Power composite grease testing service

Power Composite Grease Testing Service – Performance Verification for Electrical Contacts, Bearings and High‑Load Applications

At zhongxi testing, we provide specialized power composite grease testing services to power generation companies, electrical utilities, wind farm operators, heavy machinery manufacturers, and maintenance contractors in Bahrain. Power composite greases are high‑performance lubricants formulated with extreme pressure (EP) additives, anti‑wear agents, corrosion inhibitors, and sometimes conductive fillers for use in electrical contacts, high‑load bearings, gearboxes, and sliding mechanisms. These greases must maintain consistency, resist oxidation, provide excellent wear protection, and, in some cases, conduct electricity while preventing arcing and corrosion. Defects such as oil separation, hardening, oxidation, contamination, or loss of extreme pressure properties can lead to premature component failure, increased friction, overheating, and electrical contact degradation. Our ISO/IEC 17025 accredited laboratory performs comprehensive testing – including dropping point, worked penetration, oil separation, oxidation stability, wear and extreme pressure (four‑ball test), copper strip corrosion, water washout resistance, low‑temperature torque, and electrical conductivity – to ensure compliance with international standards (ASTM D, DIN 51825, ISO 6743, NLGI grades) and Bahraini industrial quality requirements.

Types of Power Composite Grease Samples We Test

Our laboratory handles a wide range of power composite grease products used across Bahraini industries:

• Lithium‑based greases (multi‑purpose and high‑temperature grades)
• Lithium complex greases (high dropping point, for high‑temperature applications)
• Calcium sulfonate greases (excellent extreme pressure and corrosion protection)
• Polyurea greases (high‑temperature and oxidation‑resistant grades)
• Aluminum complex greases (water‑resistant, for wet environments)
• Barium complex greases (heavy‑duty and high‑temperature)
• Synthetic greases (PAO, ester, PAG‑based, for extreme temperatures)
• Conductive greases (with graphite, molybdenum disulfide, carbon black, or metal particles)
• Greases for electrical contacts (switchgear, connectors, circuit breakers)
• High‑load greases (for bearings, gearboxes, and heavy machinery)
• New production batches (incoming quality assurance for manufacturers and distributors)
• In‑service greases extracted from equipment (degradation and contamination assessment)
• Competitor product benchmarking (dropping point and wear resistance comparison)

Key Testing Parameters and Methods for Power Composite Greases

1. Dropping Point – ASTM D566 / ISO 2176

The primary parameter in power composite grease testing is the dropping point – the temperature at which the grease becomes fluid enough to drip from the test cup. We heat the grease sample at a controlled rate (5°C/min) in a metal test cup with a small hole in the bottom. We record the temperature at which the first drop falls. For lithium complex greases, dropping points are typically > 260°C; for standard lithium greases, 180‑200°C; for polyurea greases, > 250°C. A low dropping point (< 150°C) indicates poor high‑temperature performance and risk of leakage in hot applications.

2. Worked Penetration (Consistency) – ASTM D217 / ISO 2137

We measure the consistency (hardness/softness) of the grease by penetration (0.1 mm) using a standard cone penetrometer. We test three conditions: unworked, 60‑stroke worked, and 10,000‑stroke worked. The NLGI (National Lubricating Grease Institute) grade is determined from the worked penetration range: NLGI Grade 2 (265‑295), Grade 1 (310‑340), Grade 3 (220‑250). A significant increase in penetration after 10,000 strokes (> 30 points) indicates poor mechanical stability, leading to grease softening and leakage.

3. Oil Separation (Bleeding) – ASTM D6184 / ISO 2176

We place a 100 g sample of grease in a mesh cone and heat it at 100°C (or 140°C) for 24 hours. We measure the amount of oil that separates from the grease (%). For high‑quality power greases, oil separation should be < 5% at 100°C. Excessive oil separation (> 10%) leads to loss of consistency, reduced lubricating film, and bearing failure.

4. Oxidation Stability – ASTM D942 / ISO 4263

We place a 100 g sample in a sealed oxygen bomb at 99°C for 100 hours. We measure the pressure drop (kPa) over the test period. For lithium complex greases, acceptable pressure drop is < 34 kPa (5 psi) after 100 hours. For synthetic greases, < 20 kPa is typical. A high pressure drop (> 50 kPa) indicates poor oxidation stability, leading to acid formation, sludge deposition, and loss of lubricating properties.

5. Extreme Pressure and Wear Protection – Four‑Ball Test – ASTM D2596 / ISO 20623

We use a four‑ball extreme pressure tester to measure the weld point (kg) and the load wear index (LWI). We rotate one steel ball against three stationary balls under increasing loads (1‑10 kN) until welding occurs. For high‑performance EP greases, the weld point should be ≥ 250 kg (for lithium complex) and ≥ 300 kg (for calcium sulfonate). We also perform a four‑ball wear test at 40 kg, 60°C, 1200 rpm, for 1 hour, and measure the wear scar diameter (WSD). Acceptable WSD for power greases is < 0.6 mm. A large WSD (> 1.0 mm) indicates poor wear protection.

6. Copper Strip Corrosion – ASTM D130 / ISO 2160

We immerse a polished copper strip in the grease sample at 100°C for 24 hours. We compare the strip to the ASTM copper corrosion standard and assign a rating (1a = no tarnish to 4c = severe corrosion). For electrical greases and power transmission greases, the rating should be ≤ 1b (slight tarnish). A rating of 2c or higher indicates corrosive sulfur or acidic compounds that can attack electrical contacts and bearings.

7. Water Washout Resistance – ASTM D1264 / ISO 11009

We pack a bearing with 100 g of grease, run the bearing at 600 rpm at 79°C (or specified temperature), and spray water (5 mL/s) for 1 hour. We measure the weight of grease washed out (%). For power greases, washout loss should be < 10% for lithium complex and < 5% for calcium sulfonate. High washout (> 30%) results in grease loss, leading to bearing seizure.

8. Electrical Conductivity (for Conductive and Anti‑Static Greases) – ASTM D257 / DIN 53482

For conductive greases (used in electrical contacts, switchgear, and grounding connections), we measure the volume resistivity (Ω·cm) using a guarded electrode system at 100 V DC. For conductive greases with graphite or metal particles, conductivity should be < 10² Ω·cm (for high‑conductivity applications) or < 10⁵ Ω·cm (for anti‑static applications). For non‑conductive greases, resistivity should be > 10¹² Ω·cm (insulating).

9. Low‑Temperature Torque – ASTM D1478 / ISO 2137

We pack a bearing with grease and run it at -40°C (or -20°C) for 30 minutes, then measure the starting torque (N·cm) and running torque (N·cm). For power greases used in cold climates, the starting torque should be < 1000 N·cm at -20°C. High torque (> 2000 N·cm) indicates poor low‑temperature pumpability.

10. Evaporation Loss – ASTM D972 / ISO 2176

We heat a 10 g sample in a shallow pan at 100°C (or 150°C) for 22 hours. We measure the weight loss (%). For high‑temperature power greases, evaporation loss should be < 1% at 100°C and < 5% at 150°C. High evaporation (> 3% at 100°C) results in grease hardening and loss of lubricating film.

11. Roll Stability (Mechanical Stability) – ASTM D1831 / ISO 2176

We place 100 g of grease in a roller test apparatus with a 2 kg roller, run it for 2 hours at 165°C, and measure the change in worked penetration. A penetration increase of > 20 points indicates poor mechanical stability, leading to grease softening under high shear.

Quality Grading and Acceptance Criteria

Based on our power composite grease testing, we classify greases into three grades (clients provide specific acceptance criteria for their application):

• Grade A (Premium – High‑Load, High‑Temperature, Electrical Contacts) – Dropping point ≥ 260°C, worked penetration 265‑295 (NLGI 2), oil separation < 3% at 100°C, oxidation pressure drop < 20 kPa, weld point ≥ 300 kg, copper strip ≤ 1b, washout < 5%, conductivity as required, low‑temperature torque < 500 N·cm at -20°C.
• Grade B (Standard – General Industrial Bearings and Gears) – Dropping point ≥ 200°C, worked penetration 265‑295, oil separation < 5%, oxidation pressure drop < 34 kPa, weld point ≥ 250 kg, copper strip ≤ 2a, washout < 10%, conductivity as required, low‑temperature torque < 1000 N·cm.
• Grade C (Reject – Not Suitable) – Dropping point < 180°C, oil separation > 10%, oxidation pressure drop > 50 kPa, weld point < 200 kg, copper strip > 2b, washout > 30% – immediate batch rejection.

Reporting and Deliverables

Our power composite grease testing report includes: sample identification (grease type, NLGI grade, manufacturer, batch number), dropping point (°C), worked penetration (0.1 mm) and NLGI grade, oil separation (%), oxidation stability (pressure drop), four‑ball weld point (kg) and wear scar diameter (mm), copper strip corrosion rating, water washout (%), electrical conductivity (Ω·cm), low‑temperature torque (N·cm), evaporation loss (%), roll stability (penetration change), and a clear pass/fail conclusion based on client‑supplied criteria. Raw data (penetration curves, torque profiles, wear scar images) are archived for 10 years.

In summary, a comprehensive power composite grease testing service from zhongxi testing ensures that your lubricants provide reliable protection, reduce wear, prevent corrosion, and maintain electrical integrity in Bahrain’s power generation, industrial, and electrical infrastructure sectors. Contact our laboratory to schedule batch testing for your next grease procurement or to verify in‑service grease condition.

Applications in the Bahraini Industry

• Power generation (gas turbines, steam turbines, generators, transformers)
• Electrical utilities and switchgear (circuit breakers, disconnect switches, contactors)
• Wind turbines and renewable energy systems (main bearings, pitch bearings, yaw bearings)
• Heavy machinery and mining equipment (crushers, conveyors, shovels)
• Automotive and transportation (wheel bearings, universal joints, CV joints, chassis lubrication)