Honing process

Honing is an abrasive machining process that combines grinding and drilling operations. It uses abrasive tools to precisely machine a workpiece. Honing improves the surface quality of a workpiece and enhances the dimensional accuracy of the machined parts.

Honing imparts a precision surface finish to a workpiece, typically referring to the finishing of holes to achieve precise geometry and surface smoothness.

However, honing often refers to the final dimensional finishing of holes, creating the desired surface finish pattern on the inner surface of the hole.

"Final dimensions" refers to machining a hole with precise geometry (i.e., controlling diameter, roundness, and cylindricity).

The "machining" process is achieved through abrasive scrubbing and microgrooving mechanisms—using a tool that radially expands a grooved abrasive stone.

The grit size and grade of the abrasive stone affect the level of shape control and the resulting surface roughness. The tool (more precisely, the abrasive stone) rotates and reciprocates within the workpiece (hole), applying controlled radial expansion pressure to the abrasive stone.

This combined motion (rotation and reciprocating) creates a cross-grid pattern on the inner surface of the workpiece.

The input hole size of the workpiece is typically pre-machined by boring or reaming to achieve a certain consistency in material removal and extend the service life of the honing tool.

From a precision manufacturing perspective, a deep understanding of workpiece quality requirements, the core principles of surface structure formation, and the correct application of honing contributes to the sustainable production of high-quality finished products in numerous industries, including automotive, aerospace, and medical. By effectively utilizing the principles, functions, and advantages of honing, manufacturers can produce precision and efficient parts and products that meet the demands of modern engineering

Honing process characteristics

This is a low-speed, high-precision process.

Honing creates cross-shaped marks on the workpiece surface. This workpiece is used to hold lubricant.

It can also be used to correct the roundness of holes.

High tolerances of 2 to 3 micrometers can be achieved.

Both hard and soft materials can be honed.

Cutting speeds range from 0.25 to 1 m/s. Cutting angles range from 60° to 90°.

The pressure applied to the side areas of the workpiece during honing ranges from 1000 kPa to 2500 kPa.

Honing working principle

The following are the specific steps of the honing process:

1. The workpiece to be honed is mounted on the worktable and clamped with a fixture. The required honing tool is mounted on the spindle, and the tool's stability is checked.
2. The operator selects different parameters, such as the tool feed and speed. When the tool enters the hole, it expands due to the conical cross-section of the internal cone.
3. Forces act perpendicularly and parallel to the side areas of the hole. These forces generate cutting action through the honing stone, resulting in a good surface finish.
4. If necessary, coolant can be added during the process to prevent surface overheating. After honing, the tool is removed from the hole; the honing stone is pulled inward due to the rebound force.

5. The workpiece is then allowed to cool and removed by loosening the retaining device.

Honing related parameters

1)The choice of abrasive for honing operations largely depends on the abrasive grains used. The choice of abrasive depends on the hardness of the workpiece and the desired surface finish. For very hard workpieces, diamond can be used as the tool.

2)The spindle speed of the tool, or RPM, is an important parameter that determines different characteristics of the workpiece.

For example, if high material removal rate is the primary consideration, the speed should be minimal. If surface finish is the primary consideration, the speed should be higher.

3)The reciprocating speed of the tool relative to the workpiece affects the surface finish of the workpiece. Higher reciprocating speeds result in poorer surface finishes.

4)Honing pressure, as mentioned above, ranges from 1000 kPa to 2500 kPa. Lower honing pressure results in lower material removal rate, while higher pressure results in poorer surface finishes.

Advantages of Honing Process

1)Accuracy: Honing offers high precision and accuracy. It is particularly advantageous in industries requiring precise hole diameters.

2)Workpiece Hardness: Another advantage of honing is its ability to process any material, regardless of its hardness or molecular structure.

3)Material Removal: Honing removes relatively little material and achieves a finishing effect. This is thanks to the use of abrasive tools.

Disadvantages of Honing Process:

1)High Initial Cost: The initial cost of the equipment is relatively high. This is an economic disadvantage of honing machines

2)High Tool Wear: The honing stone is used as the main cutting edge. During honing, the roughness of the honing stone is easily reduced.

3)Hole Straightness: Honing can only improve the inner surface quality of holes or bored holes, and cannot improve the straightness of the holes.

4)Material Type: Honing is only suitable for ferrous metals and is not effective for non-ferrous metals.

Honing Applications

1)It can be used for rough and finish machining of automotive cylinder blocks.

2)Honing is used for the finishing of gears in the automotive industry.

3)It is also used for the production of hollow cylindrical holes that require precise machining.

4) It is also used to finish the inner diameters of internal combustion engines.