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Ian Melin-Jones

Ian Melin-Jones

Lightweight tool allows easy manipulation of battery cans and tab materials

Improving battery technology is necessary to respond to the global focus on electric vehicle (EV) technology. One way of improving battery pack performance is by replacing existing nickel battery tabs with copper material. Unfortunately, it has been difficult and/or expensive to weld copper using traditional methods. Now, a new touch retract tungsten inert gas (TIG) welding technology has been developed that allows safer and easy manipulation of battery cans and tab materials in a bench-top, research and development (R&D) environment. Using typical prototype tooling, the system is especially suitable for R&D on battery pack concepts and assembly, low-medium volume battery pack manufacturing, and battery pack repair/rework applications. Longer term uses include maritime, aviation, energy, and consumer goods.

Battery pack welding for EV market

Market analysis suggests that electric cars will cost the same as gasoline vehicles within eight years, pushing the global EV fleet to 530 million vehicles by 2040. About 90 gigawatt hours of EV lithium-ion battery manufacturing capacity is currently online, and this is set to rise to 270 gigawatt hours by 2021.

Switching from nickel to copper tabs for battery connections can increase EV battery life by up to 20 percent, so manufacturers are looking for the most cost-effective technologies to do so. Available battery pack welding technologies include traditional resistance welding, laser welding, and TIG welding.

Resistance welding is considered the standard for welding non-copper electrical components. Quick, simple, and very low cost, resistance welding has many benefits. Unfortunately, copper is harder to resistance weld. Resistance welding relies on the inherent electrical resistance in a material to create heat, which melts the metal and creates the bond. Copper is conductive to electricity, so it does not generate much heat; what heat it does generate is largely directed away from the area.

Laser welding works well for welding copper to tabs, but it can be an expensive solution. In addition to the cost of the lasers themselves, tooling equipment is necessary to hold the parts firmly in place. Because no mechanical force holds the parts together, tooling is required to ensure the proper contact before welding. The higher cost makes laser welding copper tabs best for high volume manufacturing factory production lines, not lower volume R&D applications.

Micro arc welding is a highly efficient method for generating localised heat. With TIG welding, the operator strikes an arc on an electrode. Operators point the electrode at the part to be welded, and then use a high voltage to create a spark (similar to lightning) between the electrode and the material. That arc generates quite a bit of heat, which melts the material together and forms a strong bond. Due to the high voltage used, traditional TIG welding is safer and most effective in machines where there is no physical contact – and when it is in the hands of a skilled operator who can control the arc gap. Using traditional high voltage TIG welding in R&D applications, hand held assembly, and low volume manufacturing presents health and safety problems. While those working in these settings may hold a PhD in battery science, they are not likely to be highly skilled TIG welders.

Recently, a new type of touch retract TIG welding torch technology has been developed that does not involve physical contact. The electrode is pulled back with an electronic solenoid, eliminating the high voltage ignition and making it a lot safer and easier to use. The touch retract torch is extremely repeatable. It does not require maintaining a given distance – pulling back at the same distance every time. In effect, anyone can create a repeatable weld.

 Figure 1 shows the three steps in the touch retract TIG torch process. (Left – approach) The electrode extends below the nozzle, enabling the operator to see where they are placing the weld. (Center – compression) During the compression step, the operator pushes down on the torch. A small current detects that the electrode is in contact with the workpiece. (Right – retraction) In the final retraction phase, the electrode retracts, drawing an arc with an intermediate current. When the mechanism is at full travel, the main welding current is applied.

Fig 1. Three step approach, compression, retractionFig 1. Three step approach, compression, retraction

Advantages of the new TIG torch technology for battery pack welding

Figure 2 shows the new AMADA MIYACHI TR-T0016A, supplied in a plastic carry case, which includes the welding torch fitted with cables, instruction manual, spare nozzle, spare ceramic, spare spring, spare electrode Hex wrench, and spannerFigure 2 shows the new AMADA MIYACHI TR-T0016A, supplied in a plastic carry case, which includes the welding torch fitted with cables, instruction manual, spare nozzle, spare ceramic, spare spring, spare electrode Hex wrench, and spannerThe new TR-T0016A touch retract torch manufactured by AMADA MIYACHI, was developed primarily for use in battery pack welding for electric vehicle (EV) applications, in which hundreds of small cells are welded together into modules. In the past, nickel bus bars were used to join up positive and negative terminals, but new designs are seeking to join copper strips to the battery can. The new touch retract TIG torch welder offers effective welding of copper with relative ease compared to traditional resistance welding techniques. For hand assembly, touch retract starting is a safer method than high voltage. It also costs less than a typical laser system.

For example, major global automobile manufacturers seeking to weld their own battery packs may opt for a robotic laser system that costs about half a million dollars and is used in an automated production line. But for those looking to conduct rapid evaluation of battery pack designs or other R&D work, and for production of small volume prototypes, small to medium scale battery pack repair or rework, or even Formula 1 racing teams, the hand held touch retract TIG torch welder is an attractive solution that works well. It can also be a tool for investigating and fixing process issues. Rather than simply disposing of parts, the touch retract torch can be used to fix loose joints.

The flexible nature of the retractable TIG torch allows concepts to be quickly manufactured and tested so it fits well with R&D organizations working on the evaluation and production process design of their battery pack concepts. The technology offers a high repeatability rate with one weld per second. It also has a narrow (7 mm) nozzle and protruding electrode for better weld location control.

While designed for hand use, the touch retract TIG torch can be incorporated into an automated manufacturing line, so it would be appropriate for low-medium volume production applications. For example, it would be a good option for university spinoffs that have done R&D and are now looking to scale up for production, and want the repeatability of an automated machine.

The new system has been extensively tested for welding typical battery tab materials (copper, nickel, and aluminium, up to a thickness of 0.5 millimetres (mm)) onto 18650 and 21700 battery can material. It can also be used to join other metals, including stainless steel, gold plated stainless steel, and many others.

Figure 3 shows an example of a battery tab welding application.Figure 3 shows an example of a battery tab welding application.

Safer and cost-effective solution for R&D environments

Offering ease of joining copper strips on a battery and a high repeatability rate, the new lightweight, handheld tool TIG torch can be used for rapid design evaluation of battery pack concepts, small-medium scale manufacturing, and manufacturing scale-up. Equally good for hand production and rework and automation, the new product features a low voltage arc to encourage operator safety.

Regrettable decision necessary due to combination of weakening demand, rising imports coupled with insufficient EU trade protection, high energy costs and rising carbon costs 

ArcelorMittal has just announced its intention to temporarily idle production at its steelmaking facilities in Kraków, Poland and reduce production in Asturias, Spain. In addition, the planned increase of shipments at ArcelorMittal Italia to a six million tonne annual run-rate will be slowed down following a decision to optimise cost and quality over volume in this environment. 

arcelormittal logoTogether, these actions will result in a temporary annualised production reduction of around three million tonnes.

Commenting, Geert van Poelvoorde, CEO, ArcelorMittal Europe – Flat Products, said:

“The difficult decision to temporarily reduce our European primary flat steel production has not been taken lightly. We understand the impact this has on employees and the local communities and will be working to ensure social measures are in place to support them during this period.

“These actions reflect the weak demand environment in Europe today, a situation further compounded by increased imports despite the safeguard measures introduced by the European Commission. High energy costs and increasing carbon costs are adding to the tough environment.

“We are engaging with stakeholders to request that the safeguards are strengthened to prevent a further increase in imports as a result of continued global overcapacity and a weakening economy in neighbouring countries including Turkey. We will also continue to make our case for a green border adjustment to be introduced to ensure that imports into Europe face the same carbon costs as producers in Europe. The steel industry in Europe can have a strong future but there must be a level playing field to ensure that an unfair advantage is not given to competitors outside the region.”

In Kraków, the primary production (blast furnace and steel plant) will be temporarily idled. The Polish steel market has been particularly hard hit, due to a near fourfold year-on-year increase in Russian steel imports in 2018, and among the highest electricity prices in Europe.

In Asturias, primary production will be reduced. Electricity costs are also very high in Spain, and the southern European market has been hit by an unprecedented rise in imports from outside the EU.

Despite the introduction of the permanent EU safeguard tariffs in February 2019 there has been a continued and consistent rise in flat steel imports into Europe. Flat steel imports into Europe are currently at record highs, with imports of hot rolled coil up 37 per cent this year from 2017, on an annualised basis. In addition, the price of carbon has risen by approximately 230 per cent since the start of 2018, placing further competitive pressure on European steelmakers. In the EU Emissions Trading System (ETS), only steel produced in Europe is subject to a carbon levy. ArcelorMittal has previously called for the introduction of a green border adjustment whereby steel imported into Europe has the same standards applied on CO2 as European produced steel under the ETS.

About ArcelorMittal

ArcelorMittal is the world's leading steel and mining company, with a presence in 60 countries and an industrial footprint in 19 countries. Guided by a philosophy to produce safe, sustainable steel, we are the leading supplier of quality steel in the major global steel markets including automotive, construction, household appliances and packaging, with world-class research and development and outstanding distribution networks.

Through our core values of sustainability, quality and leadership, we operate responsibly with respect to the health, safety and wellbeing of our employees, contractors and the communities in which we operate.

For us, steel is the fabric of life, as it is at the heart of the modern world from railways to cars and washing machines. We are actively researching and producing steel-based technologies and solutions that make many of the products and components people use in their everyday lives more energy efficient.

We are one of the world’s five largest producers of iron ore and metallurgical coal. With a geographically diversified portfolio of iron ore and coal assets, we are strategically positioned to serve our network of steel plants and the external global market. While our steel operations are important customers, our supply to the external market is increasing as we grow.

In 2018, ArcelorMittal had revenues of $76.0 billion and crude steel production of 92.5 million metric tonnes, while own iron ore production reached 58.5 million metric tonnes.

ArcelorMittal is listed on the stock exchanges of New York (MT), Amsterdam (MT), Paris (MT), Luxembourg (MT) and on the Spanish stock exchanges of Barcelona, Bilbao, Madrid and Valencia (MTS).

For more information about ArcelorMittal please visit: http://corporate.arcelormittal.com/

Sunday, 05 May 2019 18:08

Biggest Glycerin Tank in Denmark

Completely made from quality stainless steel

The biogas plant in Hammel near Aarhus can now consider its latest tank as the biggest glycerin tank in Denmark. It contains 4.500m³ glycerin in a fully insulated digester made from long-lasting stainless steel.

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The tank
The project is part of an existing biogas plant with a power of two Megawatt. The diameter of the new biogas tank is 25m with a height of almost 9m. It is constructed with stainless steel shell plates in a segment-like design. At the height of almost 9m, seven rings of the shell plates are necessary. The lower five rings are made from stainless steel 1.4462 and the upper two rings from stainless steel 1.4571 to prevent from corrosion

The roof
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The digester is covered with a stainless steel roof pillared by a central support. Being composed of an inner and outer screwed element, the outer ring is attached to the top of the tank, whereas, the inner ring is posed higher. Thus, a decline of 10° occurs. The roof is designed for insulation and cladding. It is completed by two inspection openings.

The accessories
Equipped with a heating system and full insulation it has the basic accessories of a digester. Moreover, the biggest glycerin tank in Denmark has two gas-tight wall bushings, two working platforms with ladders and three powerful submersible motor agitators in stainless steel.

The substance glycerin
The basis for the fermentation process is glycerin with a pH value between 3,5 and 8. It is a waste from the production of biodiesel. Having a density of 1,3 kg/l, the glycerin is heated up to 52°. Glycerin is considered to be the most valuable input for the fermentation process because the bacteria transform almost all of the glycerin. Thus, there are almost no fermentation residues. A comparison between the output of corn and glycerin illustrate the energetic value of glycerin. General guidance levels say that one ton of corn yields to 200-250 m³ gas, whereas, glycerin yields to 1.000 m³ gas.

The construction
The most crucial part of the project was the construction phase due to the enormous size of the tank. After the assembly of the first ring including the roof, the whole digester was electrically lifted up. 37 pillars were used to lift up the first ring and another four we needed to lift up the central support as well. Then the second ring was assembled and the tank was lifted several times until the seventh ring was constructed.

The reason why
It was a simple decision explains the plant owner. We have decided for stainless steel because it is the most durable material in terms of corrosion. And the decision for Stallkamp was easy as well. With the experienced and reliable distribution partner Biogas Teknik A/S, we knew that this project would going to be a success.

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Learn more about Stallkamp: http://www.stallkamp.de/en

 

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