How To Select The Right Turning Insert

Choosing the appropriate turning insert requires a delicate balance of numerous key parameters.

Good chip control and machining performance of these metal lathe tools are influenced by a variety of factors, including:

• Insert geometry
• Grade
• Shape
• Size
• Nose radius
• Entering angle

Each of these factors significantly influences the overall result. The geometry of the insert should be matched to the type of operation—whether it’s finishing, medium, or roughing—which directly affects how well the insert performs.

Material properties also significantly influence the choice of turning inserts. Characteristics like hardness, toughness, and thermal conductivity must be considered to select an insert that complements the machined material. Insert size, too, is important and should be chosen based on the depth of cut and cutting length required. Comprehending these parameters enables you to make informed decisions that boost your machining efficiency.

Cutting Edge Length

Select the Cutting Edge Length based on the depth of cut.  Deeper cuts (and higher MRR’s) require larger inserts.

Selecting the appropriate cutting edge length requires consideration of the tool holder’s entering (lead) angle and machine specifications. This guarantees the tool’s accuracy and efficiency all through the machining process.

Nose Radius

The nose radius of a turning insert plays a major role in reducing vibration and enhancing the workpiece’s surface finish. A larger nose angle provides increased strength, but it also requires more machine power. Additionally, it has a higher tendency for vibration. Conversely, a smaller nose angle is less strong but reduces vibration and cutting force.

Matching the nose radius to the depth of cut helps minimize vibration tendencies. A smaller radius, such as 0.4mm or 0.2mm, is recommended for finishing operations to avoid vibration and achieve a better surface finish. Adopting a smaller nose radius also contributes to better chip control and less vibration.

Nose Angle

Nose Angle is largely a function of the insert’s shape.  Larger Nose Angles result in stronger inserts.  Select the largest possible Nose Angle to maximize strength.  You need to ensure that the Nose Angle will clear all the features of the part you are machining.

Practical Tips for Correct Turning

Securing optimal turning performance extends beyond merely choosing the right insert. Practical tips for achieving this include:

• Choosing the proper insert size and geometry
• Modifying machining parameters
• Monitoring tool wear
• Ensuring effective chip evacuation to avert damage to both the workpiece and the insert.

These tips help machinists achieve better results and extend the life of their tools, ultimately leading to more efficient and cost-effective operations.