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For professional fabricators and structural engineers across New Zealand, the choice of welding wire is never trivial. The wrong consumable can delay an entire project, cause costly rework, or create unsafe working conditions. When Nelson-based Trinder Engineers found themselves fighting a persistent CO2 gas supply problem, they needed a smarter solution fast. Their answer was the Hyundai SC-420MC dual-shield flux-cored MIG wire, and the results exceeded every expectation.
This case study explores why Trinder Engineers made the switch, how the SC-420MC flux-cored wire performed on a demanding real-world infrastructure project, and what fabricators across New Zealand should know before choosing their next MIG wire.
The Challenge: CO2 Supply Issues with Hyundai Supercored 71H
Trinder Engineers had long relied on the Hyundai Supercored 71H, a well-regarded E71T1 titania flux-cored CO2-shielded MIG wire widely used in structural steel and general fabrication. The 71H delivers consistent arc performance and solid all-position capability, making it a trusted choice for workshops running high-volume weld schedules.
However, the 71H wire has one firm dependency: CO2 shielding gas. As supply chains tightened across New Zealand, obtaining a reliable flow of CO2 cylinders became increasingly difficult for the Trinder Engineers team. Delays in gas supply led to delays on the workshop floor, resulting in missed project milestones and unnecessary operational pressure.
As Prosser, an experienced fabricator at Trinder Engineers, explained: "We just switched to that SC wire from the old 71H because it was hard to get the CO2 gas."
Rather than work around the problem indefinitely, the team decided to evaluate a flux-cored wire with greater shielding gas flexibility.
The Hyundai SC-420MC is a dual-shield, all-position rutile flux cored wire classified to AWS E71T-1. It is available in 1.2mm and 1.6mm diameters on 15kg spools and is suited to a wide range of structural and fabrication applications.
The term "dual-shield" is important. Unlike a single-shield flux cored wire that relies solely on gas generated from the flux core, dual-shield flux cored wire uses both the flux core and an external shielding gas. The SC-420MC can operate with CO2 alone or with a mixed argon/CO2 shielding gas, giving operators genuine flexibility depending on what shielding gas is available on site or in the workshop.
This flexibility is precisely what resolved Trinder Engineers' supply chain problem. When CO2 was scarce, the team could switch to a mixed gas without changing their wire or adjusting their WPS significantly. The SC-420MC flux-cored wire worked reliably with both shielding gas options, keeping the workflow running without interruption.
Key technical characteristics of the SC-420MC include:
For fabricators seeking a high-performance MIG wire that does not lock them into a single gas type, the SC-420MC presents a compelling case.
The most significant project Trinder Engineers undertook with the SC-420MC flux-cored wire was the construction of a replacement bridge for the Maitai Golf Course. The previous bridge had been destroyed by severe flooding, and the new structure needed to meet stringent engineering and compliance standards.
The brief called for a 36-metre-long bridge built in three separate sections. Every joint, every weld, and every pass was catalogued, numbered, and recorded as part of a thorough quality management process. There was no room for inconsistency. The SC-420MC was selected from the outset because of its ability to produce high-quality, repeatable welds with minimal cleanup between passes.
Structural steel bridge fabrication places specific demands on a MIG wire. Out-of-position welding, particularly vertical-up runs on web and flange connections, requires a wire that maintains arc stability and controls the weld pool without excessive heat input. The SC-420MC delivered precisely this. Its low-spatter arc, excellent slag release, and controlled bead profile made vertical weld passes straightforward, even for less experienced operators on the team.
Prosser noted that the SC-420MC proved "much more forgiving than the old wire," particularly in vertical weld applications, which are notoriously demanding even for seasoned fabricators.
Based on experience with Trinder Engineers, the SC-420MC offers clear performance advantages over many conventional flux-cored MIG wires.
Reduced Spatter and Fume Generation
One of the most immediate improvements the Trinder Engineers team noticed was the reduction in spatter. Less spatter means less time spent grinding and cleaning between passes, directly reducing labour costs on high-volume fabrication projects. It also means a cleaner working environment, which is important for workshops where health and safety are taken seriously.
Welding fume generation was also noticeably lower with the SC-420MC compared to the Hyundai Supercored 71H. For shops that weld in enclosed or partially enclosed spaces, lower fume output reduces the burden on extraction systems and helps meet workplace exposure standards.
Excellent Vertical Weldability at Low Current
The SC-420MC is specifically designed to excel in out-of-position welding, including vertical-up applications. By delivering a stable arc at relatively low current settings, it gives the operator better control over heat input and weld pool behaviour. This makes it significantly easier to produce uniform, correctly profiled welds in the vertical position without resorting to a weave technique, saving time on every pass.
Superior Arc Stability and Crack Resistance
The SC-420MC produces a smooth, stable arc that is consistent across a wide range of parameters. This consistency is critical in structural work, where operator variability can introduce quality risks. The wire also offers excellent crack resistance, an important property in applications subject to dynamic loading such as bridges, vehicle chassis, and crane components.
User-Friendly for All Skill Levels
Perhaps the most telling feedback from Trinder Engineers came regarding apprentice welders. In a workshop environment, newer operators are often given simpler tasks while they develop their technique. With the SC-420MC, apprentices were able to complete complex structural welds with confidence from the outset. As Prosser put it: "This stuff just seems much more user-friendly and easier to use."
For workshop managers, this is a significant operational benefit. A forgiving, easy-to-set-up flux-cored MIG wire reduces training overhead on each new job and limits rework that can otherwise arise when less experienced operators tackle challenging positions.
Switching welding consumables always prompts the question of cost. Prosser summed it up plainly: "Everyone's happy if the gas is cheaper and the wire works just as good."
The SC-420MC delivers on both counts. Its compatibility with argon/CO2 mixed gas means workshops can take advantage of mixed gas pricing, which in some markets is more stable and accessible than bulk CO2 alone. Combined with reduced spatter cleanup time, lower fume extraction load, and greater first-pass success rates, the total cost of use for the SC-420MC compares favourably with alternatives, even when the per-kilogram price of the wire itself is similar.
For fabricators running projects with tight margins and firm delivery schedules, these efficiency gains compound quickly across a full welding programme.
Browse the full range of MIG wires available at Proline Industrial to compare options for your application.
Who Should Consider the Hyundai SC-420MC?
The SC-420MC is not a niche product. Its all-position classification, dual-shield capability, and broad application range make it suitable for a wide variety of structural and fabrication workshops. It is particularly well-suited to:
Structural steel fabricators working on bridges, buildings, and infrastructure
Workshops with mixed or variable gas supply that need a wire that tolerates both CO2 and Ar/CO2
Shops training apprentices, where a forgiving, easy-to-dial wire reduces rework
Projects with rigorous quality management requirements, where weld consistency and traceability matter
Applications requiring out-of-position welding, including vertical-up and overhead passes
If your team is currently using the Hyundai Supercored 71H and experiencing any of the challenges described above, the SC-420MC is a direct, proven upgrade path worth evaluating.
Conclusion
Trinder Engineers' shift to the Hyundai SC-420MC demonstrates something that experienced fabricators know well: the right welding wire does more than produce a bead. It determines how smoothly a workshop runs, how consistently apprentices and experienced welders can hit quality targets, and how resilient an operation is when supply chains become unpredictable.
The SC-420MC flux-cored MIG wire resolved a genuine supply chain problem, improved weld quality and operator experience, and proved itself on a demanding structural infrastructure project. For New Zealand fabricators seeking a reliable, versatile, and user-friendly flux-cored wire, this product warrants serious consideration.
View the Hyundai SC-420MC Dual-Shield Flux Cored MIG Wire or explore the full MIG welding range at Proline Industrial.
Welding fume is a confirmed human carcinogen. The International Agency for Research on Cancer classified it as Group 1 in 2017, and WorkSafe New Zealand continues to update its guidance on controlling worker exposure to welding fumes in industrial environments. Despite this, many workshops across Aotearoa still treat fume management as an afterthought, relying on open doors and natural ventilation to do the heavy lifting.
Trinder Group is not one of them. Under the leadership of Managing Director Kerry Hill, this Nelson-based engineering firm has positioned itself at the forefront of workplace health and safety, investing seriously in at-source welding extraction to protect its workforce. Their story is worth sharing, because it illustrates exactly what responsible industrial practice looks like in the real world, and why the choice of industrial fume extractor matters far more than most businesses realise.
Welding fumes are not simply smoke. They are a complex mixture of metallic oxides, silicates, and fluorides generated when base materials, coatings, and filler metals are heated above their melting points. Particles at the ultrafine end of the spectrum, those under 0.1 microns in diameter, penetrate deep into the alveolar region of the lungs and are not expelled through normal respiratory function.
Short-term effects include irritation of the nose, throat, and eyes. Long-term, repeated exposure is associated with chronic obstructive pulmonary disease, lung cancer, neurological damage from manganese, and in some cases, metal fume fever. The risk is not theoretical. It is the daily reality for welders who work in environments without adequate extraction and filtration.
For Trinder Group's welding supervisor Wayne Martin, this is personal. Years of working in environments with limited fume control left him with respiratory issues that continue to affect him today. That lived experience is precisely why he has become one of the most vocal advocates for upgrading welding extraction systems across the business. When someone with that background tells you the new equipment makes a visible difference, it carries real weight.
Kerry Hill frames Trinder Group's approach to welding extraction in straightforward terms: "Welding fume isn't good for you, and so we're looking for every practical way to reduce the fume."
That principle has driven a series of equipment upgrades focused on at-source capture, the most effective method of controlling welding fumes because it intercepts contaminated air before it has any opportunity to disperse into the breathing zone of the welder or surrounding workers. Rather than relying on general ventilation to dilute fumes across a large workshop space, at-source systems draw contaminated air directly away from the arc point, filter it, and return clean air to the environment.
This approach aligns with WorkSafe NZ's hierarchy of controls, which prioritises elimination and engineering controls above administrative measures and personal protective equipment. At-source fume extraction sits at the engineering control tier, making it one of the most defensible and effective strategies available to workshop operators.
Trinder Group has integrated purpose-built welding fume extraction systems into their welding operations, selecting equipment that captures fumes directly at the torch rather than relying on ambient extraction alone. The results have been immediately observable.
Understanding the mechanics helps demystify the technology. A quality industrial fume extractor operates on the same fundamental principle as a high-powered vacuum, but engineered for the specific demands of welding environments rather than general industrial cleaning.
Inside the unit, a motor drives a turbine that generates significant negative static pressure. This pressure differential draws contaminated air through a suction point positioned close to the welding arc. That air travels through internal filtration stages, typically including a pre-filter to capture larger particles and a high-efficiency main filter designed to capture ultrafine metallic particulates. Cleaned air is then returned to the workshop.
At-source extraction torches take this a step further. A fume extraction MIG torch functions identically to a standard MIG torch in terms of welding performance, using the same consumables, wire, and cable. The difference is a built-in housing and a front-end shroud that captures fumes as they are generated, before they can rise toward the welder's face. A secondary hose running alongside the torch cable carries the captured fumes back to the extractor unit.
The critical calibration point is vacuum pressure. Too low, and fumes escape capture. Too high, and shielding gas is drawn away from the weld puddle, risking porosity. Finding the right balance is straightforward once operators understand the adjustment range, and modern extraction units make this easier with adjustable flow controls.
The filter tray tells the story plainly. Senior tradesman Damian at Trinder Group describes the revelation of opening the tray after a relatively short period of use: "It's surprising how much it picks up when you empty the tray." That accumulated particulate is material that, without extraction, would otherwise have been breathed in by the people working alongside him.
New Zealand's Health and Safety at Work Act 2015 sets a clear legal obligation to manage workplace hazards so far as is reasonably practicable. For most industrial environments, investing in modern welding extraction equipment is entirely within that definition of reasonable practicability, particularly given how significantly the technology has advanced and how competitively it is now priced.
Kerry Hill does not stop at the legal argument, however. "There's a moral obligation as well just to be doing the right thing," he says. That statement reflects a broader shift in how forward-thinking New Zealand businesses are approaching occupational health. Compliance sets a floor, not a ceiling. The question Hill poses, "Is the minimum good enough?", is one every workshop operator should be asking themselves.
Extraction and filtration equipment innovators in the industrial sector are increasingly designing systems that do not require operators to make trade-offs between welding performance and fume management. Modern at-source extraction integrates with standard MIG setups without disrupting arc stability or welder workflow, removing the traditional friction point that led many businesses to deprioritise fume control.
The business case reinforces the moral one. Respiratory illness results in ACC claims, lost productivity, reduced workforce capability, and reputational consequences that extend beyond a single site. The cost of prevention is a fraction of the cost of management.
Not every workshop has the same requirements. The right industrial fume extractor for a single-operator MIG bench differs from what a busy production floor with multiple welding stations needs. Key considerations include:
Number of welding positions. Multi-station environments benefit from systems capable of handling simultaneous extraction points, or separate units allocated per station to maintain consistent capture efficiency.
Process type. MIG welding with standard wire typically generates different fume compositions than flux-cored, stainless steel, or aluminium welding. Confirm that the filtration specification of any unit you consider is rated for the materials you work with.
Filter change intervals and running costs. A lower purchase price means little if filter consumables are expensive or require frequent replacement. Ask for guidance on filter life based on your expected hours of use.
Mobility requirements. Fixed-position welding suits bench-mounted extraction. Mobile operations or site work require units with appropriate portability, hose length, and stability for varied environments.
Compliance documentation. For businesses subject to audit, choose equipment with documented filtration ratings and retention filter specifications that can be referenced in health and safety records.
Proline Industrial's welding fume extraction range includes options suited to both single-operator setups and higher-demand multi-station environments, with units available for MIG torch extraction and freestanding ambient extraction to complement at-source systems. If you are unsure which configuration suits your workshop, the team can advise based on your specific processes and layout.
Trinder Group's investment in welding fume extraction is not an isolated decision. It reflects a gathering shift across New Zealand industry, as more businesses move from reactive to proactive health and safety management, particularly in the welding sector where fume exposure risks are well established and the tools to address them are readily accessible.
Kerry Hill and his team have demonstrated that prioritising at-source welding extraction does not require compromising on productivity, throughput, or weld quality. It requires choosing the right equipment, understanding how to set it up correctly, and committing to a standard of workplace health that goes beyond the minimum required by law.
For workshops that have not yet reviewed their fume management approach, the filter tray test is a sobering starting point. Run your current setup, open the tray, and see what your workers have not been breathing in. Then consider what they have been.
Proline Industrial supplies welding fume extraction systems throughout New Zealand, with warehouses in Nelson and Auckland for fast, reliable delivery. Explore the full range of welding fume extraction equipment online.
If you work with steel on a regular basis in a fabrication shop, on a construction site, or in a rural engineering workshop, the annular cutter is one of the most important tools you can add to your setup. Also widely known as a drill cutter, broach cutter, or core drill cutter, the annular cutter has largely replaced the twist drill bit for large-diameter hole cutting in metal across professional trades in New Zealand and around the world. Yet there are still plenty of tradespeople who have never used one, or who underestimate what a properly specified drill cutter can do for their productivity and hole quality.
This guide covers everything you need to know: what an annular cutter is, how it works, the difference between HSS and TCT types, how to match a cutter to a machine, correct operating technique, and which applications are best served by a drill cutter rather than a conventional bit. By the end, you will have a clear picture of why this tool is considered the gold standard for metal hole cutting in professional environments.
An annular cutter is a hollow, cylindrical cutting tool with teeth around its circumference, designed to cut only the outer ring of a hole in metal rather than removing the entire cross-section of material. The word "annular" comes from the Latin annulus, meaning ring, which describes exactly what the tool cuts. As the cutter advances through the material, it leaves a solid plug of metal in the centre, known as the slug, which is then cleanly ejected through the hollow body of the cutter once the cut is complete.
This ring-cutting principle is what separates an annular cutter from a conventional twist drill bit, and it is the root cause of nearly every performance advantage the drill cutter offers. Because only a narrow ring of material is being displaced rather than the full diameter, the cutting forces are dramatically reduced. Less energy is consumed per cut, less heat is generated at the cutting edge, and the machine doing the driving, typically a magnetic drill, experiences far less strain. The result is a faster cut, a longer-lasting tool, and a cleaner, more accurate hole.
A pilot pin sits in the centre of the annular cutter and contacts the workpiece first, centring the tool precisely on the marked position before the cutting teeth engage the metal. This means no centre punching, no pilot hole, and no step drilling. The cutter goes straight in and produces a finished hole to the correct diameter in a single pass.
Annular cutters are available in diameters ranging from 12mm up to 100mm or beyond, and in two standard depth-of-cut series. Short series cutters offer a 25mm depth of cut, which covers the vast majority of structural steel applications. Long series cutters extend to 50mm, making them the right choice for thicker sections, box sections, or where the drill must penetrate multiple layers of material in a single pass.
Most metalworkers start their careers using twist drill bits, and for small-diameter holes in light materials, a twist drill is adequate. The problems begin when the hole diameters increase, and the material gets thicker.
A twist drill bit removes every scrap of material across the full face of the hole. At 10mm or 12mm in steel, this is manageable. At 25mm, 35mm, or 50mm, the torque requirements climb sharply, heat builds rapidly, the drill tends to wander off centre, and the hole quality typically becomes rough, oversized, and with a pronounced burr, making it difficult to control. Step drilling through progressively larger bits helps, but adds time and compounds the accuracy issues at each stage.
An annular cutter, by contrast, does none of this. Because the centre material is left intact and only the perimeter is cut, a 35mm drill cutter running in a magnetic drill requires a fraction of the torque of a 35mm twist drill in a standard drill press. The cut is completed faster, the hole wall is smooth and square, there is no burr to dress, and the finished diameter is accurate to within tight tolerances without any secondary work. In high-volume fabrication environments, these advantages compound, yielding significant productivity and cost savings over hundreds of holes per day.
The trade-off is that annular cutters require a dedicated machine, the magnetic drill, rather than a standard corded drill or drill press. But for any professional working regularly with steel with a diameter of 12mm or above, this is not a trade-off at all; it is simply the correct tool for the job.
When selecting an annular cutter or drill cutter in New Zealand, the most important decision is the material from which the cutting teeth are made. There are two main options, each suited to different working conditions.
High-Speed Steel (HSS) annular cutters are manufactured from M2 or M2AL grade tool steel, which is tough, sharpenable, and best suited to commonly used mild steel and other softer materials; it also places less stress on magnetic drills, making HSS a strong option for lightweight machines. HSS cutters are sharp from new, respond well to regrinding when they dull, and represent excellent value for most general fabrication and construction applications. Rotabroach’s Raptor M2AL Short Series HSS Annular Cutters are the go-to choice for everyday work, available in diameters from 12mm to 60mm with a 25mm depth of cut. Where thicker sections need to be drilled, the Raptor M2AL Long Series HSS Annular Cutters provide a 50mm depth of cut across the same diameter range. For tradespeople new to annular cutters, the Rotabroach 14-22mm Short Annular Cutter Kit (7-Piece) covers the most commonly used sizes in a single cost-effective set.
Tungsten Carbide Tipped (TCT) annular cutters take HSS performance a step further by brazing tungsten carbide inserts onto the cutter body's cutting edges. Tungsten carbide is significantly harder than high-speed steel, and its cutting edge provides exceptional durability and wear resistance for hard, abrasive materials such as stainless steel and cast iron, making TCT drill cutters the right choice for continuous production environments, for cutting harder or heat-treated steels, or anywhere the cutter will be run for extended periods without a cooling-off time. The higher initial cost of a TCT cutter is offset by a substantially longer service life and reduced downtime for tool changes in busy shops. Rotabroach’s TCT Short Series Annular Cutters and TCT Long Series Annular Cutters are available from 12mm to 52mm diameter, and are a popular choice across NZ fabrication and structural engineering firms running high-output production.
A simple rule of thumb: if you are drilling intermittently across a variety of jobs, HSS is the practical and economical choice. If you are running the same cutter size continuously through a production run, TCT pays for itself quickly.
An annular cutter cannot be used in a standard handheld drill or conventional drill press. It requires a magnetic drill, also known as a mag drill, which provides the two things a drill cutter needs to perform correctly: a stable, fixed base and a precisely controlled feed rate.
The magnetic base of a mag drill uses a powerful electromagnet to clamp directly to the steel workpiece, eliminating movement during the cut and allowing the operator to drill in any orientation, including vertically overhead or horizontally into a vertical beam face. The feed arbour then advances the annular cutter into the material at a consistent rate, maintaining the optimal chip load on the cutting teeth throughout the cut.
Proline Industrial stocks the complete Rotabroach Element magnetic drill range, which works seamlessly with Rotabroach annular cutters. The Rotabroach Element 30 Magnetic Drill is the compact, site-portable option with a 32mm cutting capacity, ideal for maintenance work and on-site fabrication where access is restricted. The Rotabroach Element 40 Magnetic Drill steps up to a 40mm capacity and suits the majority of general fabrication shop requirements. The Rotabroach Element 50 Magnetic Drill delivers heavy-duty performance at 50mm capacity for demanding structural applications, while the Rotabroach Element 75 Magnetic Drill handles the largest-diameter work in high-output production settings.
Every annular cutter setup also requires a correctly sized pilot pin, matched to the cutter series HSS 25mm, HSS 50mm, TCT 35mm, or TCT 50mm. Always verify that the pilot pin is correctly seated before beginning a cut, as it keeps the cutter centred during the initial engagement with the material.
Correct technique is what separates a drill cutter that lasts hundreds of holes from one that fails prematurely. The most critical habit is the consistent application of cutting lubricant. An annular cutter generates significant heat at the cutting teeth, and without lubrication, that heat accelerates wear rapidly. A cutting paste or fluid should be applied to the entry point before cutting begins, and reapplied whenever cutting slows or the cut's pitch changes. This single habit has more impact on a cutter's life than any other factor.
Speed matters too. Annular cutters operate at considerably lower RPM than twist drills, generally between 180 and 450 RPM, depending on the cutter diameter and material. Larger cutters run slower; harder materials require lower surface speeds. Running a drill cutter too fast burns the cutting edge in seconds. Too slow, and you are simply wasting time without any quality benefit. The Rotabroach speed and feed charts provide precise guidance for each diameter and material type, and it is worth taking 5 minutes to consult them before starting on unfamiliar stock.
Feed pressure should be firm and consistent. Annular cutters do not like hesitation or chattering; let the machine advance steadily under its own feed mechanism and resist the urge to force it. When the cutter breaks through the underside of the material, ease off the feed slightly to avoid tearing the exit face. Once the cut is complete, the pilot pin spring-ejects the slug cleanly through the body of the cutter.
Inspect your annular cutters before each use. A chipped or blunt tooth does not just produce a poor hole; it places excessive load on the magnetic drill arbour, can cause the mag drill to lose its hold on the workpiece, and significantly increases the risk of a dangerous kickback event. Keeping a spare cutter of each common size on hand is standard practice in any professional shop. Browse the full range of annular cutters at Proline Industrial to keep your kit stocked.
The annular cutter earns its place across virtually every sector of New Zealand's metal-working industry. In structural steel fabrication, it is the primary tool for producing bolt holes, connection plate penetrations, and anchor point holes in I-beams, RHS sections, and channels. In commercial construction, it handles the penetrations for HVAC, electrical conduit, and pipe work that must pass through structural steel members cleanly and without distortion. Rural engineering workshops across the South Island and Waikato rely on drill cutters daily for fabricating farm equipment, trailer chassis, and machinery mounts where accuracy in mild steel is essential, but production speed is equally important.
In the automotive sector, annular cutters are used for chassis modification, roll cage fabrication, and custom exhaust work, where a clean hole in thin and medium steel is needed without warping the surrounding material due to heat. The marine and shipbuilding industries active in ports including Tauranga, Auckland, and Nelson use drill cutters for hull frame penetrations, deck fittings, and structural connection points, where both precision and corrosion-resistant finishes make hole quality critical from the outset.
Switching from twist drills to annular cutters is one of the highest-impact changes a metalworking tradesperson or shop can make. The gains in speed, hole quality, and tool longevity are immediate and measurable from the very first cut.
Proline Industrial supplies the complete Rotabroach annular cutter and magnetic drill range to tradespeople and businesses across New Zealand.
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