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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.
A solid drill is a rotating end- or side-cutting tool with one or more cutting edges and one or more straight or helical grooves for the passage of chips and the admission of coolant. An indexable-insert drill accepts inserts that clamp into a tool body designed to accept them. A cutting edge of an insert is used until it becomes dull, then it is indexed, or turned, to expose a fresh cutting edge. When all cutting edges of an insert are dull, it is usually discarded and replaced with a new one.
Hole Diameter
Solid and indexable-insert drills each have advantages and disadvantages, and the type selected for the job depends on the application. Hole diameter is one consideration. Toolmakers can produce indexable drills with much larger diameters than solid tools, while solid drills can be made with significantly smaller diameters.
The diameter of a solid-carbide drill will typically range from about 3mm (0.118") to 20mm (0.787"). A solid-HSS drill can be larger than 20mm in diameter, but it will not be as accurate as a solid-carbide tool. When an application calls for hole diameters larger than 20mm, explore indexable options.
A factor to remember is that the horsepower required for drilling will increase as the drill diameter increases. If a parts manufacturer is purchasing a machine that it knows will be used to drill large diameters, the company must check that the machine has the required horsepower.
Horsepower concerns really come into play when switching to an indexable drill from a solid drill, whether HSS or carbide. With two inserts in use, users must reference the torque and horsepower charts that come with every machine. For example, the charts on machines at Dormer Pramet clearly state that a machine can run at 40 to 45 hp for 15 minutes. Going beyond that point can cause the machine to stop and trigger an alarm.
Guangzhou Ruiyi Technology Co., Ltd. Product Page
Tolerances are another differentiator between solid-carbide and indexable drills, with the former able to achieve tighter tolerances than the latter. Using the ISO 286 hole-tolerance scale, where the smaller the number, the more precise a hole&#;s diameter, a solid-carbide drill can deliver an H9 tolerance while an indexable drill can only reach H10 to H12. So, for example, an 18mm-dia. (0.709") hole that&#;s H9 on the ISO scale will have a tolerance of 43µm (0."), whereas an H11 hole&#;s tolerance for the same size hole would be 130µm (0.005").
Investment and Maintenance
From a cost perspective, indexable inserts and their holder&#;the cutter body that accommodates the inserts&#;represent a significant investment. However, when a cutting edge is worn and needs replacement, the ease of replacing an insert is more efficient than exchanging a solid tool because only the insert needs to be indexed or changed. A solid drill, on the other hand, usually requires removal from the toolholder and resetting the depth of the drill after the tool is changed.
To help support the long-term investment of indexable inserts, they are interchangeable and versatile. Machinists can reuse the cutter from one job while easily switching out the inserts for another job that requires machining a different workpiece material.
Solid drills offer a long-term investment advantage of their own because they can be reground, sometimes seven to 10 times. On the other hand, indexable inserts are typically not reground.
Performance Standards
The geometry, substrate and coating of a solid drill determine its performance. Drills that optimize each element for a specific application have the potential to be more accurate than general-purpose tools.
Looking at geometry, the 118° conical point is the most common drill point. When properly produced, it will effectively drill a variety of materials. The drill point may require some form of web thinning when used on a drill whose web thickness has increased because of repeated resharpenings or on a drill with a heavy web construction.
In addition, the split point was originally developed for use on drills designed for producing deep oil holes in automotive crankshafts. Today, the split point is used on many designs of drills for cutting various hard and soft materials. The split point can be applied to a variety of drill point angles, with the most common being 135°. The main benefits of the split point are that it enables self-centering of a drill and prevents the tool from &#;walking&#; before penetrating a part&#;s surface.
The split point greatly reduces thrust and adds a positive-rake cutting edge, which extends to the center of the drill. The split point also acts as a chipbreaker to produce small chips, which can be effectively evacuated through the flutes. This is beneficial in most applications, but especially when using a portable drill or a drill press where bushings cannot be used.
Conversely, indexable drills offer a versatility that is beyond the capability of solid tools. Inserts can provide stable results even in adverse conditions and are able to perform multiple operations beyond the scope of solid drills. These operations include plunging, helical interpolation, profiling and enlarging a hole.
For example, when a manufacturer needed to remove material as fast as possible, it plunged with an indexable drill. The company applied a 1"-dia. (25.4mm) drill that plunged straight up and down, then moved it more than ¾" (19.05mm) and plunged straight up and down again. For quickly removing material, it was a great solution&#;and one a solid drill couldn&#;t accomplish.
Both solid drills and indexable-insert ones have distinct advantages and disadvantages based on workpiece material, the application and operational requirements. They complete a toolmaker&#;s standard offering by providing users overlapping diameters so tooling engineers can assess applications and advise parts manufacturers where and when it is appropriate to apply each.
HSS is a very tough, but not very wear-resistant, material. HSS tools are applied in many common, demanding applications.
Carbide is the most widely used wear-resistant cutting tool material and is suitable for making solid tools and indexable-insert tools. Approximately 85 percent of all carbide indexable inserts are coated.
Indexable inserts are made of cermet, ceramics, polycrystalline cubic boron nitride (PCBN) or polycrystalline diamond (PCD).
Cermet provides effective flank- and crater-wear resistance and is not prone to built-up edge. Because of this, the cutting edge maintains its sharpness for a long time.
Ceramic has a wide application area in cutting materials hardened to 45 to 55 HRC and has a high resistance to abrasive and thermal conditions.
PCBN offers an extremely high thermal resistance, and PCBN tools are applied for cutting challenging materials such as hardened steels and cast iron.
There are two types of PCD: natural and industrial diamond. PCD tools are suitable for machining nonferrous materials, such as aluminum, because of PCD&#;s high resistance to wear. Because PCD is extremely hard and brittle, it is not a good choice for high-hardness or high-impact applications.
Development is ongoing for new geometries, new coatings, new substrates and advanced manufacturing processes, including edge preparations, surface finishing and other treatments.
&#;G. Kirchoff and J. Nava
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