Product Overview
DUROLUB DL is a high-tech polymer-based lubrication system made from ultra-high molecular weight polymer combined with a synthetic, temperature-stable base oil. Through a heat treatment process, a solid porous polymer matrix is formed within the bearing cavity. The oil is retained within this matrix structure by surface tension, providing continuous and stable lubrication.
Unlike conventional greases that fill only 25–30% of the bearing space, DUROLUB DL fills the entire bearing cavity (100%) and rotates together with the cage and rolling elements, effectively eliminating condensation risk with no relubrication required.
Lubrication Mechanism
- The lubricant supplies oil via the sliding contact surfaces between the rolling elements and raceways
- As temperature rises, the thermal expansion of the polymer matrix is lower than that of the base oil, causing more oil to be released and providing more abundant lubrication
- Oil viscosity decreases as temperature rises, further promoting lubrication efficiency
- When the bearing is at rest, the polymer matrix reabsorbs the excess base oil, maintaining an optimum lubricating film under all operating conditions
Conventional grease — fills only 25–30% of bearing space
DUROLUB DL — polymer matrix fills the entire bearing space (100%)
DUROLUB DL vs. Conventional Grease
| Comparison | Conventional Grease | DUROLUB DL |
|---|---|---|
| Bearing space fill rate | 25–30% | 100% (entire bearing cavity) |
| Rotation behaviour | Mostly stationary | Rotates with cage and rolling elements |
| Condensation risk | Present | Eliminated |
| Relubrication requirement | Periodic | Not required |
| Oil storage capacity | Standard | Up to 5× higher |
Variants / Base Oil / Designation
| Variant | Application | Viscosity (40°C) | Viscosity Index | Operating Temperature Range | Recommended Max Temp | Absolute Max Temp |
|---|---|---|---|---|---|---|
| DUROLUB DL | Ball bearings (standard) | 68 mm²/s | 153 | -40°C ~ +100°C | < 85°C | 120°C |
| DUROLUB DL32 | Low-temperature applications | 32 mm²/s | 130 | -50°C ~ +100°C | < 85°C | 120°C |
| DUROLUB DL150 | Roller bearings | 140 mm²/s | 160 | -35°C ~ +100°C | < 85°C | 140°C |
| DUROLUB DLSxx | Special / vacuum applications | On request | On request | On request | On request | On request |
Designation suffix guide: DL = standard viscosity (68 mm²/s), DL32 = low viscosity (32 mm²/s), DL150 = high viscosity (140 mm²/s), DLSxx = special formulation (e.g. vacuum applications).
Base Oil Properties
- Universal synthetic oil, suitable for the food and pharmaceutical industries
- Optimum wear protection
- High resistance to oxidation and ageing
- Excellent corrosion protection
- Wider temperature application range compared to mineral oil
- Neutral to elastomers and plastic materials
Special Features
- Extended bearing service life (oil storage capacity up to 5×)
- Prevention of condensation inside the bearing
- Sealing effect against external contaminants
- Supports integrated seal design
- Minimal oil dripping
- Reduced maintenance requirements
- Environmentally friendly (oil enclosed within the matrix)
- Food-safe compliant (NSF H1 / InS / Halal / Kosher certified)
- Eliminates relubrication intervals, reducing operating costs
Compliance & Certifications
NSF H1 food-grade certified, compliant with DIN 51517 CLP, neutral to elastomers and plastics.
Speed Guide Values
Once filled and heat-treated, DUROLUB DL hardens and rotates together with the cage. This results in a reduction of the limiting speed.
Speed guide values are expressed as ndm values, calculated by the formula:
ndm = dm × n
where: dm = [D (outer diameter mm) + d (bore diameter mm)] × 0.5
Limiting speed: ng [min-1] = ndm / dm (at ambient temperature 20°C)
The following guide values are based on an ambient temperature of 20°C, with a bearing temperature rise of approximately 60°C at maximum speed. The actual achievable limits are often higher but must be tested and verified in the specific application. Limiting speeds vary depending on bearing brand and design, especially cage design — steel sheet cages are most suitable; polyamide (PA) and brass cages show more variable results.
| Bearing Type | Maximum ndm Value |
|---|---|
| Steel cage | |
| Deep groove ball bearing | 300,000 |
| Angular contact ball bearing | 150,000 |
| Self-aligning ball bearing | 150,000 |
| Cylindrical roller bearing | 150,000 |
| PA cage (plastic) | |
| Deep groove ball bearing | 50,000 |
| Angular contact ball bearing | 50,000 |
| Self-aligning ball bearing | 50,000 |
| Cylindrical roller bearing | 50,000 |
| Other bearing types | |
| Tapered roller bearing | 50,000 |
| Insert bearing / Y-bearing (UC/Y type) | 50,000 |
| Needle roller bearing | 50,000 |
| Full complement cylindrical roller bearing | 50,000 |
| Yoke-type cam follower / support roller | 50,000 |
| Deep groove ball bearing (double row) | 40,000 |
| Angular contact ball bearing (double row) | 40,000 |
| Spherical roller bearing | 40,000 – 80,000 |
Maximum Permissible Speed and Ambient Temperature
When DUROLUB DL-filled bearings are used at ambient temperatures above 20°C, the limiting speed ng must be multiplied by the derating factor fT:
nreduced = nguide × fT
| Ambient Temperature | Derating Factor fT |
|---|---|
| 20°C | 1.0 |
| 30°C | 0.8 |
| 40°C | 0.7 |
| 50°C | 0.55 |
| 60°C | 0.35 |
Load Ratings / Dimensions / Tolerances / Bearing Clearance
DUROLUB DL filling does not change the basic load ratings, dimensions, tolerances, or internal clearance of the bearing. All values are identical to those of the same unfilled bearing type and can be taken directly from the manufacturer's bearing catalogue.
Bearing Friction
After filling with DUROLUB DL, bearing friction increases by a constant value. The fundamental friction behaviour remains consistent with the selected bearing type.
Maximum Application Temperature
Short-term use up to 100°C is permissible; the recommended continuous operating temperature is below 85°C. Compared to mineral oil-based greases, the synthetic base oil provides significantly longer oil service life at elevated operating temperatures.
Absolute temperature limits: 120°C for DUROLUB DL and DL32 (limited by the matrix/base oil), and 140°C for DL150.
Low Temperature Application
Near and below the freezing point, the oil thickens rapidly. Due to the high viscosity, the load-independent friction torque caused by the lubricant increases significantly, leading to high energy consumption during cold starts and operation at low ambient temperatures.
DUROLUB DL exhibits significantly lower load-independent friction torque at low temperatures compared to conventional lithium soap / mineral oil greases (viscosity index VI 74).
The low-temperature variant DUROLUB DL32 can operate at -50°C, while the standard DL is rated down to -40°C.
Viscosity comparison at -10°C: DUROLUB DL / DL32 viscosity is significantly lower than standard grease and other compound products
Assembly
The maximum assembly temperature for bearings filled with DUROLUB DL is 120°C.
Induction heating is the recommended installation method. Hot plates or oil bath heating are not suitable for DUROLUB DL-filled bearings.
Colour
DUROLUB DL appears white or blue in colour, depending on production batch availability. The colour difference does not affect the performance or function of the matrix or base oil — both colours have identical technical characteristics. Special colour requirements must be specified at the time of ordering and may be subject to a minimum order quantity.
Bearing Compatibility
In principle, any bearing with adequate internal clearance can be filled with DUROLUB DL. The larger the clearance, the higher the lubrication efficiency.
51416M thrust ball bearing with DUROLUB DL
Tapered roller bearing with DUROLUB DL150
- Rolling bearings with steel or plastic cages are most suitable
- Bearings with large brass cages are less suitable
- Thrust bearings and tapered roller bearings require special equipment for filling
- Customers may supply their own bearings for filling
Labeling
Original manufacturer markings are retained on the bearing, which is returned in its original packaging with a DUROLUB label added. EAN barcodes can be provided within 48 hours upon request.
Original packaging with DUROLUB label
DUROLUB DL specification label
Equivalent Products by Manufacturer
| Manufacturer | Equivalent Product |
|---|---|
| SKF | Solid Oil (W64) |
| NSK | Molded Oil (L11 / L12) |
| NTN | Solid Grease (LP03 / LP09) |
| SNR | Lubsolid (LSx) |
| Schaeffler | Lubtect (LT) |