There are various machines and techniques that can be used to polish metal, depending on the size, shape, and type of metal being polished. Some common machines used for metal polishing include:
 

1.Bench Grinder: This is a stationary machine that typically has two wheels, one for grinding and one for polishing. The polishing wheel is typically made of soft material like cloth or felt, and it is coated with a polishing compound.
 

2.Belt Grinder: This machine uses a rotating abrasive belt to grind and polish metal. It is typically used for larger metal pieces or for removing heavy material.
 

3.Orbital Sander: This handheld machine uses a rotating sanding disc to smooth and polish metal surfaces. It is often used for smaller metal parts or for finishing work on larger pieces.
 

4.Rotary Polishing Machine: This machine uses a spinning pad or buffing wheel to apply polishing compound to metal surfaces. It is typically used for larger metal pieces or for high-volume polishing work.
 

5.Vibratory Tumbler: This machine uses a vibrating container filled with polishing media (such as steel shot or ceramic beads) to polish metal parts. It is often used for small or intricate metal parts that require gentle polishing.
 

6.Ultrasonic Cleaner: This machine uses high-frequency sound waves to agitate a cleaning solution, which can be used to remove dirt, grime, or other contaminants from metal parts. It can also be used to polish metal by adding a polishing compound to the cleaning solution.
 

In addition to these machines, there are also various polishing compounds and techniques that can be used to achieve different levels of polish on metal surfaces. These can include using progressively finer grits of abrasive paper, applying polishing compounds by hand, or using polishing wheels or pads. Ultimately, the choice of machine and technique will depend on your needs of the job and the desired level of polish.