Industry · Site
How to Choose Grease for a Cement Kiln, Girth Gear and Ball Mill
A cement line is three lubrication duties. Slow open gears want a residual film, hot kiln rollers want an honest temperature limit, and dusty mill bearings fail from clinker before they fail from viscosity.
Direct answer
A cement line is three lubrication problems: slow, heavily loaded open gears that want a residual compound; hot kiln support rollers that need a high-temperature grease whose operating limit, not its dropping point, is honest; and dusty ball-mill bearings that fail from contamination more than from viscosity. One lithium EP2 drum does not cover all three.
- Walk the kiln, the mill and the open gear as separate duties before you name a thickener.
- Girth gears are judged by residual film, solids and how the lubricant is applied, not by an NLGI 2 habit.
- ASTM D2265 dropping point is not the continuous temperature of a kiln roller bearing.
- Clinker dust, seal condition and relube interval usually beat a change of soap.
- A custom cement SKU is a bill of materials plus named methods, not a new label on the same EP2.
Map of lubrication points on a typical kiln line
Treat the plant as a map, not a grease cupboard. A typical pyro line has a girth gear and pinion on the kiln and often another on the ball mill, support rollers and tyres that see radiant heat, trunnion or roller bearings that see dust, and a long tail of fans, conveyors, bucket elevators and cooler drives that are ordinary industrial bearings. Those last points can live on a straightforward NLGI 2 lithium or lithium-complex grease. The first three cannot share that drum just because the storekeeper wants one code.
Write the duty before the chemistry. For each point record speed, load type, ambient and metal temperature if you can measure it, whether water or slurry is present, how dust gets in, and how the lubricant is applied: spray, paddle, bath, drip or grease gun. ISO 6743-9 and ISO 12924 give a grease a letter code. They do not choose the point. The mill OEM lubrication chart is the start, then you correct it for the water, dust and relube interval you actually have.
- Open girth gear: slow, sliding, heavily loaded, open to dust, film must stay visible on the flank.
- Kiln support roller: heat is the argument; dropping point is only a lab screen.
- Ball-mill bearing: contamination and shock, with relube that has to reach the race.
- Auxiliary drives: keep them on a normal industrial grease so the speciality SKUs stay special.
Open-gear compound vs spray vs grease
An open gear does not want the same product as a rolling bearing. The tooth sees low speed and high load, so the film is boundary and mixed, not a high-speed elastohydrodynamic oil film. Residual compounds — heavy base oil, often with a diluent so a spray system can atomise it, plus graphite or molybdenum disulfide — are built to leave a visible coating after the solvent flashes. A stiff NLGI 2 grease can sit on the tooth root, miss the flank, and still look “applied” from the walkway.
Sprayable products are a system, not a thicker grease in a drum. Nozzle size, air pressure, interval and sump cleanliness decide whether the film is continuous. A tackifier that helps a paddle-applied compound can block a nozzle. If the plant already sprays, formulate for spray and then check four-ball load and wear on the grease methods: ASTM D2596 for weld load and ASTM D2266 for wear scar. Timken, ASTM D2509, is a screen some buyers still ask for; it is not a girth-gear life test. Say so on the data sheet.
Manufacturing detail for this family sits on the open-gear grease formulation page. This note only decides when that page is the right brief, and when a bearing grease would be the wrong one.
Kiln roller: LiX vs CaSX vs graphite compound
Support-roller and tyre lubrication is a temperature argument that plants keep losing to the dropping point. ASTM D2265 tells you the temperature at which a grease becomes fluid in a small cup under a standard load. It does not tell you the temperature at which the oil in that grease still lubricates a roller for a campaign. A lithium-complex grease with a dropping point in the mid-250 °C class can still oxidise, bleed and harden well below that number. Calcium sulfonate complex often shows a very high or unobtainable drop point and carries inherent extreme-pressure response from its calcite structure, which is attractive next to heat and occasional water. It is also thicker to pump. Graphite compounds and blocks are a different product again: they are for sliding contact on tyres and girth gears where a soap grease would glaze or run off, not a default fill for every roller bearing.
Ask for the continuous limit in bearing-life language. DIN 51821 (FE9) and ASTM D3336 are closer to a hot bearing than D2265. Oil separation, ASTM D6184, tells you whether the grease will dump its oil into a hot housing and leave a dry soap. Oxidation, ASTM D942, is a storage and heat-aging screen, not a kiln campaign. If the buyer wants a high-temperature roller grease rather than an open-gear compound, the bench path is the high-temperature grease formulation page, with the operating temperature written as a measured metal temperature, not as the drop point copied onto the TDS.
Contamination control beats a ‘better’ thickener
Ball-mill trunnions, pinion bearings and many kiln auxiliaries fail because clinker and cement dust get in, not because the thickener family was unfashionable. Abrasive dust turns a correct NLGI grade into a lapping compound. Water washout, ASTM D1264, and water spray-off, ASTM D4049, matter where the mill is wet or the seals are washed. They do not describe a dry, dusty housing. Rust methods — ASTM D1743 or ASTM D6138 — belong on the sheet if the plant is coastal or the mill is down for long monsoon stops. They are screens, not a guarantee against a failed seal.
Relube interval and the path the grease takes are part of the spec. A perfect calcium sulfonate complex does nothing if the nipple is painted over or the centralised injector is starved. Worked penetration, ASTM D217, confirms you are still in the NLGI grade after milling; roll stability, ASTM D1831, is the screen for a grease that softens once it is worked in a dusty, vibrating housing. If penetration drifts, fix the process before you blame the duty.
What to change first
- Stop dust at the seal and the housing, and photograph the failed race before you argue about soap.
- Set the relube volume so fresh grease actually displaces dirty grease, without bursting the seal.
- Only then decide whether lithium complex, calcium sulfonate or an open-gear compound is the chemistry for that point.
What a custom cement SKU looks like on the BOM
A cement SKU worth commissioning is a short set, not a universal drum. Typical split: one open-gear compound or sprayable residual for girth gears, one high-temperature grease for rollers whose metal temperature justifies it, and one contamination-tolerant bearing grease for the mill and the auxiliaries that truly see dust and shock. Each line on the bill of materials names a function. Thickener family. Base-oil viscosity measured by ASTM D445 and stated as an ISO VG, because film thickness on a slow gear is mostly the oil, not the NLGI grade. Solids only where the contact slides. A tackifier only where adhesion is the application method. An extreme-pressure addition only if the thickener does not already carry that response, proved by D2596 or D2266 rather than by the word “EP” in the product name.
Lubechem is an independent formulation practice in New Delhi, not a grease store and not the plant’s lubricant vendor of record. The engagement, if you want one, is the grease formulation service: a duty brief, a candidate, a kettle SOP and a test file under the contract. No cement client is claimed on this page. No saving is claimed. The TDS may list only methods you ran, on the oil you will actually buy.
What Lubechem will and will not claim
This article will not tell you that a named cement group runs a Lubechem formula, and it will not quote a kilowatt-hour or campaign-life saving. Those numbers do not exist in our file as public evidence. Illustrations on the page are conceptual. They are not photographs of a client kiln.
What we will say is narrower. Dropping point is ASTM D2265, not a service temperature. Open gears and roller bearings are different lubricants. Compatibility between the old grease and the new one is a screen, not a licence to top up, and the method for that question is discussed in the compatibility note rather than assumed here. Patents and supplier brochures are prior art, not a TDS. If the next step is a kettle, send temperatures, application method, the current data sheet and a photograph of the flank or the race. Legal clearance of a filing is outside formulation scope.
Three cement duties — do not cover them with one drum
| Point | What the lubricant must do | Method that belongs on the file | Poor substitute |
|---|---|---|---|
| Girth gear and pinion | Stay on a slow, loaded, dusty flank | D2596 / D2266 load and wear; visual film after spray or paddle | A stiff NLGI 2 bearing grease that never wets the tooth |
| Kiln support roller | Survive heat without pretending the drop point is the limit | D2265 as a screen; DIN 51821 FE9 or ASTM D3336 nearer the duty; D6184 bleed | Copying the dropping point onto the operating-temperature line |
| Ball-mill bearing | Tolerate dust, shock and the real relube path | D217 grade, D1831 roll stability, D1264 only if water is real | A thicker soap while the seal still ingests clinker |
| Auxiliary fans and conveyors | Ordinary industrial life | D217 plus the OEM chart | The open-gear compound, because it was already on the indent |
People-first note: this is dated editorial for choosing a cement-line grease. It is not a client case study, not a certificate, and not a kettle SOP. Manufacturing steps stay on the formula pages linked here.
Questions plants actually ask
Can one lithium EP2 grease run the kiln gear, the support rollers and the ball mill?
No. The gear wants a residual film that stays on a slow tooth, the roller wants a high-temperature product whose limit is not the dropping point, and the mill bearing is usually a contamination problem. Split the SKUs.
If the dropping point is 260 °C, can we write 260 °C as the service temperature?
No. ASTM D2265 is a laboratory fluidity point. Continuous duty is argued with oxidation, oil separation and bearing-life methods such as DIN 51821 FE9 or ASTM D3336, plus the metal temperature you measured.
Are graphite and molybdenum disulfide automatic upgrades for every cement bearing?
No. Solids help sliding open gears and some fretting contacts. In a rolling bearing they are an abrasive risk unless the duty truly needs them. Do not add them because the gear compound already contains them.
Who owns the formula if we commission a cement SKU set?
Ownership is the assignment clause in the contract, including what is excluded as background know-how or third-party chemistry. Ask for that language before the first kettle. This article is not the contract.
Literature and prior art
Citations below are orientation, not a freedom-to-operate opinion. Lubechem does not copy claimed compositions and does not treat a patent as a product endorsement.
- ASTM D217, D2265, D2266, D2596, D1264, D4049, D6184, D1831 — Grade, drop point, wear, EP weld, washout, spray-off, oil separation and roll stability — screens, not a kiln campaign.
- DIN 51821 FE9 and ASTM D3336 — Bearing-life methods closer to a hot roller than dropping point.
- ISO 6743-9 and ISO 12924 — Grease classification and specification language. Letter codes do not replace a duty brief.
- Mill OEM lubrication chart — Start point for each nipple and spray bar. Correct it for the dust, water and interval on site.