Almost Like in Swiss Tunnel Construction: Deep Hole Drilling From Both Sides

Contract Manufacturer Lehner Relies on Iscar's Sumogun Exchangeable Head Drill for Deep Hole Drilling Almost Like in Swiss Tunnel Construction: Deep Hole Drilling From Both Sides

2025-05-26 Source: Press release | Translated by AI 5 min Reading Time

Related Vendors

For a large cooling component made of tool steel, contract manufacturer Lehner needed to make through-holes more than 700 millimeters long (approx. 27 inches)—30 per component. The solution: Iscar's SumoGun interchangeable head deep hole drill and a daring strategy ensure a safe and economical process, high productivity, and short machining times at 103 minutes per component. The daring strategy involved machining the holes from both sides, similar to Swiss tunnel construction, where the holes must meet precisely.

Contract manufacturer Lehner introduces the 30 through-holes using an exchangeable head drill from Iscar's Sumogun family.(Image: Iscar) — Contract manufacturer Lehner introduces the 30 through-holes using an exchangeable head drill from Iscar's Sumogun family.
(Image: Iscar)

Founded in 1968, Ludwig Lehner GmbH in Zweibrücken (Germany) is a contract manufacturer with around 50 employees. Customers come from almost all industrial sectors and appreciate the quality, flexibility, and reliability of the family business.

Small Batch Sizes From Aluminum, Cast Iron, Steel, Inconel, Titanium

"We machine everything our business partners need, and we are not afraid of new materials or processes," says Nicolas Heinrich, Assistant to the Management at Ludwig Lehner GmbH. The company works with aluminum, castings, all types of steel, Inconel, and titanium. The typical batch size ranges from 1 to a maximum of 50 pieces. "The spectrum ranges from parts the size of a shoebox to 40-ton components," Heinrich explains. "Our specialty is machining components with complex requirements—highly precise and usually very short-term."

Gallery

The modular tool has a diameter of 15 millimeters (approx. 0.5 inches) and is 400 millimeters (approx. 16 inches) long.(Image: Iscar)

Worked out the right strategy together (from left): Patrick Muller (Product Manager Drilling at Iscar), Nicolas Heinrich (Assistant to the Plant Management), Felix Lehner (Assistant to the Management, both Ludwig Lehner GmbH), Erik Eckes (Iscar Application Engineer) and Thomas Baumann (Consulting and Sales at Iscar).(Image: Iscar)

Discussing the deployment of the Sumogun as a tunnel boring machine (from left): Thomas Baumann (Consulting and Sales), Erik Eckes (Application Engineer, both Iscar), Nicolas Heinrich (Assistant to the Plant Management at Ludwig Lehner GmbH), and Patrick Muller (Product Manager Drilling at Iscar).(Image: Iscar)

Nicolas Heinrich, Assistant to the Plant Management, Ludwig Lehner GmbH: "The drillings are excellent, with a deviation of less than one millimeter over the 360-millimeter-long (approx. 14 inches) borehole, which is suitable for coolant transport. And the process runs absolutely reliably – not even the otherwise often problematic breakthrough into the counterbore causes any issues for the Sumogun."(Image: Iscar)

Gallery with 6 images

30 coolant channels: l = 720 millimeters (approx. 28 inches) at D = 15 millimeters (approx. 0.5 inches)

These properties also apply to a cooling component for a customer in general mechanical engineering. Into components made of tool steel, measuring 600 x 700 x 800 millimeters (approx. 23 x 27 x 31 inches) and weighing around 800 kilograms, 30 coolant channels had to be drilled during processing—each 720 millimeters (approx. 28 inches) long and 15 millimeters (approx. 0.5 inches) in diameter.

"In this form, it was initially a unique project with 25 workpieces to be machined," explains Heinrich. "However, we regularly have such types of components on the machine."

Economic Solution: Interchangeable Head Deep-Hole Drill

Therefore, he set out to find a flexible concept that would allow for a safe and economical process and could be easily transferred to similar projects. Lehner had previously successfully worked with a SumoGun interchangeable head drill from Iscar for shorter drilling operations. Heinrich knew that the tool was available for greater drilling depths. He promptly called Thomas Baumann, who handles consulting and sales at Iscar and with whom he has worked trustingly for many years, to describe the task.

Modular Drilling System With a Length of 400 Millimeters (approx. 15 inches)

Together with application technician Erik Eckes and Patrick Muller, Product Manager Drilling, Baumann examined the case and presented a suitable tool: Iscar's SumoGun with a diameter of 15 millimeters (approx. 0.5 inches) and a length of 400 millimeters (approx. 15 inches). "The SumoGun is a modular deep hole drill with diameters from 10 to 25 millimeters (approx. 0.4 to 1 inch) for deep drilling up to 400 millimeters (approx. 15 inches) in solid material with interchangeable drill heads and clamping sleeves," explains Patrick Muller. This tool features a solid steel drill body. Thanks to its solid construction, the tool delivers excellent performance even in materials with a tensile strength exceeding 1000 Newtons per square millimeter and can transmit large torsional forces even at high cutting values.

The drill body features two straight flutes for optimal chip removal and an internal coolant supply that acts directly in the cutting zone. Users benefit from the wide range of drill heads and bodies, resulting in flexibility. The deep-hole drills can be equipped with different standard Sumocham drill heads.

The user can precisely tailor the tools to their requirements and utilize various material-optimized drill head geometries. The drill head change is performed with the drill body clamped, resulting in virtually no setup times. The holder for the clamping sleeves is also designed modularly: users can quickly and easily exchange them via a threaded interface. The special fine thread and axial flat surface at the interface ensure optimal concentricity values.

Approach the Task From two Sides—Pilot Holes Play a Decisive Role

Together with Nicolas Heinrich, the Iscar trio worked out a suitable process. "We decided to approach the problem from both sides, so to speak," says Eckes. To achieve the targeted drilling depth, 30 holes, each 360 millimeters (approx. 14 inches) deep, were to be drilled from both sides, meeting in the middle of the component. "Just like in tunnel construction," jokes the application engineer.

"Precision and minimal deviation are crucial here to ensure the holes align precisely." The team ensured this by using a Sumogun in 3xD for a pilot hole.

The necessary machine power, the corresponding travel path, and the coolant pressure required for the deep vertical drilling were provided by the Hermle C62. "With an 800-millimeter (approx. 31 inches) special version of the Sumogun, we could have achieved the total depth from one side. However, the required travel path and the challenging chip evacuation at such a depth argued against it," says Muller.

Absolutely Reliable Deep-Hole Drilling Process

A trial run at Lehner was meant to show whether the idea is practical. "It worked great from the start. We just tweaked the cutting values a bit – and bingo," Heinrich says happily.

Subscribe to the newsletter now

Don't Miss out on Our Best Content

Business E-mail

Please enter a valid mailadress.

By clicking on „Subscribe to Newsletter“ I agree to the processing and use of my data according to the consent form (please expand for details) and accept the Terms of Use. For more information, please see our Privacy Policy. The consent declaration relates, among other things, to the sending of editorial newsletters by email and to data matching for marketing purposes with selected advertising partners (e.g., LinkedIn, Google, Meta)

Date: 08.12.2025

Naturally, we always handle your personal data responsibly. Any personal data we receive from you is processed in accordance with applicable data protection legislation. For detailed information please see our privacy policy.

Consent to the use of data for promotional purposes

I hereby consent to Vogel Communications Group GmbH & Co. KG, Max-Planck-Str. 7-9, 97082 Würzburg including any affiliated companies according to §§ 15 et seq. AktG (hereafter: Vogel Communications Group) using my e-mail address to send editorial newsletters. A list of all affiliated companies can be found here

Newsletter content may include all products and services of any companies mentioned above, including for example specialist journals and books, events and fairs as well as event-related products and services, print and digital media offers and services such as additional (editorial) newsletters, raffles, lead campaigns, market research both online and offline, specialist webportals and e-learning offers. In case my personal telephone number has also been collected, it may be used for offers of aforementioned products, for services of the companies mentioned above, and market research purposes.

Additionally, my consent also includes the processing of my email address and telephone number for data matching for marketing purposes with select advertising partners such as LinkedIn, Google, and Meta. For this, Vogel Communications Group may transmit said data in hashed form to the advertising partners who then use said data to determine whether I am also a member of the mentioned advertising partner portals. Vogel Communications Group uses this feature for the purposes of re-targeting (up-selling, cross-selling, and customer loyalty), generating so-called look-alike audiences for acquisition of new customers, and as basis for exclusion for on-going advertising campaigns. Further information can be found in section “data matching for marketing purposes”.

In case I access protected data on Internet portals of Vogel Communications Group including any affiliated companies according to §§ 15 et seq. AktG, I need to provide further data in order to register for the access to such content. In return for this free access to editorial content, my data may be used in accordance with this consent for the purposes stated here. This does not apply to data matching for marketing purposes.

Right of revocation

I understand that I can revoke my consent at will. My revocation does not change the lawfulness of data processing that was conducted based on my consent leading up to my revocation. One option to declare my revocation is to use the contact form found at https://contact.vogel.de. In case I no longer wish to receive certain newsletters, I have subscribed to, I can also click on the unsubscribe link included at the end of a newsletter. Further information regarding my right of revocation and the implementation of it as well as the consequences of my revocation can be found in the data protection declaration, section editorial newsletter.

The drillings are top-notch, and the deviation of less than a millimeter over the 360-millimeter-long (approx. 14 inches long) borehole is suitable for coolant transport. The process runs absolutely reliably – even the otherwise often problematic breakthrough into the counterbore doesn't pose any issues for the Sumogun.

Nicolas Heinrich, Assistant to the management, Ludwig Lehner GmbH

Short Processing Time, Quick Drill Head Change

Thanks to a cutting speed of 65 meters (approx. 213 ft) per minute and a feed rate of 0.16 millimeters per revolution, Lehner requires only 103 minutes per component. "We can process two complete components before changing the drill head after 120 holes as a precaution," says Baumann.

"The quick and easy drill head change is a huge advantage here. The worker simply unscrews the old drill head and inserts the new one." Since the drill body remains in the machine during this process, it can immediately continue working without re-measuring. "This reduces setup time to almost zero; changing only the relatively small head also saves raw materials and is more cost-effective," Muller enumerates. "Lehner takes sustainability a step further and continues to use the exchanged heads—such as for pilot drilling."

Nicolas Heinrich is very satisfied with the solution in particular and with the collaboration with Iscar in general. "Iscar is always there when we need support, for example, when known solutions reach their limits or when we are trying new approaches."

(böh)