A short drive across the border from Dyson's new headquarters in Singapore is the boomtown built around its business: a Malaysian industrial area dominated by its biggest supplier, ATA IMS Bhd.

ATA, one of Malaysia's top electronics manufacturing services providers, rode Dyson's success in high-end vacuum cleaners and air purifiers, supplying parts for a company that came to account for 80% of its revenue.

Ten current and former employees, and a former ATA executive, say the growth came at an unseen cost: its mostly migrant workforce worked up to 15 hours a day, were often asked to skip rest days to keep up with demand, and were coached to hide true working and living conditions from labor inspectors and Dyson.