There are various types of drills used for metal drilling, such as:

• HSS drill: This is the most commonly used drill for metal and is used for drilling holes in various materials, such as wood, plastic, and metal.
• Center drill: This drill is used to create a starting point in the center of a workpiece, where a larger drill can be used to create the final hole.
• Step drill: This type of drill is designed to drill a series of hole sizes in one operation.
• Machine taper drill: This drill is used for heavy-duty drilling and is commonly used for drilling large holes in metal.
• Cobalt drill: This type of drill is made from high-speed steel coated with cobalt, making it more durable and suitable for drilling harder materials.
• Carbide drill: This type of drill is made from tungsten carbide and is suitable for drilling materials such as cast iron, stainless steel, and hardened steel.

The type of drill used for metal drilling will depend on the specific material to be drilled and the desired size and finish of the hole.