Our factory does OEM for listed companies in China/Korea, but nobody replies when I try to expand internationally — what am I doing wrong?

Hey everyone, not sure if this is the right sub but figured I'd try.

My family runs a precision optics manufacturing company in China (started by my father, I'm second-generation now running international sales). We do things like lenses, prisms, windows, mirrors — grinding, polishing, thin-film coatings, the whole process in-house. Been at it for 20 years, and honestly the manufacturing side is solid — we do OEM for listed companies in China and also partner with listed companies in Korea, so quality has never really been the issue. Our tolerances, coatings, and QC all hold up to what those companies demand.

But when it comes to building relationships abroad — US, Europe, Middle East — I keep hitting a wall. I do a lot of LinkedIn outreach, cold emails, try to be genuine and not spammy, but conversion is really slow. Sometimes I get a good conversation going, sample requests, even NDAs signed, and then it just... stalls. No response for weeks.

I know part of it might just be how B2B/industrial sales works — long cycles, trust takes time, especially since we're not a big-name brand internationally yet, even though the quality is there. But I'd love to hear from people who've actually built export or industrial sales pipelines from scratch: what actually worked for you? How long did it realistically take before things started converting? Any mistakes you made early on that you'd avoid now?

Not trying to sell anything here, genuinely just trying to get better at this. Appreciate any perspective.