A Guide to Metal Turning Tools: Understanding Indexable Inserts and Their Purposes

Metal turning is a crucial process in the manufacturing industry that involves removing material from a workpiece to create precise shapes and sizes. To achieve optimum results in metal turning, the selection of the right tools is paramount. One of the most critical components of a metal turning tool is the indexable insert, a replaceable cutting edge that significantly impacts cutting performance and tool life. In this blog post, we will delve into the world of metal turning tools, exploring the different types of indexable inserts and their specific purposes.

What are Indexable Inserts?

Indexable inserts are cutting tool inserts made from various materials, such as tungsten carbide, cermet, ceramic, cubic boron nitride (CBN) and also High Speed Steel (HSS). They are designed to be easily mounted onto compatible tool holders, making them replaceable when the cutting edge becomes worn or damaged. This feature drastically reduces downtime and increases productivity, making indexable inserts an essential component of modern metal turning tools.

Types of Indexable Inserts and Their Purposes

  1. Tungsten Carbide Inserts

Tungsten carbide inserts are the most commonly used type of indexable inserts in metal turning due to their excellent combination of hardness and toughness. They consist of a carbide substrate, often with a coating of titanium nitride (TiN), titanium carbonitride (TiCN), aluminium oxide (Al2O3) or other materials, enhancing wear resistance and tool life. Carbide inserts are versatile and suitable for a wide range of applications, including turning, facing, profiling, and threading both ferrous and non-ferrous materials.

  1. Cermet Inserts

Cermet is a combination of a ceramic and a metal (CERamic and METal). They usually consist of a (Titanium) carbonitride substrate. Cermet inserts are ideal for high-speed machining of softer / non hardened steels. They can withstand high temperatures and provide superior wear resistance, making them well-suited for finishing operations. However, ceramic inserts have a lower tensile strength than carbide, requiring a good cutting strategy, especially with direction of cut to avoid breakage.

  1. Ceramic Inserts

Ceramic inserts are ideal for high-speed machining of cast irons, hardened materials and heat-resistant alloys. They can withstand extreme temperatures and provide superior wear resistance, making them well-suited for roughing and finishing operations. However, ceramic inserts are more brittle than carbide, requiring proper handling and a stable cutting environment.

  1. CBN Inserts

Cubic boron nitride (CBN) inserts are often the go-to choice for hard turning applications. CBN is a synthetic material that rivals the hardness of diamond, allowing it to cut through hardened steel and cast iron effortlessly. These inserts excel in producing precision finishes on hardened workpieces and are particularly valuable in industries like automotive and aerospace.

  1. Diamond Inserts

Diamond inserts are exceptionally hard and excel at machining non-ferrous materials like aluminium, copper, and other non-metallic substances. These inserts are perfect for achieving superior surface finishes, especially in high-precision applications like jewellery making and optics manufacturing. Diamond inserts are not suitable for machining of steel materials.

Purposes of Indexable Inserts

  1. Roughing Inserts

Roughing inserts feature a robust cutting edge designed for aggressive material removal rates during the initial stages of turning. They efficiently remove large amounts of material, reducing cycle times and maximising productivity.

  1. Finishing Inserts

Finishing inserts have a sharper cutting edge and are intended for precise, high-quality surface finishes. They produce smooth surfaces with minimal tool marks and are essential for achieving tight tolerances and fine details on workpieces.

  1. Grooving Inserts

Grooving inserts are specialised tools for creating grooves, slots, and recesses on a workpiece. They come in various geometries, enabling users to achieve different groove widths and depths, as well as varying levels of precision.

  1. Thread Turning Inserts

Thread turning inserts are optimised for threading operations, including internal and external threads. They are available in many thread profiles and pitches, allowing manufacturers to produce threads of different sizes and specifications.

  1. Drilling Inserts

Drilling inserts are optimised for hole-making operations, usually producing holes from solid, with optimised grades and geometries for all drilling operations, for all drill depths.

Indexable inserts play a vital role in metal turning, empowering manufacturers to achieve high precision, improved efficiency, and prolonged tool life. By understanding the different types of indexable inserts and their specific purposes, you can make informed decisions when selecting the right tool for a particular machining task. Whether it's roughing, finishing, grooving, threading or drilling, the versatility of indexable inserts ensures that they remain an indispensable asset in the world of metal turning.

If you have any questions or need assistance on choosing the right insert for you, please contact us.

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