Bearing Life Testing
Designed to confirm the effectiveness of materials, product design, and manufacturing process, Napoleon Engineering Services’ dynamic testing program is generally done at an accelerated condition to match the clients time and budgetary constraints. Maintaining a fatigue failure mode or one consistent with that found in the application NES is able to increase the client's knowledge of the design and manufacturing capability of the product resulting in reduced risk of employing a new or alternate product. NES’s dynamic testing program provides outputs that give our clients the information they need to make informed choices in regards to their own application. Listed below are the different output types NES offers through dynamic testing programs.
Life Adjustment Factors
NES understands the importance of determining how the design, material choices, and manufacturing differences combine to provide an empirical life for comparison to the theoretical calculated life. Through this information we are able to determine the life adjustment factors for each supplier. To determine the life adjustment factors the bearing is tested through sudden death (first-in-four) or classical test methods both of which provide failure data points that are vital in producing a weibull plot similar to the one depicted to the right.
Understanding the weibull plot and the data collected shows the relative difference or life adjustment from one supplier to the next. If a client understands their application well enough they are now able to determine the increase or decrease associated with the use of an alternate supplier.
Load Rating Validation
Load rating validation is performed through an extensive maximum likelihood testing process that allows for confirmation that a bearing will work in a specific application. This quick and effective process allows customers to evaluate a bearing against its load rating instilling confidence and furthering the OEM, end user relationship. Depending on time and budget constraints, NES can determine if a supplier meets the load rating without running to failure. Although this testing does not state how much better or worse a product is against its load rating it does provide a high level of confidence that a product will meet its desired load rating.
Fast Track Qualification
This twenty-eight hour process is likely the shortest and least scientific method offered at NES to determine the relative quality of a bearing against a baseline supplier. Primarily used for tapered roller bearings, this method is ideal for clients who are constrained by time but still wish to make an informed, educated decision when qualifying a new supplier. During testing, the axial load of a four bearing set is gradually increased from zero to a maximum axial load over an eight hour period. The testing process is continued until the bearing operating temperature stabilizes. Acceptance of a product occurs when an alternate supplier achieves equal or lower temperature and torque values than the baseline product.
Napoleon Engineering Services can also evaluate the effectiveness that different lubricants have on temperature and torque as well as its relationship to surface durability. The resulting difference in stabilization temperatures of particular lubricants can be graphically shown using fast track qualification testing. Bearing durability testing is then performed for each oil type holding its own stabilization temperature. Failure data is then compared to determine the relative life adjustment for both lubricants.
Weakest Link Failure Mode
Dynamic testing can highlight design or manufacturing flaws that can result in surface and subsurface initiated failures. The weakest link failure mode can also confirm the knowledge gained through Source Qualification Inspection. Weakest link failure mode can identify the following.
- High Operating Temperatures
- Cage Issues
- Surface Finish Issues
- Poor Contact Load Profile
Clients who employ the use of model software to enhance the performance of their products are able to combine the empirical test results with the data from our Source Qualification Inspection Program (SQI) to improve the accuracy of the model. Napoleon Engineering Services’ model correlation capability has supported a multitude of customers for a wide array of industries.
Material/Process Validation Endurance Testing
Primarly used by bearing manufactures to test specific bearing components such as ball and cage materials Napoleon Engineering Services’ material/process validation testing is an effective way to determine the different wear, fatigue or lubrication properties of different materials or specialty processes