What are the typical cutting speeds and feed rates used with indexable U drills?

Indexable U drills, also known as U-shaped insert drills, are popular cutting tools used in various machining operations to create holes in metal and other materials. The cutting speed and feed rate are critical parameters that directly influence the performance, efficiency, and tool life of the indexable U drills. However, the specific cutting speeds and feed rates used with these drills can vary depending on several factors, including the workpiece material, tool material, tool diameter, and the specific machining operation being performed. In this article, we will explore the typical cutting speeds and feed rates used with indexable U drills and the factors that affect their selection.

Cutting Speed:

Cutting speed refers to the speed at which the cutting tool's edge moves relative to the workpiece material. It is typically measured in surface feet per minute (SFM) or meters per minute (m/min). The cutting speed is a crucial parameter that directly affects the tool's ability to remove material efficiently and the tool life. For indexable U drills, the cutting speed is influenced by the following factors:

a. Workpiece Material:

Different materials have different cutting speed recommendations due to their varying hardness, heat resistance, and machinability. For example, softer materials like aluminum and brass can be machined at higher cutting speeds, while harder materials like stainless steel and hardened steel require lower cutting speeds.

b. Tool Material:

The material of the indexable inserts in the U drill also influences the cutting speed. Different insert materials have distinct properties, such as hardness and heat resistance, which affect their performance at various cutting speeds.

c. Tool Diameter:

Larger diameter U drills require lower cutting speeds compared to smaller diameter drills. This is because larger drills have a higher peripheral speed at their cutting edge, leading to increased heat generation, which can affect tool life and performance.

d. Machining Operation:

The type of machining operation being performed (e.g., drilling, boring, or reaming) can also influence the cutting speed. Some operations may require higher or lower cutting speeds to achieve the desired results.

Typical Cutting Speed Ranges for Indexable U Drills:

The typical cutting speed range for indexable U drills can vary depending on the workpiece material and other factors. Here are some general cutting speed ranges for common workpiece materials:

Aluminum and soft non-ferrous materials: 500 - 2500 SFM (150 - 750 m/min)

Mild steel: 150 - 600 SFM (45 - 180 m/min)

Stainless steel: 100 - 350 SFM (30 - 105 m/min)

Cast iron: 100 - 400 SFM (30 - 120 m/min)

Hardened steel: 50 - 200 SFM (15 - 60 m/min)

Feed Rate:

The feed rate, also known as the feed per tooth or chip load, refers to the distance the cutting tool advances into the workpiece for each revolution of the cutting tool. It is typically measured in inches per revolution (IPR) or millimeters per revolution (mm/rev). The feed rate is crucial for achieving the desired surface finish, chip evacuation, and avoiding tool wear or tool breakage. The feed rate is influenced by the following factors:

a. Cutting Speed:

The cutting speed and feed rate are interrelated. When the cutting speed increases, the feed rate should also be adjusted to maintain the optimal chip load.

b. Tool Material and Coating:

The material and coating of the indexable inserts can influence the recommended feed rate. Different inserts have varying edge strength and wear resistance, which affects the appropriate feed rate.

c. Workpiece Material:

The workpiece material's hardness and machinability influence the recommended feed rate. Softer materials can tolerate higher feed rates, while harder materials may require lower feed rates.

d. Tool Diameter:

Larger diameter U drills generally require higher feed rates to achieve optimal chip evacuation and tool performance.

Typical Feed Rate Ranges for Indexable U Drills:

The typical feed rate ranges for indexable U drills can vary depending on the cutting speed and workpiece material. Here are some general feed rate ranges for common workpiece materials:

Aluminum and soft non-ferrous materials: 0.002 - 0.010 inches per revolution (0.05 - 0.25 mm/rev)

Mild steel: 0.002 - 0.010 inches per revolution (0.05 - 0.25 mm/rev)

Stainless steel: 0.001 - 0.006 inches per revolution (0.03 - 0.15 mm/rev)

Cast iron: 0.002 - 0.010 inches per revolution (0.05 - 0.25 mm/rev)

Hardened steel: 0.001 - 0.004 inches per revolution (0.03 - 0.10 mm/rev)

It is important to note that the cutting speed and feed rate recommendations provided here are general guidelines and should be adjusted based on the specific machining application, tool condition, and machine capabilities. Additionally, always refer to the manufacturer's recommendations and cutting data charts for the specific indexable U drill and insert being used.

The cutting speed and feed rate are critical parameters when using indexable U drills for machining operations. The cutting speed determines the relative speed at which the tool moves with respect to the workpiece material, while the feed rate controls the distance the tool advances into the workpiece per revolution. The selection of appropriate cutting speeds and feed rates depends on factors such as the workpiece material, tool material, tool diameter, and the specific machining operation. Following the recommended cutting data and adjusting the parameters based on the actual cutting conditions will help ensure optimal tool performance, surface finish, and tool life while maximizing productivity and efficiency in machining operations.