Orbexa Precision Bearings

Product families · nine lines · bore 5–140 mm

The grade is a name. The runout is a number.

Nine families sorted by the direction the load takes through the rings: 70xx, 72xx, 718xx and 719xx angular contact, cylindrical and tapered roller, screw support, thrust, thin-section, spindle units, cages and balls.

Kia 2.5 µm @ 30–50 mm bore, P2 ISO 492 radial runout limit, inner ring · quoted per bore band and class

01 · Index

Nine families, sorted by load path

Standard tables run 5–140 mm bore; tolerance tables extend to 315–400 mm bore classes. Each card carries the axis that separates it from the next.

  • A single angular contact ball bearing on a pale seamless sweep, ground rings, a dark phenolic band and the ball set visible in the bore
    01

    Angular contact ball bearings

    Series 70xx, 72xx, 718xx ultra-thin and 719xx. Contact angle 15°–40°: smaller runs faster, larger carries more axial load.

  • A cylindrical roller bearing photographed square on a pale sweep, ground inner and outer rings with a brass cage holding the rollers
    02

    Cylindrical roller bearings

    Single-row N for high-speed machining spindles, double-row NN and NNU for lathe rigidity. Tapered bore clearance CC9, CC0 or CC1.

  • A tapered roller bearing on a pale sweep: a chrome cone, tapered rollers held in a brass cage, and the matching outer cup behind
    03

    Tapered roller bearings

    Radial and axial load together, preload set on the nut. TDO double-cup and TDI double-cone, metric and inch.

  • A flanged screw support unit on a pale sweep: a black flange housing, a ground chrome cylindrical body and its bolt circle
    04

    Screw support bearings

    60° contact angle, with standard preloads for 2-, 3- and 4-row matched sets, flanged or unflanged.

  • A thrust pad assembly on a pale sweep: brass pad segments set into a dark grey carrier ring and held by fastening screws
    05

    Thrust bearings

    Axial load only: not specified for radial load or high-speed rotation. Tolerance classes follow ISO 199.

  • A thin-section bearing ring on a pale sweep: a ground chrome ring with brass cage pockets, a dark phenolic band and a mirror-finished raceway
    06

    Thin-section and crossed roller

    Thin-section rings from 10 to 45 mm bore for robot joints, gimbals and rotary stages; crossed roller runout holds to 0.005 mm, in P5 to P2.

  • A motorised spindle unit on a pale sweep: a polished chrome-steel cylindrical body with a bolted front flange and a tapered nose
    07

    Spindle units

    Ground to P2 for motorised spindles: grease limiting speed 110,000 rpm at 5 mm bore, temperature rise under 50 °C.

  • A glass-filled polyamide cage ring on a pale sweep: a cream cage with oval pockets and black polished balls seated in them
    08

    Cages and rolling elements

    Brass MR, PEEK TP/T6/T9, phenolic T/T1 and polyamide T2/TYA cages, chosen by speed, temperature and application.

  • A graded row of mirror-polished steel balls on a pale sweep, the largest in front and many smaller ones ranked behind
    09

    Precision balls

    Silicon nitride balls are about 58% lighter than steel; dental handpiece units run 1.0 mm balls at 400,000 rpm.

02 · Flagship line

Angular contact spindle bearings, bore by bore

Ratings differ by contact angle, cage design and whether a bearing or a single row is quoted, so every row below is one bearing as published. A cell we cannot source is marked on request.

Bore d in mm · Cr and C0 in kN · rpm grease then oil · Kia in µm at the class named in the same row
Series d Cr C0 rpm Kia Class
725C · miniature 5 2.15 0.66 110,000 / 167,000 on request on request
70xx · 10 mm 10 2.4 1.0 63,000 / 95,000 2.5 P4
3MMV9105 (row) 25 7.99 4.03 36,600 / 73,200 3 P4
7005B 25 11.3 7.4 36,600 / 73,200 3 P4
7009 45 24 19.4 17,500 / 27,000 4 P4
BNH017TU 85 35.5 40.0 11,000 / 16,000 5 P4
H71922–H71928 110–140 41–59 38–67 7,000–11,000 / 11,000–18,000 on request on request
Double row · paired 50 93.6 85 on request 4 P4

Every row is one bearing as published: ratings differ by contact angle, cage design and whether a bearing or a single row is quoted. Outside diameter, width, angle and cage are quoted per drawing.

03 · Magnitude

What four micrometres looks like next to thirteen

ISO 492 sets a radial runout limit for the bore band and the class. Drawn to scale, the P6 limit at 80–120 mm bore is 13 µm against 2.5 µm at P2, so the class letter carries a factor of five.

ISO 492 Kia limits in micrometres, by bore band and class Bar chart of ISO 492 Kia limits in micrometres for bore bands 10 to 120 mm: four bars per band for classes P6, P5, P4 and P2, with the market best under 1 µm marked. 10 5 0 µm 7 4 2.5 1.5 8 4 3 2.5 10 5 4 2.5 10 5 4 2.5 13 6 5 2.5 cobalt line: market best, under 1 µm 10–18 18–30 30–50 50–80 80–120 Bore d, mm

Fig. 01 Bars left to right in each band: P6, P5, P4, P2. The cobalt line is the best non-synchronous runout published for a precision bearing, under 1 µm.

04 · Accuracy

What the class letters hold, by bore and outside diameter

Radial runout of the assembled bearing, inner ring (Kia) and outer ring (Kea), in micrometres. The two tables are read against different dimensions, so they are not interchangeable.

Kia · inner ring radial runout, max µm
Bore d, mm P6 P5 P4 P2
10–18742.51.5
18–308432.5
30–5010542.5
50–8010542.5
80–12013652.5
Kea · outer ring radial runout, max µm
OD D, mm P6 P5 P4 P2
18–309642.5
30–5010652.5
50–8013854
80–120181065

P6 runs to 30 µm at 315–400 mm bore, which is where a single class letter stops telling you much. Bore deviation Δdmp is always negative: at P4 it is 0/−6 µm for 30–50 mm bore. Thrust bearings are covered by ISO 199, not ISO 492.

05 · Scope of the grade

The five things a grade letter does not fix

An ISO or ABEC class controls dimensional tolerance and runout. Load capacity, steel and ball grade, raceway finish, clearance, cage, lubrication, noise and vibration are separate.

Choice axes: contact angle, internal clearance, preload, vibration grade and cage material
Axis Options How the choice is made
Contact angle 15° · 18° · 20° · 25° · 30° · 40° Smaller angle for speed, larger for axial rigidity.
Internal clearance C2 < CN (C0) < C3 < C4 < C5 CN carries no suffix in the part number, C2 to C5 do. Under a light load the reading inflates 4–6 µm at 18–50 mm bore.
Preload GL · GN · GM · GH Extra light, light, average, strong; special preloads on request.
Vibration grade V3 · V4, in µm/s V4 is the tighter grade. A high noise grade Z does not imply a high V.
Cage material MR · T / T1 · TP / T6 / T9 · T2 / TYA Brass, phenolic, PEEK or polyamide, by speed and temperature.

06 · Two families apart

Screw support and spindle units

A machining-centre spindle unit standing on the workshop floor: teal painted cast housing, chrome spindle nose held in its fixture, clamp plates and a cable bundle trailing to the right

Screw support bearings carry the axial load of a ball screw and take preload from a nut, so they are ordered as a matched set: 60° contact angle, standard preloads for 2-, 3- and 4-row sets, open or with contact lip seals.

Spindle units move the other way: bearings ground to P2, temperature rise target under 50 °C, and 110,000 rpm on grease at 5 mm bore.

How the runout on those sets is measured

Fig. 02 A machining-centre spindle unit before assembly: housing, nose and clamp hardware.

07 · Before the order

Four questions that decide the part number

Four standard levels: GL extra light, GN light, GM average and GH strong. Special preloads are quoted on request.

C2 to C5 per ISO 5753-1:2009. CN, also written C0, carries no suffix in the part number, and C2 to C5 do. Under a light measuring load the reading inflates: correct by 4 to 6 µm at 18–50 mm bore.

15, 18, 20, 25, 30 or 40 degrees. The smaller angle runs faster and the larger carries more axial load.

Silicon nitride balls are about 58% lighter than steel, raise the limiting speed by up to 20% and double grease life. Those are the published figures for Si₃N₄ balls, not measurements taken on our line, and the dimensions are interchangeable with the all-steel version.

A macro plate of a precision bearing ring: brushed steel grain and machined grooves under a soft cobalt wash, darker on the left where the type sits

08 · Request slip

Take the specification sheet for your series

Give us the bore, the contact angle and the grade. The sheet comes back with the runout actually measured on the lot we would ship you.

A written answer within two working days, quoting the runout figure actually measured for that lot.

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