Linear Guide vs Ball Screw: The Complete Linear Motion Sourcing Guide

2026-09-05

If you build CNC routers, laser cutters, 3D printers or pick-and-place stages, you buy linear motion components regularly. The category is technical and the spec language is full of confusing codes. Here is a clean buyer's view of what to specify, what to skip and how to source from China.

1. What is linear motion, in one paragraph

Two jobs need doing: slide (something moves along a straight line) and drive (something pushes it). The slide is done by a linear guide (or shaft + linear bearing). The drive is done by a ball screw (or lead screw). Motors turn the screw, the screw turns into linear travel, the linear guide keeps it straight.

2. Linear guide - what to specify

Rail width — HGR20, HGR25, HGR30, HGR45 (millimetres). Most CNC and automation uses HGR20 or HGR25.
Block type — flange (HGH-HA / HGR) or slim (HGH-CA / HGH-CB). Flange is more common for retrofit.
Block length — standard or long. Long block = higher load capacity, more rigid.
Preload — ZC0 light (general), ZC1 medium, ZC2 heavy.
Length per rail — cut to your machine (typically 200–3000 mm).

3. Ball screw - what to specify

Diameter and lead — SFU1605 = 16 mm diameter, 5 mm lead. SFU2005, SFU2505, SFU3205, SFU5010 are the workhorse sizes.
Precision grade — C7 (general CNC), C5 (precision CNC, machining centres), C10 (light duty).
Nut type — single flange (standard), double nut (preloaded, no backlash).
End-machining — fixed end (BK block side) and supported end (BF block side). Standard length or cut to your drawing.

4. Lead screw - the budget alternative

If the load is light and the speed is low (3D printers, lab equipment, sliding doors), a TR8 / TR10 / TR12 trapezoidal lead screw with a brass or POM nut is 5–10× cheaper than a ball screw. It is self-locking (won't back-drive), which is good for vertical axes.

5. Linear bearing and shaft

LM8UU / LM10UU / LM12UU / LM16UU / LM20UU closed-type sleeve bearings, mounted on chrome-plated hardened shaft. Cheaper than a linear guide, suitable for light loads and clean environments. SK / SKM pillow blocks support the shaft ends.

6. Sourcing from China - what to ask for

Material and origin of the rail (20 Mn / 55 Cr or imported).
Ball screw grade certificate (C5 / C7 / C10) and run-out report.
Preload per block.
Cut-to-length tolerance (typical +/-0.2 mm for rails).
End-machining drawing for ball screws (with bearing block part number).
OEM logo on packaging if you want private label.

Bottom line: Linear motion is one of the easiest B2B categories to source from China — factories are mature, spec language is standard, and lead times are short. Send your rail length, ball screw size and end-machining drawing and you will get a competitive quote within 24 hours.

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