01 Challenges and Innovation Trends in Deep Hole Drilling

There is no unified standard for defining whether a drilling operation qualifies as deep hole machining. Traditionally, operations with hole depth-to-diameter ratios reaching or exceeding 5:1 were considered deep hole drilling. However, with advancements in metal cutting technology, this standard has been raised to ratios of 10:1 or even 12:1. Today, the term "deep hole drilling" not only refers to exceptionally deep hole machining but also encompasses specialized methods for both relatively "shallow" and truly "deep" holes.

Beyond challenges common to all drilling operations, deep hole drilling presents specific difficulties. A major issue is poor chip evacuation. In deep hole drilling, chips clogging the machined hole can reduce surface quality and potentially cause drill breakage. While "peck drilling" can alleviate this problem, it reduces production efficiency and increases machining costs. Another challenge is limited coolant supply, which not only weakens the cooling and lubrication required for effective cutting but also affects chip evacuation efficiency. Additionally, decreased drill rod rigidity may lead to drill deflection, "walking," and vibration—all negatively impacting machining accuracy and tool life.

These challenges have driven the development of advanced deep hole drilling tools. New designs focus on: efficient and reliable chip evacuation to prevent clogging; precise coolant supply to improve cooling/lubrication and assist chip removal; enhanced tool rigidity to withstand deformation and vibration loads; and adoption of advanced cutting materials to extend tool life. Consequently, technological innovations include optimized flute geometry, reinforced chip-splitting cutting edges, precise internal coolant channels, advanced coatings for carbide grades, and other new features. ISCAR's latest expansion of its deep hole drilling product line exemplifies these ongoing innovation trends.

02 New Carbide Grades Enhance Wear Resistance

Recently, ISCAR introduced two new carbide grades specifically developed for BTA deep hole tools. The first grade, IC948, is suitable for use with brazed carbide drills or indexable inserts, machining steels and stainless steels (ISO P and ISO M application groups). This grade features a submicron substrate with a nano-composite TiAlCrN PVD coating, offering excellent oxidation wear resistance and chipping resistance.

The second grade, IC8355, is primarily designed for drills with indexable inserts, machining carbon steels, alloy steels, and martensitic/ferritic stainless steels (ISO P application group). Its multi-layer CVD coating combined with post-treatment technology significantly improves wear resistance and fracture wear resistance, enabling longer tool life under medium to high cutting conditions.

03 Extra-Long Solid Carbide Drills Enhance Machining Performance

In small-diameter deep hole drilling (typically ≤12 mm diameter), solid construction dominates. Naturally, the one-piece structure provides the highest rigidity among all feasible options. However, for small-diameter solid deep hole drills, there are considerable difficulties in maximizing rigidity, ensuring effective chip evacuation, and providing precise cooling—especially given the limited available design options.

ISCAR has added extra-long twist drills to its solid carbide deep hole drill series, with depth-to-diameter ratios of 30×D, 40×D, and 50×D, covering diameter ranges of 3–10 mm, 3–8 mm, and 4–6 mm respectively. These drills feature a 135° point angle, double margin design, polished flutes, and helical internal coolant channels. These combined characteristics enable stable, efficient drilling of small-diameter deep holes in solid workpieces (primarily steel materials, ISO P application group).

Recently, ISCAR further expanded its solid deep hole drill series by adding drills for machining cast iron (ISO K application group). As mentioned, these drills include polished flutes and coolant channels, along with a triple margin design and a low helix angle to further enhance rigidity and optimize drilling performance—applicable in scenarios such as inclined entry/exit and cross holes.

The newly introduced drills cover diameter ranges of 3–12 mm, with depth-to-diameter ratios of 16×D, 20×D, and 30×D.

04 Three-Flute Design Concept Boosts Production Efficiency

When seeking to improve the production efficiency of standard two-flute drills and after exploring other optimization avenues, increasing the number of flutes becomes the next intuitive improvement. However, increasing metal removal rate requires larger effective chip evacuation space—i.e., larger flute volume—which can weaken the drill body's structural performance, especially in high length-to-diameter ratio applications.

The newly introduced exchangeable three-flute carbide drills in the QUICK-3-CHAM modular drill series achieve an effective balance. Their unique flute design minimizes impact on strength and rigidity, enabling significant production efficiency improvements even when drilling holes up to 10×D depth. Practical applications show that this design can increase metal removal rate by up to 50%.

05 Synergistic Advantages for Efficiency Leap

In deep hole drilling, generating small chips significantly improves chip evacuation, enabling higher feed rates and increased production efficiency. To this end, ISCAR has adopted chip-splitting geometries on cutting edges in various deep hole tool designs, particularly in the newly launched TRIDEEP series of exchangeable carbide insert deep hole drills.

These inserts feature a chip-splitting design on the main cutting edge and a secondary wiper edge for excellent surface finish, manufactured using the advanced IC948 carbide grade. Compared to previous deep hole drill designs, the new tool utilizes a reinforced drill body to enhance strength and prevent deflection.

The synergistic effect of chip splitting, advanced carbide material, and reinforced drill body structure greatly promotes increased metal removal rates in deep hole drilling. The standard deep hole drill product line is designed for efficient machining of holes with depth-to-diameter ratios up to 25:1. Additionally, ISCAR can provide customized TRIDEEP solutions supporting maximum drilling depths up to 1650 mm.

Deep hole machining has long been a significant technical challenge in manufacturing. ISCAR's innovative series of tools provide reliable solutions to break through this technological bottleneck, delivering remarkable improvements in deep hole machining efficiency.