Precision surface machining is a post-treatment in many parts manufacturing industries such as the automotive, aerospace and medical industries. Among them, the honing process is frequently used, which is suitable for precision parts of various shapes and sizes. However, the best results can only be achieved through understanding the process.
This article explains the honing process, the different honing machines available, and their application in industrial manufacturing.
What is manufacturing improvement?
Honing is an abrasive machining process that can be used for polishing hole geometry, dimensional control, final surface finishing and surface texturing. A honing tool made of glue sticks glued together with oscillating and rotating movements is used. This tool slowly removes material from the machined surface and inner diameter of holes to achieve the desired shape and finish.
Parts manufacturers use the honing process for machined surfaces in grinding, drilling and boring operations. During use, the quality of the piece improves due to longer contact with the sharpening stones. Additionally, errors from previous editing processes can be corrected.
Why should you use honing on machined parts?
Sharpening offers many advantages. Some of them are explained below.
1. Improve accuracy
Honing allows the tight tolerances of many machined parts to be maintained, ensuring that these parts meet the standard. Furthermore, precision is the main difference between honing and grinding as honing is more precise. The material removal rate in honing is slower than in precision grinding, resulting in less heat generation.
2. Versatility and Compatibility
The versatility of honing is unparalleled. The honing tool can process many materials, including cast iron, carbon steel and composites. It is important to note that there are different settings for different materials. To ensure a smooth process, machinists may need to adjust parameters when honing metals.
Furthermore, honing is compatible with parts of different lengths and weights. Even very small parts can be sharpened without stress.
3. Faster and more efficient production
The honing machine can run for several days without interruption. Operating the machine at the highest level does not affect the quality of the final result. This makes honing an economical machining option for hole polishing.
4. Pay attention to security
Honing ensures the safety of the operator and other employees. This is due to total automation, which leaves no room for human intervention. Furthermore, most honing machines are equipped with protective housings. This prevents the occurrence of occupational hazards caused by flying particles.
Types of honing processes
There are two main types of honing operations, depending on the level of human intervention or automation.
Machine sharpening
Machine honing is the most commonly used honing process by many parts manufacturers. A CNC machine controls the rotary and reciprocating movements of the standard pressure honing tool. Therefore, this honing process requires little to no human intervention to create the desired patterns in the holes. As the process is fully automatic, very hard materials can be processed with precision.
Manual honing process
Grinding stones are used to obtain the perfect size and surface finish of the holes. During this honing process, the machinist moves the part with his hands over the rotating honing wheel. This gives you more autonomy in the honing process.
However, the popularity of hand honing is declining for several reasons. A common reason is that manual honing is a time-consuming process. Another reason is that the shape of the hole may deviate from the normal shape if the workpiece is not properly supported.
Various surface honing machines
There are two main types of honing machines. To get great results, it's important to understand how each machine works.
1. Horizontal honing machines
Here the machine works parallel to the honing tool and the workpiece. The machine has a head and tailstock, which serve as the main components. Additionally, the worktable is located between the headstock and tailstock, which are located on opposite sides of the machine. The spindle and honing tools are located directly above the workpiece.
Gravity pulls the chips into the base while the tool shapes the hole. Then, the operator removes the chips to avoid accumulation. Furthermore, this machine is suitable for honing long and cylindrical metals such as shafts, bars and tubes.
2. Vertical honing machines
Vertical honing machines are less complex than horizontal ones. In the vertical honing machine, the spindle works vertically to the ground. The operation of this honing machine is relatively simple. The honing tool is clamped in a tool holder that rotates along the X and Z axes. The block then holds the workpiece and moves around the Y axis.
This honing machine is important for parts where high precision and consistency are required. They are the right choice for parts with complex geometries in the aerospace and automotive industries. Furthermore, a vertical honing machine is suitable for mass production of parts.
What typical tools are used in honing?
There are different types of tools. They have different functions and work together to create the smoothest surface possible.
1. Sharpening stones
The sharpening stone is without a doubt the most important honing tool. These are abrasive tools that remove a small amount of material from the surface to produce a fine finish. Additionally, sharpening stones can be made from a single piece of abrasive material.
In addition, there are types with many layers of material fixed to a metal base. There are different materials from which you can make sharpening stones. Diamond and silicon carbide are the most common.
Diamond sharpening stones
A diamond sharpening stone has a metal base with diamond particles attached to it. This makes it very hard and strong. It is available in various grain sizes and shapes and is ideal for grinding tough metals.
Silicon Carbide Sharpening Stones
A silicon carbide honing stone cuts more aggressively and provides a more precise and consistent surface finish. Parts manufacturers use silicon carbide polishing stones for softer metals, including aluminum and brass.
note : It is important to consider the material being sharpened and the size of the hole before selecting a honing stone for a part.
2. Fee
The honing chuck positions the sharpening stones during the honing process. Hondorns are available in various sizes and shapes to suit different holes. Just like a honing stone, the mandrel can be made from a variety of materials, with aluminum oxide, diamond and silicon carbide being the most common.
3. Grinding oil
Honing oil serves as a lubricant in the honing process. The lubricant is similar to that used in fine machining systems. This oil contains additives that provide a smoother and more precise finish. Furthermore, honing oil is not just for lubrication. For example, it reduces the heat generated during honing.
Note : It is important to remove excess oil to avoid an oily final product.
Honing applications in various industries
Part manufacturers often use honing for cylindrical parts. Below are just a few apps.
Auto Industry
Honing is an important aspect of automobile manufacturing. Helps polish holes in various car components. The honing process occurs immediately after drilling to finish automobile engine cylinders. This ensures a proper fit between the piston rings and the cylinder walls.
Additionally, honing the cylinder surface also facilitates proper oil retention and lubrication. Auto parts manufacturers also use honing to adjust cylinder bore size.
aerospace industry
Aircraft manufacturers often use the honing process in the manufacture and maintenance of engine components. Honing can also be used for routine maintenance of engine components. Furthermore, honing is not limited to aircraft engines and hydraulic systems. It is one of the final steps in the production of aerospace bearings and fasteners.
Mold making
Honing also plays a role in mold making. A mold must have high dimensional accuracy and a fine surface finish. This property is important because a defective shape means a defective final part. Honing creates precise surfaces on mold surfaces. This, in turn, ensures adequate quality and consistency of the parts.
Medical industry
Honing is important in the manufacturing of medical devices, including surgical instruments and implants. Helps improve the consistency and surface geometry of finished medical products. Additionally, the honing machines are compatible with medical-grade materials, including stainless steel and titanium.
Additionally, variations in size and shape can affect the functionality of an orthopedic implant. Honing can achieve the strict technical tolerances required for many surgical devices.
Differences between honing and lapping
Although honing and lapping are both grinding processes, there are clear differences between the two processes.
1. How it works
Lapping uses abrasive particles pre-mixed with an oil or water-based liquid called paste. This paste helps to achieve precise finishing on curved or flat surfaces. Honing, on the other hand, uses glued sharpening stones to achieve finer surface finishes on cylindrical holes.
2. Amount of material removed
Lapidary is a gentler grinding process. Compared to honing, polishing removes less material from a surface. This is important when processing sensitive metals. Lapping is a corrective process to eliminate irregularities caused by previous machining.
3. Accuracy
The lapping process is more precise, especially for small parts. When improving, adjusting old faults can create new faults. The continuous rotation associated with honing can be a limitation. This is because a small change in pressure can result in an oval hole. However, manufacturing can be simplified to avoid deformation and human error.
4. Process technology
Operating a lapping machine is labor intensive and requires skilled operators, unlike honing machines, which are easy to set up and operate. Furthermore, unlike the honing process, polishing does not require a special workpiece holder.
Concluding
Honing is essential for parts to function correctly. This process guarantees a smooth surface, prevents wear and extends the useful life of a part.
Common questions
Why should honing be preferred over other hole machining processes?
Honing offers many advantages compared to other machining processes. First, the sharpened parts are always within the desired tolerance limits. Additionally, there is improved surface quality with minimal material removal. This is an important aspect with expensive materials.
Which honing tool is best?
No one honing tool is considered the best. Choosing the right tool for your project depends on several factors. It is important to consider the shape and size of the hole. Additionally, the desired surface finish may influence your choice in selecting the right tool for your application.
Are there any restrictions when sharpening?
As with other machining processes, there are some shortcomings in honing. Honing is a time-consuming finishing process. Furthermore, any small error can result in a distorted final product.
