KANEGASAKI, Japan – Kanto Auto Works says the first-time defect rate has hit a nearly perfect 99.9% at its Iwate plant here, which builds cars for Toyota.

The complex comprises two lines (actually two plants), each with dedicated welding, painting and final assembly operations but sharing a stamping shop.

Both lines make the Aqua and Prius C Line No.1 also builds the Blade, Scion xD and ist, while Line No.2. produces the Belta and Ractis. The Belta is sold only in Japan, while most Ractis multipurpose vehicles are exported to Europe.

Due to early popularity of the Aqua – Kanto produced 51,132 units in January and February and had planned a production run of 30,000 in March – the auto maker reportedly will shift Ractis output to its Higashi-Fuji plant in Susono, Shizuoka prefecture.

The Iwate plant employs 1,700 workers on two shifts.

Engines are supplied from Toyota’s Kamigo plant in Aichi prefecture. Later this year, 1.5L engines for the Aqua and Prius C hybrids will be sourced from Toyota Motor Tohoku’s Taiwa facility north of Sendai.

Transmissions, both automatic and manual, come from Aisin and Toyota Motor Hokkaido.

A supplier park is housed inside the 10.4 million-sq.-ft. (964,000-sq.-m) plant. Toyota Gosei makes door trim, glass run, weatherstrip and steering wheels; Toyota Boshoku Tohoku produces seats, fender liners and engine undercarriage shields; Howa Textile makes headliners and dash insulators; and FTS manufactures fuel tanks.

Prior to entering the paint shop, doors, hoods and bumpers are manually attached to the body-in-white. Each car receives four coats. The shop has adopted a cartridge system for surface coating, substantially reducing the number of times paint lines must be purged.

In the final assembly shop, many components are shipped to the line in kits (usually 10 parts per kit) as the car moves up the line. Kits are organized in a staging area off the main line.

In final inspection, Kanto employs 28 inspectors per shift per line. Automated inspection is limited to five items, including water testing. The auto maker employs 15 test drivers per line.

Cumulative production at the plant totaled 1,401,000 units through 2011.