Lead Screw
Transmission Parts

A lead screw is a precision threaded shaft used to convert rotary motion into linear motion (or vice versa) in positioning systems, lead screw linear actuators, and machine tool slides. Unlike a power screw (optimised for force transmission), a lead screw is optimised for positional accuracy — the linear travel per revolution (the lead) must be accurate and consistent along the full length. Trapezoidal lead screw thread forms (DIN 103) and ACME lead screw forms (ASME B1.5) are the standard thread profiles for lead screws in CNC machines and actuators.

Lead screw: sliding contact between screw thread and nut (trapezoidal or ACME). Higher friction → lower efficiency (20–40%), self-locking (won't back-drive under load), lower speed capability. Advantages: simple, low cost, self-locking for vertical actuators, tolerates side loads. Ball screw: rolling contact via recirculating steel balls. Lower friction → higher efficiency (90–95%), not self-locking, capable of high speeds and duty cycles. In the lead screw vs ball screw decision: ball screws are preferred for CNC machine axes; lead screws for slower linear actuators, jigs, fixtures, and vertical lifting where self-locking is needed.

DIN 103 / ISO lead screw accuracy classes: P7 — general industrial actuators, ±0.1 mm/300 mm. P5 — standard CNC machine positioning, ±0.023 mm/300 mm. P3 — precision CNC and optical equipment, ±0.015 mm/300 mm. P2 — high-precision measuring machines, ±0.008 mm/300 mm. For manual machine tool tables and jigs: P5–P7. For CNC axes: P3–P5. For precision laser and optics stages: P2–P3.

Trapezoidal (Tr) — DIN 103 / ISO 2904: 30° thread angle, metric pitch. The European standard for machine tool lead screws. Designated Tr (major diameter) × (lead), e.g., Tr32×6. Common metric trapezoidal lead screw sizes: Tr8×1.5, Tr10×2, Tr12×3, Tr16×4, Tr20×4, Tr24×5, Tr32×6, Tr40×7, Tr50×8. ACME — ASME B1.5: 29° thread angle, inch pitch. The American standard. Widely used in the USA and for replacement parts on American machine tools. Stub ACME — shallower thread depth than standard ACME, for applications with limited radial space. HXC grinds both Tr and ACME profiles to P2–P7 accuracy in single-start and multi-start (double-lead) configurations.

Lead error is the deviation of the actual axial advance per revolution from the nominal lead. It has two components: periodic error (repeating with each revolution — caused by grinding wheel runout); and cumulative error (increasing over the screw length — caused by machine thermal drift or lead inaccuracy). Measured with a laser interferometer or precision leadscrew tester. DIN 103 P3: cumulative error ≤ 0.015 mm over any 300 mm length. HXC measures lead error at 25 mm intervals and provides the full error plot with every precision lead screw order.

Screw materials: C45 (medium-duty), 42CrMo4 induction-hardened HRC 50 (standard precision screws), and stainless steel (SUS304/316) for corrosive and medical environments — our stainless steel lead screw and stainless steel trapezoidal lead screw options. Nut materials: PB2 phosphor bronze (CuSn8) — the standard bronze lead screw nut material with good lubricity, wear resistance, and corrosion resistance against steel screws; aluminium bronze (AB2) for higher load capacity; PTFE-impregnated bronze for dry-running vertical actuators; acetal (POM/Delrin) for low-cost self-lubricating plastic lead screw nuts; and cast iron for large machine tool tables where the nut is machined integral with the slide. Material selection depends on load, speed, duty cycle, and environment.

Anti-backlash lead screw nuts use two nut halves spring-preloaded against each other — each nut half engages opposite flanks of the thread, eliminating the free play between nut and screw. Backlash in a standard nut is 0.1–0.5 mm; an anti-backlash (zero-backlash) nut reduces this to 0.005–0.02 mm at the cost of slightly higher friction and faster wear. Anti-backlash is essential for CNC axes and positioning stages where the axis changes direction. HXC supplies both standard and anti-backlash lead screw nut assemblies, including split-nut and half-nut configurations.

A lead screw is self-locking when the lead angle is smaller than the friction angle between nut and screw — meaning the axial load on the nut cannot back-drive the screw without an external torque. Standard trapezoidal screws (Tr, 30° flank) are typically self-locking for leads ≤ 1/3 of the major diameter. Self-locking is important for vertical lifting actuators (the screw holds the load without a brake) but a disadvantage for CNC axes (the motor must overcome stiction at direction reversal). Multi-start (double-lead) ACME screws have a larger lead angle and are generally not self-locking.

Yes — HXC standard lead screw supply includes custom end machining: ground bearing journals (k6 for rolling bearing press fit) at both ends, ground flange faces, tapped end holes for coupling attachment, and keyways where required. We also supply matching lead screw end support bearing blocks (fixed/floating sets) and thrust bearing arrangements. End machining is included in the quoted price — all features are machined and ground in one setup for concentricity between the thread and bearing journals. Specify the required bearing type and any coupling configuration on your drawing.

Yes — HXC is a custom lead screw and lead screw nut manufacturer and supplier based in China, producing custom lead screws, trapezoidal lead screws, ACME lead screws, bronze and plastic lead screw nuts, flanged nut housings, and lead screw end bearing blocks to your drawing. Our lead screw manufacturing process covers turning, thread grinding, induction hardening, and laser lead-error inspection in-house. Whether you need a single prototype (MOQ 1) or production batches of custom acme lead screws and precision lead screw assemblies, we machine to DIN 103, ISO 2904, and ASME B1.5 standards with full ISO 9001:2015 quality control and dimensional reports.

Standard Tr or ACME screw, P5 or P7, C45 or 42CrMo4: 7–10 days prototype, 10–16 days for 20–100 pcs. P3 precision ground lead screw: 10–14 days prototype, 14–20 days production. P2 ultra-precision: 14–20 days. Nut machining: 3–5 days additional. End bearing block sets: 3–4 days additional. Stainless steel screws add 2–3 days. Rush production available — contact us with your deadline.