1. Needle Bearing Product Overview
Needle Bearing Design Overview
5/16/2007
Needle Bearing Product Overview
Narrated by
David Beach
Motion Industries Retired
BEGIN THE SERIES OF MODULES ON ROLLER BEARINGS STARTING WITH THE NEEDLE BEARING WHICH WE TYPICALLY THINK OF AS THE SMALLEST DIAMETER ROLLER IN THE GROUP.
NEXT SLIDE BEGINS WITH THE DIFFERENT TYPES OF NEEDLE BEARINGS AVAILABLE
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Needle Bearing Overview.PPTA

2. Needle Bearing Design Overview
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Agenda
Study of Roller Bearings Begins Here
Loose Rollers
Cage & Roller
Drawn Cup
Solid Race
Thrust Products
Summary
Begins the roller bearing segment of Rolling Bearings
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3. Needle Bearing Design Overview
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Needle Bearing Design Overview
Loose Rollers
Our first section will cover loose needle rollers. Loose rollers are typically used in applications that are of moderate speed and require maximum load carrying capability. Loose rollers are very cost effective when it comes to the procurement of parts themselves. Assembly can be a challenge and requires the use of automated tooling or diligent assemblers to align rollers correctly. We will cover some of the characteristics associated with loose rollers.
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4. Needle Bearing Design Overview
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Loose Needle Rollers
52100 bearing grade steel
Hardened and precision ground
Standard hardness RC (or equivalent)
Multiple uses as bearing elements, precision shafts or pins
Diameter: – 0.500” (1.52 – 12.7 mm)
Length: – 2.000” (2.5 – 50.8 mm)
Length to diameter: 4:1 – 10:1
Loose needle rollers are typically made of bearing grade steel. The components are typically hardened to about Rockwell C, similar to bearing rings. Rockwell C Hardness = Test to determine hardness of the metal used in the manufacture of component parts of a bearing
To be classified as a needle roller, the length to diameter ratio must be a minimum of 4:1.
Ratio can be higher, but this is the minimum ratio. Example: 5mm diameter, 20mm length
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5. Full Complement Clearance Radial (RIC) & Circumferential (cc)
Needle Bearing Design Overview
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Full Complement Clearance Radial (RIC) & Circumferential (cc)
Successful operation of a full complement of rollers not only requires careful selection of radial internal clearance (RIC) but, more importantly, depends on proper circumferential clearance (or the total clearance between rollers)
Successful operation of a full complement of rollers not only requires careful selection of radial clearance but, CLICK more importantly, depends on proper circumferential clearance, CLICK , or the total clearance between rollers. More Load Capacity. Assembling very important (Spacing, lubrication, etc.)
Customer Engineering can assist customers with the optimum loose roller selection based on customer shaft and housing requirements.
“G” Radial Clearance
“CC” Circumferential Clearance
Radial Clearance
Circumferential
Clearance
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6. Needle Bearing Design Overview
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Loose Needle Rollers
Benefits of loose rollers
Reduced component cost
Reduced cross section
Weight savings
Load-carrying capability
Added design flexibility
Customer requirements
Assembly techniques
Loose roller feeding capabilities
Precision manufacturing & heat treat of raceway surfaces
You may ask, what are the benefits of using loose rollers? CLICK
First is the reduction in component costs. Rather than buying an entire bearing assembly, loose rollers are less expensive.
Next is reduced cross section since loose rollers are more power dense than using a caged roller assembly.
Or instead of a reduced cross section the engineer can maximize load carrying capability by increased number of rollers or size of rollers to replace the comparable caged design or drawn cup design. Also relieved roller ends reduce stress concentration and result in a more uniform stress distribution and improved fatigue life.
Finally added design flexibility and weight savings allow the engineer some options in the application.
Along with these benefits come customer requirements.
The customer is responsible for assembling the loose rollers into the application. This can be done manually or through some automated roller feeding capability.
The customer is also responsible for manufacturing of the inner and outer races. They need to control surface finish, hardness and size for the shaft and housing.
Proceeding Next to Cage & Roller Assemblies
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7. Needle Bearing Design Overview
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Needle Bearing Design Overview
Cage & Roller Assemblies
Now let’s look at cage and roller assemblies.
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8. Cage & Roller Assemblies
Needle Bearing Design Overview
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Cage & Roller Assemblies
We have already discussed the loose rollers or rolling elements so we will focus on the cage design features within the cage and roller bearing. Cages are manufactured in steel and polymer materials. Polymer cages are cost effective when it comes to tooling since the mold can be less than wrap and welded steel designs. In addition polymer cages are easier to design when being considered as split cages for crankshaft positions.
No Identifiable Markings on needle roller and cage radial assemblies to indicate the bearing part number.
Parts are specified by bore diameter, outside diameter, and width
Steel
Polymer
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9. Needle Bearing Design Overview
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Cage Functions
Retain Rollers
Makes for a unitized bearing assembly
Easier handling
Easier customer assembly
Easier customer serviceability
Guides Rollers
Outside load zone
Engineered for application
What are the purposes of cages? They are used to retain the rollers as an assembly. The cage and roller design facilitates the assembly process for customers and also makes it easier for customers to service the application. The second function of the cage is to guide the rollers outside the load zone of the bearing. This prevents roller skewing and sliding and reduces heat generation.
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10. Needle Bearing Design Overview
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Cage Functions
Separate Rollers
Reduces heat and wear at high operating speeds by cutting the relative surface speed in half
Allows for increased lube flow through the bearing
The last function of the cage is to separate the rollers in the complement. This reduces the incidental contact to prevent rubbing wear between the rollers. In addition for higher speed applications, lubrication gets in between the rollers easier than with a full roller complement to remove the heat generated from the rolling contact.
Without Cage
With Cage
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11. Cage and Roller - Advantages
Needle Bearing Design Overview
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Cage and Roller - Advantages
Over a Full Complement
Easier to handle
Less friction
Higher speed
More debris tolerant
More misalignment tolerant
Holds more grease
Over other Bearings
Smaller cross section
Easier installation & replacement
Lighter weight
Size Range
0.2 – 8 inch (5 – 200 mm) bore (Conversion: One Inch = 25.4mm)
Now let’s summarize the advantages of a cage and roller design over a full complement of rollers or other types of bearings. A cage and roller design is advantageous over a full complement of loose rollers for several reasons. It is easier to handle and install into customer applications since it is 1 piece or unitized. As we have discussed the cage provides a separator for the rollers to minimize rubbing contact so the bearing can run at higher speeds. Next, cage and roller product is more tolerant to debris since it allows more lubricant to get in between the rollers to flush out debris from the system. Finally this product type can handle more misalignment than loose rollers since the cage can guide the rollers in the misaligned conditions as oppose to loose roller complements when they loose tractive forces and tend to skew and slide.
Cage and roller products have advantages over other bearing types such as smaller cross sections compared to ball or other roller bearings. Easier installation and replacement since the unitized assembly slides onto the shaft and into the housing. Like a loose roller complement, the customer is responsible for providing a shaft and housing surface that is a bearing quality. And finally in most cases, the cage and roller design will be a lighter weight compared to other bearing types. As you can see we have a wide size range of products from .2 inch to 8 inch bore.
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12. Needle Bearings Overview
Needle Bearing Design Overview
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Needle Bearings Overview
Drawn Cup
Now let’s focus on the features and advantages of using drawn cup needle bearing.
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13. Needle Bearing Design Overview
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Introduction
Types of inch series drawn cup needle roller bearings
When it comes to drawn cups, there are 2 different designs, full complement or the “B” bearing (No Cage) and caged product or the “J” bearing. The main advantages of caged product is the increased speed capability. Typically caged designs can run approximately 2 times faster than full complement. The main advantage of the “B” bearing is the load carrying capability which is typically 50% more than the caged product due to the increased number of rollers.
The Torrington Company patented the drawn cup bearing in 1934 by forming or drawing strip stock through a progressive die set. Strip stock is formed through a series of progressive dies creating the basic shape with 1 curled end and 1 non-curled end. The entire bearing is case hardened except the end of the race where the rolling elements will be loaded. After heat treat the roller complement or cage and roller complement is installed through the non curled or open end. Finally the open lip is curled with a roll form tool.
B Bearing
J Bearing
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14. Needle Bearing Design Overview
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Drawn Cup - Closed End
M-type
Available as either full complement or caged
Allows for a through bored housing
Good contamination resistance
One variation to the standard drawn cup bearing is the “M” type closed end. This is available in either full complement or caged design. This allows customers to through bore their housing making for easier machining setups. The bearing is pressed into the housing forming a sealed arrangement.
Part Numbers stamped on face of outer ring
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15. Design Features - Seals
Needle Bearing Design Overview
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Design Features - Seals
Drawn Cup bearings can utilize a seal on one or both ends
Sealed bearings can be pre-greased (greased for life) if the application warrants it
Seals can be used in the drawn cup bearing on 1 CLICK or both sides CLICK depending on the application. The seals are a moderate barrier to contamination. If more robust designs are required we suggest an external seal be used for the application. In addition to pre-sealed configurations, these bearings can be pre-greased as well to eliminate this step for customers.
SEALED
ONE SIDE
SEALED
TWO SIDES
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Needle Bearing Overview.PPT

16. Drawn Cup Roller Clutches, Roller Clutch & Bearing Assemblies
Needle Bearing Design Overview
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Drawn Cup Roller Clutches, Roller Clutch & Bearing Assemblies
Transmits torque in one direction
Free overrun in opposite direction
Torque applied thru shaft or housing
Available as:
Clutch-only
Clutch bearing assembly
Rollers wedge against internal ramps to transmit torque
Operates on hardened shaft
Another deviation to the standard drawn cup is the roller clutch used in consumer and industrial type applications where torque is required to be transmitted in 1 direction and the shaft can rotate freely in the reverse direction. The rollers lock to transmit torque by wedging themselves against internal ramps in the drawn cup. We make these as a clutch bearing assembly or clutch only. As you can see the size range is 1/8 inch bore to 1 inch bore.
Indexing
Size Range
Inch: 1/8 in. - 1 in. bore
Metric: 4mm - 30mm bore
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17. Needle Bearing Design Overview
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Drawn Cup Advantages
Thin cross section
Cost effective
Existing production parts
New parts
Ease of assembly – no retention feature needed
Bearing quality housing not necessary
Housings can be cast iron, aluminum, plastic
Special features
Seals
Closed end
Oil holes for lubrication and debris
Wide size range – drawn cups
.125 – 5.5 inch ( mm) bore
What are the advantages of using drawn cup bearings?
They have a thin cross section with a relatively high dynamic capacity allowing them to carry large radial loads. Current parts are cost effective.
Drawn cups offer ease of assembly for customers since the bearing is retained in the housing with a press fit. No other retention is required. And unlike cage and roller or loose roller designs, a bearing quality housing is not required. A nice feature of drawn cup bearings is that they can be used in non-ferrous housings such as aluminum or plastic. The shaft still needs to be made to bearing quality. If the customer cannot hold the proper specifications for the shaft, Timken can provide a machined or drawn sleeve for them.
As discussed drawn cup bearings can be made with special features such as seals, closed ends and oil holes for increased lubrication. Manufacturing capabilities for drawn cups range from 1/8 inch bore to 5 ½ inch bore.
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18. Needle Bearing Product Overview Part A
Needle Bearing Design Overview
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Needle Bearing Product Overview Part A
End of Module
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This concludes our needle bearing product overview.
5/16/2007
Needle Bearing Overview.PPT