Neometrix / Precision Bearings & Rotating Components / Precision Bearings & Slewing Rings / NMX-PSR-24

NMX-PSR-24 · ENGINEERED-TO-ORDER CLASS — FORGED · HARDENED · GROUND · GEARED

Hardening moves the raceway. Grinding brings it back true.

Name: Precision Bearings & Slewing Rings
Brand: Neometrix
SKU: NMX-PSR-24

A slewing ring is not just a large bearing. It carries axial, radial and tilting load together, and it is often the gear that turns the whole assembly — a pinion drives teeth cut into the same ring that carries the load.

It starts as a forged blank, not a casting. Its raceway is hardened for wear life, which throws it slightly out of round, and it is ground again afterward — because a ring that is merely hard is not yet a bearing.

Discuss a bearing or ring Capability note (PDF)

A precision machine shop with three forged steel bearing rings of different diameters standing on a floor rack, one with gear teeth cut into its outer edge, and a large ring grinding machine behind them holding a similar ring flat on its rotary table with the grinding wheel poised above it; a small trolley with coiled cable and a tray of steel balls stands to one side, and there are no people

Fig · 01 — A precision bearing ring line: forged blanks, a ring on the grinding spindle, and finished rings ready for inspection — illustrative render.

The blank

a forged ringnot cast, not cut from plate

The load

axial, radial, tiltingcarried together

The raceway

hardened, then groundtrue again after distortion

The drive

often geareda pinion turns the ring

Status

engineered to orderno delivered unit claimed

ISO 9001ISO 14001ISO 76 load ratingsNABL-accredited testingReverse engineering from a sample

Overview

Why a slewing ring is not just a big bearing, and why the grinding comes twice.

Because it does two jobs in one component, and one of its own manufacturing steps works against the other.

Fig · 02 — What one ring carries: load from three directions at once, and often the gear teeth that turn it, all in a single forged component.

A ring that is merely hard is not yet round. Grinding is what makes it a bearing.

What the ring is actually for

A slewing ring lets one part of a machine turn on another — a crane's upper works on its chassis, a turret on its hull, a pedestal on its base — while carrying the load of everything above it.

Ordinary bearings mostly take load from one direction. A slewing ring takes axial, radial and tilting load at once, because the load above it is rarely centred and never purely vertical.

Why it is often a gear as well

Many slewing rings carry gear teeth cut into the same ring, on the inside or the outside. A pinion, driven by a motor, meshes with those teeth to turn the whole assembly.

That means the same component carries the structural load and transmits the turning force — if the teeth and the raceway are not true to each other, the drive binds under load.

Why the blank is forged, not cast

A forged, rolled ring keeps its grain flowing around the circle. A ring cast, or cut from flat plate, does not — its grain runs across the section, which is weaker against the fatigue a rolling raceway sees over millions of cycles.

So the ring starts life as a seamless forging, close to its final shape, before any raceway is cut into it.

Why hardening and grinding both happen, in that order

The raceway is hardened locally, to resist wear, without hardening the whole ring through — a hard skin on a tough core. But the heat of hardening moves the steel.

So the raceway is ground again after hardening, back to the roundness and size the rolling elements actually need. Skipping this step is the single most common way a bearing fails early.

Two routes to the same ring

Some rings are made to the customer's own drawing. Others exist only as a worn part with no drawing behind them — in which case the ring is measured, its material verified, and redrawn before it is remade.

The cycle

Forge, machine, harden, temper, grind true, then prove it.

A ring runs from a stored process plan, not from habit, which is what makes one ring repeatable against the next.

FIG · 02PRECISION BEARING & SLEWING RING · FORGE / MACHINE / HARDEN / TEMPER / GRIND / GEAR & CERTIFY — THE DISTORTION AND THE CORRECTION

The step people underrate is the second grinding. Hardening buys wear life and spends roundness; grinding buys the roundness back.

Fig · 03 — A plain bearing takes load from one direction. A slewing ring takes axial, radial and tilting load together — a drawing of the idea, with no values.

1 · Forge

A seamless rolled ring blank, close to the final shape, with its grain running around the circumference.

2 · Machine

The raceway contours, seal grooves, bolt holes and pilots are turned to size, ready for heat treatment.

3 · Harden & temper

The raceway surface is hardened to a controlled depth, then tempered at once to relieve the quench stress before it can crack the surface.

4 · Grind true

The raceway is ground back to its final roundness, size and finish — correcting what the hardening moved.

5 · Gear & drill

Gear teeth are cut, if the ring is geared, and the bolt holes are finished, all kept true to the ground raceway.

6 · Assemble & certify

Rolling elements, cage and seals go in, then material, hardness and dimensional records are issued with a stated load rating.

Work content

What a ring contains, element by element.

Read it as a checklist: a ring missing a row will fail early, in a way that looks like a design fault but is really a process one.

A single large steel bearing ring with gear teeth around its outer edge resting on a granite inspection table, with a coordinate measuring machine probe arm reaching down and touching the ring's inner raceway surface in a clean metrology room

Fig · 04 — A finished ring under dimensional inspection: the raceway, the gear teeth and the bolt circle, all measured against the record — illustrative render.

Element	What it does	What matters
Forged ring blank	starts the ring close to its final shape	grain flowing around the circumference, not across it
Raceway geometry	the surface the rolling elements run on	profile, roundness and finish, cut before hardening
Induction hardening	hardens the raceway surface	controlled depth; a tough core stays behind it
Tempering	relieves the quench stress	applied at once, before the stress can crack the surface
Finish grinding	restores the raceway after hardening	corrects the distortion; sets the final roundness and size
Gear teeth (option)	lets a pinion turn the ring	cut true to the ground raceway, internal or external
Bolt holes	fix the ring to the structure on each side	positioned and finished after the raceway is true
Rolling elements	balls or rollers that carry the load	matched in size and hardness, sorted into sets
Cage & spacers	keep the rolling elements apart	even spacing under load and during rotation
Seals	keep lubricant in and contamination out	chosen for the environment and the rotation speed
Corrosion protection	protects the finished ring in service	coating or plating suited to the application
Material certification	proves what the ring is made of	traceable to the cast or forging batch
Non-destructive testing	checks the forging for internal flaws	before the expensive machining goes in
Dimensional & hardness inspection	proves the ring meets its drawing	raceway, gear and bolt circle all checked
Reverse-engineering route	rebuilds the drawing from a sample	used only where no drawing exists
Load rating & documentation	states what the ring is good for	expressed to ISO 76, with full traceability

The row that decides whether a ring survives is never the forging. It is the grinding that follows hardening. A hard raceway that is not true again is a bearing that will fail early, and look like a material problem when it was a process one.

Fig · 05 — The route when no drawing survives: measure the worn ring, verify its material, redraw it, then qualify a first article before a batch is made.

Full specification — expand

System	Precision bearing or slewing ring: forged ring blank, machined raceways and seal grooves, induction-hardened raceway, tempering, finish grinding to final roundness and size, optional internal or external gear teeth, bolt holes, rolling elements with cage and seals, corrosion protection, material certification, non-destructive and dimensional inspection, and a stated load rating
The One Idea	Hardening does not finish the raceway. It moves it. Grinding after hardening is what makes the ring round again, and it is the step a rushed process is most tempted to shortcut
Why A Slewing Ring	It carries axial, radial and tilting (moment) load together, in one component, where an off-centre or cantilevered load makes a plain, single-direction bearing the wrong choice. Many slewing rings also carry gear teeth, so the same ring both supports the load and is driven by a pinion to turn it
Why Forged	A seamless rolled ring blank keeps its grain flowing around the circumference. A ring cast, or cut from flat plate and rolled or welded into a circle, does not, and is measurably weaker against the fatigue a rolling raceway experiences over its working life
Hardening & Grinding	The raceway is induction-hardened to a controlled depth - hard surface, tough core - then tempered at once to relieve quench stress. Hardening distorts the ring slightly, so the raceway is ground again afterward, to the roundness, size and surface finish the rolling elements actually need
The Gear	Where the ring is geared, teeth are cut on the inner or outer circumference, kept true to the finished raceway, so a pinion can drive rotation without binding under load
Two Routes To The Ring	To the customer's own drawing, where one exists; or reverse-engineered from a sample where it does not - the worn ring is measured, its material and hardness verified, and a drawing reconstructed before the replacement is made
Standards	ISO 76, the public standard for static load ratings of rolling bearings, is the reference for how a ring's load capacity is expressed. NABL-accredited laboratories verify material and dimensions. Neometrix claims no certification of a customer's own design
Configurations	Plain bearing ring, without gear teeth; geared slewing ring, with a pinion drive; and a reverse-engineering case for a ring already in service, with no surviving drawing - one manufacturing route across all three
Scope Boundary	This page is the ring itself - forging, hardening, grinding, gear machining. Hydraulic and electro-mechanical legacy-component work is the T-72 actuating cylinder indigenisation page's ground. Proving a bearing already in hand is the bearing test bench and the 70,000 rpm aerospace bearing test bench - this page makes the ring, they prove it
Status	Neometrix engineers precision bearings and slewing rings to order, from a forged blank through raceway hardening, grinding and gear machining to final inspection, and no delivered precision bearing or slewing ring is claimed.

Configurations

One manufacturing route, three ways to use it.

The forging, hardening and grinding sequence is shared. What changes is the gear and where the drawing comes from.

Plain ring

Bearing ring, no gear

A forged, hardened and ground ring that carries the load and lets the assembly turn, with no gear teeth of its own.

Geared ring

Slewing ring with pinion drive

The same ring, with gear teeth cut true to the raceway, so a motor and pinion can turn the assembly under power.

Reverse-engineered

Replacement for a ring already in service

Where the original drawing no longer exists, the worn ring is measured and verified, and the replacement is made to a rebuilt drawing.

Fig · 06 — Three ways to reach the same ring: to a live drawing, as a geared ring with a pinion drive, or reverse-engineered from a worn sample.

And the part that is not steel at all, yet decides all three: the process plan and the inspection record — the same forge-harden-grind sequence, and a paper trail a customer's inspector can follow line by line.

Where it is used

Wherever one part of a machine turns on another, under load.

The common thread is a heavy, off-centre load that has to rotate, not just sit still.

Cranes & material handling

The ring that lets the upper works, jib or crane turn on its base while carrying the load and its own overturning moment.

Pedestals, mounts & turrets

The ring beneath a rotating mount or turret, carrying its weight and letting it traverse under drive.

Wind turbines & heavy industry

Yaw and pitch rings on a turbine nacelle, and slewing rings on excavators, mixers and other rotating industrial equipment.

Legacy fleets & obsolescence

A ring for a machine still in service whose original maker, or original drawing, is no longer reachable.

FAQ

Common questions.

Longer answers, for readers who want the reasoning.

Q · 01 What actually makes a slewing ring different from an ordinary bearing?

The direction the load comes from. An ordinary bearing is usually chosen for one dominant load direction: a shaft bearing takes mostly radial load, a thrust bearing takes mostly axial load. A slewing ring exists because the load above it does not cooperate that way. Picture a crane jib reaching out to one side, or a turret with its mass sitting above and slightly off-centre from the ring that carries it: the weight pushes down (axial), pushes sideways as the structure sways (radial), and, because it is not centred, tries to tip the ring over (a moment, or tilting, load). A slewing ring is designed to carry all three at once, usually through rows of balls or rollers arranged so that the geometry itself resists the tipping load, not just the straight-down one. That combined-load duty, more than its size, is what separates a slewing ring from an ordinary bearing, and it is also why a slewing ring's rated capacity is expressed as a combination of all three loads together, not as a single number.

Q · 02 Why does the same ring often carry gear teeth?

Because turning a heavy, slow-moving structure is easiest done right at the ring that already carries its load. Many slewing rings have gear teeth cut into the inner or outer circumference, and a pinion — driven by a hydraulic or electric motor through a gearbox — meshes with those teeth to rotate the assembly above the ring. Putting the drive there, rather than somewhere else in the structure, means the turning force is applied exactly where the load is already reacted, with no separate large gear to support and align. The cost of that convenience is precision: the gear teeth have to stay true to the raceway that the balls or rollers run on, because if the two are out of alignment, the pinion mesh varies as the ring turns and either binds under load or wears unevenly. That is one more reason the raceway grinding step, which sets the true geometry the rest of the ring is built around, comes before the gear teeth are finished.

Q · 03 Why start from a forging rather than a casting or a cut ring?

Because of how the metal's internal grain ends up running. A casting cools from a liquid, and its grain structure is essentially random, with a risk of internal porosity or inclusions from the pour. A ring cut from flat plate, or rolled and welded into a circle, has its grain running mostly in the original straight direction of the plate, which curves across the ring rather than following it. A forged, rolled ring is different: the ring-rolling process works the material so that its grain flows continuously around the circumference, following the shape the ring will actually see load in. For a component whose raceway is rolled over by balls or rollers millions of times in service, that difference matters, because fatigue cracks tend to start at grain boundaries and internal flaws, and a forging has fewer of the kind that a casting or a welded ring carries. So the ring blank for anything that will be hardened and used as a bearing race starts as a seamless forging, and the shape is refined from there, not built up from a flatter starting point.

Q · 04 Why does hardening the raceway also mean grinding it again?

Because the two steps do opposite things to the ring's shape, and both are necessary. The raceway needs to be hard, because balls or rollers rolling over a soft surface millions of times will wear a groove into it and the bearing will fail early. So the raceway is induction-hardened: heated locally and rapidly, then quenched, so a controlled depth of the surface becomes hard while the bulk of the ring stays tougher and more resistant to cracking. That local, rapid heating and cooling is exactly what makes the ring move: thermal expansion is never perfectly even, and the steel's structure changes as it hardens, so the ring that goes into the hardening process round does not always come out round. Immediate tempering relieves some of that stress, but it does not put the geometry back. The only way to do that is to grind the raceway again, after hardening, back to the roundness, size and surface finish the design calls for. A ring that is hard but not reground is not a finished bearing race; it is a hard ring of the wrong shape.

Q · 05 Can a ring be made without an original drawing?

Yes, and it is one of the two routes this page describes. Some machines stay in service for decades after the ring's original manufacturer has stopped supporting it, or after the drawing itself has simply been lost. In that case, the starting point is not paper but the worn ring itself. It is measured — raceway profile, ball or roller size and count, bolt circle, gear form if it is geared — and a sample of the material is checked to identify what it is and how it was hardened, so the replacement is not just the same shape but the same kind of steel treated the same way. From those measurements a drawing is reconstructed, and the first ring made against it is treated as a first article: checked especially closely before a batch is committed to. The result is a ring that fits and performs like the original, even though no drawing for the original ever reached the workshop that makes the replacement.

Q · 06 Has Neometrix built one of these?

We would rather answer this plainly than let a page imply otherwise. Neometrix engineers precision bearings and slewing rings to order, from a forged blank through raceway hardening, grinding and gear machining to final inspection, and no delivered precision bearing or slewing ring is claimed. What stands behind the offer is adjacent and real. Neometrix engineers precision test equipment for bearings — our bearing test bench and our 70,000 rpm aerospace bearing test bench prove rotating components under controlled load and speed — and we reverse-engineer and manufacture legacy mechanical assemblies to a customer's own drawing, as on our T-72 actuating cylinder indigenisation page. Precision machining, heat treatment and dimensional inspection are disciplines we already run daily. So the honest position is this: the class is engineered to order, the manufacturing disciplines are in the building, and the first ring of this exact type will be built around a customer's drawing or a customer's sample rather than lifted off a shelf. If that matters to how you buy, say so early and we will scope it that way, with the reference work open to inspection.

Q · 07 How is a ring's capacity stated, and who decides it is fit for use?

ISO 76 is the public standard for the static load ratings of rolling bearings, and it is the reference this page points to for how a ring's combined axial, radial and tilting capacity is expressed. It does not, by itself, tell a buyer what rating a specific application needs — that depends on the mass, the geometry and the duty of the machine the ring goes into, and it is worked out for each case rather than published on a page like this one. What Neometrix controls, and states plainly, is the manufacturing side of that promise: the forging is sound, the raceway is hardened to the depth and profile the design calls for, the ground geometry is verified, the material is certified, and the finished ring is inspected before it ships, ordinarily through a NABL-accredited laboratory for material and dimensional checks. Acceptance of the ring against the customer's own drawing, and any wider qualification of the assembly it goes into, rests with the customer and their inspection authority. Neometrix does not claim certification of a customer's design, only of the ring it delivers against it.

Q · 08 What do you need from us to quote?

Six things, and most of them are about the ring rather than about us. First, the drawing or the sample: a drawing set and technical conditions if you hold them, or the worn ring itself and access to measure it if you do not. Second, the size: the ring's diameter class and cross-section, which sets the forging and the machine tools needed. Third, the duty: whether it is a plain bearing ring or carries gear teeth, and whether that gear is driven continuously or only occasionally. Fourth, the load case: the axial, radial and tilting loads the ring sees, or a description of the machine and its duty if you do not have those figures to hand. Fifth, the environment: temperature, contamination and rotation speed, which drive the seal and lubrication choice. Sixth, the quantity and programme: a one-off replacement or an ongoing requirement, and the delivery you need it against. From that we come back with a system definition you can check, a manufacturing route, an inspection plan and a budgetary price. If you would rather start with a conversation, that works too — most of these projects begin with somebody describing a ring that has finally worn out.

The bench beside it, and the legacy work around it.

Three neighbours in the same precision-mechanical family.

↗ The proving side

Bearing Test Bench

Where a bearing is proven under controlled load and speed, rather than made — this page is the ring itself.

↗ The high-speed side

70,000 RPM Aerospace Bearing Test Bench

The same proving discipline at aerospace speeds, for bearings far smaller than a slewing ring.

↗ The other legacy work

T-72 Actuating Cylinder Indigenisation

Reverse engineering and manufacture of a legacy electro-hydraulic assembly, where this page is a rotating steel ring.

Browse all Neometrix product lines.

Get a quotation

Send us the drawing, or the ring
that has finally worn out.

The projects desk replies within two working days with a system definition you can check, a manufacturing route, an inspection plan, and a budgetary quotation. Write to [email protected] or use the form.

Enquire — bearing or slewing ring Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED-TO-ORDER CLASS — PRECISION BEARINGS & SLEWING RINGS FORGE · MACHINE · HARDEN · TEMPER · GRIND · GEAR & CERTIFY — GRINDING BRINGS IT BACK TRUE ENGINEERED IN NOIDA · INDIA

Hardening moves the raceway. Grinding brings it back true.

Why a slewing ring is not just a big bearing, and why the grinding comes twice.

What the ring is actually for

Why it is often a gear as well

Why the blank is forged, not cast

Why hardening and grinding both happen, in that order

Two routes to the same ring

Forge, machine, harden, temper, grind true, then prove it.

1 · Forge

2 · Machine

3 · Harden & temper

4 · Grind true

5 · Gear & drill

6 · Assemble & certify

What a ring contains, element by element.

One manufacturing route, three ways to use it.

Bearing ring, no gear

Slewing ring with pinion drive

Replacement for a ring already in service

Wherever one part of a machine turns on another, under load.

Cranes & material handling

Pedestals, mounts & turrets

Wind turbines & heavy industry

Legacy fleets & obsolescence

Common questions.

The bench beside it, and the legacy work around it.

Bearing Test Bench

70,000 RPM Aerospace Bearing Test Bench

T-72 Actuating Cylinder Indigenisation

Send us the drawing, or the ring
that has finally worn out.

Similar Products

Share This Page

Hardening moves the raceway. Grinding brings it back true.

Why a slewing ring is not just a big bearing, and why the grinding comes twice.

What the ring is actually for

Why it is often a gear as well

Why the blank is forged, not cast

Why hardening and grinding both happen, in that order

Two routes to the same ring

Forge, machine, harden, temper, grind true, then prove it.

1 · Forge

2 · Machine

3 · Harden & temper

4 · Grind true

5 · Gear & drill

6 · Assemble & certify

What a ring contains, element by element.

One manufacturing route, three ways to use it.

Bearing ring, no gear

Slewing ring with pinion drive

Replacement for a ring already in service

Wherever one part of a machine turns on another, under load.

Cranes & material handling

Pedestals, mounts & turrets

Wind turbines & heavy industry

Legacy fleets & obsolescence

Common questions.

The bench beside it, and the legacy work around it.

Bearing Test Bench

70,000 RPM Aerospace Bearing Test Bench

T-72 Actuating Cylinder Indigenisation

Send us the drawing, or the ringthat has finally worn out.

Similar Products

Share This Page

Send us the drawing, or the ring
that has finally worn out.