Robot Micro Screw M4×0.7-6g-5.00

Overview

Robot micro screws are the sub-M2 fasteners used inside articulated robot joints, end effectors and humanoid actuator housings. The requirement differs from consumer electronics: the joint is in continuous motion, so the screw sees cyclic load rather than a single assembly preload, and a backed-out screw inside a joint can destroy the mechanism rather than simply loosen a cover. This listing: size M4×0.7-6g-5.00, material SCM435, grade Class 12.9, finish Zinc-nickel alloy.

Advantages

Preload is specified as a band rather than a maximum, because both under-tightening (loosening under vibration) and over-tightening (yield in a 1.4 mm section) cause the same field failure.

Coating choice is driven by wear at the driver interface, since actuator housings are assembled in volume and the recess is engaged by robotic drivers that will cam out of a worn recess.

Tight dimensional control on head diameter allows the screw to sit inside a bearing race envelope without fouling adjacent rotating parts.

Thread form and material are selected for fatigue rather than for one-time clamp: a rolling thread root on a case-hardened screw resists the notch sensitivity that causes micro screws to snap after thousands of load cycles.

Applications

Harmonic and cycloidal actuator housings, robot wrist and elbow joints, end-effector gripper bodies, linear actuator end caps, and humanoid robot hand assemblies where fastener mass affects dynamic response.

For joints in continuous motion specify prevailing torque or a pre-applied patch rather than relying on torque alone; a plain screw in an aluminium actuator housing will lose preload within a few thousand cycles. Check that the screw material is compatible with the lubricant used in the joint.

Product information is supplied by Toprecision. Custom parts can be produced to drawing — contact us for samples or a quotation.