Dongfeng Bearing
LMK Series Double-Length Linear Ball Bearing
LMK Series double-length square-flange linear ball bearing with two independent ball recirculation circuits, delivering 2,350 N dynamic load at LMK16UU and 60% longer rated travel life. Designed for packaging machinery, textile equipment, and high-duty reciprocating axes where standard single-circuit bearings wear prematurely.
Key Features
- Double ball circuit distributes load across 1.8× longer contact area — rated travel life increased by approximately 60%
- 2,350 N dynamic load at LMK16UU versus 1,370 N for standard single-circuit LMF16UU
- Square 4-bolt flange follows JIS B 1185 LMK standard — interchangeable with THK, IKO, MISUMI equivalents
- UU-type double rubber seals retain grease and block contamination in the extended ball circuit
- Longer sleeve body reduces angular deflection under moment loads — critical for cantilevered packaging and textile axes
- H5 precision grade available on request for LMK8–LMK40
Common Sourcing Problems & How We Solve Them
Buyer Pain Points
- Inconsistent dimensional tolerances across batches cause machine downtime and re-work costs
- Suppliers unable to provide material certs, inspection reports or CE documentation for customs clearance
- Long lead times and high MOQ requirements make sample evaluation and first orders difficult
Dongfeng Solution
- ISO 9001:2015 process controls with CMM dimensional inspection on every production batch
- Full documentation package: material cert, SGS test report, CE declaration, packing list on request
- Flexible MOQ from 1 piece for samples; bulk order lead time 15–20 working days
Performance Data
- 10+ years of linear motion component manufacturing — 50+ export markets served
- Hardness tested to HRC 58–62; dimensional tolerance held to JIS / ISO / DIN standard grade
- CE & SGS certified; ISO 9001:2015 quality management system in production
Utility record
| Bearing Series | LMK 6–50 (10 sizes) |
|---|---|
| Flange Type | Square, 4-bolt diagonal |
| Outer Ring Material | Chrome Steel GCr15 (52100) |
| Ball Material | Chrome Steel GCr15 |
| Retainer | PA66-GF Glass-Fiber Nylon |
| Shaft Diameter | 6 mm – 50 mm |
| Dynamic Load (LMK16UU) | 2,350 N |
| Static Load (LMK16UU) | 3,680 N |
| Precision Grade | Normal / H5 |
| Standard Reference | JIS B 1185 LMK (double-length) |
Application fit notes
User Pain Point + Solution + Data
Standard LM series bearings have a single ball circuit that handles moderate loads, but packaging machinery, textile equipment, and high-speed pick-and-place systems need longer bearing life under continuous reciprocating duty. The LMU/LMK double-length bearing solves this by doubling the ball circuit length: two independent ball recirculation tracks run in series within one outer sleeve, distributing the load across a 1.8× longer contact area. The result is 2,350 N dynamic load at LMK16UU (versus 1,370 N for standard LMF16UU), with a 60% increase in rated travel life. The square flange body uses a 4-bolt mounting pattern compatible with JIS B 1185 LMK standard.
Complete Specifications
| Parameter | Value |
|---|---|
| Bearing Series | LMK 6 / 8 / 10 / 12 / 16 / 20 / 25 / 30 / 40 / 50 |
| Flange Type | Square flange, 4-bolt diagonal pattern |
| Outer Ring Material | Chrome Steel GCr15 (52100 equiv.) |
| Ball Material | Chrome Steel GCr15 |
| Retainer Material | PA66-GF Glass-Fiber Nylon |
| Shaft Diameter Range | 6 mm – 50 mm |
| Dynamic Load (LMK16UU) | 2,350 N |
| Static Load (LMK16UU) | 3,680 N |
| Precision Grade | Normal / H5 (on request) |
| Sealing | Double rubber seals (UU type) |
| Standard Reference | JIS B 1185 LMK (double-length) |
Product Advantages
Double Ball Circuit
Two independent ball recirculation tracks distribute load across 1.8× the contact length of standard LM bearings. This reduces per-ball contact stress and extends rated travel life by approximately 60% under equivalent load conditions.
+60% LifeSquare Flange Mounting
4-bolt square flange follows JIS B 1185 LMK dimensional standard. Interchangeable with THK, IKO, and MISUMI double-length flange bearings of the same size without housing modification.
JIS StandardReduced Deflection
The longer sleeve body provides greater shaft contact area, reducing angular deflection under moment loads. This is critical for cantilevered axes in packaging machines where the bearing must resist tilt as well as radial load.
Low DeflectionSealed for Long Service
UU-type double rubber seals on both ends retain grease and block dust ingress. The extended ball circuit benefits especially from sealed operation since contamination in a longer track is harder to flush out.
UU SealedEnterprise Strength
Xiamen Dongfeng Bearing Mechanical & Electrical Co., Ltd.Ltd. — established 2014, 10+ years manufacturing precision linear motion bearings. Our 5,000 m² Xiamen facility operates 12 production lines with 200+ employees. The linear bearing cell produces LM/LME/LMF/LMK series at 150,000+ pieces per month, including double-length variants for high-duty applications.
Certifications: ISO 9001:2015, CE conformity, SGS factory audit. Export markets: 50+ countries including Germany, Italy, USA, Japan, South Korea, Turkey, and Brazil. Partners: Supplying packaging machinery manufacturers, textile equipment OEMs, and automation system integrators.
Pre-sales: Application load-life calculation and bearing size selection within 4 hours. After-sales: 18-month quality warranty, technical travel-life estimation service. Customer case: Supplied 25,000 LMK16UU bearings to a German packaging machinery manufacturer — 3-year continuous operation, 0.04% defect rate, rated life exceeded by 15% in actual field conditions.
Manufacturing, Exhibition & Quality Controltrol
Production Process & Quality Assuranceance
Process: GCr15 raw tube → CNC turning (outer sleeve, square flange, dual raceway grooves) → induction hardening (HRC 60–64) → precision grinding (both raceway tracks in one setup for alignment) → dual ball circuit assembly with PA66-GF retainer → seal installation → 100% running smoothness test → packaging.
Quality testing: Bore and flange dimensions verified on air gauges (±2 µm), dynamic load validated on endurance rig (1,500 km travel at rated load), dual-circuit alignment verified by measuring running torque variation (≤8% fluctuation). Exhibitions: Regularly exhibited at PTC Asia (Shanghai), Interpack (Düsseldorf), and ITMA (textile machinery) to engage high-duty application manufacturers directly.
FAQ
What is the MOQ for LMK double-length bearings?
MOQ is 100 pieces per size. Mixed sizes accepted in one order with 100-piece minimum per individual size. Sample quantities of 10–20 pieces available for qualified buyers — contact us with your required sizes.
What are the shipping options and lead time?
FOB Xiamen. In-stock sizes (LMK6–LMK25): 7–10 business days. Larger sizes (LMK30–LMK50): 15–20 business days. Express courier (DHL/FedEx): 5–7 days for samples. Sea freight: 25–35 days to Europe, 18–25 days to USA.
How are LMK bearings packaged?
Individual anti-corrosion oiled wrapping in plastic bags, then packed in partitioned cartons (50 pieces per carton for LMK6–LMK16, 25 pieces for LMK20–LMK30, 10 pieces for LMK40–LMK50). Wooden pallet packing for bulk export orders.
What payment methods do you accept?
T/T (30% deposit, 70% before shipment). L/C at sight for orders above USD 15,000. PayPal for sample orders under USD 2,000. Western Union for small orders on request.
Are samples available for testing?
Yes. Samples of 10–20 pieces per size available with buyer covering shipping. Sample cost is credited toward bulk orders of 500+ pieces. Provide your required shaft diameter and quantity to arrange.
Do you offer OEM branding and custom packaging?
Yes. Custom logo engraving on flange face available for 200+ piece orders. OEM branded packaging with buyer design available for 500+ piece orders. Custom seal colors and retainer materials can be discussed for high-volume orders — share your requirements.
Request a Quote for LMK Double-Length Bearings
Send your shaft diameter, flange type, quantity, and any OEM requirements — we reply within one business day.
Request a QuoteWhy Buyers Choose Dongfeng Bearing
Xiamen Dongfeng Bearing Mechanical & Electrical Co., Ltd. — direct factory, 10+ years precision linear motion manufacturing
ISO 9001:2015, CE Declaration of Conformity, SGS test reports. Documentation available for EU and North American import requirements.
12 precision grinding and CNC machining lines; monthly output 500,000+ pieces across linear bearing and guideway series.
Germany, USA, Japan, South Korea, India, Southeast Asia and 40+ other countries. FOB Xiamen with DHL / FedEx / sea freight options.
Technical selection support before order. Dimensional drawing, material cert and inspection report with shipment. 12-month warranty on manufacturing defects.
Manufacturing Process & Quality Assurance
Precision Machining
CNC grinding centers hold ball raceway geometry to ±0.003 mm. Induction hardening targets contact zones to HRC 58–62 without embrittling the full body.
CMM Dimensional Inspection
Every batch passes coordinate measuring machine (CMM) verification. Key dimensions — bore, OD, length, raceway radius — are logged against JIS / ISO tolerance bands.
Certification & QC
ISO 9001:2015 controls govern raw material intake, in-process check, and final inspection. SGS and CE documentation issued on request for each shipment.
Trade Shows & Partnerships
Regular exhibitor at Canton Fair and Hannover Messe. Established supply partnerships with automation integrators and machine tool OEMs across Europe and Asia.
Customer Application Cases
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