EuroFasteners March 2023

ISSN: 2633-9706 print

ISSN: 2633-9714 online

March 2023 www.read-eurofasteners.com

Industry and technology news from the world of fasteners

Photo by Paolo Nicolello, Unsplash

Contents March 2023

Diary of events

6-8 March 2023 Cables (AMI event) Trade Exhibition Cologne, Germany Organisers: AMI www.ami-events.com 7-10 March 2023 Global Industrie Trade exhibition Lyon, France Organisers: Global Industrie www.global-industrie.com

EF 3 / 57

Corporate News

Products

EF 6 / 60

Technical Article Corundum thin film coating technology for 30 years of life

EF 9 / 63

EF 8/62

9-11 May 2023 Interwire Trade exhibition Atlanta, Georgia, USA Organisers: Wire Association International www.wirenet.org

9-11 May 2023 Made In Steel Trade exhibition Milan, Italy Organisers: Siderweb SpA www.madeinsteel.it

10-13 May 2023 Lamiera Trade exhibition Milan, Italy Organisers: CEU-Centro Esposizioni Ucimu SpA www.lamiera.net 18-20 May 2023 China (Guangzhou) International Metal and Metallurgy Exhibition Trade exhibition Guangzhou, China Organisers: Guangzhou Julang Exhibition Design Co Ltd www.julang.com

EF 6/60

Shows correct at time of publication, please check to ensure the event is going ahead

EF 2/56

www.read-eurofasteners.com

March 2023

Corporate News

PSEP’s six-die multi-stage forging machine can produce complex parts

Tong Ping Siong and Philips George received the award on behalf of their team

TR PSEP Malaysia receives prestigious award

roof-mounted solar panels that not only provide the location’s energy needs, but also enable the company to sell the overcapacity back to the national grid. Supplying more than 5,000 companies around the world, TR Fastenings’ primary sectors are light vehicle, heavy vehicle, health and home, energy, tech and in frastructure, general industrial and dis tributors. Its own-brand products include Hank® rivet bushes and self clinch fasten ers, screws for plastic, blind rivet nuts, Binx® self-locking nuts, security fasteners, plastic fasteners, cable management and enclosure hardware products. Worldwide operations span 34 locations within the UK, Asia, Europe and the USA, including seven high-volume manufacturing sites. TR Fastenings www.trfastenings.com

The company’s experience of Japanese materials, methodology and expectations has ensured growth within the Malaysian automotive sector, both with the two major Malaysian brands and the Tier 1 companies that TR PSEP supplies. TR PSEP, established in 1972, is accredited to IATF 16949 and was acquired by Trifast plc in 2011. The company manufactures multi-stage and safety-critical cold-forged products at both of its facilities in Shah Alam, Malaysia. Mr Tong commented, “Following some difficult trading conditions due to the pandemic, receiving this award has really lifted everyone’s spirits. We look forward to working even more closely with Boon Siew Honda. We are very grateful for this recognition.” TR PSEP has continued to invest in its facilities, completing the installation of

The management team of TR Fastenings PSEP were presented with an award by Boon Siew Honda, when they visited its manufacturing facility in November. Tong Ping Siong and Philips George received the award on behalf of their team. The award was given based on service and quality as “the best Chutanki – cold forging manufacturer” in their supply chain managing over 130 parts. This was of special significance to the TR team, as the pandemic and manufacturing restrictions imposed by the Malaysian government to control Covid meant that they had to work diligently to ensure that no customers were impacted. Boon Siew Honda is a joint venture company formed in 2008 between Honda Motor Company and Oriental Holdings Bhd. TR PSEP has many years of experience in supplying Japanese OEMs and has been a vendor to Honda since 2001.

Graphics bigstockphoto.com/Artist tereh

FA 57 EF 3/57

www.read-fastenersasia.com www.read-eurofasteners.com

March 2023

Corporate News

CGR to acquire UK spring manufacturer

Spring scholarship winners

Comptoir General Du Ressort SAS (CGR) is to acquire the entire share capital of John Binns & Sons (Springs) Ltd, based in Skipton, North Yorkshire, UK. CGR is a France-based engineering business with operations in Europe, America and Asia, specialising in co-engineering and serial production of metal and plastic components based on cold forming technology. The group works in the supply automotive, aviation and electronics industries, and in 2022 had turnover of €196mn. John Binns & Sons (Springs) Ltd has been operating for 125 years from its base in Skipton, and recently invested in new technology, supporting lean tech for its complex spring production for a broad customer base. The company will continue with its present management team under CGR ownership. Jean-Marie Lavirotte, business development manager at CGR, commented, “JB Springs is a fantastic opportunity for CGR to establish a first base in the UK. [Legal adviser] DMH Stallard played a key role helping us to close the deal.” CGR www.cgr-international.com John Binns & Sons (Springs) Ltd www.jbsprings.co.uk

Nuts, Bolts & Thingamajigs® (NBT), the foundation of the Fabricators & Manufacturers Association, Int’l (FMA), has announced that 30 students will be receiving scholarships for the 2023 spring semester. This year, with donations and grants from across the metal fabrication industry and beyond, NBT is awarding a total of $45,000 to support tuition, book and school fee costs. “We are pleased to be providing scholarships to enable these students to pursue their passion in manufacturing,” said Ed Dernulc, NBT foundation director. “We hope that this gives them the foundation to become lifelong contributors to this dynamic industry.” Since 1990, NBT has awarded over $1.3mn to more than 675 students to pursue manufacturing careers across the USA. The FMA is a professional organisation with more than 2,500 members working together to improve the metal processing, forming and fabricating industry. Founded in 1970, it brings metal fabricators and equipment manufacturers together through technology councils, educational programmes, networking events and the FABTECH® trade show. Fabricators & Manufacturers Association, Int’l www.fmamfg.org www.nutsandboltsfoundation.org

Hilti invests in sustainability drive and commits to SBTi

triple-digit million Swiss franc amount to incorporate systematic changes into its own business processes and to further encourage the development of its partners. Construction is the most resource intensive industry, generating around 40 per cent of the world’s carbon footprint. SBTi enables businesses to set ambitious targets to reduce CO 2 emissions; it engages companies worldwide to significantly

Hilti Group has committed to the Science Based Targets initiative (SBTi) in line with the goals of the Paris Agreement. As a core element of its corporate strategy, Hilti is enhancing its contribution to reducing carbon emissions across the entire value chain. This step tackles the emissions outside Hilti’s own operations to accelerate its net zero transition and support customers on this path. The company will invest a

Jahangir Doongaji, Hilti Group CEO

to net-zero,” said Jahangir Doongaji, Hilti Group CEO. “With our commitment to science-based targets we will decrease emissions along the entire value chain. This supports our customers’sustainability initiatives and enables us to contribute to the much-needed transformation of our industry.” After this commitment to SBTi, Hilti will – via an advanced action plan – develop and submit targets for validation within 24 months. Hilti North America www.hilti.com

reduce their carbon footprint by 2030 and to achieve net-zero by 2050. The SBTi is a partnership between the Carbon Disclosure Project, the United Nations Global Compact, the World Resources Institute and the World Wide Fund for Nature. “Beyond our ambition to become CO 2 -neutral by 2023, we are also tackling emissions outside of our own operations on our path

Hilti is committed to reducing carbon emissions

EF 4/58

www.read-eurofasteners.com

March 2023

Corporate News

A constant buzz at busy exhibition stands Lesjöfors, a frequent exhibitor at trade shows, has reported that the Scandinavian industrial event Elmia Subcontractor and Valve World Expo in Düsseldorf, Germany, in mid-November were both very successful. The company states that meeting customers and partners in person and discussing challenges and opportunities is an important key to the group’s success. To listen to the industry’s top topics helps to understand where the market is heading, so exhibiting at trade shows is something the Lesjöfors companies do on a regular basis. The Elmia Subcontractor trade show – an annual event held in Jönköping, Sweden – continues to be the largest marketing activity within the whole Lesjöfors group. At the latest show, four themes were in focus: smart industry, sustainability, competence and collaboration. Anna Haesert, the group’s sustainability manager, gave a talk on how Lesjöfors is accelerating its sustainability work. Henrik Berner, business development manager and Lesjöfors’ coordinator for Elmia Subcontractor, commented, “Elmia Subcontractor is a very important arena for the Nordic subcontractor industry – the place to demonstrate new springs and pressings, discuss solutions and the obvious hub to meet potentially new customers. Several long-term customer relationships have their origin at Elmia over the years. One of the major cases we could bring back home for further discussions this year is a multi-million case if we can find a partnership.” The exhibiting teams at Elmia and Valve World considered both shows very successful. Experienced staff from several Lesjöfors companies at both shows invited visitors to experience a wide range of spring knowledge, including products from specialised companies within the group.

Lesjöfors regularly attends trade exhibitions

The Lesjöfors heavy springs team was happy with the outcome from Valve World Expo. Bonnie Mockett, head of sales and marketing, Lesjöfors Heavy Springs Division, said, “This was our debut at Valve World and the quality of the visitors and our resulting volume of leads demonstrated it was the perfect show to launch at and represent the larger wire diameter springs across the division. New and existing customers across the onshore, offshore and subsea energy sectors engaged with us at a technical, production and commercial level and we also broadened our knowledge of the sector, especially in the constantly evolving hydrogen valves niche.” Lesjöfors AB www.lesjoforsab.com

Fastener Fair Global 2023 set for strong comeback After four years, Fastener Fair Global 2023, the 9 th international event dedicated to the fastener and fixing industry, returns to Stuttgart, Germany, from 21 to 23 March. Taiwan, India, Turkey, Netherlands, the UK, Spain and France.

predictions of growth at a steady rate (CAGR +4.5 per cent from 2022 to 2030) due to population growth, high investment in the construction sector and rising demand for industrial fasteners in the automotive and aerospace sectors, Fastener Fair Global 2023 seeks to show the innovations and companies at the forefront of this growth in the industry. An online show preview offering an overview of the innovations, technologies and systems to be presented at the event is available on the exhibition website. In preparation for their visit, attendees will be able to discover the highlights of this year’s event and select in advance the products and services they are interested in.

Ahead of the event, Liljana Goszdziewski, portfolio director for the European Fastener Fairs, commented, “After four years since the last edition, it is rewarding to be able to welcome the international fastener and fixing industry at Fastener Fair Global 2023. “The high turnout of exhibiting companies confirmed at the event reflects an eagerness for the sector to get together face to face and participate in the show to allow plenty of business networking activities and enable new sales and learning opportunities in a fast-growing market.” The global industrial fasteners market was valued at $88.43bn in 2021. With

The exhibition represents an opportunity to establish new contacts and build business relationships between suppliers, manufacturers, distributors, engineers and other industry professionals from various production and manufacturing sectors looking for fastening technologies. Taking place across halls 1, 3, 5 and 7 at the Messe Stuttgart exhibition centre, more than 850 companies have already confirmed their participation at Fastener Fair Global 2023, covering a net exhibition space of over 22,000m 2 . International firms from 44 countries will exhibit at the show, representing SMEs and large multinational companies from Germany, Italy, China,

Mack-Brooks Exhibitions www.fastenerfairglobal.com

EF 5/59

www.read-eurofasteners.com

March 2023

Products

Dropping in the capsule during Kwik-X baseplate installation

Anchor system combines adhesive performance and screw speed and simplicity

Rafael Santos, senior director of the Hilti North America fastening and protection business unit, said, “Contractors can save time and money by reducing the complexity of installation with the Kwik-X, leading up to a four times faster installation over traditional adhesive anchors and combined with Hilti’s industry-leading expertise, thereby reducing labour costs and helping deliver peace of mind to a jobsite.” Hilti also supplies products for powdered actuated fastening, drilling, diamond cutting and coring, and screw fastening. Hilti North America www.hilti.com

need for accessories like brushes, air compressors and dispensers. This simplicity results in increased productivity by reducing the risk of human error. Additional features such as the ability to remove and reinstall the anchor in the same borehole cater to the needs of the installer. With fewer steps in the anchor installation process, Kwik-X is claimed to reduce installation time by up to 70 per cent and save up to 20 per cent in total cost of installation when compared to traditional adhesive anchoring systems.

Hilti North America, a provider of tools, technology, software and services to the commercial construction industry, has introduced the Kwik-X dual-action anchor system, combining the high performance of adhesive anchors and the installation speed and simplicity of screw anchors. Comprising the convenient Kwik-X pre portioned adhesive capsule and Kwik HUS-EZ screw anchor, the system provides the necessary performance for safety critical applications. It reduces the number of steps in the installation process – such as hole cleaning, curing time and dispensing – eliminating adhesive waste and the

Graphics bigstockphoto.com/Artistnd 3000

EF 6/60

www.read-eurofasteners.com

March 2023

Products

Marine-grade 316 stainless steel fasteners for corrosive environments

Mr Lehmann added, “Most people assume that all stainless screws are the same – it’s a common misconception. But stainless steel is not impervious to corrosion. It can still stain and rust just like iron, given the right environment, like in or near water, especially salt water. There are different grades of steel depending on the metals used in the alloy. 316 stainless steel fasteners are harder to find – ‘big box’ stores usually carry the corrosion prone 304 stainless, also known as 18 8. Fair Wind Fasteners only carries 316 stainless when it comes to stainless steel, again, because it’s a high-quality product and it’s the only grade of stainless that I’d be comfortable with on my own boat.” Officially established in 2020, Fair Wind Fasteners got its start back in 2010, when Robert Lehmann needed a few screws to help repair his vintage wooden boat. After a lot of stripped silicon bronze screws, Mr Lehmann learnt that cheaper is not always better. In Newport, Rhode Island, USA, he opened a shop and built a reputation for silicon bronze fasteners.

Fair Wind Fasteners has added marine- grade 316 stainless steel fasteners to its growing boat-repair inventory. Curated by owner and career seaman Robert Lehmann, Fair Wind Fasteners carries a corrosion-resistant range that includes nuts, bolts, wood screws, machine screws, carriage bolts, hex bolts, lag bolts, washers, nails and wood plugs. All Fair Wind fasteners are available directly from the company’s website in the exact quantities needed, with discounts for buying in bulk. “We started up just two years ago, but we’re growing fast and already well known for our high-quality silicon bronze fasteners,” said Mr Lehmann. “I started the business after recognising a need in the industry for high quality silicon bronze fasteners, and I personally checked tolerances, had alloy testing done and visited manufacturers before even considering putting them on my shelf. Living and working here in Newport, the ‘sailing capital of the world’ and home to many fine boat builders, it’s important to me that I only sell fasteners I would personally use on my own boat.”

Robert Lehmann, founder of Fair Wind Fasteners

through-bolts and nails for fast, strong, secure connections. • Ledger screws – offered in a variety of lengths, for a faster way to install ledger boards. The screw’s flat head finishes flush with the material, so it does not interfere with joist hangers or other materials. These screws can also be used in multi-ply applications. • Framing screws – 2½" and 3", designed for wood-to-wood framing connections, deck blocking and interior/exterior general construction projects. • Multi-purpose screws – available in flat and hex head, to replace lag bolts and through-bolts for framing. In addition to the Protech Ultra 4 coating, they are available in hot-dip galvanised options for coastal applications. The new Camo Structural Screws are backed by a lifetime warranty when installed according to guidelines. Camo Fasteners www.camofasteners.com Since then, Fair Wind Fasteners has expanded inventory to include copper and a variety of other hard-to-find fasteners, such as marine-grade 316 stainless steel. The company supplies parts to boatbuilding colleges such as IYRS, large boatbuilding companies, DIY boatbuilders around the world, and OEMs in the marine, electrical and component manufacturing industries. Fair Wind Fasteners www.fairwindfasteners.com

New code-compliant structural screws Known for delivering tools and fasteners for deck builders, National Nail’s Camo® brand is taking its product range to a new area with a line of high-performance structural screws. proprietary Protech™ Ultra 4 coating, a four-layer system for corrosion resistance that is tested two times longer than industry standards.

The ledger, multi-ply and truss screws require fewer fasteners per job. All Camo structural screws can be used for interior and exterior projects. The Camo Structural Screw product line includes: • Truss screws – six-inch screws to help contractors make connections easily and quickly. They replace hurricane ties for general interior construction and exterior decking applications. The included hands-free truss guide helps contractors fasten at the right angle. The Camo truss screw can be used in interior wall and exterior beam-to-joist connections. • Multi-ply screws – available in specific lengths for both sawn and structural composite lumber beams, replacing

Certified IRC/IBC code compliant and rigorously third-party tested and certified by DrJ Engineering, Camo Structural Screw applications include deck substructures, internal framing, ledger and general construction. “The Camo team is excited to unveil Camo Structural Screws, the next generation of structural fasteners to help builders with the deck structure and beyond,” said Doug Hutchings, vice president of product development, National Nail. “The new screws offer builders excellent holding power and stronger connections.” Engineered to start fast without pre drilling, to drive smooth and to hold strong, the screws feature Camo’s

EF 7/61

www.read-eurofasteners.com

March 2023

Products

Fasteners for precision weighing Swedish specialist fastener manufacturer Bumax has supplied its premium Bumax 88 fasteners for one of Flintec’s most recent weighing modules to meet industry strength and reliability requirements as well as European standards. manager at Flintec Germany. “The Bumax 88 fasteners used in our 55-20 weighing module have proved to be highly reliable and we have had no issues to date. We are very likely to use Bumax fasteners on future products, depending on the environmental and design specifications we have.”

in faster deliveries, lower costs, better logistics and, consequently, our Asian customer satisfaction.” The purchaser of the new Vector furnace is a manufacturer specialising in flat thread rolling dies, header punches, various bolt forming tooling and drill point dies, with 30 years of experience. For further busi ness development, the customer needed to add a vacuum furnace that would allow treatment of tools for fastener production. Liu Yedong, managing director of Seco/ Warwick China, commented, “Vector gives our customers the comfort of reliable production planning as well as great flexibility and independence. The parts produced must be of high quality, because they are subject to very high requirements in terms of quality, durability and precision. “Thanks to the unique design benefits such as directional cooling, we can be sure that the final product will meet these high expectations.” Seco/Warwick, Inc www.secowarwick.com silos, tanks or other storage solutions. The built-in load cell offers a wide range of precise weighing capacities from 7.5t to 300t. The 55-20 is equipped with an integrated lift-off system and bump stops. The low-temperature toughness of Bumax 88 is a crucial property for the 55 20 weighing module that helps to avoid breakages in low temperatures, when conventional steel can become brittle. The module has an operating temperature range of -40°C to +80°C. The enhanced properties of Bumax 88 fasteners are achieved through a higher molybdenum content (minimum 2.5 per cent), a unique manufacturing processes and the sourcing of high quality European steel. Bumax AB www.bumax-fasteners.com Flintec (UK) Ltd www.flintec.com

Flintec, a manufacturer of precision weight-measurement technologies, chose Bumax as the supplier of premium fasteners for its latest load cells. The load cells are electro-mechanical sensors used to measure force or weight, and provide accurate performance across a diverse range of applications, from automating car manufacturing to weighing shopping at supermarket checkouts. New types of load cells are continuously being designed to meet the needs of this ever-changing market. “When we designed the new 55-20 weighing module, Bumax was able to meet all our demands for high-strength fasteners to ensure performance and reliability,” said Klaus Fuchs, engineering

The properties of the Bumax 88 stainless steel fasteners include high strength, corrosion resistance and durability. They are also maintenance-free. The Flintec 55-20 weighing module is a low-profile unit that enables customers to install load cells beneath the legs of their

Flintec’s weighing module with Bumax fasteners

Hardening and tempering of thread rolling dies for fasteners

the furnace, even parts with problematic shapes. The furnace is equipped with a convection heating system to improve heat transfer efficiency during heating at lower temperatures. A round heating chamber with good temperature distribution and an efficient and ergonomic vacuum pumping system are characteristics of this furnace. An efficient cooling system ensures a maximum hardening pressure of up to 15 bar abs. “Asia is an important market for us, where we have had our branch and production

An Asian thread rolling die conglomerate has chosen Seco/Warwick as a vacuum furnace supplier. The Vector® on order will be used for vacuum hardening and tempering fastener dies, and will be the third delivery for this customer. The Vector vacuum furnace ordered features a compact design. The heating chamber’s medium size (600 x 600 x 900) enables efficient simultaneous heat treatment of many types of parts. The characteristic feature of the design is directional cooling, which ensures uniform cooling of all of the work inside

plant since 2010,” said Maciej Korecki, vice president of the Seco/Warwick Group’s vacuum segment. The rapid development in the region was recognised by the Contract Heat Treatment Association (CHTA), which awarded Seco/ Warwick with the title of ‘top 10 brand for customer satisfaction’. The fact that we can produce our furnaces directly at the location of companies from the Fortune Global 500 list results

The Vector vacuum furnace will be the third delivery for the customer

EF 8/62

www.read-eurofasteners.com

March 2023

Technical Article

Corundum thin film coating technology for 30 years of life for fasteners and metal hardware as per ISO10683/ASTMF3393: up to 6,000 hours SST

By Kalyan Dhakane, Effco Finishes & Technologies Pvt Ltd Co-author PP Deshpande, Dept of Metallurgy and Material Science, College of Engineering, University of Pune, India

Corrosion performance of the coated samples was assessed by electrochemical impedance spectroscopy over a frequency range of 100 kHz to 0.1 Hz using amplitude signal 10 mV rms (ASTM G106 and ASTM 2005b). For all of the electrochemical experiments, 3.5 wt % NaCl aqueous solution was used. All measurements were carried out five times to obtain good reproducibility of the results, and these results are reported in this work. Results and discussion Scanning electron microscopic images and XRD of the 0.5mm, 1mm and 1.5 2mm cut sectioned Ecomet corundum samples are shown in Figures 1, 2, 3, 4, 5 and 6 , respectively.

Ecomet corundum-coated bolts having 0.5mm and 1mm cuts in the coating do not show sign of corrosion, even in the scratch. The Ecomet corundum-coated bolt having a 1.5 to 2mm cut shows rusting in the cut section within one to two days after the scratch is made in the coating. At the cut edges, zinc corrodes preferentially, providing sacrificial protection to the base steel. The resulting product then fills the cavities in the coating and inhibits further corrosion. However, as the size of cut gets increased beyond critical value, there is reduction in Zn content in the surface layer of the scratched portion of the coating. This leads to the corrosion in the scratched region.

Introduction Low-carbon steels corrode in most atmospheric environments when the relative humidity exceeds 60 per cent. Effective coatings used to prevent corrosion contain environmentally hazardous pigments. Effco Finishes and Technologies Pvt Ltd (Pune, India) introduced a non-toxic and environmentally friendly paint formulation under the trade name Ecomet corundum. It is found that the Ecomet corundum-painted bolts having 0.5 and 1mm scratches do not corrode, whereas a bolt having a 1.5mm scratch corrodes within one to two days after the scratch is made. The aim of these investigations is to find out reasons of corrosion in the scratched region of the coated steel bolt.

Ecomet corundum + Ecomet Top Clear sol gel technology coated, with five times torqueing test as per ISO16047, followed by SST as per ASTM117 for 1,200 hours. No metal rust observed

Experimental characterisation Scanning electron microscopy using a field emission scanning electron microscope (FE-SEM, Sigma IV Carl Zeiss UK) was conducted at 3,000 X to examine the morphology of the coating. X-ray diffraction (Bruker AXS DS Advance, Germany) was carried out to study the composition of the compound formation at the scratch. Corrosion studies A corrosion cell having three-electrode geometry of coated steel bolt as working electrode, platinum as counter electrode and saturated calomel electrode (SCE; pH Products, Hyderabad, India) as a reference electrode was used. The cell related to Gamry reference system 1000 (Wilmington, USA) for electrochemical measurements.

Figure 1: SEM of the Ecomet corundum 0.5mm cut sample at 500 X

M10 Hex bolts coated with Ecomet Corundum. Cut made until 500 microns wide

Figure 2: XRD of the Ecomet corundum 0.5mm cut sample

Compound name

Colour

Formula Wt %

Blue Red

Iron Zinc

Fe Zn

32.4 27.5 40.1

Corundum Al 2 O 3

Green

Table 1: Semi quantitative analysis of the Ecomet corundum 0.5mm cut sample

EF 9/63

www.read-eurofasteners.com

March 2023

Technical Article

Initial open circuit potential, mV

Final open circuit potential, mV

Sample

Z mod . ohm- cm 2

Z real ohm- cm 2

0.5mm cut 1mm cut 1.5-2mm cut

161.5 79.12 38.75

162.5 72.19 22.93

-982.5 -955.6 -823.4

-987.5 -960.7 -884.3

Table 4: Impedance parameters

Electro chemical investigations

Corrosion protection mechanism It is suggested that corundum coating functions by three mechanisms – barrier protection, galvanic protection and the formation of corrosion-inhibiting products. The coating, being barrier, precludes water and oxygen from reaching the metal substrate. Al-oxide imparts dielectric properties to the coating, opposes the passage of corrosive species and improves the barrier action. The barrier mechanism is effective as long as the coating is intact. When the scratch is made, at the cut edges, zinc corrodes preferentially providing sacrificial protection to the steel. The resulting product then fills the cavities in the coating and inhibits further corrosion. As the exchange current density of zinc dissolution (10-7A/cm 2 ) is lower than that of the steel (10-6A/cm 2 ), it begins to corrode first in the case of the damage of the coating, and it corrodes more slowly than the steel, thereby protecting the steel for a longer period. This is the basis of galvanic protection of steel. It should be noted that Zn is sufficient in the surface layer on the bolt to provide electrical contact up to a certain scratch size only. As the scratch size increases beyond the critical value, Zn is not adequate to impart sacrificial protection to the base steel ( Table 3 ). The underlying steel gets exposed due to the increased scratch size. Since Al is in oxide form, it works as a cathode with respect to the steel. Hence, steel begins to corrode and thereby leads to the formation of iron oxide, ie red rust. Coating thickness should be increased to impart corrosion protection to the bolt if the scratch size is 1.5 to 2mm.

Table 4 the electrochemical impedance spectroscopic investigations just after immersion and open circuit potential measurements in 3.5 % NaCl. Table 4 reveals a decrease in impedance values of the coating with the increase in the size of the cut section. This points out the corrosion tendency of the coated bolt as a function of scratch size. Negative shift in open circuit potential confirms cathodic protection of the bolt steel. contains results of

Figure 3: SEM of the Ecomet corundum 1m cut at 500 X

Figure 4: XRD of the Ecomet corundum 1mm cut

Compound name

Colour

Formula Wt %

Blue Red

Iron Zinc

Fe Zn

21

39.7 39.3

Corundum Al 2 O 3

Green

Table 2: Semi quantitative analysis of the Ecomet corundum 1mm cut sample

After 1,200 hours SST as per ASTM117. No metal rust observed even in cut sections. Very high cathodic protection compared to only 72 hours mentioned under ISO10683. Coating applied: Ecomet corundum by dip spin method

Figure 5: SEM of the Ecomet corundum 1.5 to 2mm cut at 500 X

Figure 6: XRD of the Ecomet corundum 1.5 to 2mm cut

Compound name

Colour

Formula Wt %

Red

Iron

Fe

54.9

Corundum Al 2 O 3

19

Green

Blue Pink

Zinc

Zn

15.5 10.6

Tested bolts with five times torqueing as per ISO16047 with lower COF values. Coating system: Ecomet corundum + Ecomet Top Clear with sol gel technology. Coating done by dip spin method

Effco Finishes & Technologies Pvt Ltd Pune, India Website: www.effcoindia.com

Fe 2 O 3

Hematite

Table 3: Semi quantitative analysis of the Ecomet corundum 1.5 to 2mm cut sample

EF 10/64

www.read-eurofasteners.com

March 2023