Technical Sharing | Complete Guide to Hole Machining Tools: Choose the Right Tool for Twice the Result with Half the Effort
SNSTC 2025-12-17
In machining, hole-making is a critical process, and selecting the right tool is essential for ensuring both quality and efficiency. Today, we’ll explore tool types, applications, features, and materials used for hole machining—helping you make the right choice and handle every hole-making challenge with ease.
1.Types of Hole-Making Tools
①Drills: As the most common and widely used tools in hole machining, drills are primarily used to create holes in solid materials. There is a wide variety of drills available, each suited to different applications. Twist drills are the most widely used and are suitable for drilling a broad range of materials. Diamond drills are specifically designed for hard materials, offering exceptional wear resistance and extremely high cutting efficiency. U drills perform outstandingly in large-diameter hole machining, providing stable cutting and making them ideal for mass production. Gun drills, on the other hand, are indispensable for deep-hole machining, ensuring high accuracy and excellent surface quality.
②Reamers: When a hole has already been formed in the workpiece, reamers come into play. They are used for secondary machining of holes to significantly improve dimensional accuracy and surface finish. Easy to operate and highly efficient, reamers are an excellent choice for precision hole machining.
③Countersinks/ Spot facing Tools: These tools are mainly used for machining special hole forms such as cylindrical counterbores, tapered holes, and end-face profile holes, meeting diverse machining requirements.
④Combination (Composite) Tools: These tools integrate two or more hole-machining functions into a single tool. A typical example is a skiving and roller-burnishing head, which combines rough boring, finish boring, and roller burnishing in one operation. Designed for high-efficiency machining, such composite tools can significantly improve both productivity and machining accuracy.
⑤Boring Tools: For internal hole machining with diameters larger than 60 mm, boring tools are the ideal choice. Available in various designs—such as single-point, double-point, and floating boring tools—they can accommodate the machining requirements of different large workpieces, offering both high productivity and excellent machining accuracy.
2.Applications and Characteristics of Hole-Making Tools
①Twist Drills: Widely used for drilling a variety of materials, twist drills offer broad applicability and versatility. However, they typically generate higher cutting forces and are more prone to wear. Even so, they remain a highly cost-effective option thanks to their relatively affordable price.
②PCD Drills: Specifically designed for drilling hard materials, PCD drills offer excellent wear resistance and high cutting efficiency. They are a reliable solution when machining high-strength and difficult-to-machine materials.
③U Drills: U drills excel in large-diameter hole machining, delivering smooth cutting performance that ensures high stability and consistency throughout the process. They are particularly well-suited for mass production, helping to improve productivity while effectively reducing manufacturing costs.
④Gun Drills: As specialists in deep-hole machining, gun drills deliver high accuracy and excellent surface quality. Even in demanding deep-hole applications, they maintain stable and reliable performance, making them the preferred choice for machining holes with large length-to-diameter ratios.
⑤Reamers: Essential tools for precision hole machining, reamers significantly enhance hole accuracy and surface finish. They are ideal for applications with strict dimensional tolerances and play a critical role in ensuring machining precision.
⑥Countersinks / Counterbores: Designed for machining specially shaped holes—such as cylindrical counterbores and tapered holes—these tools effectively meet diverse product design requirements and provide reliable solutions for specialized hole features.
⑦Combination Tools: Such as skiving and roller burnishing heads, these tools integrate multiple machining functions into a single tool. They not only improve machining efficiency but also ensure high accuracy, reduce tool changes, and lower production costs, representing a key trend in modern high-efficiency machining.
⑧Boring Tools: Suitable for both roughing and finishing of large-diameter holes, boring tools offer high machining efficiency and excellent accuracy. They meet the processing requirements of large workpieces and are essential tools for machining major components in heavy machinery.
In hole machining, achieving optimal results and extending tool life depends on selecting the right cutting tools based on specific machining requirements and material characteristics.
3.Materials of Drills
①High-Speed Steel (HSS): First introduced in 1910, HSS has been in use for more than a century and remains one of the most widely used and cost-effective cutting tool materials. It can be applied both to hand drills and to more rigid setups such as drilling machines. Moreover, HSS tools can be repeatedly re-sharpened, significantly reducing overall tooling costs.
②Cobalt High-Speed Steel (HSSE): Compared with standard HSS, HSSE offers higher hardness and better hot hardness, along with improved wear resistance, though its toughness is slightly reduced. Like HSS, cobalt HSS drills can also be reground to extend their service life.
③Carbide: Carbide is a metal-matrix composite material with tungsten carbide as the base, produced by hot isostatic pressing and sintering. It delivers significantly higher hardness, hot hardness, and wear resistance than HSS, albeit at a higher cost. Carbide tools offer clear advantages in tool life and cutting speed, but they require specialized grinding equipment.
④PCD Drills: Polycrystalline diamond (PCD) drills are manufactured by sintering diamond microcrystalline powder with a metallic binder to form a composite cutting material. They feature extremely high hardness, excellent toughness, and outstanding wear resistance, making them particularly suitable for machining aluminum alloys, composite materials, plastics, and other non-ferrous materials.
⑤CBN Drills: Cubic boron nitride (CBN) drills are manufactured by sintering cubic boron nitride particles with metallic binders to form a highly durable composite cutting material. They offer extremely high hardness and excellent thermal stability, making them an ideal choice for machining high-hardness materials such as hardened steels and various alloys.
4.Applicable Materials for Drills
Drills are among the most commonly used cutting tools, with a wide range of applications spanning from professional machining workshops to everyday DIY projects at home. In theory, they can drill almost any material; for example, drills are capable of cutting not only metals but also wood, glass, and other materials. In the field of metalworking, drills with different designs are tailored to suit various metal materials and specific machining requirements.
5.Drill Materials and Their Applications
High-Speed Steel (HSS): Primarily used for machining soft metals, iron, and general-purpose steels, HSS is cost-effective and easy to re-sharpen, making it the preferred choice for beginners and small-scale machining tasks.
Cobalt High-Speed Steel (HSSE): With higher hardness and improved wear resistance, HSSE is suitable for machining higher-hardness materials, effectively enhancing machining efficiency and extending tool life.
Carbide: With extremely high hardness and excellent wear resistance, carbide is suitable for machining high-strength materials such as alloy steels and stainless steels. It demonstrates good performance when processing most materials, although its cost is relatively higher.
6.Drill Construction and Types
①Solid Drill: Manufactured from a single-piece material, it offers a simple structure and high rigidity, making it suitable for general machining applications.
②Brazed-Tip Drill: The carbide tip is brazed onto the drill body, combining the advantages of different materials to significantly enhance tool life and machining performance.
③Straight-Shank Drill: Suitable for hand-held electric drills and bench drills, offering convenient and flexible operation. They are ideal for small-scale machining tasks.
④Taper-Shank Drill: Designed for high-power industrial drill presses, it delivers increased torque and stability, ensuring precise and efficient machining.
⑤Center Drill: Designed to create a pilot hole before drilling, ensuring accurate hole positioning and serving as a basic tool for precision machining operations.
⑥Twist Drill: The most widely used drill in industrial manufacturing, offering good cutting performance and versatility.
⑦Carbide Drill: Featuring a tip or full-body construction in ultra-hard carbide, it is designed to handle extremely hard materials such as cemented carbide and ceramics.
⑧Deep Hole Drill: Engineered for deep hole machining, it features a specialized structure and cooling system to efficiently manage chip evacuation and heat dissipation.
⑨Taper Drill: Designed for machining tapered holes, it meets the specific requirements of specialized components.
⑩Cylindrical Hole Drill: Equipped with a reduced-diameter tip, it is designed for machining cylindrical holes, ensuring roundness and dimensional accuracy.
⑪Conical Hole Drill: Designed for machining conical holes, it is widely used in the fitting of mechanical components.
⑫Triangular Drill: Designed for use with specific electric drills, it features a special shape and structure to fulfill specialized machining requirements.
7.Drill Regrinding：
The re-sharpening of drills and their service life has always been a key topic in machining. During use, drill tips gradually wear down, which can affect machining performance. However, most drills can be restored using specialized re-sharpening equipment, such as dedicated drill grinders. Both HSS and carbide drills can be re-sharpened by selecting the appropriate grinding wheel, allowing for quick and easy restoration of sharp and durable drill points. Drill point angles typically range from 90°to 135°, with 118°being the most common. After re-sharpening, the drill’s performance can be restored close to that of a new drill, not only extending its service life but also reducing overall machining costs.
In conclusion, as a professional manufacturer of non-standard cutting tools, SNSTC fully understands the diversity and complexity of machining requirements. We therefore offer a comprehensive range of tailor-made tool solutions to meet the specific needs of different customers. Whether standard tools or special customized designs, we can fully satisfy your machining demands. From initial drill selection to subsequent regrinding and maintenance, SNSTC provides complete support and services throughout the entire process. You are always welcome to contact us for SNSTC PCD tools—with our professional technical team and high-quality service, we are committed to delivering the most suitable machining solutions to help make your operations smoother and more efficient.
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