Deep Groove Ball Bearings vs Cylindrical Roller Bearings for Pure Radial Loads: Load, Speed and Misalignment

Which type the radial load magnitude points to

Start with the load, not the price. A ball bearing carries load through point contact, where the balls meet the raceway over small ellipses; a roller bearing carries it through line contact along the roller length^6,10.

That geometry is why a roller bearing generally carries a higher basic dynamic load rating than a ball bearing of the same bore and outer diameter. And why the selection rule of thumb is light-to-moderate loads to ball bearings and heavy loads to roller bearings^10,15.

For a pure radial load, a Cylindrical Roller Bearings is the type that geometry favours, and a Deep Groove Ball Bearings is the type that suits lighter radial duty. The same line contact that raises capacity also generates more friction and heat per revolution, so the load advantage is not free¹⁰.

Before you commit, ask each supplier for the Cr and C0r of their candidate at your bore, because the sources do not carry a CRB rating at a comparable bore to any DGBB reference.

Whether the required speed rules the roller bearing out

Line contact generates more friction and heat per revolution than point contact, so roller bearings generally carry a lower limiting speed and dN value than a comparably sized ball bearing^10,15.

If your speed target is high, that mechanism is what decides the type: the DGBB is the one that can reach it, and the CRB is the one you may have to rule out.

The 6304ZZ, a 20 mm-bore DGBB, shows how much the seal choice alone moves the ceiling: 14000 rpm in ZZ/2RS form, 10000 rpm with DU/DDU contact seals, and 17000 rpm open². Seal drag is the reason the sealed figures sit below the open one^1,2.

So a sealed DGBB can still meet a speed target that an open one would clear more easily, and the gap between the two is thousands of rpm at this bore².

No source in this set publishes a CRB limiting speed at the same bore, so you cannot read a like-for-like speed comparison off this page . Ask the supplier for the CRB limiting speed and dN at your bore and compare it against your required rpm¹⁵.

When misalignment removes both types from the shortlist

Neither a deep groove ball bearing nor a cylindrical roller bearing is a self-aligning design^5,8,12. If perfect alignment cannot be guaranteed, the guidance is to lean toward self-aligning designs or build in more generous internal clearance⁵.

Long shafts, low mounting accuracy or a risk of shaft deflection point the same way⁸. A self-aligning ball bearing lets the bearing articulate without binding, but its load capacity runs lower than a comparable deep groove bearing, so you trade capacity for alignment¹².

Misalignment and housing distortion also reduce actual life below the calculated L10, and the sources describe FEA and optimized roller crowning as ways to minimize that reduction rather than eliminate it²⁰.

No source in this set gives a permissible angular misalignment in degrees or mrad for either a DGBB or a CRB, so you cannot check a misalignment angle against a published limit here.

If your shaft or housing alignment is uncertain, ask the supplier what angular misalignment their specific design tolerates and how they derate life for it.

Whether the application needs any axial location

A pure radial load does not by itself settle the type, because the arrangement may still need to locate the shaft axially. A DGBB can carry radial loads plus axial loads in both directions; under pure radial load its contact angle is nominally zero.

And when axial load is applied a contact angle develops, but the axial capacity typically does not exceed roughly 20-30% of the static radial load rating¹. A standard cylindrical roller bearing is radial-only unless a ribbed design such as NUP or NH is specified^17,19.

A CRB with one straight race is the preferred float-side bearing, because the rollers slide on the straight race and the bearing accommodates axial displacement instead of fighting it¹⁹. That makes the standard CRB a good fit for a float position and a poor fit for a locating position.

If your arrangement needs any axial location, either specify a DGBB or move to a ribbed NUP/NH roller design, and confirm with the supplier which of their CRB variants carries axial load.

Friction, heat and stiffness: what the sources do and do not give

The friction difference follows the same geometry as the load difference. Point contact gives the DGBB lower friction and heat per revolution, while the CRB's line contact generates more of both^1,10.

That is the directional answer, and it is consistent across the sources. What the sources do not carry is a friction-torque value or a radial stiffness value for either type at a common bore, so you cannot put a number on the difference from this page.

If friction torque or radial deflection matters to your design — for example where heat rejection or shaft stiffness is a constraint . Request those figures from the supplier for their specific candidate at your bore, alongside the load rating.

The type choice can be made on the directional evidence; the magnitude of the friction and stiffness penalty cannot.

Lubrication and sealing: settle the seal choice with the speed target

Seal drag reduces the DGBB speed limit, so the sealing decision and the speed requirement have to be settled together rather than one after the other^1,2. The 6304ZZ illustrates the size of that effect: 14000 rpm in ZZ/2RS form against 17000 rpm open, with DU/DDU contact seals at 10000 rpm².

If you specify a sealed DGBB for contamination protection, you are accepting a lower speed ceiling than the open version of the same bearing. The sources describe DGBB sealed variants and their speed effect, but give no sealing or oil-flow data for a cylindrical roller bearing.

So you cannot assume a sealed CRB option exists or what it would cost you in speed. Before writing the RFQ, confirm with the supplier which sealed or shielded variants they actually offer for the type you have chosen, and what limiting speed applies to that variant.

What to obtain from the supplier before committing the type

The sources give no like-for-like price, MOQ, lead time or inspection-certificate data for these two types at a common bore. So the commercial case has to be built from supplier responses rather than from this page.

The cost evidence is directional only: a DGBB is described as generally the most economical ball bearing option because of mass production. And roller bearings are usually more expensive at the same size and grade^1,25.

Use the checklist below to collect the figures the sources do not carry.

• ✓Cr and C0r for the candidate CRB at your bore, to compare against the DGBB rating
• ✓Limiting speed and dN for the candidate CRB at your bore, to compare against your required rpm
• ✓Permissible angular misalignment for the specific design, since no angle is published for either type
• ✓Friction torque and radial stiffness at your bore, since the sources give neither
• ✓Sealed or shielded variant availability and its limiting speed, for whichever type you choose
• ✓Unit price, MOQ and committed lead time for both types at your bore, since only directional cost evidence exists
• ✓Precision class and running accuracy the supplier proposes, and the inspection certificate they will supply with it

Where the sources frame the cost difference differently

The two cost statements below are not contradictory — one describes ball bearings as the economical general choice, the other describes roller bearings as more expensive at the same size and grade . But they frame the comparison differently, so a buyer should not read either as a unit price.

Treat both as directional and ask each supplier for their own figures.

Before you request a quote

• The evidence leaves this open — put it to the supplier: no Cr or C0r values for a cylindrical roller bearing at a comparable bore to the 6304ZZ DGBB.
• The evidence leaves this open — put it to the supplier: no L10 life calculation for either type under your actual radial load and speed.
• Ask for relevant export destinations, installed-base references and comparable customer contacts.
• The evidence leaves this open — put it to the supplier: no permissible angular misalignment in degrees or mrad for either DGBB or CRB.
• The evidence leaves this open — put it to the supplier: no quantified effect of a given misalignment angle on load distribution or life for either type.
• The evidence leaves this open — put it to the supplier: no permissible Fa/Fr ratio table for either type.
• The evidence leaves this open — put it to the supplier: no friction torque or radial stiffness values for either type at a common bore.
• The evidence leaves this open — put it to the supplier: no lubrication method or oil-flow requirements specific to CRB.
• Request a written quote with price basis, MOQ, tooling, payment terms and production lead time.
• Request certificate numbers, issuing bodies, scope and validity for the exact model and destination market.
• The evidence leaves this open — put it to the supplier: no sealed or shielded variant availability information for CRB.