Two Mill/Turn Machines Add the Finishing Touches

March 4, 2021
Grinding machine experts at Kapp Niles expanded and updated new M40-G and RX 59 units, to increase productivity, stability, accuracy, reliability, and availability.

Kapp Niles has developing and building gear-cutting and -finishing machines for more than 120 years, with a portfolio that also includes grinding tools and, since 2017, measuring machines. The company has nine production sites in Germany, the U.S., Brazil, Japan, and China, and nearly 1,000 staff worldwide. Soon, it will be managed by the third generation of the Kapp family: Michael and Matthias.

Typical Kapp Niles applications are in automotive and aviation manufacturing sectors, but its larger grinding machines are supplied to the mining, wind energy and rail sectors, among others. Its main products are generating grinding machines, and profile grinding machines (along with measuring machines and grinding and dressing tools) for workpieces with diameters from 8 to 8,000 mm and up to 2,200 mm long.

Special machines on for processing high-precision aviation components and screw rotors represent a large market segment.

The complete package. “Maximum accuracy and optimal surface quality play a central role at Kapp Niles and are the most important features required of our machines,” according to Michael Kapp, production director. Strength is a hugely important property for gear teeth: Once the workpieces have been hardened, they can be ground in the Kapp Niles machines.

Reproducibility is another critical requirement, and Kapp Niles is a system supplier that offers not only grinding machines but also the corresponding tools, technological expertise and coordinate measuring machines, thereby giving its customers real added value.

Kapp Niles also emphasizes service, in everything from the overhaul of machines to repairs, as well as conventional services.

Now, the concept of digitalisation is becoming increasingly important, and a new user interface (KN grind) with optimum user-friendliness has been integrated into the new generation of grinding machines. The machines are able to network with each other and feature a closed-loop connection to the coordinate measuring machine, which issues correction instructions directly. 

At Coburg, Germany, where Kapp Niles has about 450 employees, about 60 of whom manufacture new machines. In 2014, some of the Coburg operations was moved to a new, larger building, with two M40-G MillTurn complete machining centers with a machining length of up to max. 2,200 mm. 

The growth of complete machining. According to Sascha Forkel, head of Cubic Machining, the concept of complete machining was introduced around 15 years ago and has had a great impact on production as a whole.

The advantages of complete machining were already clear at that time, which is why Kapp Niles invested in two complete machining centers. The experience gained with those machines was influential when it came to replacement investment. The search was on for a counter-spindle machine with tool turret. Based on a market analysis and a detailed investigation into possible suppliers, Kapp Niles again opted for new MillTurn centers from WFL MillTurn Technologies. “We chose the machines that made the greatest impression on us in terms of quality, and these were the MillTurns from WFL,” said Michael Kapp, production director.

The initial MillTurn machines Kapp had reached their limits with some machining tasks, but with the new MillTurns from WFL, the full performance potential can be fully exploited.

Impressive stability, quality, and reliability. When purchasing the machines, our primary concerns were to increase productivity, stability, accuracy, reliability, and availability. We are working on the assumption that we will be using the machines for much longer than 10 years,” according to Forkel.

The slant bed concept and the compound slide structure of the MillTurns from WFL ensure long-term stability and accuracy. Unique to the market is the mechanical turning-boring-milling unit, which boasts unrivalled performance and minimal interfering contour. This structure allows short tools to be used, thereby achieving maximum accuracy and material removal.

Another reason for purchasing the machines was the service that is available. “We asked around and received excellent references for WFL,” Forkel continued. “The longer service life of a MillTurn in comparison with other complete machining centers was what ultimately convinced us to purchase the machines.”

The two new MillTurns are being used to produce the most diverse range of components for Kapp Niles grinding machines, such as spindles, tool bodies, bearing housings and further machine components. While the previous machines were incapable of carrying out hard turning with the required tolerance, the new machines are now producing reliable results. “In terms of both machining and tools, there is still huge potential,” said Michael Kapp.

From commercial and technical aspects, right through to software considerations during order processing, the entire process was watched over by a competent WFL project manager. This meant that all issues and concerns could be dealt with quickly. 

Uncompromising efficiency. The two M40-G MillTurn machining centers are used to produce various parts for Kapp Niles grinding machines, including a wide range of flange and shaft parts. They produce workpieces that are particularly rotationally symmetrical. 

“Many of the components for our machines are machined on the MillTurns,” said Michael Kapp. The MillTurns also have optimized machining times, as the machines are more powerful and ultimately more stable. All programs are currently being rewritten and transferred to the MillTurns, and Kapp Niles hopes to make even further advancements in production efficiency in the future.

Kapp Niles develops machine programs using Siemens NX CAD, and before the program is transferred to the machine all processes are documented and simulated. Two employees are responsible for programming a wide range of workpieces on the two MillTurns, and also for calculating new clamping situations and making machining as efficient as possible.

Focussing on the details. The full machining lengths and diameters offered by the two M40-G MillTurns are being utilized. “The portfolio of workpieces ranges from coffee-cup size to the maximum turning diameter of 520 mm,” Forkel explained. The core of the machine is the turning-boring-milling unit with X-, Y- and B-axis, with an output of up to 33 kW and a torque of up to 214 Nm.

The design of the milling spindle with 12,000 revolutions per minute enables the efficient use of very small tools and meets all of Kapp Niles’ requirements,” emphasized Bruno Reisbeck, regional sales manager at WFL.

The left-hand turning spindle was specifically designed for the toughest machining tasks and, with an output of 54 kW and a torque of 2,000 Nm it delivers the required degree of productivity during turning.

The right-hand turning spindle is equipped with a highly dynamic, integrated spindle motor with a maximum output of 33 kW and torque of 550 Nm. In order to guarantee the necessary machining performance, tool life, and process stability in the case of very hard and difficult-to-machine materials, the machines feature 150-bar coolant pumps. These ensure good chip breakage and optimal cooling of the cuts as well as a longer tool life.

On the lower slide system, a 2x12-position disc turret with driven tools reliably goes about its work. The upper and lower system can be used on both spindles or on one spindle, simultaneously. A decisive factor in productivity is the large swing of 350 mm above the tool turret, which enables even very large parts to be automatically transferred to the counter spindle.

Due to the enormous versatility and machine options, it soon became clear to Kapp Niles that the M40 variant with counter spindle was the right choice.