At a glance RESEARCH REPORT: TESTED: INVERTER WELDERS

Transcription

1 TESTED: INVERTER WELDERS Josh Giumelli KONDININ GROUP Ben White At a glance Lightweight inverter welders offer flexibility and portability in a small package. s range from $260 to more than $1000, so consider all options carefully. Using microprocessor control, inverter welders take the pain out of using difficult, sticking electrodes. Hot-start functions on inverter units make striking an arc easier than traditional transformer welders. While inverter welders can be used as tungsten inert gas (TIG) welding power supplies, some are more suited to the task than others. Inverter welders are now safer to use with generators and long extension leads. Inverter welders are a revolution in technology, giving farmers the option of a lightweight and efficient tool to repair machinery at an affordable price. In this report, Farming Ahead writer and engineer Josh Giumelli along with fellow Kondinin Group engineers Ben White and Tim Andrew respond to member feedback and present the results of on-farm tests of 13 inverter welders to help separate the tools from the toys. Cash-strapped farmers in the market to buy a portable welder could save almost 60 per cent on the price of a new unit. In an Australian first, this exclusive Farming Ahead Research Report shows one inverter welder that cost just $308 offered a viable low-cost alternative to the more expensive brand-name units on the market. But for farmers willing to invest more money in an inverter welder, several excellent machines offering a range of functions were identified. Helping keep costs low Kondinin Group engineers said the results were excellent news for farmers battling successive poor seasons and those keen to reduce their costs by completing fabrication and repairs themselves. The results also showed product price was no guarantee of performance. Farmer demand sparks tests Members calls for performance data on inverter welders prompted Kondinin Group engineers to test 13 popular inverter welders in a bid to help farmers reduce their costs. One portable inverter welder at just $308 offered a low-cost, entry level unit, suited for farmers who might baulk at the cost of a $1000 unit. Engineers tested the BOC Inverweld 110, BOC Smootharc 130, CEA Rainbow 150, Cemont Colt S3200, Cigweld Transarc 131i, Esseti 150CS, Euroarc 140, Fronius 1400, Kemppi Minarc 120, Lincoln Invertec V145S, Migomag 155 DCI, Tokentools Miniarc 142 and the TWM IN Farming Ahead February 2007 No

2 TESTED: INVERTER WELDERS Photos: Ben White Big and small: Kondinin Group tested 13 portable inverter welders to gauge how well each unit worked, suitability for on-farm applications and value for money. The smallest inverter welder tested was the TWM IN2500 and the largest was the Lincoln Invertec V145S. A revolution in welding Inverter technology has revolutionised stick or manual metal arc welding (MMAW) by providing a more efficient and versatile welding power source. At less than one-tenth the weight and about twice the efficiency, inverter welders can be carried with little effort and run using extension leads or generators. According to manufacturers, sales of traditional heavy stick welders have fallen dramatically in recent years as inverter-based units have become cheaper. Low-cost imported units from China have placed pressure on established brands, forcing down prices. In addition, inverter welders offer the versatility of direct current (DC) welding rather than the limited alternating current (AC) welding from heavy transformer units. DC tungsten inert gas (TIG) welding also is possible with most of the welders tested. Heat put on welders Most machines tested were easy to use. The main downside was the price, with some units costing more than $1000. But Kondinin Group s engineers discovered several cheaper inverter welders such as the $308 Tokentools 142 and the $539 Cemont Colt S3200 and the $324 BOC Smootharc 130 proved capable. Yet buyers need to be careful as the small and compact $260 TWM IN2500 was completely useless and could only just run a 2.5-millimetre electrode. Kondinin Group s independent tests showed how inverter welders worked using a range of welding electrodes commonly used on-farm. All other welders tested could run 3.2mm and 4mm electrodes, although some lower-rated Portability has convenience benefits: Welders fitted with a shoulder strap and a carry handle were the most convenient units to move about such as the Kemppi Minarc (left). While the BOC Inverweld 110 had a handy strap, it lacked a handle (right). Plugs and leads: Most welders were fitted with a 15A plug (below, left) but some had 10A plugs even though they could draw more than 10A. Operate portable inverter welders with 15A-rated extension leads to reduce voltage losses. Test equipment: Group engineers used a DC clamp meter to monitor output an input current during tests. Farming Ahead February 2007 No

3 TESTED: INVERTER WELDERS Clear operation: The CEA Rainbow (top) featured an arc TIG selector switch with a setting especially for stainless (CrNi) electrodes, while the Lincoln Invertec had a soft mode for rutile flux (a mineral form of titanium dioxide) and stainless electrodes, a crisp setting for basic and cellulose flux electrodes. machines struggled to find full penetration with larger 4mm rods. Generally, an output of 140A or more is needed to operate a 4mm electrode successfully. Staying power All welders, whether they are stick, metal inert gas (MIG) or tungsten inert gas (TIG), are sold with a rated duty cycle. The duty cycle is written as a rated level of output current and a percentage, which is a proportion of time the welder can hold the output current at the rated level. A welder cannot operate indefinitely at high outputs without being damaged due to heat produced inside the transformer. Duty cycles Some welders are more heavily constructed and have better internal cooling systems and will have a higher duty cycle. A welder with a duty cycle of 150 amperes at 20 per cent can produce 150A for just two minutes out of every 10 before the current level either falls or the machine shuts down. This machine also might have a rating of 95A at 100%, which means it can weld continuously at 95A and not overheat. To assess portable welder performance, Kondinin Group engineers operated the 13 units at maximum output for 10 minutes using 3.2mm electrodes and recorded output current and voltage (see Table 1). Performance tests While some units shut down due to overheating, many worked well for the entire period of testing. Although most output currents fell during this period, most machines produced quality welds. Kondinin Group engineers judged all welders on their ability to operate a range of welding rods commonly used on farms. These included generalpurpose E4113 electrodes (3.2mm and 4.0mm), AC mm hardfacing electrodes (1855 A4), stainless steel 3.2mm electrodes (E316L 16) and E mm cellulose flux electrodes. The engineers used the E4111 electrodes because these have a high open circuit voltage requirement of 70 volts and can be difficult to strike on some machines. The drought has increased pressure on farmers to reduce their costs but there are some toy welders on the market that perform poorly and are unsuitable for farm conditions. The 4mm E4113 electrodes tested the welders capacity to operate a large diameter electrode, with all but the TWM IN2500 passing the test. But penetration was poor with many units more suited to 3.2mm electrodes. Engineers also measured the welders maximum current draw with 4mm electrodes. Tests were carried out using a 10-metre, 15A extension lead, as in most situations welding units are operated with some form of extension cord. Limited voltage Because air is a poor electricity conductor, a welder needs a high initial voltage to enable the arc to be struck between the work and the electrode. This open-circuit or no-load voltage is limited to 110V DC or 80V AC under Australian design rules. After an arc is struck, it travels across the molten pool of metal and requires a far lower voltage to maintain it, usually 20 30V. Some units such as the Esseti 150CS, Lincoln Invertec V145S and Kemppi Minarc 120 were fitted with voltage reduction devices (VRDs). These are required for mine-site safety as they lower the open-circuit voltage to a safer level of 35V or less. When the welder senses a load with a resistance less than a certain level (often 200 Ohms) the voltage is increased to help start the welding arc. A load with higher resistance would indicate the current might be flowing through the operator instead. The price of safety While VRD safety benefits are obvious it increases the welder purchase price and can make some welding electrodes more difficult to start. TABLE 1 Inverter welder performance as tested by Kondinin Group Make and model Rated Measured Average Average Average Open Duty cycle Current VRD Insulation Weight Country maximum maximum minimum output input circuit maximum at 100% fitted protection E (kg) of origin (with GST) welding welding welding B voltage B current B voltage C current D duty cycle D (amperes) (Class) current current A (amperes) (amperes) (volts) (amperes) (volts) (amperes) (amperes) (amperes) BOC Inverweld A at 50% 80 Yes IP Finland $1077 BOC Smootharc A at 35% 118 No IP China $326 CEA Rainbow at 30% 100 No IP Italy $990 Cemont Colt S A at 15% 60 No IP China $539 CIGWeld Transarc 131i A at 40% 100 No IP Not listed $880 Esseti 150CS A at 30% 95 Yes IP Italy $1289 Euroarc A at 25% 85 No IP Italy $660 Fronius 1400* A at 35% 100 No IP Germany * Kemppi Minarc A at 50% 80 Yes IP Finland $1265 Lincoln Invertec V145S A at 60% 120 Yes IP Italy $1280 MigoMag 155 DCI A at 35% 110 No IP France $1045 TokenTools Miniarc A at 35% 70 No IP China $308 TWM IN A at 35% 50 No IP China $260 A. Measured using a 4mm electrode. B. In 10-minute test. C. Measured. D. Manufacturer s rating. E. IP23 offers superior category of insulation to IP Combination of average 2. Across a range of welding electrodes tested. * This unit has been superseded by the 1500 model for $1628. ** Higher percentage scores indicate better performance. 18 Farming Ahead February 2007 No

4 TESTED: INVERTER WELDERS Performance tests: Kondinin Group engineer Josh Giumelli tested the welding performance of each of the 13 units. Inset: Examples of welds using (from left to right) hardfacing, 3.2mm and 4mm general purpose, stainless steel and 4111 stovepipe electrodes (matching electrodes are pictured inset bottom, also from left to right) to test welder performance. Unique fittings (pictured top): The Esseti 150CS (left) was the only unit tested with large-diameter welding lead bayonet fittings, as opposed to the more normal smaller fittings. Annoying features (pictured bottom): Often simple features can become annoying. Rear-mounted power switches (left) are not visible to the operator and require reaching behind the machine, compared with those fitted to the front panel (right). The Kemppi Minarc had a key-operated switch on its rear allowing the VRD to be switched off. Kondinin Group engineers expected the VRD to make starting some welding rods more difficult but most units performed well. TIG welding was not tested While all units tested were capable of TIG welding to some degree, this feature was not 10-minute Ease of striking Weld quality 2 load test 1 arc (% rating)** (% rating)** (% rating)** output current and time in operation after 10 minutes. evaluated as additional equipment was required for TIG welding such as a handpiece and shielding gas bottle. Many machines had a separate TIG function, which could be selected using a switch on the front panel. Welders equipped with lift-start TIG are superior to those with scratch-start TIG, as the arc will start when the electrode is lifted off the work piece. Keep in mind that aluminium TIG welding is not possible with DC power. Running on generators In the past, inverter welders gained a bad reputation for unreliability when operated off an extension lead or generator. But now, some manufacturers guarantee machines for operation in these situations. For example, the Lincoln Invertec V145S is guaranteed generator safe and can be powered using a 60m extension lead. Most welders tested could operate off a six kilovolt ampere (6kVA) generator. Safety cut-off Previous issues associated with low- or highsupply voltages are now taken care of by the welder s computer, which will shut down the machine if the voltage is not within its working limits. If in doubt, check with the supplier before buying a unit. Tests showed product price was no guarantee of performance. Farming Ahead February 2007 No

5 TESTED: INVERTER WELDERS How do inverter welders work? Traditional welders use a transformer to lower the input line voltage and boost the current to a level suitable for welding. The frequency of Australian mains voltage is 50 hertz alternating current (AC), which means the voltage cycles from positive to negative 50 times a second. While the alternating nature of AC current is essential to create a magnetic field and allow the transformer to operate, it is not very efficient at 50Hz, with up to 50% of electricity wasted as transformer heat. A transformer needs to be built heavily to withstand heat and portability is compromised as a result. FIGURE 1 How inverter welders work Source and illustration: Kondinin Group. 20 Farming Ahead February 2007 No

6 TESTED: INVERTER WELDERS A sophisticated tool The inverter welder uses far more sophisticated electronics including microprocessor control to produce a more versatile welding unit (see Figure 1). Rectifiers enable the transformer to produce less heat, which means the welder can be packaged for portability. To increase the current using a small transformer the inverter welder uses a combination of rectifiers (which chop off the negative half of the voltage cycle), inverters and switching circuits to boost frequency to tens of thousands of cycles. As a result, the transformer operates more efficiently, producing less heat and allowing the inverter welder to be packaged for portability. Flexibility a bonus The rectified welding supply in an inverter welder is direct current (DC), which has several advantages over AC welders. Vertical and upside-down welds are easier to produce when the electrode is connected to the positive terminal and the work to the negative terminal. The result is a steady and strong arc which concentrates heat at the electrode tip. Positive versus negative electrodes Most DC welding is performed with a positive electrode. A negative electrode produces a thinner, deeply penetrating weld as heat is concentrated in the work instead of within the electrode tip. This type of electrode is more suited to flatposition welding. Smart electronics help welds A hot-start function is common this device momentarily boosts current to assist arc initiation. To prevent sticking electrodes, most units will shut down when they detect a short circuit. Range of electrodes More advanced features found on some portable machines help the user weld with different electrodes. For example, the Lincoln V145S inverter welder tested has a soft mode for rutile flux and stainlesssteel electrodes. In addition it has a crisp mode for basic and cellulose flux electrodes. The CEA Rainbow 150 has a special setting for Cr Ni (stainless) electrodes. The microprocessor control inside an inverter welder adjusts welding current and voltage to best suit different situations and electrode types. This space is deliberately blank Farming Ahead February 2007 No

7 RESEARCH : REVIEWS INVERTER WELDERS Choice governed by suitability for the job Kondinin Group engineers judged all 13 inverter welders on their ability to operate a range of welding rods commonly used on farms. The units were tested at maximum output for 10 minutes using 3.2-millimetre electrodes and the output current and voltage were recorded. Switchable voltage-reduction device. Tungsten inert gas function. Compact. Front power switch. Terminal polarity labelling. Radio interference. 10-ampere plug. BOC INVERWELD 110 The BOC Inverweld 110 is a sleek and compact inverter welder. But tests showed it lacked enough current for full penetration on the four-millimetre electrodes. Hardfacing and 4111 electrodes were easy to use but stainless and 4mm electrodes were a little difficult to start. Output current was extremely stable at all times. $ (includes tax). Terminal polarity well marked. Switch at front and a comfortable handpiece. Value for money Large fan. 10-ampere plug. No tungsten inert gas function. BOC SMOOTHARC 130 The unit had an excellent all-round performance with adequate penetration on all welds and a high weld deposition rate. A small hesitation when using the 4mm electrodes made striking an arc a little difficult but all other electrodes start and run well. At this price, it represents an excellent value entry-level machine. $ (includes tax). Compact and well-built. Lift tungsten inert gas function. Heavy-duty lead. Safe to use with 60-metre extension lead. No shoulder strap included. Radio interference. Weld quality was brilliant with low spatter and excellent penetration. The arc was easy to start and there was little difference between using 3.2mm or 4mm electrodes. The welder was a pleasure to use. $990 (includes tax). CEA RAINBOW Farming Ahead February 2007 No

8 INVERTER WELDERS REVIEWS : RESEARCH CEMONT COLT S3200 A simple but capable welder which produced consistent welds after easy starting but poor penetration when using 4mm electrodes. This welder represents value for money and is only let down by a lower duty cycle. An excellent choice for farmers not welding continuously. $539 (includes tax). Lightweight yet robust. Simple and easy to use. Value for money. Terminal polarity labelling. Low duty cycle. CIGWELD TRANSARC 131i All welds were even and well formed, except when using 4mm electrodes where penetration was low. The welder has a soft and gentle arc but starting the 4111 electrodes was a little difficult. A simple, compact and easy-to-use welder. $880 (includes tax). Compact and solid build. Simple to use. High duty cycle. Low radio interference. Fitted with a 10-ampere plug. No shoulder strap. No tungsten inert gas function. ESSETI 150CS The Esseti 150CS produced its best results when operated flat-out but output current dropped during the 10-minute test. An unstable output current produced slightly uneven welds but output was high and penetration was satisfactory. The 4111 electrodes were more difficult to start when the using voltage reduction device (VRD). $ (includes tax). Key-operated VRD. Tungsten inert gas function. Heavy-duty power lead. High current and penetration. High open circuit voltage (116V). Cost. EUROARC 140 An impressive output current gave excellent penetration and deposition rates. But weld quality was affected by a fluctuating output current. The welder performed well in the 10-minute test but was difficult to start with the 4111 electrodes. $660 (includes tax). Output current performance. Face panel protects controls. High weld deposition rate. TIG function. No handle and poor quality power lead (3 x 1.5mm 2 ). Lightweight tungsten inert gas switch. Radio interference. Farming Ahead February 2007 No

9 RESEARCH : REVIEWS INVERTER WELDERS FRONIUS 1400 All-round performance. Robust and compact. Weld quality. High duty cycle.. An excellent, high-end and compact machine that produced perfect, even welds with high penetration and deposition rates. All electrodes were easy to start and output current was steady. The unit has been replaced by the 1500 model at $1628 (includes tax). KEMPPI MINARC 120 Compact and well built. Performance under load. IP23C insulation rating. Quality leads. Guaranteed generator safe. Fitted with a 10-ampere plug but drew up to 24A. Fiddly rear switch. Difficult-to-read terminal polarity. A solid performing welder that just lacked enough current to produce full penetration when using 4mm electrodes. Both 4mm and 4111 electrodes were difficult to start. But performance in the 10-minute test was excellent. $1265 (includes tax). LINCOLN INVERTEC V145S Construction quality. Performance with 4mm electrodes. VRD can be switched off. Soft, crisp and tungsten inert gas function. Generator-safe guarantee. IP23C insulation rating. Power switch on rear. Larger size. While expensive, the Lincoln Invertec V145S produced excellent penetration on all welds and was a standout performer with the 4mm electrodes. Kondinin Group engineers found it difficult at times to strike an arc when the voltage reduction device was on, especially with the 4mm electrodes. Although the welder was the largest tested, it was not heavy. $1280 (includes tax). Expensive. TWM IN2500 Compact and lightweight. Kit form with leads and rods. Performance and low duty cycle. Cannot reliably weld electrodes more than 2.5mm. This welder is rubbish. Spend the extra $48 and buy the Tokentools Miniarc 142. $260 (includes tax). Fitted with a 15-ampere plug but draws 6 7A. 24 Farming Ahead February 2007 No

10 RESEARCH : REVIEWS INVERTER WELDERS Heavy power lead. High current output. IP23C insulation rating. Guaranteed generator safe. No leads included. Current drops off under high-duty cycle work. Radio interference. MIGOMAG 155DCI Kondinin Group s test engineers rated highly this unit s welding performance as it produced high deposition rates and was easy to start. High current output ensured full penetration on all welds but current fell away during the 10-minute test. $1045 (includes tax). Excellent value for money. Simple machine. Supplied with case and accessories. Reasonable performance. Light build. Radio interference. Fluctuating current led to uneven welds. Accessory quality. TOKENTOOLS MINIARC 142 While a fluctuating output current led to less than perfect weld beads there was no doubt about this welder s value for money. Penetration performance was poor when tested with 4mm electrodes. But the welder was excellent during the 10-minute test. Kondinin Group engineers believed a small outlay would reward owners with a capable welder. $308 (includes tax). Contacts Manufacturer Phone and web site BOC contact@spr.gases.boc.com CEA Contact local retailers export@ceaweld.com Cemont Contact local retailers com.cemont@airliquide.com Cigweld cigweldsales@cigweld.com.au Esseti (02) warren@woodfields.com.au Fronius (03) fronius@smenco.com.au Kemppi (02) info.au@kemppi.com Lincoln (02) (NSW) (07) (Queensland) (03) (Victoria) (08) (WA) Migomag (03) info@migomag.com.au Tokentools (02) sales@tokentools.com.au RESEARCH ENGINEERS Ben White (pictured from left), Josh Giumelli and Tim Andrew tested and evaluated the inverter welders for this report. TEST EQUIPMENT SUPPLIERS BOC Gas and Gear, WA, and Chris Birchall (BOC Inverweld 110 and Smootharc 130); Burnback Welding, WA (CEA Rainbow 150, Cigweld Transarc 131i, Kemppi Minarc 120, Migomag 155 DCI); Gentronics, WA (Cemont Colt S3200, Esseti 150CS, Fronius 1400); Neil Bowers, Lincoln Electric, WA (Lincoln Invertec V145S); Kondinin Group bought the Tokentools Miniarc 142 (from and TWM IN2500 ( WIA was unable to supply WIA and Miller welders at the time of testing. 26 Farming Ahead February 2007 No