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SOLID VS INDEXABLE DRILLS

Tom Beaumont

Product Training Manager

18 years engineering experience, specializing in 3 & 4 axis CNC milling, turning and horizontal boring.

 When it comes to drilling operations, having the right tool is essential to ensure accuracy, efficiency, and cost-effectiveness.

 

Two popular options that often come into consideration are solid drills and indexable drills. Each type offers unique advantages and considerations, making it important to understand their characteristics to make an informed decision.

What are Solid Drills?

Solid drills, as the name suggests, are made from a single solid piece of high-speed steel (HSS) or carbide. They are characterised by a fixed cutting edge and are available in a variety of diameters, coatings, lengths, and point geometries.

Solid drills are primarily used for machining diameters up to 12mm, therefore it is advised to switch to indexable drills on larger sizes as these are much more cost-effective once you reach this size.

They are often used, but not limited to, hand-held drills or drill presses and can produce precise holes with high accuracy. Solid drills are available in different types, including twist drills, step drills, core drills, countersinks, and reamers, each with their own specific applications and advantages.

 

Twist Drills: Twist drills are the most common type of solid drill. They feature a helical flute design that allows for efficient chip evacuation during drilling. Twist drills are versatile and can be used for various materials, including metal, wood, and plastic. They come in different diameters and lengths, most commonly stub (3xD) and jobber (5xD), however, they can reach up to much longer, especially in carbide drilling where rigidity and accuracy are higher. Twist drills are suitable for creating both blind and through holes and are commonly used in applications such as general metalworking, woodworking, and construction.

Cutwel offers a high performance, material specific carbide drills from leading brand YG-1. The Dream drill range offers a wide range of geometries for material specific applications including: Dream Drill Steel, Dream Drill Inox, Dream Drill Pro, Dream Drill Alu, Dream Drill High Feed, Dream Drill Flat Bottom, Dream Drill MQL and Dream Drill Hardened Steel.

Step Drills: Step drills are designed with multiple cutting edges in the form of stepped cones. Each step has a progressively larger diameter, allowing for drilling holes with different diameters in a single operation. Step drills are commonly used in sheet metal fabrication and electrical work, where the creation of precise holes with varying sizes is required. They can also be used for deburring or enlarging existing holes.

Countersinks: Countersinks are solid drills that combine drilling and chamfering functions. They have a conical cutting head with multiple flutes that create a bevelled recess at the opening of a drilled hole. Countersinks are commonly used to remove burrs or sharp edges from holes, allowing screws or fasteners to sit flush with the material surface. They are frequently used in woodworking, metalworking, and assembly applications.

Reamers: Reamers are solid drills used for precision hole-sizing and finishing. They have multiple cutting edges and are used to improve the accuracy, surface finish, and dimensional tolerance of drilled holes. Reamers are commonly employed in metalworking applications, such as automotive manufacturing and machining, where high-precision holes are required.

What are Indexable Drills?

Unlike solid drills, indexable drills consist of two main components: a drill body and an indexable insert. The drill body holds the indexable insert, which contains the cutting edges.

Indexable drills offer the advantage of easily replacing worn or damaged cutting edges without discarding the entire tool. This makes them more cost-effective and convenient for large-scale production environments. It is often advised to use indexable drills when machining diameters above 12mm.

Indexable drills are available in a wide range of types, including U-Drills and modular drills. Please see below for a summary of the two:

U-Drills: U-drills are indexable drills that use replaceable inserts with multiple cutting edges. The inserts can be rotated or replaced independently of the drill body, extending the tool's life and reducing costs. U-drills are commonly used in high-volume production environments, such as automotive and aerospace manufacturing. They are suitable for drilling a wide range of materials, including metals, plastics, and composites.

Cutwel offers a wide range of U-Drill ranges, including:

Korloy King Drill: The Korloy King Drill is a high performance dual U-Drill system available in 12-60.5mm diameters in 0.5mm increments. They are the most reliable and accurate indexable drill system, they are available with through coolant capabilities with drill depths of 2xD, 3xD, 4xD & 5xD.

Korloy King Drill XL: The Korloy King Drill XL is an adjustable system for large diameter machining and is available in 60-100mm. The drilling diameter can be adjusted up to 5mm in 1mm increments and they are available with through coolant capabilities with drill depths of 2xD, 3xD, 4xD & 5xD.

Mammut U-Drills: The Mammut U-Drill is the best-selling economy replaceable insert drilling system, it uses SPMG ISO 4 corner drill inserts and they are available with through coolant capabilities with drill depths of 2xD, 3xD & 4xD.

ISO WCMX U-Drills: The ISO WCMX U-Drills are for low cost, general purpose, economical drilling for 16-60mm diameters. The WCMX inserts can be used with other manufacturers holders and are available with drill depths of 2xD, 3xD & 4xD.

Modular Drills: Modular drills consist of a drill body and modular components, including the shank, intermediate modules, and cutting heads. This modular design allows for customization and flexibility in adapting the drill to different drilling requirements, for example a spade drill can machine multiple diameters with just one holder. Modular drills are often used in industries that require versatility and quick tool changeovers, such as oil and gas, where drilling conditions can vary.

Cutwel offers a wide range of Modular Drills, including: 

Supercut Spade Drills: The Supercut Spade Drill is the most versatile drilling system in the world. It is ideal for large diameter drilling between 9.5-114mm. The holedrs are available for long length drilling up to 25xD. Supercut spade drill inserts are fully ground and self centring HSS, Carbide and Powder Metal.

i-Dream Drills: The i-Dream Drill is a high performace replaceable carbide insert system for high feed drilling from 12-31mm. It is optimised for high precision, performance, chip control and reliability. They are through coolant holders with max drill depths of up to 7xD and features a one step clamp system for reduced setting times.

Korloy TPDC Plus Drills: The Korloy TPDC Plus Drill is a high performance and high feed replaceable head drilling system for diameters of 12-31.75mm. They are extremely cost effective with excellent cost performance ratio for entry level high performance drilling for medium-large patch machining. These holders are through coolant with max drill depths of up to 7xD.

i-One Drills: The i-One Drills are high performance replaceable carbide insert system for dedicated steel and cast iron high performance drilling. They feature high accuracy with unique pin-key clamping and self centring inserts. The inserts are available for 10-33.73mm in 0.1 incraments. The holders are through coolant with max drill depths of up to 7xD.

 

Advantages of Solid Drills:

Solid drills and indexable drills each have their own advantages and are suitable for different applications. Here are some advantages of solid drills over indexable drills:

Cost Efficiency in Smaller Diameters: Solid drills tend to be more cost-effective compared to indexable drills for smaller drilling projects and intermittent use. They typically have a lower initial cost since they do not require additional inserts or indexable components.

Simplicity: Solid drills are simple in design and use. They consist of a single piece of high-speed steel or carbide, without the need for additional components or insert replacements. This simplicity makes solid drills easy to handle, set up, and use, particularly in manual drilling operations.

Precision: Solid drills offer high precision and accuracy in drilling operations. They have a fixed cutting edge, which ensures consistent hole quality and dimensional accuracy. Solid drills are often preferred for applications that require precise hole sizing and positioning, such as in machining critical components.

Versatility: Solid drills are available in a wide range of sizes, point geometries, and materials, making them versatile for drilling various materials and hole sizes. They can be used for general-purpose drilling across multiple industries, including metalworking, woodworking, and construction.

Compact Size: Solid drills are generally more compact in size compared to indexable drills, which can be advantageous in tight spaces or when drilling in confined areas. The compact design of solid drills allows for better manoeuvrability and accessibility in certain applications.

Lower Setup Time: Solid drills do not require the indexing and setup time associated with indexable drills. Since there are no inserts to change or index, solid drills can be set up quickly and efficiently, reducing downtime and increasing productivity.

Rigidity and Stability: Solid drills provide excellent rigidity and stability due to their one-piece construction. This results in improved accuracy and precision during drilling operations.

Superior Performance: Solid drills are known for their high cutting speeds and chip evacuation capabilities, ensuring efficient material removal and reduced cycle times.

 

Advantages of Indexable Drills:

Cost Efficiency in Larger Diameters/High Volume: Indexable drills can be more cost-effective in high-volume production environments. While the initial cost of indexable drills may be higher due to the need for inserts and a body, in the long run, this can work out cheaper. When an insert becomes worn or damaged, only the insert needs to be replaced, rather than the entire drill, resulting in reduced tooling costs over time. Also for larger diameters, specifically in carbide, this could cost more in solid form whereas in an indexable drill, only the insert is typically made of carbide meaning the cost is lower.

Versatility: Indexable drills provide versatility in terms of cutting edges and insert geometries. Different inserts can be chosen to accommodate specific drilling requirements, such as material type, hole size, and cutting conditions. This versatility allows for customization and optimization of the drilling process.

Longer Tool Life: Indexable drills often have longer tool life compared to solid drills. When an insert becomes dull or damaged, it can be easily replaced, extending the overall life of the drill. This reduces downtime for tool changes and increases productivity.

Cutting Performance: Indexable drills can offer improved cutting performance due to specialized insert designs. Inserts can be optimized for specific materials and cutting conditions, resulting in enhanced chip evacuation, reduced cutting forces, and improved tool life. This makes indexable drills particularly advantageous in challenging drilling applications.

Reduced Machine Downtime: Indexable drills allow for quick and efficient insert changes, reducing machine downtime during tooling replacements. This is especially beneficial in high-production environments where minimizing downtime is crucial for maintaining productivity.

Flexibility: Indexable drills provide flexibility by offering a wide range of insert sizes, geometries, and coatings. This flexibility allows for easy adaptation to various drilling requirements and materials, optimizing performance and efficiency.

Enhanced Chip Control: Indexable drills often feature chip-breaking designs and specialized insert geometries, enabling efficient chip evacuation and improving surface finish.

 

Choosing between a Solid or Indexable Drill:

When deciding between solid and indexable drills, several factors should be considered:

Application Type: Consider the scale, material, and specific requirements of your drilling application. Solid drills are versatile and well-suited for a wide range of drilling tasks, while indexable drills excel in high-volume production environments.

Cost Considerations: Evaluate the cost-effectiveness based on the scale of your operation. For smaller-scale operations, solid drills may provide a more affordable option, while indexable drills are advantageous for large-scale and continuous drilling tasks.

Tool Life and Maintenance: Assess the expected tool life and maintenance requirements. Indexable drills offer longer tool life due to the replaceable inserts, reducing the need for frequent tool changes and associated downtime.

Precision and Performance: Consider the desired accuracy and performance level for your drilling operations. Solid drills offer excellent rigidity and stability, ensuring precise drilling results, while indexable drills provide flexibility and adaptability to changing drilling conditions.

 

Summary:

Choosing between solid and indexable drills depends on various factors such as the application type, scale of operation, cost considerations, tool life expectations, and desired precision. Solid drills are renowned for their versatility, stability, and performance, making them a preferred choice for many drilling tasks. On the other hand, indexable drills offer cost efficiency, flexibility, and extended tool life, particularly in high-volume drilling operations.

By understanding the characteristics and benefits of solid and indexable drills, you can make an informed decision that aligns with your specific drilling needs. Ultimately, selecting the right drill will enhance your drilling productivity, accuracy, and overall operational success.

For expert advice on your drilling application please contact our technical team on 01924 869 615 or email sales@cutwel.net

 

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