Category: Applications

Nothing kills grease like a continuous furnace environment. Roiler bearings inside continuous casting machines, reheat furnaces and galvanising lines see 150-250 °C at the bearing, splash from scale and cooling water, and shock loads every time a slab enters the roll gap. Standard lithium grease carbonises within weeks.

What heat actually does to grease

Grease fails in heat through two mechanisms. First, the base oil evaporates and oxidises – the grease dries into a hard crust that no longer lubricates. Second, the thickener itself melts at its dropping point, and the whole structure collapses into soup. At 200 °C bearing temperature, conventional lithium (dropping point ~190 °C) has zero margin; the oil fraction is boiling off long before the thickener fails.

Options that survive

Polyurea (dropping point 250 °C+): The default answer for continuous 150-200 °C. Exceptional oxidation stability means the oil does not acidify quickly, extending relubrication intervals even in heat. Our polyurea line is specified by steel mills across Southeast Asia for caster and furnace door bearings.

Lithium complex (dropping point 240-260 °C): Better shear stability than polyurea under heavy shock load, slightly lower oxidation resistance. Preferred where loads are extreme and speeds are low.

Calcium sulfonate complex (dropping point 300 °C+): The premium answer – also handles water and scale contamination better than anything else. Costlier per kilogram, but on a caster segment bearing that costs hours to reach, the extended interval pays for itself.

Application discipline matters as much as the product

• Shorten intervals drastically. Rule of thumb: relubrication interval halves for every 15 °C above 80 °C. At 200 °C you are relubricating weekly or daily, not annually.
• Provide bleed paths. Fresh grease must be able to push the old, oxidised grease out. Blocked relief ports turn relubrication into churning.
• Watch for carbon build-up around the bearing – it is both an insulator (trapping heat) and a sign your interval is too long.

A real setup from our export book

A Vietnamese reheat furnace client runs our polyurea NLGI 2 on their walking-beam bearings at 180-210 °C, relubricated every 40 hours through insulated lines. Bearing life went from 5 months (with a generic lithium complex) to 22 months. The grease change paid back in the first swap-out avoided.

Running 200 °C+ positions? Send us the bearing type, temperature profile and current relubrication schedule – we will spec the grade and calculate the interval with you, samples free.

Mining loads are not gentle. A primary crusher shaft bearing sees impact spikes several times rated load; excavator bucket pins hammer and twist under full stall torque; vibrating screens shake their own frames apart over years. Add abrasive dust and high-pressure washdown water, and you have the most hostile lubrication environment in industry.

What shock load does to a grease film

Under steady load, a grease’s base oil maintains a hydrodynamic film on the raceway. Under shock load, that film is squeezed out in milliseconds, and metal contacts metal briefly – a phenomenon called boundary lubrication. The grease must contain extreme-pressure (EP) additives that react chemically with the steel surface at that contact instant, forming a sacrificial layer that prevents welding and scoring.

The EP toolbox

Sulfur-phosphorus EP additives: The standard chemistry. Effective across a wide temperature window, works in most lithium EP grades. Our Black EP line carries a 4-ball weld load above 3,100 N (ASTM D2596).

Molybdenum disulfide (MoS2): A solid lubricant suspended in the grease – typically 3% in our moly grades. MoS2 plates onto the metal surface and shears easily, providing lubrication exactly when the oil film fails. Ideal for sliding contacts: bucket pins, bushings, fifth wheels. Note: avoid MoS2 in rolling bearings running wet – it can abrade with the water present.

Calcium sulfonate: Naturally high EP capacity without additives, plus the best water resistance in the industry. The premium answer for wet, shock-loaded positions.

Matching grade to position

Relubrication is the other half of survival

Mining maintenance teams under-lubricate far more often than they over-lubricate – the schedule exists but the shut-down windows do not. Automating what you can (single-point lubricators on remote crusher bearings) and making pin grease-ups part of the shift routine, not the weekly routine, moves bearing life dramatically.

We export to mining operations in 20+ countries and can share reference setups for your equipment type. Black EP and moly samples ship free for bench and field trials.

“Food-grade grease” is one of the most requested – and most misunderstood – product categories we export. This post clarifies what NSF H1 actually means, where it is legally required, and what documentation you should demand from any supplier.

What NSF H1 actually certifies

NSF (National Sanitation Foundation, USA) administers the registration program originally defined by the USDA. An H1 registration means: this lubricant is composed of substances acceptable for incidental food contact – components evaluated against FDA 21 CFR 178.3570 and related listings. It does not mean the lubricant is edible, and it does not mean any amount is acceptable. “Incidental contact” is defined as technically unavoidable traces – a leaking bearing over a conveyor, grease migration at a chain.

Where H1 is required

• Any lubricated position where leakage could drip, mist or migrate into food, packaging, or food-contact surfaces: conveyor bearings above product lines, chains and oven chains, gearbox output shafts near open product, filling machine slides.
• Export goods to the USA, EU, Canada, Australia, Japan: H1 (or local equivalent, e.g. ISO 21469 certification) is either legally required or demanded by retailer audit standards (BRCGS, SQF, FSSC 22000).

Where H2 is fine: positions with zero possibility of food contact – the compressor in a separate machine room, forklift chassis, the outside of sealed equipment. H2 greases are cheaper and perform better in extreme loads. Over-specifying H1 everywhere wastes money.

The paperwork that backs the claim

Any genuine H1 product has three things you can verify:

1. An NSF registration number – check it live at nsf.com (search “NSF White Book” – registrations are public and free to verify).
2. A COA per batch matching the registered formulation.
3. ISO 21469 certification (optional but stronger) – adds hygiene manufacturing requirements, not just formulation review.

Buying “food-grade” grease without a verifiable NSF number is buying a label. We have seen quote sheets where the “H1” line item has no registration behind it at all.

Our H1 line

LLF Grease manufactures NSF-registered H1 greases in both aluminium-complex and calcium-sulfonate chemistries, NLGI 1 and 2, suitable for bakery ovens (up to 200 °C), bottling lines (water washdown), and general food-plant bearings. Registration numbers are printed on the COA and available for your audit file before you order.

Auditing your lubrication positions and not sure which need H1 vs H2? Send us your line layout sketch – we will mark the positions and quote accordingly.