywheels.

Plateau finish

The plateau finish is one characterised by the removal of "peaks" in the metal while leaving the cross hatch intact for oil retention. The plateaued finish increases the bearing area of the finish, and does not require the piston or ring to "break in" the cylinder walls. Plateau Honing Specification 1. Rz ....3-6 Micron; 2. Rpk....<=0.3 Micron; 3. Rk.....0.3-1.5 Micron; 4. Rvk....0.8-2.00 Micron.