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FEATURE CABLES & CONNECTORS
sponsored by Power to the PeoPle: the
role of cold forming in the fast-charging revolution
As the production and sale of electric vehicles continue their steep upward trajectories, the need for fast-charging stations will likewise
increase. Power connectors will play a key role in transferring energy from such stations to vehicle batteries. Les Reeves, joint managing
director at Dawson Shanahan, describes an efficient and cost-effective method for the manufacture of these complex components
S
ales of electric vehicles are poised to explode, but there is a significant factor preventing many drivers of petrol- and
diesel-powered cars from making the switch. Range anxiety is the fear of being unable to drive long distances owing to the poor state of the infrastructure for charging electric vehicles. Charging such vehicles can be a slow process. While most drivers are accustomed to filling their petrol or diesel tanks in less than five minutes, electric vehicles, depending on the size and specifications of their batteries, can take hours to re-charge using standard chargers. By contrast, fast-charging stations can
almost completely recharge a battery in around 30 minutes. Typically, these deliver up to 350 kilowatts or more of energy an hour to the battery of a vehicle and power connectors play a vital role in this process. To minimise power loss, these connectors need to be shaped precisely. They also need to be light in weight, durable and cost-effective to manufacture.
Mass-Production
Given the sophistication of the technologies involved, it is perhaps surprising to some that a technique that can trace its roots back to the Victorian age – cold forming – is particularly suitable for the production of such power connectors. However, cold forming has been refined significantly since these early days. Production rates of over 300 parts per minute can be achieved using the process and, compared with machining processes, scrap rates can be reduced by up to 80%. Using cold forming, metals are forged at near-
room temperature by forcing them at high speed, and under high pressure, into dies. It can be used, for example, on aluminium, copper and ferrous metals. For power connectors, oxygen-free, highly conductive metals are typically used.
the benefits
Given that it takes place at ambient temperatures, cold forming is faster and easier to set-up and carry out than machining
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Power connectors play a vital role in fast-charging
almost no limit to the shape, size or complexity of the metal components that can be produced using the process. Simple cold-headed parts or highly complex cold-formed and finished machined components can be manufactured for a wide range of applications.
Myriad aPPlications
At Dawson Shanahan we have adapted the cold forming process for the manufacture of a wide range of high- quality components, including: • Precision connectors for drive-train systems in electric vehicles;
processes. This means that parts can be made-to order, cutting lead times. The process also ensures a high-quality
product. Using it, metals are plasticised along their grain boundaries, rather than across them. This generates extremely low levels of stress deformation in the metals and high levels of mechanical integrity, resulting in parts with improved performance and reliability. Another strength of the process is its
precision. Even parts with complicated internal and external contours can be produced with pronounced definition. Dimensional tolerances of plus or minus two microns can be achieved. Furthermore, parts produced using cold forming are characterised by their extremely fine surface finishes, both internally and externally, which often eliminates the need for further machining or polishing. Parts undergo work hardening, which
dislocates the structure of the metal in a way that prevents further dislocations during the cold forming process, improving their machinability and durability. The increase in strength generated through work hardening is comparable to that achieved through a heat treatment, so it can be more cost-effective to cold-work a cheaper and weaker metal than to hot-work a more expensive metal, particularly where a precision finish is required. Cold forming is also highly versatile. There is
4 DESIGN SOLUTIONS NOVEMBER 2022
• Nozzles made from advanced copper alloys for use in computer-numerical control laser-cutting systems;
• Valve sleeves for advanced low-emission diesel engines;
• Parts for use in high-voltage power generation and distribution equipment.
Feature
Given the current economic climate, the
speed and resource-efficiency of cold forming is highly attractive. In addition, as we have seen, lead times for cold formed parts are short, and the parts themselves demonstrate excellent mechanical performance and a mirror-like surface finish. As demand for fast-charging stations increases in line with that for electric vehicles themselves, cold forming could prove to be a highly suitable solution for the production of the necessary power connectors.
Dawson Shanahan
https://dawson-shanahan.co.uk
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