BIELEFELD, Germany -- Automakers will demand much more production flexibility from suppliers of parts for electric cars to deal with unpredictable levels of demand, said Francisco Riberas, CEO of Spanish metal parts supplier Gestamp.

"Probably none of our customers are absolutely sure how fast the market is going to move to EVs. in the future they're going to demand much more flexibility in our investments to cope with this," Riberas told journalists at the supplier's factory here on Tuesday.

Gestamp will make the steel boxes to house the battery packs for Volkswagen Group cars built on the new MEB electric platform, starting later this year at its Bielefeld plant. VW Group recently doubled its original order from Gestamp to 570,000 boxes a year, indicating greater confidence that customers will switch to EVs as European laws tighten on CO2 emissions starting in 2020.

Not all customers are confident, Riberas said. Automakers usually demand that Gestamp's production of body-in-white and chassis parts can cope with a 10-15 percent increase in demand. Riberas however predicts that will rise to 30 percent to 40 percent in the future as automakers grapple with uncertain demand for EVs. "This is a big challenge and much more difficult for us," he said.

One way Gestamp will cope is by moving to new flexible robot cells that can quickly shift between making one part to another as demand. Riberas gave the example of its work with Audi on its new PPE premium electric vehicle platform. "The issue is they will keep on with the sister platform for combustion-engine cars and at the same time build the new platform for EVs, but they are not convinced how fast how it's going to sell," he told Automotive News Europe on the sidelines of the event.

"They award you a part that's a similar part to the EV and say they want 80 percent for the combustion-engine car and 20 per cent for the EVs, but they want to have the flexibility to move to 30 percent EV in case that they are wrong," he said.

Gestamp will normally tool up production to match the ordered quantities but Riberas argues the old way of working will need to change. "I need a much more flexible idea. Maybe it's less productive but it's much more flexible," he said.

Gestamp is positioning itself to become a key supplier of EV-specific chassis parts and body parts. "Battery boxes are very important opportunity for us in terms of growth," Riberas said.

The market for metal battery boxes alone will reach 5-7 billion euros globally by 2026, the company estimates. Battery boxes often need to be a structural part of the body in designs where the battery pack is sandwiched in the floor between the two axles. Only in lower-range urban electric cars is the pack small enough not to reach the sides, and therefore become subject to increasingly stringent crash tests.

As well as Volkswagen's MEB platform, Gestamp has orders to build battery boxes for Jaguar Land Rover and BMW. The company has more than 20 battery boxes in design for clients it said, without being specific.

The inclusion of the battery box pushes the weight up of the body-in-white of a typical electric car by 60kg, prompting car companies to looking for more weight-saving solutions. Lightweight aluminum is becoming one of the most popular metals to use for the boxes, Gestamp said. The company earlier this year established two joint ventures with aluminum extrusion specialist Etem Bulgaria, a division of Belgium-based Viohalco.

Gestamp also makes chassis parts for EVs, including subframes for the VW Group's MEB models.