Considering the variety of welding processes available, selecting the right one for your shop could be a confusing and difficult decision. In any manufacturing operation, matching the best process to the application can be the difference between profit and loss on a job.
Likewise, welding has many variables in terms of matching methods and materials. By properly selecting a welding process, many hours may be saved in production, repairs, polishing and grinding, or rejected welds.
An example of a fitted tank
The object of welding, whether it’s done on a production basis or occasionally, is the same: To produce a quality weld in the least amount of time. Welding quality is determined by the success one has in creating a weld that penetrates sufficiently, without pores, pockets or gaps. Good surface finish is also a factor.
When you have 139 years of collective experience in welding between the management team, you figure that this company can weld.
It all starts back in 1957 when Arthur Johnson, now 75, and still very active in the business, completed his welding training in the UK. For the next eight years Arthur worked for engineering companies, started his own business and family, and generally learnt the art of metalworking, but always with an emphasis on welding, and more specifically with a bias towards aluminium welding. This experience would be invaluable when he decided to uproot the family and move to South Africa in 1972.
It did not take Arthur long to get on his feet, and by 1975 he established his first South African company, A Johnson & Sons, a company that grew over the years on welding applications and general fabrication.
“I had almost become a specialist in aluminium welding during this time,” said Arthur.
“Welding aluminium poses some unique challenges. In addition to a low melting point and high thermal conductivity, aluminium is especially prone to burn-through on thin sections and may experience lack of fusion on thick ones. Weld defects like cracking, weld smut/soot, and porosity are also real concerns.”
Various tanks manufactured by Multi Tanks International
“With manual welding you will never achieve the same consistency of a weld over the length of the tank that could be 1500mm, and you can’t duplicate the same weld, but with a machine you can, as long as you have a fixture to hold the material in place.” The latest addition is a two station Yaskawa Motoman robotic welding machine equipped with a manipulator and a jig that the company has manufactured itself
“Still, aluminium’s ability to resist corrosion, its high strength-to-weight ratio, as well as its high electrical conductivity make it an excellent choice for many applications from aerospace to heat exchangers, trailer fabrication and, most recently, automotive body panels and frames.”
“To avoid a negative impact on productivity and quality, it is important to understand the causes of aluminium weld defects, implement steps to prevent them, and find ways to quickly rectify errors should they occur.”
“As with any welding process on any material, following some basic guidelines is critical to obtaining the best results. Aluminium’s mechanical and chemical composition can make the process a bit tricky. Always follow best practices for cleaning and storing the material and filler metals, and carefully select the right equipment. After all, having everything in order before welding is easier than trying to fix problems later.”
Today aluminium welding is still one of the processes used in the company that has changed its name to Multi Tanks International, however the company is much more than that.
Multi Tanks International is a family-owned business that manufactures affordable high quality after-market aluminium fuel tanks for a variety of companies. There are no formal job titles in this tight-knit family-owned business run by Arthur Johnson and his two sons, Lee and Craig. Lee joined the company shortly after leaving school in 1992, and the young Craig joined in 2002.
The Yaskawa Motoman robotic welding machine welding the tank ends
Lee, Arthur and Craig Johnson from Multi Tanks International – a local fuel tank manufacturing company, creating products as good as any OEM could offer
Multi Tanks International began operating in 2000, and tank manufacturing has been the core of the business for the last 16 years.
“Our first attempt at manufacturing a fuel tank was 20-odd years ago. Out of the blue we received a call from a truck distribution company who knew that we had some experience in aluminium welding. They wanted us to manufacture some aluminium chequered-plate mud guards, which you couldn’t buy in South Africa.”
“When we delivered the mud guards, we were intrigued to see that their trucks didn’t have aluminium tanks so we decided to ‘test the waters’ and manufacture one. It was at a time when OEMs were under pressure to look at reducing the weight of vehicles and trucks so as to achieve cost reductions and take environmental considerations into account. Aluminium was a great alternative and an intelligent solution to allow maximum weight savings while still retaining the integrity and safety of the product or component. The added advantage is that the material is corrosion resistant.”
“You can achieve weight savings of up to 45% when using aluminium, whether it is formed, machined or cast. It is not ideal for every application but time has shown that the use of aluminium in the transport industry has grown beyond expectations.”
The prototype aluminium fuel tank was the beginning of a new era in the lives of the Johnsons, one that would lead to them changing the company name and the services it offered.
The first area Multi Tanks International gave attention to was in the press department. The company invested in a 100 ton hydraulic forming machine and have subsequently manufactured a further four presses
A tank in its final stages of manufacture. The tank sizes on the fuel side range from 160 litres to 1000 litres and Multi Tanks International now manufactures fuel tanks for about 90 percent of all truck vehicle makes on the road
“Our focus had always been on welding, but with the introduction of the fuel tank manufacturing we realised that to offer an off-the-shelf product, it entailed more than just welding metal together. There is plasma cutting, shaping, roll and press forming and welding of the sheet. But then there are all the accessories that are part of the final product. These include nipples, caps, sockets, filters, flanges, shoulder fittings, ant fuel theft necks and components and many others. In total there are about 45 different components that we regard as the accessories used to make up the various tanks that we manufacture.”
“Many of these components have to be machined or cast, and press formed in the case of the fuel tank ends. We were not equipped with any of the equipment to perform these processes and in the beginning we had to outsource most of the components,” continued Lee.
“The number of different varieties of standard tanks that we manufacture is 40, but we are not limited to just being a production operation because we have many requests for custom made tanks and other products. Another one of our standard products that we offer is hydraulic tanks that are used on heavy equipment such as backhoes, excavators, cranes, side tippers, large off-road trucks, and generator and pump sets,” explained Lee Johnson.
Multi Tanks International is not restricted to just manufacturing tanks. Any fabrication that needs welding they are able fabricate
Multi Tanks International is not a production shop but still needs many of the components that are welded on to the tanks to be machined
“The tank sizes on the fuel side range from 160 litres to 1000 litres and we now manufacture fuel tanks for about 90 percent of all truck vehicle makes on the road. This includes Volvo, Freightliner, Hino, Isuzu, Ford, MAN, Nissan, Mercedes Benz, Scania, Peterbilt, Iveco and International. The tanks are also used on the buses of the various OEMs. However, we must emphasise here that we are not manufacturers for and suppliers to the OEMs. We supply the aftermarket sales industry and the panel beaters are probably our biggest clients.”
The latest version of fuel tank products that Multi Tanks International has added to its range is one that accommodates AdBlue. AdBlue is a diesel exhaust fluid used in modern trucks that have a selective catalytic reduction (SCR) system. Using AdBlue in line with manufacturers’ requirements and a catalytic converter reduces the level of oxides of nitrogen emitted from engines. It is not a fuel, nor a fuel additive but a high purity urea solution that must be used in a dedicated tank.
“Vehicle manufacturers, and first and foremost those of large goods vehicles, have had to re-think the exhaust system on their vehicles. More and more diesel cars, tractors and other off-road vehicles are also now equipped with the SCR system in the exhaust,” explained Craig Johnson.
“There is a separate tank used for AdBlue that is generally located next to the fuel tank. AdBlue and diesel mixed can do un-repairable damage so the two must not be mixed, hence the second tank. In our case we are still manufacturing the one tank system for clients but within this tank there is a separate compartment for the AdBlue.”
Multi Tanks International has grown impressively over the years and can now easily manufacture 50 tanks in a week. So too has the equipment and processes it uses to manufacture the tanks and other equipment grown.
“Shortly after manufacturing our first few tanks and deciding that this was the direction the business was going to evolve in, we soon found out that relying on outsourcing was not going to work for us. We needed to be independent of suppliers’ whims and embarked on a plan to bring everything in-house. Besides relying on material suppliers we are now capable of completing all the processes that we need in our manufacturing operation. We are lacking in a few of them in terms of productivity but we are addressing them as we speak. Punching and rolling is one area that we are addressing,” said Craig.
An example of an aluminium flange that Multi Tanks International used to have cast at a local foundry but are now pressed in the press department. The castings were never on time and the blow-hole problems were always a challenge. They would be welding the component to a tank and it would virtually explode in their faces. So Multi Tanks International designed and manufactured their own pressing mould and no longer has these problems
“The first area we gave attention to was in the press department. We soon invested in a 100 ton hydraulic forming machine and have subsequently manufactured a further four presses ourselves. We made our own mould for the forming of the tank ends, and the collection of moulds grew as word spread about our capabilities,” explained Craig.
“We are also making other components in this area now and they are realising big cost savings for us. An example is an aluminium flange that we used to have cast at a local foundry. The castings were never on time and the blow-hole problems were always a challenge. We would be welding the component to a tank and it would virtually explode in our faces. So we designed and manufactured our own pressing mould and we do not have these problems anymore.”
“Forming components with more consistency than we had been receiving with the sourced supplier results in better repeatability and has streamlined our downstream welding operations.”
A press brake, guillotine and two roll roller soon followed. A ClearCut CNC plasma was also a welcome addition to the shopfloor equipment. The company then addressed the component-manufacturing headache.
“We are not a production shop but still need many of the components that are welded on to the tanks to be machined. Here we acquired a Yunnan CY Group flatbed CNC lathe. It more than takes care of our machining requirements.”
The introduction of a Yaskawa Motoman robot
While always introducing new equipment into the company the Johnsons have continually looked to improve on their manufacturing processes and production methods.
“Innovation has been a part of our culture since the establishment of this company. One tank used to take us a whole day to manufacture, but now it takes us about an hour, all because we have constantly looked at improving our operating procedures,” says Lee.
The latest addition is a two station Yaskawa Motoman robotic welding machine equipped with a manipulator and a jig that the company has manufactured itself.
“While visiting exhibitions in Europe we learnt that many aspects of welding are robotically done. We recognised this as an opportunity for a significant process improvement. Many of the tanks that we manufacture are in a cylindrical form and the sheet needs to be welded together before you weld on the tank ends.”
Another one of Multi Tanks International’s standard products that they offer are hydraulic tanks that are used on heavy equipment such as backhoes, excavators, cranes, side tippers, large off-road trucks, and generator and pump sets
“With manual welding you will never achieve the same consistency of a weld over the length of the tank that could be 1500mm, and you can’t duplicate the same weld, but with a machine you can, as long as you have a fixture to hold the material in place.”
“So it is not only the quality of the weld that improves, but also the big savings in time as an additional benefit. Where it used to take me about seven or eight minutes to weld the ends on a tank, the robot will do it in two and a half minutes.”
“Because of the positive results that we have achieved with the Yaskawa Motoman robot we are now seriously considering installing a second robot. The robot installation has not replaced any members of staff, it has just given us an opportunity to improve the aesthetic look of the tanks as well as the quality.”
The company has been able to develop rapidly in the last five years because it moved into a new 1200m² factory in 2010 in Delporton, Krugersdorp, Gauteng. The spotlessly clean facility has been divided into process operations, including a wash bay, and has allowed Multi Tanks International’s production capabilities to expand, evolve and respond to rapidly changing market challenges.
Lee points out that their products are already at an international level. He says they recently made a tank for a vehicle that went to a major manufacturer’s head office, and when it arrived, the guys couldn’t believe the tank was made in this country.
After hearing all this, it’s no surprise to learn that the company’s tanks are used all over Africa in countries such as Mozambique, Zambia, Zimbabwe, Namibia and Botswana.
Arthur points out that the company doesn’t only manufacture tanks. It can make anything out of aluminium.
“We manufacture side-skirts, line hauling under-belly tanks on trailers and exhaust covers, truly anything in aluminium on a truck or bus. The latest product that we are gearing up for is tanks to be used on a pontoon. We have the equipment, so it wouldn’t make sense not to, however the manufacture of tanks will remain our core business.”
“Everything we manufacture is welded in some form or another. We were lucky that we recognised that there was a niche in the market for fuel tank manufacturing, and we have the expertise in aluminium welding and can create products as good as any OEM can offer.”
For more information contact Multi Tanks International on TEL: 011 665 3022