Use of ball spline

Author：Shenzhen King Square Technology Co., Ltd.
Date：2021-11-03
Reading volume：3,410 Views

Precision ball spline pairs combine linear reciprocating motion with bidirectional torque transmission within a single shaft axis. While the recirculating steel balls move axially along precision ground raceways on the spline shaft, they transmit large rotational torques without backlash.

Figure 1: King Square Integrated Gear Rack & Ball Spline Dual-Motion Unit

1. Distinct Engineering Advantages

Multi-Row Load Distribution: Unlike conventional drive keys that concentrate shear stresses on a single contact line, ball splines distribute forces across 3 to 6 symmetric ball rows.
Zero Rotational Play: Preloading suppresses angular play to zero, making it ideal for robotic wrist positioning and indexing tables.
High-Speed Axial Movement: Permissible linear speeds reach up to 2 m/s while sustaining full transmission torque.
Long Service Life: Ground high-carbon chromium steel shafts (GCr15, 58–62 HRC) withstand high fatigue cycles.

2. Typical Automation Applications

Industry / Application	Motion Requirements	Spline Role
SCARA Robot Arm Z/θ Axis	Simultaneous Z-stroke & θ-rotation	Transmits joint torque while driving vertical pick-and-place
Semiconductor Die Bonder	High-speed indexing & vertical stamping	Zero-backlash rotational alignment and rapid plunging
Medical Specimen Tube Decapper	Torque unscrewing & vertical extraction	Performs rotary cap unscrewing and upward lifting simultaneously
Automated Tool Changer (ATC)	Tool selection & insertion motion	Compact dual-function actuation replacing two separate actuators