EV Half Shaft with Flange Face Runout 0.01mm, Spline to Journal Coaxiality 0.01mm and Journal Runout 0.008mm

The middle of a half shaft does almost nothing. The flange bolts to the wheel hub or the gearbox output, the spline engages the joint, and the journal carries the bearing — and each end has its own idea of where the axis is. If the flange face is not square to the spline, the joint runs at an angle; if the spline is not coaxial with the journal, the bearing takes a side load it was never designed for. Measured separately, both ends pass. Measured against one datum, the part is out.

So the ends are machined from a shared reference rather than as two independent jobs: the shaft is turned between centres, the spline and the journal are generated on that same axis, and the flange face is faced after the spline so its runout is measured against the spline pitch diameter rather than against the bar. The part is then balanced, because an unbalanced half shaft at motor speed transmits a vibration the wheel bearing hears as a rumble.

• Material: 42CrMo, SCM435, 40Cr, 20CrMnTi for case hardened splines, 17-4PH for corrosion resistance, 300M class steels on request.
• Treatments: induction hardening, carburising, nitriding, shot peening of the spline root, black oxide, zinc-nickel plating.
• Ends: flange with 4 or 6 bolt holes, threaded stub, spline, taper seat, circlip groove, CV joint boot groove, cross hole.
• Shaft forms: solid, hollow, stepped, with damper mass or balance pad.
• Size: length 150 mm to 900 mm, flange diameter 60 mm to 160 mm, journal 15 mm to 60 mm.
• Input: STEP, IGES, DXF, PDF drawing, or a sample shaft we measure and re-model.

A half shaft defines the interface between a gearbox and a wheel, so the drawing reveals spline geometry, flange pattern and load class — that is confidential vehicle engineering, not a commodity dimension. We sign a mutual NDA before any file is opened, in English or Chinese or on your own form, and return a countersigned copy before work starts. Access is limited to the project engineer, the lathe programmer and the cell supervisor, with the file in a restricted folder rather than the open shop network. No photographs of customer parts are taken for our catalogue or website, customer parts are never displayed or reused as samples, subcontracting requires your written approval, and at program close files and inspection data are deleted or returned with written confirmation.

Dongguan Changxinda Precision Technology Co., Ltd has been machining custom parts since 2008: 15+ years, 90 to 100 staff, 50–60% exported to North America and Europe, 200+ customers served, turnover in the RMB 10–20 million band. The floor holds CNC lathes, turn-mill combined centres with live tooling and sub-spindle, and 4-axis / 5-axis machining centres under an ISO 9001:2015 system, producing parts for automotive, medical, robotics, aerospace, automation, laser, LED, lithium battery and precision instrument programs. Turning, spline and flange machining, hardening coordination, balancing and CMM inspection are managed in our own plant in Dongguan.

Drivetrain and turned components from this plant ship into ten industries. Each line is a category we machine regularly, with the parts customers actually order.

All ten sectors run through the same plant and the same ISO 9001:2015 inspection discipline — only the material, finish and documentation package change.

• Prototype: 5–8 working days including hardening and balancing; 3–5 days for a soft-state sample.
• Small batch 10–100 pcs: 10–18 working days.
• Repeat orders: run from archived programs, centres and spline tool list; flange runout and coaxiality repeat to the same values.
• Capacity: 10,000 pieces per month across the plant.
• Visibility: a dated progress note with photographs of your actual shafts at spline cutting, flange facing and inspection.
• Shipping: splines sleeved, threads capped, shafts in v-groove cradles or tubes, flanges protected so a face cannot be nicked in transit.
• Rush: hardening and balancing slots booked weekly; tell us the deadline and we confirm before you order.