Turned components for e-bike drive units: bicycle volumes, automotive discipline

An e-bike mid-drive is a gearbox, a motor and a torque sensor in a housing the size of a fist. The turned parts inside it are small, highly loaded and made in numbers that look like automotive.

The electric bicycle turned a low-volume niche into a series industry within a decade. A mid-drive unit contains shafts, pins, bushings, spacers and sensor components that are turned parts by nature — small diameters, tight tolerances, produced in hundreds of thousands.

What makes these parts demanding

• Load in a small envelope. A mid-drive multiplies rider torque through a compact gear train. The shafts inside are slender and highly loaded at the same time, which is exactly where case-hardening steel and a controlled surface matter.
• Noise. A bicycle has no engine to mask anything. Surface finish and runout that would be irrelevant in a car become audible on a quiet cycle path.
• Corrosion. The unit lives outdoors, in rain and road salt, and is washed with a hose. Zinc-nickel and stainless appear for reasons the drawing does not always explain.
• Weight. Every gram is argued over. Aluminium turns up wherever the load allows it.

Why automotive discipline suits it

Drive unit manufacturers increasingly ask for what a car maker asks for: PPAP, capability evidence, IMDS, traceability, controlled changes. The reason is simple — the volumes and the liability are now comparable. A shop already set up for IATF 16949 does not have to invent anything for this industry; it is the same system applied to a smaller part.

What we bring to it

Sliding head automatics for slender shafts and pins, turning and milling in one setup for sensor and housing components, 100% camera sorting on critical characteristics, and finishing coordinated through qualified partners. Diameters Ø 2 to Ø 52 mm, series from 5,000 pieces.

Send a drawing to info@kovinski-izdelki.si, or see what we machine.