Correct

花键

/ huā jiàn / 
Strokes

Example

As a Noun

spline

1
Huājiànzuò
花键座

splined hub

2
Huājiàn
花键
zhóu
轴

spline shaft

3
Huā
花
jiànxǐchuáng
键铣床

spline miller

4
Huājiàn
花键
gǔnchǐjī
滚齿机

spline hobbing machine