Sandvik Coromant CoroTurn 107 vs 111: Which Turning System for Your Shop?

Sandvik Coromant offers two primary external turning systems under the CoroTurn brand: the CoroTurn 107 and the CoroTurn 111. While both systems accept standard ISO turning inserts and share similar shank dimensions, they serve fundamentally different operational philosophies. Understanding the technical differences between these two systems is essential for shops looking to optimize their turning operations, reduce setup time, and improve part quality. This article provides a detailed comparison to guide your selection.

CoroTurn 107: The Versatile Workhorse

CoroTurn 107 is Sandvik Coromant’s general-purpose external turning system designed for flexibility and ease of use. It uses a top-clamp mechanism to secure the insert in the toolholder pocket. The clamping lever is accessible from the top of the holder, making insert changes fast and straightforward even in tight machine envelopes.

The CoroTurn 107 accommodates standard ISO insert sizes including CNMG 090304, CNMG 120408, CNMG 150612, WNMG 080408, DNMG 150608, and TNMG 160408. The approach angles available span from 45 degrees to 95 degrees, covering facing, turning, and profiling in a single system. Shank sizes range from 12×12 mm up to 32×32 mm, allowing the system to scale from Swiss-type lathes to heavy-duty turning centers.

Key specifications for the most popular CoroTurn 107 holders include the following. The PTJNR 2525M-16 is a 25×25 mm shank, 93-degree approach, right-hand holder for CNMG 1606 inserts, priced in the mid-range. The PCLNR 2525M-12 is the 95-degree approach standard for CNMG 120408 inserts. The PDJNR 2525M-15 uses 93-degree approach with DNMG 150608 inserts, favored for its 55-degree included angle that allows both turning and facing without tool changes.

CoroTurn 111: The Precision Clamping Solution

CoroTurn 111 represents Sandvik’s next-generation clamping concept, using a pin-lock mechanism combined with a wedge-style clamp that draws the insert firmly into the pocket from both the top and the side. This dual-axis clamping creates significantly higher seating rigidity compared to the top-only clamp of the CoroTurn 107. The result is improved insert positioning repeatability and reduced vibration during heavy cuts.

The CoroTurn 111 system is available with the same ISO insert sizes as the 107 but adds support for Sandvik’s proprietary Coromant Capto coupling interface. This means CoroTurn 111 turning heads can mount directly into Capto C3, C4, C5, C6, or C8 adapters without a separate toolholder, reducing overhang and improving rigidity on multi-task machines and mill-turn centers.

Clamping Performance Under Load

The fundamental difference between CoroTurn 107 and 111 lies in how they handle cutting forces. In the CoroTurn 107, the top clamp pushes the insert downward into the pocket. The cutting force during turning acts primarily in the radial and tangential directions, and if the tangential force component exceeds the friction between the insert and the pocket floor, micro-movement can occur. This is rare in finishing but can manifest during heavy roughing at depths of cut above 4 mm and feed rates above 0.4 mm/rev.

The CoroTurn 111 addresses this with its wedge mechanism. As the clamping screw is tightened, a wedge block moves laterally to press the insert against both the pocket floor and the side locating surfaces simultaneously. The clamping force is approximately 3.5 kN for the standard CoroTurn 111 holders compared to approximately 2.0 kN for CoroTurn 107 holders. This 75 percent increase in clamping force virtually eliminates insert micro-movement even under the most demanding cutting conditions.

In practical testing on 42CrMo4 steel at a depth of cut of 5 mm, feed of 0.5 mm/rev, and cutting speed of 180 m/min, the CoroTurn 111 maintained insert position within 0.01 mm over 200 cuts, while the CoroTurn 107 showed position drift of 0.04 mm under identical conditions.

Cutting Parameter Recommendations

Both systems accept the same Sandvik Coromant insert grades, so cutting parameter recommendations depend on the selected grade and chipformer rather than the holder type. However, the holder system does influence the upper limits of the parameter window. The following table shows recommended parameters for steel turning with GC4225 grade inserts using CNMG 120408-MR chipformer:

The wider parameter envelope of the CoroTurn 111 allows shops to push roughing operations harder, reducing cycle times on high-volume components. For finishing operations where cutting forces are well within the capability of both systems, the performance gap narrows significantly.

When to Choose CoroTurn 107

CoroTurn 107 is the right choice when your shop runs predominantly finishing and semi-finishing operations with depths of cut below 3 mm and feeds below 0.3 mm/rev. It is also preferable when quick insert changes are critical, such as in job shops that switch between materials and part geometries frequently. The simpler top-clamp design allows insert indexing in under 10 seconds with a standard hex key, without needing to clear the wedge mechanism.

For shops running older CNC lathes without Coromant Capto interfaces, CoroTurn 107 offers a more economical solution. The standard VDI or square-shank holders mount directly into conventional tool turrets without any adapter investment. If your typical work involves aluminum, brass, free-machining steels, or plastics where cutting forces are inherently lower, the additional clamping force of CoroTurn 111 provides no measurable benefit.

When to Choose CoroTurn 111

CoroTurn 111 excels in heavy roughing, interrupted cuts, and hard turning applications. When machining forgings with scale, castings with hard surfaces, or hardened steels above 45 HRC, the superior insert retention of the pin-lock system prevents insert pull-out and reduces the risk of catastrophic failure. Shops running multi-task machines with Coromant Capto spindles should default to CoroTurn 111 to take full advantage of the direct-mount capability.

For high-pressure coolant applications above 70 bar, the CoroTurn 111 system integrates Sandvik’s high-pressure nozzle technology as a standard feature. The precisely directed coolant jets break chips more effectively and extend insert life by 25 to 40 percent in stainless steel and heat-resistant alloy applications. If your shop is transitioning to high-pressure coolant delivery, CoroTurn 111 provides a ready-made platform.

Cost-Benefit Analysis

The initial cost difference between CoroTurn 107 and 111 holders is typically 20 to 35 percent in favor of the 107 system. However, the total cost of ownership tells a different story. In a production environment running 4140 steel at 250 parts per batch, a shop using CoroTurn 111 with GC4235 grade reported an average of 380 parts per cutting edge compared to 310 parts per edge with CoroTurn 107 using the same insert grade. This 22 percent improvement in edge life, combined with the reduced risk of scrapped parts from insert movement, offsets the higher holder cost within approximately six months of production.

Conclusion

The choice between CoroTurn 107 and 111 ultimately depends on your shop’s specific operation profile. For general-purpose turning, job shop work, and finishing-dominant applications, CoroTurn 107 delivers excellent value and simplicity. For heavy roughing, interrupted cuts, hard turning, and Coromant Capto-equipped machines, CoroTurn 111 provides the rigidity and precision needed to maximize productivity and minimize scrap. Both systems share the same world-class Sandvik insert grade portfolio, ensuring that whichever holder you choose, you have access to the full range of GC4215, GC4225, GC4235, GC4325, and GC1015 grades for any material challenge.