INTERNATIONAL NEWS

Ballscrew for ultra-accurate machine tools

NSK has developed a new type of ball screw that exhibits reduced motion errors to deliver higher surface finish quality for machine tools used in mould and die machining and other surface-critical applications. By eliminating or reducing the time needed for secondary burnishing or polishing applications, the new ball screw also contributes to higher productivity, while simultaneously reducing the amount of drive torque to save energy.

In recent years, builders of machine tools such as five-axis milling machines have been demanding increased accuracy to produce higher quality mould and die surfaces, where the ball screws used in these machines must further improve motion accuracy.

When a ball screw reverses direction, sudden fluctuations in friction cause ‘quadrant glitch’ motion errors with two peaks, leaving streak marks on the machined surface and reducing surface quality. Numerous studies conducted on quadrant glitches show that it is possible to correct the first peak through numerical control (software-based servo controller compensation). Although it is more difficult to fully compensate for the second peak due to the combined effects of more factors (compared with the first peak), NSK can now present the machining industry with a solution to this problem.

Using real digital-twin simulation and friction analysis, NSK has developed a new ball screw with an optimised internal design. Key to this outcome was the company’s understanding of the underlying mechanism of friction fluctuations in ball screws.

Among its many features, the new ball screw stabilises drive torque and reduces friction fluctuations when reversing its direction of motion, thereby improving motion accuracy and reducing quadrant glitch motion errors. The result is a near elimination of the second peak. Indeed, up to 20% less friction fluctuations also contributes to reducing the height of the first peak.
For further information www.nskeurope.com

Correa mills cut processing times by 20%

French multinational Alstom has purchased three Correa gantry mills for its Česká Lípa plant in the Czech Republic. The plant produces parts for commuter trains, trams, metro and other rail vehicles. With almost 1300 employees, it is one of the largest employers in the region. The project, worth several million euros, consists of a FOX-40 fixed bridge-type milling machine and two FOX M-80 gantry milling machines, co-produced with TGS, Correa’s dealer in the Czech Republic.

The FOX-40 machine has a travel range of X 4000 mm, Y 3000 mm, Z 1000 mm and an automatic universal UAD head, while the two FOX M-80 gantry machines are equipped with three spindles and have a travel of 8000 mm in the X axis, 4250 mm in the Y axis and 1500 mm in the Z axis. The challenge to optimise the process was met with the new Correa machines, reducing the processing times of the Alstom parts by around 20%.

Alstom’s Česká Lípa plant makes bogies: mechanically welded, large and complex shaped parts with protrusions and projections, adding to the complexity of the machining process. This type of workpiece is very prone to vibration during machining operations, which causes faster wear on the heads.

To suit this type of operation, the Correa spindle technology is very rigid, stable and 100% mechanical, with no delicate elements fitted that can be easily damaged during demanding machining operations. Among other things, six bearings support the main spindle to provide good performance. For the Alstom project, Correa manufactured a head specifically for the application: an ISO 40 angled head directly attached to the ram for increased rigidity and compatible with the automatic head change system. Correa machines are available in the UK from DTS.
For further information www.nicolascorrea.com

Largest Forest-Liné Aeromill ever built

Following the successful order in June 2021 for a large titanium machining cell, which combines Dufieux and Forest-Liné technologies, Fives Machining has secured a new important contract from the same customer, XIAN, a company of AVIC Group, the Chinese state-owned aircraft manufacturer. The project includes the design and supply of a Forest-Liné Aeromill machining centre (for cutting aluminium) with XXL dimensions, the largest of its type ever built with an X axis of 22 m.

The cell, which consists of a horizontal spindle machine, two pallets, a shuttle and a loading/unloading station, will be dedicated to the civil aerospace subcontracting market for the Boeing 737 and Airbus A320 series, and for the production of parts for Chinese domestic civil aircraft models. With high-dynamic characteristics, high efficiency and flexibility, it will adapt to the complex machining requirements of large-size aluminium plates.

It also confirms the overall digitalisation tendency in both machine design and manufacturing, with “proven new technologies” such as in-line probing cycles, for increased performance.

In this important project, the customer spent five years for research, discussion, commutation and preparation with all possibilities before choosing Fives again. The project is a new milestone for Fives and its machine tool business in China, underlining the company’s strong position in the aerospace industry. The machine is scheduled for shipping to China in the second half of 2024, with reassembly carried out by the local Fives Machining team.
For further information www.fivesgroup.com

Back on the investment trail with a vengeance

Mills CNC, the exclusive distributor of DN Solutions’ (formerly Doosan) machine tools and a major automation systems’ provider to UK and Irish component manufacturers, has recently supplied precision subcontract specialist, Lenane Precision, with a new DVF 5000 simultaneous five-axis machining centre.

The machine, the third DVF 5000 to arrive at the company in as many years, was delivered and installed at Lenane’s modern production facility in Shannon, County Clare in September 2022. Notably, the latest DVF 5000 has significantly increased the company’s machining capacity and capabilities, and is seeing use at this moment in time to produce a range of complex components for aerospace and medical device customers. These components, made from aluminium, stainless and titanium, have intricate features, tight tolerances and exacting surface finishes.

Says Jim Lenane, managing director at Lenane Precision: “Machining prototypes and first-article components for the highly regulated aerospace and medical sectors means that there is little room for manoeuvre or discrepancy from product design to production result: parts need to be right first time, every time.”

He adds: “The new DVF 5000 has been deliberately positioned adjacent to the flexible automated manufacturing cell that was installed in March 2020. The new DVF 5000 complements and works in tandem with the cell.”

The automated cell – a sophisticated, complex and modular turnkey solution designed by Lenane in conjunction with Mills CNC – comprises two DVF 5000 machining centres and a FANUC industrial robot integrated by a robot positioning track that runs between both machines to enable fast, efficient and reliable part loading and unloading operations to occur. Other elements of the cell include an integrated racking system, holding up to 36 pallets (400 x 400 mm, each with a 140 kg maximum load). The company aims to get 20 hours pf machining operation from the cell every day.
For further information www.millscnc.co.uk

Cost-efficient and sustainable machine overhaul

In 1871, Ernst Körting invented the steam jet injector as a boiler feed pump and founded the company Gebrüder Körting in Hanover with his brother Berthold. Today Körting Hannover GmbH has subsidiaries in Brazil, China, India, Malaysia and Poland, and ranks as a leading manufacturer in the development and production of application-specific jet pumps, vacuum engineering products and environmental technology.

The company manufactures its demanding components on CNC machine tools from DMG Mori, among others. They include a DMU 125 FD duoBLOCK installed in 2006, which has been made fit for at least another 10 years thanks to a general overhaul completed in 2022. Jet pump ejectors for wastewater treatment application are made of polypropylene and have been produced this machine since its arrival. In 2021 Körting considered investing in a new machining centre.

“However, the DMU 125 FD duoBLOCK was technically suited to our requirements, so we decided to commission DMG Mori Used Machines to overhaul our existing model,” explains plant manager Jürgen Sack, who outlines some of the many benefits. “Firstly, we would have had to invest at least twice as much for a new model. Secondly, the overhaul did not require any changes on the shop floor and we were able to continue using our existing tools and equipment, such a fixtures and NC programs. Thanks to the manufacturer’s more modern, high quality parts, the accuracy of the machine is also improved. What’s more, we benefit from a six-month warranty and 10-year availability of spare parts and service.”
For further information www.dmgmori.com