What Is Buffing Machinery?
A buffing and polishing machine is a type of polishing machine. It is mainly used for applications such as surface finishing of stainless steel. The two main purposes of buffing are “to clean the surface” and “to remove burrs and chips.” Since the optimum roughness of polishing differs depending on the purpose, care must be taken when working with the machine.
Uses of Buffing Machinery
Buffing is used to create a mirror finish in the final polishing process. It is mainly used for stainless steel, but can also be used for other metals such as aluminum and titanium, and resins such as acrylic and ABS resin.
Metal processed products as they are contain “burrs generated during processing” and “adhesion of chips, oil, dirt, etc.” These must be removed to ship the product as a finished product. For this reason, surface treatment must be performed through the polishing process described above.
Buffing is suitable for the final process among surface treatments because it smoothes out surface irregularities and removes stains that could not be polished out in the previous processes, such as rough grinding and intermediate finishing.
Principle of Buffing Machinery
In buffing, a “buff” made of cotton, felt, wool, or sponge is rotated and applied to the object to remove surface defects and perform surface treatment. The process requires great delicacy, as the finish can be affected by the slightest force or blurring of the polishing position during polishing.
The roughness of the polishing is distinguished by a number, called the “grit”, and generally, the larger this number is, the finer the polishing is. Normally, polishing is performed in several stages, from coarser to finer grits.
In addition to the feature of being able to clean surfaces, buffing offers the following advantages:
- Diffused reflections are reduced.
Surface treatment methods that do not provide a sufficiently smooth surface finish can cause diffuse reflections, but buff polishing can also suppress diffuse reflections by providing a mirror-like surface finish.
- Product precision is improved.
Buffing reduces surface irregularities more and improves product precision.
Types of Buffing
Buffing requires the proper selection of buffing type, buff and abrasive, depending on the desired surface finish. There are four main types of buffing depending on the target surface roughness.
Rough Polishing
This method is suitable for uneven or scratched metal surfaces and uses a fine-grained buff such as emery buff to achieve a target surface roughness of 2 μmRz and a certain degree of cleanliness. The use of a relatively coarse-grained hemp buff is suitable.
Medium Polishing
This polishing process finishes the metal surface after rough polishing to the target surface roughness of 0.3 to 0.6μmRz. It is necessary to use different buffs depending on the material. Sisal buffs are suitable for hard materials such as stainless steel, while cotton buffs are suitable for relatively soft materials such as brass and aluminum. Since it produces a slightly shiny finished surface, stainless steel and items that are to be plated in a subsequent process may be finished here as the final finish. The use of a relatively coarse linen buff is suitable.
Finish Polishing
This polishing process is to achieve a target surface roughness of 0.2 μmRz or better and is called a quasi-mirror finish. A buffing pad with a high number (#600 to #800) is used, and chromium oxide or alumina-based abrasives are suitable for this process. Since the evaluation of the quality of luster and the condition of buffing scratches is very severe, care must be taken in selecting the buffing material and abrasive. Cloth buffs or wool buffs made of soft materials such as towels and impervious cloth are suitable for use. For car waxing, a sponge buff with a soft surface is suitable.
Mirror Finish
This is a buffing process to achieve a target surface roughness of 0.1 μmRz or better after finishing polishing. This polishing method uses a #800 buff to finish metal surfaces to a clean mirror surface. The buffing process is so meticulous that the landscape can be seen without scratches, and it also features excellent sterilizing and cleaning properties. Soft cloth or wool buffs are suitable.
Automatic Buffing Machinery
In the case of small or complex shapes, buffing is performed by manipulating the object to be buffed or the buffing machinery, and the necessary surfaces are cleaned manually by workers. While this method has the advantage of being able to polish every product carefully, it has the disadvantage of poor productivity in the case of mass-produced products.
For mass-produced products with simple shapes and relatively flat surfaces, automatic buffing machinery is widely used to operate and finish either the object automatically to be polished or the buffing machinery. For example, automatic buffing machinery is used to improve productivity for flat materials such as stainless steel sheets, cylindrical objects such as stainless steel poles, and relatively simple shapes with many flat surfaces, such as guitars.