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SPINEA s.r.o.: Precision paired with productivity in the robotics industry

SPINEA manufactures high-precision reduction gears. Developed and perfected for the robotics industry, the gears are used by leading robot manufacturers. Precision is therefore a must during production: with the JUCRANK and JUMAT grinding machines from JUNKER, SPINEA can ensure that its products meet stringent quality requirements.

Industrial robots are performing ever more challenging tasks. The components must also be of the highest quality so that the motion sequences run smoothly and the complex technology is always ready for operation. The gears represent the linchpin here: they control the three-dimensional movements of the robot arms in the joints. SPINEA specializes in the production of these gears, in outstanding quality.

SPINEA was founded in 1994 in Prešov, Slovakia, in the open countryside. The founder’s aim was to make fault-free operating sequences a reality when using robots, through the use of quality gears. “Our mission is to manufacture quality products, which set us apart from other suppliers,” explains Peter Sedlák, who is responsible for automation technology at SPINEA.

The plan worked: today, with its unique technology, the company is a world market leader in the field of compact reduction gears – and continues to grow. One of the reasons for this success is its collaboration with grinding machine manufacturer JUNKER.

JUNKER grinding machines: precision and productivity

The first-class quality of the ultra-precision reduction gears from SPINEA calls for production technology to match. The requirements included exact circularity for workpieces with a maximum tolerance of half a micrometer. On the lookout for machines which could meet these exacting demands, the gear specialist eventually found what it was looking for. “Only JUNKER was able to meet our dimensional specifications”, reports Mr. Sedlák. Thus, in 2013, the first JUCRANK non-cylindrical grinding machine took up the challenging task of machining eccentric shafts at SPINEA. In 2014, the JUMAT external and internal cylindrical grinding machine was added, for machining housing and flanges.

Replacing the previous machines with the JUCRANK and JUMAT also had another positive effect for SPINEA: “There has been a great improvement in our production and the reproducibility of the grinding processes,” explains Peter Sedlák. On top of that, the figures have gone up, since grinding machines from JUNKER can deliver two to three times the output. The gear specialist is thus able to manage some of the rising demand from its customers with the existing machines.

JUCRANK: every micrometer counts

SPINEA uses the JUCRANK non-cylindrical grinding machine to produce eccentric shafts, the “high-speed parts” of the reduction mechanism in ultra-precision gears. The customer’s exacting requirements pose a huge challenge for the components. “When it comes to circularity, cylindricity, circular runout and surface quality, we tolerate a maximum deviation of half a micrometer,” explains Peter Sedlák. These specifications are extreme, especially for the production of eccentric shafts. The special geometry of the workpieces normally means they have to be machined in several operations. However, the required level of quality cannot be achieved with repeated reclamping.

With the JUCRANK, JUNKER is able to provide the required micrometer precision for the eccentric shafts through pre and finish grinding without reclamping. Using the oscillation grinding method, the JUCRANK completes all the grinding assignments on the shaft with just a single clamping set-up. This ability to fully machine the workpiece results in high process reliability, excellent grinding quality and outstanding dimensional accuracy. A special CNC-controlled guide rail also swivels the spindle, on which narrow grinding wheels are mounted, within the micron range during grinding. The main advantage of this adjusting axis, developed by JUNKER, is that every main and pin bearing can be given its own profile shape – compensating for tapers and without the need to change the grinding wheel.

JUMAT: one machine, many applications

The JUMAT external and internal cylindrical grinding machine also machines housing and flanges for the reduction gears in just a single clamping set-up. The robust cylindrical grinding machine simultaneously machines the workpieces on the inside and outside. The CBN and diamond grinding wheels enable high-speed grinding, which means high cutting capacity. Special grinding spindles with high speeds are also used for internal cylindrical grinding. This allows the JUMAT to reach a cutting speed of over 110 m/s, even for internal cylindrical grinding and despite the smaller diameter of the grinding wheel.

This combination of high cutting speed and precision machining was one of the deciding factors in SPINEA’s decision to opt for the JUMAT: the requested short cycle time and thereby considerably higher output are now a reality. JUMAT also impressed SPINEA with its versatility and flexibility: various sizes and a large number of wheelhead versions make it possible to create individual solutions for a variety of requirements. And changeover is quick and easy thanks to the 3-point mounting interface developed by JUNKER. This was a key selling point for SPINEA when it came to choosing a machine, as the gear specialist grinds around 20 similar types of workpiece on the JUMAT.

SPINEA and JUNKER: partners for the future

Another key factor in SPINEA’s decision to work with JUNKER is their prompt and on-site service: should an unexpected fault occur, JUNKER’s branch office in the Czech town of Holice is on hand at all times. “JUNKER is able to meet our high technical requirements with ease. And they are also a partner who thinks outside the box,” explains Mr. Sedlák, adding: “As a supplier to the automotive industry, JUNKER has experience with short production cycles and downtimes. As our partner, they have been able to use this knowledge to also advise us about setting up a robot workstation for loading and unloading the workpieces.”

It’s no wonder then that this successful collaboration between the two “partners for precision” is set to continue: SPINEA is gradually replacing unproductive or obsolete machines with models from JUNKER, which have already proven themselves in production. SPINEA also has specific plans with the JUNKER Group for the next few years. Due to the high level of demand, the specialist is set to increase its production with the JUNKER machines, which will mean further additions to the machine fleet in Prešov.

Pictured from left to right: Peter Palko (Machine Operator at SPINEA), Peter Sedlák, Daniel Adamíra (JUNKER Area Sales Manager).

Paired with the concentrated expertise of JUNKER, each machine is specially matched to the customer‘s requirements.

Special grinding spindles with high speeds are also used on the JUMAT for internal cylindrical grinding, enabling it to reach a cutting speed of over 110 m/s.

SPINEA machines flanges and housing for reduction gears on the JUNKER JUMAT.

SPINEA machines eccentric shafts, housing and flanges for the high-precision “TwinSpin” reduction gear on JUNKER grinding machines.


Erwin Junker Maschinenfabrik GmbH
Junkerstraße 2
77787 Nordrach