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Batch & Job Production

JUNKER Drives Efficiency and Accuracy


How the firm saves its clients time and money with its grinding machines.

Based in Elgin, Ill., JUNKER North America is part of The JUNKER Group, an international manufacturer of high-precision grinding machines for the metalworking industry. JUNKER North America is comprised of the company’s operations in the United States and Mexico.

JUNKER North America is currently in the process of extending its presence in the United States. Seven years ago, Sales Director for North America Sven Schoeller says, the company had only 14 employees and mainly sold to a few selected customers.

“Over the last few years, we developed the ability to increase our sales in the United States to all customers,” Schoeller says. The company since then has grown its staff to 36 employees and built a sales network that it continues to expand.

It also has increased its ability to provide service. JUNKER North America has six technicians in the United States that are located close to customers so they can easily service their machines.

“In addition to that, we have four service technicians sitting in Mexico with work visas for the United States in case we need them here,” Schoeller says. “We are willing to extend our base in Mexico and the United States so we are not limited to one country.”

A Broad Reach

Founder Erwin Junker started The JUNKER Group in 1962 in an old grain mill in the Kinzig Valley of Germany’s Black Forest. Today, JUNKER also offers conventional grinding machines, thanks to its 2014 acquisition of ZEMA, a manufacturer based in Brazil. ZEMA, which started operations in 1953, specialized in CNC grinding machines with corundum grinding wheels.

Today, Erwin Junker remains involved with his namesake company, which operates its main production plants in the Czech Republic, Germany and Brazil.

JUNKER also has sales and service subsidiaries in 14 countries, which allows it to attend to its customers wherever they are. In addition, the locations provide everything from individual machines to complete production lines based on the customer’s precision grinding needs.

The Highest Accuracy

JUNKER says it is a pioneer in its industry because it was the first grinding manufacturer to use complete machining in rotor production. That legacy of innovation continues to this day with the company’s JUMAT 6L 40-30 grinding machine, which has the ability to combine individual grinding steps for rotor pairs.

Complete grinding on the machine shortens auxiliary process times, reduces the operating workload, improves quality and increases the efficiency of the end-product. “The innovative JUMAT 6L 40-30 grinds rotors with a length from 200 to 650 millimeters and a swing diameter of up to 190 millimeters,” JUNKER says.

The rotor grinding machine also has the ability to process and measure workpieces while compensating for deviations from the nominal geometry. JUMAT 6L 40-30 also can provide repeat accuracy, ensuring that rotor pairs are perfectly matched.

Its grinding operations, JUNKER notes, consist of rough grinding the profile, grinding the outer diameter and faces, and finishing the screw profile. Its wheel heads “include an integrated, automatic, dynamic balancing system and gap elimination sensoric,” it says.

The machine also features a fully automatic tool changer with up to 20 different wheels , which saves operators the trouble of manually fitting or removing them during profile grinding. It also has the ability to perform a 3-D scanning measuring process that can determine corrections, saving the use of an external measuring machine.

In addition, the JUMAT 6L 40-30 can perform grinding, measuring and correcting steps in a single-clamping process, saving its users valuable time. It also has a fully integrated internal loading gantry, which handles workpieces and manages part exchanges. “The JUMAT 6L 40-30 delivers cost-effective complete grinding with the highest accuracy,” JUNKER says.

Powerful and Versatile

JUNKER’s latest innovations include platform 6, its “best-selling machine platform,” Schoeller declares. It offers users performance, precision and sustainability benefits through features as such new linear motors and hydrostatic guides.

These allow the machines to have shorter cycle times, maximize quality and provide cost savings to the users. Their x- and z-axes also feature high-performance linear drives, which help users achieve high travel and acceleration values as well as have reduced assembly space.

The platform 6 table machines also feature an expanded modular concept for their table assemblies, which made them more flexible and adaptable. While workhead, tailstock or steady rest assemblies are positioned for part setups automatically or manually, “Modularity shines due to its highly flexible component arrangement,” it says.

Platform 6 also provides users with increased accessibility to reduce the cost and amount of labor spent on maintenance. The company also has reduced the size of the machines, which brings savings by eliminating the need for wide load transports.

Users also enjoy green benefits thanks to cooling, pump and pressure regulation innovations that remove harmful cooling media. “These environmental improvements, along with increased energy efficiency, reduce the cost of ownership and round off the developments on the new platform 6,” the company says.

Quiet and Accurate

The new JUCRANK 8 platform allows for the machining of large workpieces with lengths up to 4.8 meters and peripheral diameters of 470 millimeters. With CBN technology and synchronous grinding spindles, users can grind crankshafts to high quality standards.

“When it comes to machining of large crankshafts, axles or drive shafts, it is all about maximum precision and top quality,” the company says. The JUCRANK 8 machines can achieve strong results on workpieces with weights of 1,000 kilograms, JUNKER adds.

Users also can complete pre- and finish grinding in a single clamping set-up, along with measurement in a grinding-measurement cycle. “The measured data is stored in the machine and can then be evaluated as required,” JUNKER says.

The JUCRANK 8 also features synchronized C-axes that are directly driven via torque motors and provide high precision and optimum torque rigidity. In addition, “The directly driven grinding spindles with structure-borne sound sensor and dynamic balancing systems ensure extremely quiet running,” JUNKER adds.

The JUCRANK 8 can grind flanges and journals in a single clamping set-up, along with main and pin bearings. This is achieved with the use of two synchronous grinding spindles with narrow CBN wheels, despite the differences in width and workpiece radii.

An adjusting axis allows the oscillation grinding method to be even more flexible on the JUCRANK 8, JUNKER notes. “It swivels the grinding spindle in the micron range during grinding,” it says. “In this way, the main and pin bearing can be given their own profile shape.”

Taper correction, it notes, also helps ensure improved production quality. In addition, “A defined crowning on the bearing positions can be created with interpolation using the aid of a narrow grinding wheel,” JUNKER says.

Setting New Benchmarks

Another JUNKER product that saves its users time is its NUMERIKA GH 3500 2W corundum grinding machine, which can synchronously machine large workpieces including axle beams, rotors and shafts. The low-maintenance machine can reduce cycle times, which makes it a good choice for producing large quantities.

The NUMERIKA has the capability of grinding workpieces with weights of 350 kilograms or up to 1,000 kilograms with the optional KARGO version. According to JUNKER, the largest version of the machine features a clamping length of up to 3,000 millimeters, grinding disc packets with maximum diameters of 915 millimeters and a service life that results in longer tool lives.

What makes the NUMERIKA so low maintenance, JUNKER notes, is its proven ZEMA hydrostatic technology. Workpiece and wheel head spindles are mounted on hydrostatic bearings, while the x- and z-axes of the compound slide rests are hydrostatic as well.

Its work heads also are driven with the same power. “This increases the torque transmission and quickly brings heavy workpieces to high speeds,” JUNKER says.

The KARGO corundum grinding machine made by JUNKER’s ZEMA subsidiary is a good fit for external, internal, surface, thread and conical grinding of large pieces. These include shafts which measure up to 4,600 millimeters long and weigh 2,000 kilograms.

The machine features a grinding length of 4,500 millimeters and a swing diameter of 850 millimeters. “With up to two integrated wheel heads, the machine concept sets new benchmarks,” JUNKER says. “Its sophisticated cross-slide design and proven ZEMA hydrostatic technology mean that the grinding machine requires little maintenance.”

A Shining Star

JUNKER’s lines also include its GRINDSTAR grinding machine, which is a good fit for manufacturing small components with diameters between two and 20 millimeters. “From batch sizes of 200,000, short cycle times and a long workpiece service life, [GRINDSTAR] can drive down costs per workpiece by up to 25 percent,” it says.

The high productivity of the machine makes it a good fit for the automotive industry. “The innovative grinding method enables the entire workpiece contour to be ground in just a single processing operation,” JUNKER says.

The machine also provides efficiency by involving far lower cutting forces than those occurring during turning. “The third success factor of this machine is the perfect coordination it allows between workpiece, abrasive and machine,” it says. “All three factors act to enable a significant increase in productivity.”


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