Miniature Linear Guides for Precision Automation — Factory Direct from DDJ

ST standard and SMT self-lubricating miniature linear guides, rail widths 3–20 mm — for the axes where repeatability has to hold and relubrication is not an option. Up to 20,000 km maintenance-free travel, drop-in interchangeability with leading brands, and selection support that answers with drawings instead of brochures.

View the Product Range Request a Quote

20,000 kmSelf-lubricating travel (SMT)

3–20 mmRail widths, 7 size series

Up to 868 kgfDynamic load rating

4 typesC / W / F / T carriage options

What actually goes wrong

Six problems engineers bring to us — and what we do about each

These are the real symptoms behind most miniature guide enquiries. Find yours, and we will tell you honestly whether a different guide fixes it.

HIGH-CYCLE DRIFT

“After a few million cycles it runs rough and quality wanders.”

Wear, play and inconsistent preload show up first as lost repeatability. We specify by cycle count, load and moment — not by rail width alone — and match preload to your accuracy target.

Typical fix: ST9 / SMT9 with controlled preload · sealed raceway

REPEATABILITY

“Every drift costs us a re-calibration and a day of commissioning.”

Parallelism, mounting-face flatness and preload decide repeatability more than the catalogue number does. We check your mounting interface and moment load before recommending a size.

Typical fix: ST7 / ST9 matched set · preload class per application

NO SPACE LEFT

“There is simply no room left in the station.”

Carriage length and height usually cost more space than rail width. Low-profile C and long L carriages, plus 3 mm and 5 mm sizes, keep the envelope while holding the load.

Typical fix: ST3 / ST5 / ST7 · low-profile C carriage

DOWNTIME

“Relubricating the guide means stopping the line.”

On equipment where the guide sits deep inside the mechanism, relubrication gets postponed until the guide fails. SMT carries its own lubricant reserve — same envelope, no added height.

Typical fix: SMT series · up to 20,000 km maintenance-free

DELIVERY PRESSURE

“Our delivery date cannot move — but the import lead time can.”

Machine builders are bound by acceptance and hand-over dates. Standard sizes are kept in stock, and custom lengths are produced in 7 working days — with one engineering contact who answers with drawings, not brochures.

Typical fix: ex-stock standards · 7 working days for custom

COST VS RISK

“Cheap parts cost us more in commissioning and complaints.”

Purchasing wants the BOM down; service pays for every early failure. Consistent batch-to-batch preload and dimensional interchangeability let you cut cost without re-engineering the axis — backed by a 1-year warranty, from a single piece.

Typical fix: drop-in replacement for MGN / MSA / LWL class guides

Describe the axis and the symptom — load, stroke, speed, orientation and what the machine does wrong — and you get a sizing recommendation, not a sales pitch. Describe your problem →

Compact motion, engineered

What are miniature linear guides?

A miniature linear guide is a compact two-row recirculating ball bearing system that constrains motion to a straight line with micron-level repeatability. Its compact cross-section carries loads in multiple directions — up, down and side-to-side — while providing low friction and precise linear travel.

They are the motion core of precision assembly stations, inspection stages, dispensing heads, medical devices and semiconductor handling modules — anywhere space is tight and accuracy is not negotiable.

Four-direction load capacity with Gothic-arch raceway
Micron-level machining tolerance for consistent raceway geometry
Batch-controlled heat treatment, hardness and preload
Stainless construction and sealing options for demanding environments

Two series, one mounting standard

Choose your series: ST or SMT

Both series share the same envelope dimensions. Choose ST for standard lubrication practice, and SMT where access is limited, duty cycles are long or maintenance downtime is costly.

DDJ miniature linear guide product array — ST rails and carriages in every size from ST3 to ST20

STANDARD SERIES

ST Series — Standard Miniature Linear Guides

The cost-efficient workhorse for general precision automation. Hardened raceways, two rows of recirculating steel balls, and a full range of C / L / S carriage lengths.

Rail widths: 3 / 5 / 7 / 9 / 12 / 15 / 20 mm
Dynamic load ratings from 30 to 868 kgf (ST3 to ST20)
Standard and long carriages on every size; short type on 7–20 mm
Best for: assembly, dispensing, inspection stages

Explore the ST Series →

SELF-LUBRICATING

SMT Series — Self-Lubricating, Maintenance-Free

An integrated Selubring element continuously supplies lubricant to the rolling elements through capillary action — with no increase in carriage height.

20,000 km self-lubricating travel performance
Lower maintenance frequency and less downtime
Lubrication element integrated inside the carriage
Best for: long-duty, hard-to-access, high-cycle equipment

Explore the SMT Series →

Product range

Shop miniature linear guides by type

Every series is available as standard (C), long (L) and short (S) carriages, plus wide (W), flange (F) and cross-guide (T) configurations.

DDJ ST7, ST9 and ST12 standard C-type miniature linear guides side by side — real product photos

ST / SMT SERIES

C Type — Standard Carriage

Compact standard-width carriage. Rail widths 7–20 mm (ST3 / ST5 ultra-compact sizes also available), dynamic load 100–868 kgf. The general-purpose entry point for precision automation.

Explore the ST Series →

DDJ STW7, STW9 and STW12 wide-type miniature linear guides side by side — real product photos

STW WIDE SERIES

W Type — Wide Carriage

Wider carriage delivers higher moment capacity and superior mounting stability in a low profile — ideal for compact machine axes.

Explore the STW Series →

T TYPE

T Type — Cross Guide

Two orthogonal rails in one unit for compact XY motion — space-saving orthogonal assembly for micro mechanisms.

Explore the T-Type Cross Guide →

Swipe the table sideways to see all columns →

Series	Rail width	Carriage options	Typical application
ST3 / SMT3	3 mm	C, L	Micro optics, lens stages and tiny mechanisms
ST5 / SMT5	5 mm	C, L	Compact medical, sensor and inspection devices
ST7 / SMT7	7 mm	C, L, S	Compact optics and micro mechanisms
ST9 / SMT9	9 mm	C, L, S	Precision automation, assembly and dispensing
ST12 / SMT12	12 mm	C, L, S	Inspection, medical and new-energy equipment
ST15 / SMT15	15 mm	C, L, S	Higher-load precision equipment
ST20 / SMT20	20 mm	C, L	Load-oriented compact machinery
STW5 / STW7 / STW9	Wide	W	Higher moment capacity in a low profile
STW12 / STW15	Wide	W	Stable mounting for compact machine axes
T-Type cross guide	—	Two orthogonal rails in one unit	Compact XY motion for micro mechanisms

Not sure which size fits? Send us your load, stroke and speed — our engineers will size it for you free of charge. Start here →

Real product photos

Straight from our production line

No 3D mock-ups — these are actual DDJ miniature linear guides photographed in our Shenzhen facility.

DDJ ST9 miniature linear guides in three rail lengths — one product family across the size range

Full Size Range

ST3 to ST20 rails and carriages — one family covering every compact axis.

DDJ STW9 wide-type miniature linear guide with black end wiper seals on white background

Sealed & Protected

End wiper seals keep contaminants out of the raceway for longer service life.

Two DDJ carriages mounted on a single miniature rail — multi-carriage axis

Multi-Carriage Axes

Two or more carriages on a single rail for higher moment capacity and stiffness.

DDJ ST7 — the most compact miniature linear guide in the range, on white background

Compact Envelope

Low-profile construction for space-limited precision mechanisms.

DDJ ST12 standard carriage with standardized mounting holes on its rail

Interchangeable Fit

Carriages mount directly on standard-pitch rails — easy replacement, easy stocking.

DDJ STW12 wide carriage — ground raceway surfaces and precision-machined body

Precision Machining

Ground raceways and standardized mounting holes on every rail.

Engineering reference

Key dimensions and load ratings — ST / SMT standard series

Four-direction load capacity and controlled preload help limit elastic deformation. All values are catalog reference data.

ST3 / ST5 — ultra-compact series

Model	Rail width	Carriage variants	Carriage weight	Drops in for
ST3 / SMT3	3 mm	C · L	0.8 g (C) / 1.2 g (L)	—
ST5 / SMT5	5 mm	C · L	3.5 g (C) / 4.5 g (L)	CPC MR5MN / MR5ML · HIWIN MGN5C

Full dimension and load datasheets for the 3 mm and 5 mm series — ask us, we send them within one business day.

ST7 – ST20 dimensions and load ratings (swipe sideways for all columns →)

Model	H (mm)	W (mm)	L C/L/S (mm)	Rail W×H	Pitch	C dyn. (kgf)	C₀ stat. (kgf)	MR / MP / MY (kgf·m)
ST7 / SMT7	8	17	23.5 / 31 / 19	7 × 5	15	100 / 140 / 96	127 / 200 / 116	0.48–0.78 / 0.18–0.49 / 0.15–0.49
ST9 / SMT9	10	20	30.4 / 40.5 / 21.5	9 × 6	20	190 / 260 / 120	260 / 410 / 151	1.2–2.0 / 0.3–1.9 / 0.24–1.9
ST12 / SMT12	13	27	34 / 44.4 / 25.4	12 × 8	25	290 / 380 / 225	400 / 600 / 243	2.6–3.9 / 0.53–3.7 / 0.46–3.7
ST15 / SMT15	16	32	42 / 56.9 / 32	15 × 10	40	470 / 650 / 356	570 / 930 / 397	4.6–7.5 / 1.2–5.9 / 1.0–5.9
ST20 / SMT20	20	40	50 / 67.7	20 × 11	60	678 / 868	926 / 1316	9.4–13.4 / 5.4–10.4 / 4.5–8.7

Units: dimensions in mm unless stated. C/L/S indicate standard, long and short carriage variants. 1 N = 0.102 kgf. Use the detailed drawing for mounting design. ST3 / ST5 dimension and load data — ask us and we will send the datasheet the same day.

Nominal travel life

L = ((C / P) × Fc / Fw)³ × 50 km — dynamic load rating C, equivalent load P, contact and load factors applied.

Permissible moments

MR rolling, MP pitching and MY yawing moments are rated per size. Calculate the equivalent load for combined loading.

Static safety factor

General machinery 2.0–2.3; with vibration or impact 3.0–4.0; machine tools with shock load 3.0–7.0.

✓

Custom rail lengths

Rails are cut to required length within the manufacturing range — hole positions and end distances confirmed on the order drawing.

The DDJ advantage

Why buy miniature linear guides from DDJ?

A better maintenance model, engineered from the raceway up.

Interchangeable carriages

Replace the carriage only — no need to swap the whole rail-and-carriage assembly. Standardized fit supports immediate assembly and minute-level service operations.

Up to 30% lower maintenance cost

Faster spare-parts inventory turnover, less disassembly work, and reduced planned service compared with traditional matched-set systems.

SMT self-lubrication built in

The Selubring element transfers a controlled oil film to the balls via capillary action — maintenance-free over the intended service period, at unchanged mounting height.

Brand interchangeability

Dimensionally compatible replacements for popular MGN / MSA / LWL-class miniature guides — drop into existing machine designs.

Factory-direct pricing & custom work

Direct from our Shenzhen manufacturing base: custom rail lengths, hole patterns, accuracy grades, preloads and surface treatments.

Engineering selection support

Send your load, stroke, speed, orientation, accuracy and environment requirements — we recommend the series, size, preload and rail configuration.

Drop-in replacement

Cross-reference: DDJ STE series vs. other brands

DDJ miniature guides are dimensionally interchangeable with common miniature guide series from leading brands. Replace without redesigning your machine.

Swipe the table sideways to see all columns →

DDJ (STE)	CPC	HIWIN	THK	PMI	IKO	NB	MISUMI
ST3C	MR3MN	—	—	—	—	—	—
ST3L	MR3ML	—	—	—	—	—	—
ST5C	MR5MN	MGN5C	—	—	—	—	—
ST5L	MR5ML	—	—	—	—	—	—
STW5C	MR5WN	MGW5C	—	—	—	—	—
STW5L	MR5WL	—	—	—	—	—	—
ST7C	MR7MN	MGN7C	RSR7M · RSR7ZM · RSH7M · RSH7ZM	MSC7M	LWL7..B · LWL7	SEBS7A-(N)	(S)SEB(Z)8
ST7L	MR7ML	MGN7H	RSR7N	MSC7LM	LWLG7..B	—	(S)SELB8
STW7C	MR7WN	MGW7C	RSR7WM · RSH7WZM · RSH7N	MSD7M	LWLF14..B · LWLF14	SEBS7WA-(N)	(S)SEBW(Z)9
STW7L	MR7WL	MGW7H	RSR7WN	—	LWLFG14..G	—	(S)SEBWL(Z)9
ST9C	MR9MN	MGN9C	RSR9KM · RSR9ZM · RSH9KM · RSH9ZM	MSC9M	LWL9..B · LWL9..BCS · LWL9	SEB(S)9A-(N)	(S)SEB(Z)10
ST9L	MR9ML	MGN9H	RSR9N	MSC9LM	LWLG9..B	SEB(S)AY-(N)	(S)SELB10
STW9C	MR9WN	MGW9C	RSR9WN · RSR9WVM · RSH9WZM	MSD9M	LWLF18..B · LWLF18..CS · LWLF18	SE(S)9WA-(N)	—
STW9L	MR9WL	MGW9H	RSR9WN	MSD9LM	LWLG18..B	SEB(S)9WAY-(N)	(S)SEBWL(Z)12
ST12C	MR12MN	MGN12C	RSR12VM · RSR12ZM · RSH12VM · RSH12ZM	MSC12M	LWL12..B · LWL12..BCS · LWL12 · LWL12CS	SEB(S)12A-(N) · SER(S)12A-(N)	(S)SEB(Z)13
ST12L	MR12ML	MGN12H	RSR12N	MSC12LM	LWLG12..B	SEB(S)12A-(N)	(S)SELB13
STW12C	MR12WN	MGW12C	RSR12WV · RSR12WVM · RSR12WZM · RSH12WZM	MSD12M	LWLF24..B · LWLF24..BCS · LWLF24 · LWLF24..CS	SEB(S)12WA-(N)	(S)SEBW(Z)14
STW12L	MR12WL	MGW12H	RSR12WN	MSD12LM	LWLFG24..B	SEB(S)12WAY-(N)	(S)SEBW(Z)14
ST15C	MR15MN	MGN15C	RSR15VM · RSR15ZM · RSH15ZM	MSC15M	LWL15..B · LWL15 · LWL15..S	SEB(S)15A-(N) · SER(S)15A-(N)	(S)SEB(Z)16
ST15L	MR15ML	MGN15H	RSR15N	MSC15LM	LWLG15..B	SEB(S)15AY-(N)	(S)SELB16
STW15C	MR15WN	MGW15C	RSR15WVM · RSR15WZM · RSH15WZM	MSD15M	LWLF42..B · LWLF42..BCS · LWLF42 · LWLF42..CS	SEB(S)15WA-(N)	(S)SEBW(Z)16
STW15L	MR15WL	MGW15H	RSR15WN	MSD15LM	LWLG42..B	SEB(S)15WAY-(N)	(S)SEBWL(Z)16

C = standard carriage, L = long carriage, W = wide rail and carriage. Confirm preload class, accuracy grade and seal option when ordering a replacement — send us the part number on your existing guide and we will confirm the match within one business day.

Where compact precision matters

Miniature linear guide applications

Pick the equipment closest to yours to see the motion problem we hear most often — and the series that usually solves it.

⚙ Precision Assembly

Connector assembly, component insertion and small-part handling with high cycle counts.

Usual problem: repeatability drifts after millions of cycles → ST9 / SMT9

Automated vision inspection and metrology stage

🔬 Inspection & Test

Vision inspection, metrology stages and optical alignment where repeatability is critical.

Usual problem: vibration blurs the image and settling time is too long → ST7 / ST9

💧 Dispensing

Adhesive dispensing, coating and precision dosing equipment.

Usual problem: fast start-stop shifts the bead path → ST9 / SMT9

Compact medical laboratory automation device

🏥 Medical Equipment

Diagnostic mechanisms and compact laboratory automation.

Usual problem: long life in an inaccessible, wiped-clean area → SMT9 / SMT12

💾 Semiconductor

Handling, inspection and clean-environment motion modules.

Usual problem: particles and drift in a clean environment → ST9 / SMT12

📱 Electronics Automation

High-cycle positioning in 3C and electronic manufacturing lines.

Usual problem: 24/7 uptime with constant line changeover → ST9 / SMT9

Lubricant film observed on the rolling elements of an SMT self-lubricating guide

Ordering information

How to specify your DDJ guide in 5 steps

Define load and moments

Magnitude, direction and any shock or vibration conditions.

Select size and carriage length

Standard (C), long (L) or short (S) to match your envelope.

Choose ST or SMT

Standard lubrication vs. maintenance-free self-lubrication.

Confirm preload and accuracy

Matched rigidity and precision to your positioning requirement.

Specify rail length & quantity

Standard hole counts or custom drilling to your drawing.

Example ordering code: SMT 9 C N 2 R 300 P II — SMT series · size 9 · C carriage · N preload · 2 carriages · R rail · 300 mm · P accuracy · matched set II.

Frequently asked questions

Miniature linear guide FAQ

What is the difference between the ST and SMT series?

Both share identical envelope dimensions and load ratings. The SMT series adds an integrated Selubring self-lubricating element that delivers lubricant to the rolling elements by capillary action, enabling up to 20,000 km of maintenance-free travel — ideal where relubrication access is difficult or downtime is costly.

Are DDJ guides interchangeable with HIWIN MGN or THK RSR/LWL guides?

Yes. The DDJ STE series is dimensionally interchangeable with common CPC MSA, HIWIN MGN/MGW, THK RSR/RSH/MSC/LWL, IKO SEB and MISUMI SEBZ series. See the cross-reference table above, and confirm preload class, accuracy grade and seal option when ordering.

Can I replace just the carriage without changing the rail?

Yes — that is the core of the DDJ interchangeable system. Rails and carriages are manufactured under controlled dimensional tolerances, so a compatible carriage can be fitted to an existing DDJ rail directly, cutting spare-parts inventory and machine downtime.

What is the minimum order quantity? Do you support prototypes?

We support prototype and small-batch orders. Standard lengths and hole configurations ship from stock; custom rail lengths, hole patterns and surface treatments are produced to your order drawing. Contact us with your quantity for a quotation.

What information should I provide for a selection recommendation?

Send your load (including moments), stroke, speed, installation orientation, accuracy requirement, environment (dust, cleanliness, temperature) and annual quantity. Our engineers will recommend the series, size, carriage style, preload and rail configuration — free of charge.

Do you export? What are the lead times?

Yes — we ship worldwide from Shenzhen, China. Standard sizes are kept in stock and usually dispatch within a few days. Custom lengths, hole patterns and matched sets are made in 7 working days. Tell us the destination in your enquiry and we will confirm the exact shipping schedule with the quote.

What is the minimum order quantity? Can I get samples for a prototype?

1 piece. Prototype and R&D orders are welcome — there is no minimum order value for the first evaluation. Order single carriages or single rails to test the fit and the running feel on your own mechanism before committing to production quantities. Sample orders ship from stock where the size is standard.

What warranty do you offer?

1 year from the date of shipment on every guide we produce, covering material and manufacturing defects. If a guide fails inside that period under correct installation and rated load, we replace the faulty rail or carriage. Inspection records and the batch number are kept so a claim can be traced back to production.

Get a fast quotation

Find the right miniature linear guide

Tell us about your application and receive a size recommendation plus factory-direct pricing — usually within one business day.

✆Tel / Mobile / WeChat: +86 189 2521 2975
💬WhatsApp: Chat with us · +86 189 2521 2975
✉Email: aria@ddjmotion.com
🌐Website: ddjmotion.com
📍No. 142 Songyu Road, Hongxing Community, Songgang Sub-district, Bao'an District, Shenzhen, Guangdong 518105, China

Standard sizes ex-stock · Custom in 7 working days · 1 pc MOQ · 1-year warranty

Request a Quote

Fields marked * are required.

Your name *

Company

Email *

Country / Region

Series of interest

Main problem to solve

Estimated quantity

Application details *