NSK7004CTYDUMPA7Super-Precision Angular Contact Ball Bearing Duplex Pair — 20 mm ID, 42 mm OD, 12 mm Width, Open, 15°, Medium Preload, Polyamide Cage

Product Description

What this part is

A matched duplex pair of NSK 7004CTYDUMPA7 super-precision angular contact ball bearings. Each bearing has a 20 mm bore, 42 mm outside diameter and 12 mm width, is open on both faces and runs a straight bore. The pair is universally ground with medium preload built in.

Decoding the designation

7004 identifies an angular contact ball bearing in the ISO 70 light series with a 20 mm bore. In the NSK scheme C sets a 15° contact angle. TY denotes a ball-guided polyamide cage. DU marks the bearings as a universally ground duplex set and the following M sets medium preload.

What these specs mean in practice

A 15° contact angle favours speed and radial stiffness over thrust capacity, which is why this configuration is standard in high-speed spindles and small precision drives. Medium preload gives more axial and radial rigidity than a light-preload set, with correspondingly higher friction and heat generation, so it suits applications where positional stiffness matters more than the last increment of speed. The polyamide cage is light and quiet with a service ceiling around 120 °C.

Load and speed data

Dynamic and static load ratings and the limiting speed are published in the specification table on this page.

Quantity and configuration

Two bearings, supplied as a matched universal duplex set. Each is single row and open, with no snap ring, seals or shields.

Fitting notes

Universal grinding allows assembly back-to-back, face-to-face or in tandem. Back-to-back or face-to-face mounting locates the shaft axially in both directions and develops the built-in medium preload as the rings are clamped; tandem mounting shares thrust in one direction only. A single row on its own takes thrust in one direction. The set is matched and stays together as supplied. Polyamide cages are handled clear of solvents and temperatures above their ceiling.

Interchange guidance

A substitution needs the same 15° angle and the same medium preload. A 7004 with a 25° or 30° angle, or with a light or heavy preload letter, shares the 20 x 42 x 12 mm envelope but is a related size rather than an equivalent. Same-spec designations from other manufacturers are listed in the cross-reference table.