K Series
Shaft and housing bore as raceways
For radial needle roller arrangements, the shaft and housing bore can serve as raceways when their hardness, accuracy and surface finish meet the application requirements.
Discuss your K projectBearing structure
Needle Roller Bearing Cages
Plastic cages that separate and guide needle rollers in compact radial bearing arrangements.
Application and design
Needle roller cages are used where radial installation space is limited. K and HK refer to different surrounding bearing structures; cage selection depends on the raceways, roller geometry and assembly interfaces.
Supply scope: Plastic cages only. Needle rollers, bearing rings, drawn cups and complete needle roller bearing assemblies are not included.
Compare series designs
HK Series
Drawn cup bearing arrangement
The cage works with a thin-walled drawn outer ring in a radial needle roller bearing. Boerjing supplies the plastic cage; the outer ring is outside the supply scope.
Discuss your HK projectMaterials & customisation
Material review considers pocket stability, assembly flexibility, moisture exposure and lubricant compatibility. The polymer and grade are agreed for the specific cage design.
Choose from the nylon materials below for your cage design and operating conditions. The specific resin grade is agreed for the project.
| Material code | Material description |
|---|---|
| PA66 | Unreinforced polyamide 66 |
| PA66-GF10 | 10% glass-fibre-reinforced polyamide 66 |
| PA66-GF15 | 15% glass-fibre-reinforced polyamide 66 |
| PA66-GF25 | 25% glass-fibre-reinforced polyamide 66 |
| PA66-GF30 | 30% glass-fibre-reinforced polyamide 66 |
| PA46 | Unreinforced polyamide 46 |
| PA46-GF15 | 15% glass-fibre-reinforced polyamide 46 |
| PA46-GF25 | 25% glass-fibre-reinforced polyamide 46 |
| PA46-GF30 | 30% glass-fibre-reinforced polyamide 46 |
Typical raw-material property ranges
| Property | PA66 | PA46 |
|---|---|---|
| Densityg/cm³ | 1.13–1.36 | 1.18–1.41 |
| Tensile stress, dryMPa | 85–190 | 100–210 |
| Tensile modulus, dryGPa | 3.0–10.0 | 3.3–10.0 |
| Melting point, DSC°C | ≈260 | ≈295 |
| Heat deflection temperature°C · 1.8 MPa | 75–250 | 190–290 |
Ranges summarise the example resin grades below for initial material selection. Finished-part performance is reviewed for the selected grade and application. Tensile stress uses dry yield or break values. Continuous operating temperature is assessed separately for the grade and conditions.
Reference grades and manufacturer data
Design requirements
- Bearing arrangement
- Identify whether the cage is used with shaft and housing raceways or within a drawn cup bearing.
- Roller and pocket geometry
- Provide the needle-roller diameter and length, roller quantity, cage envelope and critical pocket dimensions.
- Fit and operation
- Describe mounting, clearances, speed, load direction, temperature and lubrication.
Custom development and project enquiries
Boerjing develops molds and manufactures precision injection-molded plastic parts from customer drawings or approved samples. We support mold trials, sample approval, small-batch validation and repeat production.
Start with the component and intended use. Share available drawings or samples, material requirements and expected quantities.