First published in Bolted #2 2016.
Bolted joints are a key component of most machines, which make them essential to many of Japanese Sodick Corporation’s applications. The company manufactures industrial machines and machining tools as well as consumables and other products. Original research and development is a top priority, ensuring high-quality products that improve the customers’ manufacturing operations.
Sodick moulding machine engineers recently attended a seminar on solutions to the problem of loose bolts held by Ikeda Metals, a Nord-Lock Japan distributor. It touched upon exactly what they were struggling with.
Together with Ikeda Metals engineers, Nord-Lock engineers started searching for areas where they could help improve Sodick’s bolted joint design. They realized that in the Sodick moulding machines, the tie rod bolts were tightened by a traditional method. Tie rods are quite long, so if they are subject to torsion stress, and the machine is operating for a long time at the end-customer site, it is difficult to guarantee optimal performance. From the customer’s perspective, the ability to properly control the force on the joints becomes essential, because it is key to safe operation without costly downtime.
Superbolt was the perfect solution as it just has pure tension. It does not create any friction and therefore can control the force on the joints without giving off torsion stress. The people at Sodick were impressed by how diligently the Nord-Lock engineers worked at finding solutions that catered specifically to their application needs.
Superbolt tensioners are premium products and while there are cheaper alternatives in the market, Sodick firmly believes that the cost performance of the product makes it appealing. About half of Sodick’s products are sold overseas, and some big machines cannot be shipped assembled. It is essential that the moulding machine assembly and changing of parts can be carried out easily, quickly and safely at the end-customer site. Sodick is pleased to hear reports that their customers are satisfied with having smooth, speedy operations.
Operating for over 80 years, Boskalis Westminster is a leading global dredging and offshore contractor and maritime services provider. With safety and sustainability as their core values, the company has a long track record of successfully completing projects in different types of challenging offshore environments.
Among the multitude of machines and equipment Boskalis can boast, their fleet of dredgers is particularly impressive. In demanding offshore environments with limited MRO access, efficient and problem-free operations are crucial.
For one of their biggest dredgers – backhoe dredger Baldur – Boskalis has chosen Expander as their supplier of pivot pins.
Expander solutions are developed to function in extreme environments like the offshore industry, and Boskalis did not hesitate to put them to the test.
The pivot pin supplied by Expander for this project, mounted between the boom and dipper arm, is by far the largest that the company has designed and manufactured inhouse. The pin is 2230 mm long with a diameter of 320 mm and weights a whopping 1.5 tons. The sleeve alone weights 95 kg.
Downtime and production shortfalls due to pivot wear are no longer an issue for Boskalis. Expander’s design has prolonged the life span of their dredger fleet and improved their performance.
First published in Bolted #2 2016.
Project: San Francisco–Oakland Bay Bridge
Overall project cost: $6.4 billion
Application: Replacing the bridge’s east span
Boltight solution: Hydraulic bolt tensioning of cable band bolts
Contractors: American Bridge/Fluor
Engineering projects don’t get much bigger. A suspension bridge with only one tower, on limited bedrock, with ten lanes of traffic that has to be able to withstand the largest earthquake expected over a 1,500-year period.
In a 2006 joint venture contractors American Bridge and Fluor got the assignment to build the new eastern span of the San Francisco–Oakland Bay Bridge, the largest public works project in California’s history.
Most suspension bridges have multiple towers, explains Brian A. Petersen, Vice President – Western Region, American Bridge: “This bridge span only had a single tower and is essentially anchored on itself. The main cable is seated in the deck, which is an extremely involved structural engineering design achievement.”
A total number of 114 cable bands, secured around the main cable to keep the suspender ropes in place, needed to be bolted with exactly the right amount of tension. High-strength rods, which secured both the main tower as well as the bearings and shear keys at the bridge’s east end, required a high-capacity jacking system to obtain the large clamping force that the bolts were required to achieve. Over 2,000 fasteners were tensioned using the Boltight hydraulic bolt tensioners.
“Boltight’s system elongates the rod and tightens the nut, but never turns the rod, which was an important design requirement,” says Petersen. “Their equipment allowed us to properly tension the high-strength rods and bolts in a very limited space. The equipment had a high level of accuracy, and our workers could easily carry it around. No other manufacturer could meet our requirements.”
As the holiday season is upon us, the Nord-Lock Group would like to take this opportunity and wish everyone Merry Christmas and Happy New Year! With recent acquisitions and new technologies in our product portfolio it’s been quite a year for us all! We hope that 2016 has been just as memorable for you and everyone who has been helping us fulfil our mission of safeguarding human lives and customer investments.
This year the Nord-Lock Group is making a donation to Reach for Change charity on behalf of all employees. Reach for Change is an organization that finds exceptional social entrepreneurs – people that are passionate about creating a better world for children and who have an innovative idea on how to do it, and then helps them succeed. Read more at http://reachforchange.org/en/.
First published in Bolted #2 2016.
The development of new materials, for example glass-fibre reinforced plastic (GRP), has set new trends for the infrastructure of railway companies. Materials on the tracks, such as steel and timber, are increasingly being replaced by GRP for grates, walkways, bridge coverings, escape routes and service access ways. GRP makes these elements weather-resistant, slip-proof and thus safer.
Their simple, modular design, but also their low weight and high strength, make GRP profiles increasingly popular with railway operators for entire structures, such as railings, ladders, suspended stairways and work platforms. Another GRP advantage, compared to steel, is the fact that you don’t have to earth the entire structure, as the material is an electrical insulator. It is also resistant to corrosion, which significantly reduces the costs for maintenance.
Deutsche Bahn AG in particular has decided to make greater use of GRP in its infrastructure. This makes DB a trendsetter for Europe, since railway operators in neighbouring countries take cues from the continent’s largest railway industry company.
“This is a trend, because Deutsche Bahn has a complete understanding of this material’s advantages,” says Philipp Wilczek, Junior Partner and Sales Director at CTS Composite Technologie Systeme GmbH – a technology leader in the field of glass-fibre reinforced plastics. Products and structures made of GRP must be bolted together and these bolted joints can be problematic. To overcome this, CTS has decided to use the Nord-Lock X-series bolt-securing system. Maik Hartmann, Technical Director at CTS, explains: “Our material is low-maintenance in principle. However, in order to make the entire structure low-maintenance as well, we needed a solution for securing the bolts, so that we could expand the material’s advantages to the connecting elements as well.”
On or close to the tracks, shaking and vibrations from train traffic must always be expected. An increased loss of preload due to slackening (settlements and/or relaxation) should be considered when using new materials. Nord-Lock X-series washers combine the wedge-locking principle with a spring effect to prevent loosening caused by settlements and relaxation. This way, they enhance the advantages of CTS’s GRP products to offer the railway industry a safe option with many advantages.
First published in Bolted #2 2016.
Q: What are the key advantages of hydraulic tensioners?
A: A hydraulic bolt tensioning tool provides a quick, easy and safe method for tightening large diameter bolts to high and accurate preloads. It does not use torque or require forceful turning of the nut or bolt, like impact wrenches, flogging spanners or hydraulic torque wrenches, where friction is a common enemy.
A hydraulic bolt tensioner is an annular jack, which fits over the bolt and nut to be tightened. The jack pushes against the bolted joint and pulls on the end of the bolt. Because the force produced by the jack is applied directly to the end of the bolt, a tension equal to the load generated by the jack is developed in the shank of the bolt. With the jack applying tension, it is possible to rotate the nut with zero torque until it is tight. The load applied by the jack is then relaxed and a high percentage, depending on the length of the bolt and its diameter, is retained in the shank of the bolt.
Hydraulic bolt tensioning provides:
First published in Bolted #2 2016.
What fastener knowledge gaps do you see in the modern workplace?
“In North America, the general workforce is aging and companies are finding it difficult to replace experienced personnel. In the USA, over 10,000 ‘baby boomers’ retire every day. Following them is a large influx of millenials and, as a result, the workforce needs to be re-educated.
“Millennials think about work very differently than their predecessors, but are especially drawn to employers that show an interest in them. This is positive, but does present a challenge for companies who must invest in training new personnel.”
What are some fastener trends in the manufacturing and automotive industries?
“Compared to Europe, the US fastener industry has been slow in updating itself. I believe that companies here are starting to reinvest and reinvent themselves. In recent years it has been very much about lean manufacturing and driving efficiency.
“Today’s spotlight in the automotive industry is lightweighting. Auto OEMs are increasingly designing mixed material structures with a focus on aluminium, composites and ultra high strength steel. These are not possible, however, without ‘enabling’ fastening technology. Hybrid, non-traditional combinations such as aluminium to aluminium, aluminium to steel or magnesium to steel are becoming commonplace.”
What are the challenges for end-users surrounding multi-material joints?
“A unique technology is emerging, in which European companies are at the forefront. Cars have traditionally been welded together. However, when mixing materials, this no longer works. Innovative companies have introduced flow drill thread forming screws and friction welding technology to address the challenges of these new multi-material joints.”
How important is it to think about life-cycle costs when choosing fasteners?
“The automotive industry is very cost-conscious, but one client learned the hard way that price should not be the primary measure when choosing a supplier. Their price-driven ‘strategy’ has had two negative consequences. They suffered major quality spill – saving money in the short term, but their business lost out in the long term. They also found that suppliers who had previously been happy to help them with technical support were no longer able to assist them. This has had a hugely negative effect on their business.
“I believe that the pendulum is shifting back. Fasteners are not a simple commodity and customers who previously wouldn’t pay premium price for a component are now more willing to do so. They are waking up to the bigger picture.”
FACTS: Laurence Claus
Title: President, NNi Training and Consulting, Inc.
Lives: Northern suburbs of Chicago, Illinois.
Background: Graduated as a Mechanical Engineer. Has over 25 years experience in the fastener and automotive supplier industries. Bulk of career spent with an automotive fastener manufacturer, the last six as Vice President of Technology and Engineering. Started NNi four years ago.
Passion: Family. Has five children, aged between 2 and 10. NNi is named after his first three children – Noah, Nathan and Isaac.
First published in Bolted #2 2016.
Cost pressure on the growing wind energy industry makes intensive testing necessary. Consistent research on cost reduction methods is also required to strengthen wind power as an alternative, long-term energy source without subsidies.
Helping clients such as manufacturers of wind turbine generators (WTGs), wind farm operators, suppliers and energy supply companies, the German Fraunhofer Institute IWES (The Fraunhofer Institute for Wind Energy and Energy System Technology) provides industry-related research services and cooperation for a wide range of technical wind energy issues.
“The IWES is an industry institute devoted to the field of wind industry,” explains Hans Kyling, Research Associate for the current BeBen XXL project, which is researching whether business safety requirements can be met using less material.
Running between 2012 and 2017, the project is a collaboration between Fraunhofer IWES, wind turbine manufacturer Suzlon Energy GmbH (which initiated the project) and the Hamburg University of Applied Sciences (HAW). It is funded by the Federal Ministry for Economic Affairs.
The German abbreviation BeBen translates as “accelerated experimental endurance strength verification for large wind turbine components using the example of main shafts.”
“The term lightweight construction is a bit exaggerated,” Kyling points out, “because we don’t really build light, we just build lighter.”
All wind industry OEMs (Original Equipment Manufacturers) will potentially benefit from positive project results. If certification guidelines are adjusted accordingly, it will improve cost-effectiveness, as it won’t be necessary to oversize WTG components.
In addition to the main project goal, the suitability of high-tensile cast iron as a substitute for expensive forged material is also being investigated and validated. Kyling says: “We are conducting an accelerated service life test by altering some of the parameters, for instance using a higher rotation speed than during normal WTG operation, thus putting greater stress on the main shaft through a heavier rotor.”
Another thing that makes the project innovative is the creation of a so-called Wöhler curve, which determines the vibration resistance of a material or a component – especially a very large one. The automotive industry generally uses vibration resistance tests for much smaller components. For cost reasons, even the aerospace industry usually conducts tests on significantly smaller components.
Despite the huge dimensions of the WTG main shaft, the working space for bolted joints is quite limited, which can make installation and maintenance difficult – even risky.
“We created a split form of test rig,” Kyling says. “There is a steel structure, which is connected to the foundation, and an upper steel structure, which is connected to the test specimen.”
Typically, both these applications are very hard to access. The structure is designed for load-flow optimisation, which means that the bolts are sometimes placed in hard-to-reach places with little room for maneuvering the tools. Apart from the tight spaces, Kyling stresses other challenges: “The loss in pre-load should be as low as possible, and very high forces must be countered.”
These challenges were a major reason for selecting Nord-Lock products. Superbolt tensioners contribute to the safety of the project, not only because they make it possible to work in confined spaces, but also because they allow for use of lighter tools. Handling hydraulic equipment in these situations could compromise the technicians’ safety.
Superbolt tensioners are used between the two upper steel components and between the steel structure and foundation. Eight size-M80 tensioners are used in the project, along with 28 smaller M56 tensioners. Even with the large M80 Superbolt tensioners, there are still 2.8 MN (meganewtons) of force to be reckoned with, but Superbolt multi-jackbolt tensioners can handle it.
Apart from the actual parts, the BeBen XXL project also benefits from the Nord-Lock wind energy industry experience. Positioning is key to success in this market, “Because there’s always the cost pressure,” Kyling says.
Nord-Lock sales engineer Tobias Klanck says that, “As a highly qualified supplier for the wind energy industry, we are glad that the growth trend in this segment is continuing. This holds especially true for weak-wind turbines. Making full use of the existing wind, they are well suited to many locations worldwide.”
Going forward, Kyling says about wind turbine construction that, “There are still many challenges to overcome.” One of them is the use of increasingly large rotor blades. Regarding the drivetrain, there is the problem of using cast shafts instead of forged ones to keep costs down for large volumes. As there is no general drivetrain concept, bearings are another challenge for WTG manufacturers in order to meet to be competitive.
Technical insights: Products for all conditions
The Nord-Lock Group premium product range is very attractive to the wind energy industry, as it meets the tough requirements of wind turbine operators. Nord-Lock products are perfect for securing bolted joints in wind turbines that must be able to withstand enormous pressures under extreme conditions. They also provide practically maintenance-free operation.
Nord-Lock washers protect from bolt loosening due to vibration and dynamic loads, using tension instead of friction, thus reducing the risk of production failures or property damage. X-series washers offer extra safety since they, in addition to the same wedge-locking effect as original wedge-locking washers, can compensate for relaxation and settlements. They also handle dynamic loads dependably, especially in new turbines with increasingly high performance.
Superbolt tensioners are a superior choice for wind turbines. Replacing conventional nuts and bolts, they increase the lifespan of bolted joints and require only hand tools to tighten the joints. They are ideally used in the drivetrain, before and after the gearbox, at the housing and footing screws, all of which are continuously subjected to great forces.
Boltight hydraulic tools offer reliable and precise pre-tensioning for all critical bolt connections, both for construction and maintenance. Applications include tower-field connections, as well as frames, bearings, foundations and rotor blades.
M80 MULTI-JACKBOLT TENSIONER
FACTS: The BeBen XXL research project
Customer: The Fraunhofer IWES industry institute.
Location: Bremerhaven, Germany.
Project: The BeBen XXL research project, running 2012–2017.
Project goal: To determine if it is possible to reduce or change the material use for large wind turbine shafts.
Nord-Lock products: Superbolt M56 and M80 Multi-jackbolt tensioners