Four Stages in Electric Car Manufacturing

Did you know there are 36 electric car companies in the US alone? Besides EV giant Tesla, and “legacy” automakers like US automakers Ford and General Motors, there are Japanese-based Aspark, Chinese Byton, and Croatian Rimac to name a few.

So how do so many automakers build their EVs? We cover the basics today touching on interesting points like aluminum’s importance in EV manufacturing to why a low-failure rate among computers is vital in the car painting process. 

Keeping it Light – Aluminum in EV Manufacturing

Every electric car that is made starts with a design by the auto manufacturer. For EVs, this step is even more essential since their batteries add considerable weight compared to the lighter internal combustion engine or ICE powering non-EVs. And weight impacts any car from its performance, speed, to fuel consumption.

A big part of that design is the electric car be built with as many light-weight materials as possible. That is why the skeleton or frame is usually made up of aluminum. This makes it light and strong. 

The aluminum car parts most often come from suppliers. There, the body assembly process begins with coils of aluminum of different types being uncoiled by machine which then flattens the metal into blanks. These are fed into an enormous stamping press where large custom-made dies form the body panels like the doors. The stamped products are then transported to the electric car companies’ body center or body shop.

First Stage – The Subassembly of Electric Car’s Frame 

The entire process of making an electric car is a combination of robots and manual labor. In the first stage, which is the creation of the car’s skeleton or frame, most of the work is performed by robots.

In the body shop, the skeleton of the car, technically known as the “space frame,” is prepared. This is done by employees who help sequence the parts for assembly. The robots then take over.

The automated process is referred to as “subassembly.” All the different car parts are put together by a group of robots called ABB robots. At least five robotic arms are put to work to fit various parts onto the frame. 

One of the most unique aspects about subassembly is that there are five different overall joining methods used. These range from the use of adhesives, self-piercing rivets and cold metal transfer, as well as conventional resistance welding and a delta spot welding system. 

The robots are done when a fully completed car frame is sent down the line to human hands.

Inspection with a Human Touch

This part of the process prepares the frame for the painting job. 

A team of four or more people receives the car frame from the robots. First they start checking it for any defect or loose-fitting. After that, all put on gloves and take up a cloth in their hands and start cleaning.  

This cleaning activity is done with extreme precaution. A small particle of dust on the frame can ruin the entire process of a painting job. Equipment like any panel PCs around the cleaning area should have a fanless design to prevent particulates from circulating in the air. This is to ensure that no damage is done regardless how minor. 

Once the frame is cleaned and cleared by the team within the predetermined time limit, it goes on to the painting stage.

Second Stage – All Automated Paint Job 

The painting stage like subassembly is completely driven by robots. 

The electric car frame is first dipped into a tank of sealant to spread all over it. This act also officially initiates the painting job. 

The coating is dried with the help of a powerful vacuum. A minimum of five robotic arms are put to work to make sure every bit of the car frame is properly sealed. One arm for example assists in opening and closing the back and front parts. Others then use a vacuum to dry the coating.

This pre-treatment is performed to make sure the metal will accept the paint. Other robots at this stage apply primer, paint, and a clear coat. 

The stag ends when the entirely painted frame goes into an oven for the finish to cure.

Even with robotic arms, the painting process is time-consuming with the coolant dip taking seven to eight minutes alone. And since the process involves tilting and dipping the frame into a tank, any human involvement becomes difficult. There can be no room for errors. All equipment from the robotic arm to any industrial computers controlling it should have low failure rates to minimize errors, especially a breakdown. 

Manual Inspection 

After the now painted frame is cooled, it is brought to a new set of employees to examine for defects. This is done because it’s assumed 1-2 outputs after the paint job may be defective.  Any of these are set back to the previous stage to undergo the time-intensive process again. 

Testing Electric Motor

Elsewhere in the auto maker’s plant, the electric motor of the EV is assembled and tested as the frame is being assembled and painted. Testing of the motor involves revving it at full RPM. Afterwards the recorded data is reviewed by engineers. If they find any issues, the motor will be sent back to be assembled again if necessary.

Third Stage – Assembly by Hand

Painted frames are now sent to the third stage, “General Assembly.” This is where the operating components and interior of the electric car are completed at various workstations. No robotics are involved – everything is done manually because of the constant adjustments involved.

The order of the assembly stations and what’s installed at each one varies per auto manufacturer. They usually involve:

• Placing the first set of the electric car’s complex electronics. This includes the body wiring and seating of the Power Electronics Bay which holds the Propulsion Control Module.
• Outfitting the frame with body wiring, electric rearview mirrors, a seat adjustment machine, etc. 
• Installing wiring harnesses, safety and other systems, weather stripping, carpeting, instrument panels, and seating.  
• Outfitting the flooring, seats, and carpeting. 
• Placing the car console and dash.
• Filling the air conditioning, heating, and circulation systems.

Marriage of Motor and Body

Towards the end of this assembly process, the rechargeable battery pack is attached to the powertrain. It is situated in T-formation down the middle of the car, with the top of the “T” at the rear. This provides better weight distribution and safety. The pack is seated by lifting it up into the car using a special hoist up. The pack is attached to the chassis as are the axles complete with wheels and tires.

The now battery pack and powertrain assemblage is integrated into the car frame. This is called a “marriage.” The EV’s alignment is checked and adjusted, and the under-body panel is bolted into place. 

At the final workstation, the rest of the interior is fitted with last minute furnishings, the manufacturer’s emblems, and any logos. The car doors are finally added as well. 

Fourth Stage – Quality Testing 

The last stage of building an EV is Quality Testing. A comprehensive quality control check is done. Pressurized water, for example, is sprayed on the vehicle for eight minutes followed by having all car seals checked for leaks. Any rugged industrial tablets used in these tests should be rated IP65 sealed to protect their interiors.

A quality-based test drive is also done. The new EV is checked for noises, squeaks, and rattles on a specialized test track. Unique to electric cars is the fact there is no exhaust system and thus no gasses or pollutants to worry about. This allows it to be actually driven inside the plant.

The process concludes with a lengthy and thorough visual inspection of the new car before being shipped out to customers.

Closing Comments

Electric car companies are competing for today’s car shoppers’ attention with over thirty in the US alone. All, though, follow a basic four-stage format when manufacturing their EVs whether they’re exotic roadsters, compact hatchbacks, luxury sedans, or full-size commercial trucks.  

Are you looking for the right industrial computer for your EV plant? If so, contact a representative from Cybernet. They can assist you even if you’re a supplier to an electric car manufacturer like Mobis is for Hyundai. 

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