"On production" x "In production": Qual a diferença?

Olá amantes da língua inglesa!
Trabalho em uma indústria de rochas ornamentais com foco em exportação e sempre me bate essa dúvida... Quando preciso falar com o cliente que o material ainda não está pronto, mas está em produção, está em andamento... O termo mais apropriado seria "material on production" ou "material in production"?

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2 respostas
Both. But I think they are used in different ways.
In production is the most popular phrase!
*"Changes to vehicles in production cause unacceptably high costs."

*"Booms are in production and available for delivery"

*"Depend directly on production activities."

Here's what a native said about it:

"Josh Ransley
I'm not sure which is correct, but I would use and most often see "in production".
I might say "something is on the production server", but "something is in production"
PPAULO 6 48 1.2k
It may also be expressed as the stage: "the material (the stones) is in the process of being finished/polished/selection, whatever production process the stone undergoes.
Could also be generically speaking "it is in the final production stage of the production process" then it will be packaged to be shipped...etc...
Perhaps "in production" is a broad statement, enough to go back to the very extraction of the stone itself. Another concept used in a business is to set time limits, the stone will be sent to you within 2 days... To avoid a vague answer.