African Fusion

African Fusion visits the ISO 9001 2015-certified consumable manufacturing facility of Thuthuka welding, the local producer of ISOARC SMAW welding electrodes, and talks to the company’s MD, Matthew Dudley.

Having been members of the SAIW and SASSDA for over 40 years, Thuthuka Welding is a stalwart of the South African welding industry. “We were a sassda Stainless Steel Award winner some 20 years ago, and I have personally been involved with stainless steel for most of my life,” begins Dudley.

ISOARC Electrodes Thuthuka Welding“My career in the manufacture of consumables goes back to the Tec-Dur days, when we focused mostly on the hardfacing and low alloy consumables. Today, we manufacture 42 different types of ISOARC electrodes: from mild steel, low hydrogen and low alloy types; to stainless steels, cast iron and hardfacing electrode compositions,” he tells African Fusion, adding that high temperature chrome-moly and nickel-chrome-moly, and cryogenic nickel-based electrodes are also locally manufactured in Thuthuka’s Kempton Park facility.

In terms of volume, ISOARC’s 6013 range now dominates production: “We manufacture a premium-quality 6013 mild steel electrode, our ISOARC VYTEC, which was tested at the SAIW and found to be no different to any of the other premium brands on the market. We use a high purity rutile (94%) for these, along with other proprietary weldability additives that improve the strike ability of the electrode and the general ability of the welder to control the weld bead. And our VYTEC electrodes are also very competitively priced,” he continues.

“In addition, we manufacture an even less expensive general-purpose mild steel electrode, the ISOARC 112. Together, these two rutile 6013 electrodes account for about 50 t per month of this facility’s output. As well as being sold throughout South Africa, we export them into Africa and as far afield as Mauritius and Guatemala,” Dudley says.

By value, however, Thuthuka’s stain- less steel expertise has made the company’s ISOARC stainless electrode range the biggest earner. “We don’t simply offer the 308 and 316 grades. We offer 16 different compositions covering the complete range of stainless alloys: 307s, 347s, 410s and right up to the duplex (234) and super-duplex grades (2507).

“And we also offer stainless TIG, MIG, SAW and flux-cored wires – which we import – so that stainless steel fabricators can do root, fill and capping runs using multi-process welding procedures,” he adds.

The flagship stainless electrode? “The ISOARC 316L, which can be successfully used at very low amperage,” Dudley informs African Fusion.

“Hardfacing electrodes are also good for us. We manufacture ISOARC 453 chrome-carbide (CrC) electrodes for coating sugar mill rollers, for example, and these are also very price competitive. We also make HF350 and HF450 chrome manganese electrodes for railway work, which are approved by Transnet and Prasa,” he says.

Over the past few years, manufacturing output has risen to more than 120 t per month from the company’s two extrusion lines and the facility has recently converted its ISO 9001 2008 quality management system accreditation to the new ISO 9001 2015 standard.

Describing the electrode manufacturing process, Dudley says that batch mixing of the dry powders needed for the flux coating is most critical. “Almost all of the dry powders needed for these are locally sourced. The rutile, for ex- ample, comes from one of two local mines in SA, which now produce, almost exclusively, high purity (94%) rutile. And for stainless electrode coatings, chrome, nickel, molybdenum, silicates and fluorspar are all locally produced. This gives us very high percentages of local contact, almost 80% for mild and carbon steel electrodes and, because stainless wire is imported, up to 35% of the total content for our stainless electrodes,” he notes.

Turning attention back to the manufacturing process, he says the individual powders required for each coating are first carefully weighed, before being dry mixed in 200 kg batches. Then a wet mix is produced, which is pressed into nuggets of around 300 mm in diameter.

“After the core wire is straightened and cut to length, these flux nuggets are used on one of our two electrode extrusion lines to coat the core wire. The coated electrodes are then trimmed and dried for a few hours before being put into one of our two baking ovens,” Dudley tells African Fusion. Read more…

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