Plastic Bearing Design Guide

45678 Plastic Bearing Types Greene, Tweed offers three standard configurations of plastic bearings; sleeve bearings, flange bearings, and thrust bearings. The sleeve and flange bearings are available in both solid and split variations. Because plastic materials tend to expand as temperature increases and contract as temperature decreases, dimensional changes caused by thermal expansion will affect the performance of plastic bearings. At high temperature, the bearing cross-section may grow to the point of having interference with its fit, thus causing excessive friction and wear. At cryogenic...

Design Criteria STEP 1 STEP Calculate the Unit Loading, Surface Velocity, and Pressure Velocity 4 3 Define Bearing Diameter Bearing 1 Bearing 2 Bearing 3 Bearing 4 STEP 2 STEP Select Bearing Cross-Section Bearing 1 Bearing 2 Bearing 3 Bearing 4 3 Define Bearing Length Bearing 1 Bearing 2 Bearing 3 Bearing 4 Bearing performance is affected by many different factors. It is important to keep in mind the following factors when designing a bearing. BEARING LOADING It is important to maintain the lowest possible loading on a bearing. Lower unit loading on the bearing can be accomplished by increasing...

45678 STEP 5 Applications Material Code Characteristics Tough, abrasion resistant. Recommended for abrasive environments and water applications. FDA approved. 064 PTFE COMPOUNDS 015 Low deformation, good temperature dissipation. Recommended for numerous general applications. 348 FDA compliant, excellent wear properties, compatible with LOX, MMH, Hydrazine and oxidizers. Not recommended for water or steam applications. 357 Good wear, temperature and deformation properties. Non-abrasive against soft mating surfaces. Ideal for Semiconductor manufacturing applications. 379 Excellent wear and deformation...

The PV limits listed are guidelines defined at room temperature, running dry. Higher PV values and longer service life can be achieved in a lubricated environment

45678 Finish & Hardness Guidelines SURFACE FINISH Surface finish affects friction and bearing wear rate. For best bearing performance, an 8-32Ra surface finish is recommended on the dynamic surface. SURFACE HARDNESS Some of the fillers and reinforcements in the bearing materials may be abrasive to the mating dynamic surfaces. A hardened dynamic surface area to Rc-40 min. is recommended. SUGGESTED BEARING CROSS–SECTIONS Rod and Piston Sleeve Bearings A B C D E Bearing Cross Section 1/32” 1/16” 3/32” 1/8” 5/32” Y Diameter X Dia X Dia X Dia X Dia X Dia X Dia X Dia X Dia +0.062 +0.125 +0.187 +0.250...

Hardware Design L +0.000 -0.001 X +0.001 -0.000 Y L Flange Thickness Piston Flange Bearing Piston Sleeve Bearing Rod Sleeve Bearing Guidelines T Flange Diameter D Thrust Bearing Thickness 7 I.D. O.D.

STEP 6 Ordering Bearings There are two easy ways to order bearings. A) You may let Greene, Tweed Engineering design the best bearing for your application, OR B) you may provide us with a print and we’ll manufacture the bearing to your specifications. A Let Greene, Tweed Engineering Design the Best Bearing for Your Application Provide Greene, Tweed’s Engineering Staff with the operating parameters and hardware dimensions with tolerances. Greene, Tweed will design the right bearing and select the appropriate material for your application. Rod & Flange Bearings Operating Conditions Hardware Information...

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