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  • Users: enirwin
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  1. enirwin

    Asymmetrical Loading of Helical Spring

    I have two discs clamped together by a helical spring. Pressure is applied to a semi-circular area between the discs. As a result, the separating force is not applied uniformly around the circumference of the spring. Is there a way to calculate the pressure at which the discs will begin to...
  2. enirwin

    Temperature Impact on LRC

    Is there a simple way to estimate the impact of winding temperature on the locked rotor current of an AC induction motor? I know the locked rotor current at room temperature and need to estimate it at colder temperatures. I don't need an exact prediction, just a ballpark estimate. Thanks.
  3. enirwin

    Hardcoat for 2024 Aluminum

    I am experiencing fretting wear between a plate made of O-6 tool steel and a housing made of 2024 aluminum, anodized per MIL-A-8625, Type 2, Class 1. The steel part was originally aluminum but was changed to resist some pretty severe cavitation. I am working to eliminate the motion that is...
  4. enirwin

    Material Selection for Ethylene Glycol / Water Pump

    I'm considering an AC motor driven, positive displacement pump for use in a cooling system where the coolant is a 50/50 mix of water and ethylene glycol. Can hardened alloy steels be safely used (pump gears, shaft, etc.) in this environment if a corrosion inhibitor is used? Also, can the motor...
  5. enirwin

    Formability of Cast 304

    I currently have an assembly that requires a swaging operation on a wrought 304 part. Because of the complexity of the part, I've been asked if it can be cast rather than machined from barstock. Can I expect the same formability from a cast 304 part as a wrought 304 part? I don't want to...
  6. enirwin

    Metric Conversion

    I want a function to convert numbers from inches to mm using the following standard rules. 1) If the first significant digit of the metric value is greater than or equal to the first significant digit of the inch value, round the metric value to the same number of significant digits as the...
  7. enirwin

    Custom Excel Function

    I'm creating a custom function in Excel using VBA. Does anyone know how to add variable descriptions that will display in the insert function dialog box? Thanks.
  8. enirwin

    VBA Module in Excel

    I'm trying to create a custom function in Excel using a VBA module. My problem is that I can't get Pi to work. If I enter 3.14 my function works properly. If I use Pi I get an error. It seems to be using 0 for Pi. For now, I'm using 3.14159265358979 for Pi, but I'd rather just use Pi...
  9. enirwin

    B10 Life to Failure Rate

    Is there a simple way to convert a bearing B10 life into a failure rate?
  10. enirwin

    Excel to Text

    Is there a way to save an excel file as comma delimited text rather than tab delimited text? Thanks.
  11. enirwin

    Hard Particle Bearing Damage

    I'm looking at a case hardened pump shaft that also serves as an inner race for a needle bearing. The shaft has hard particle dents all over it and is starting to spall in one spot. How hard does a particle have to be to dent the surface of a steel shaft with a case hardness of HRC60? I...
  12. enirwin

    Flow Between Parallel Disks

    Does anyone know the equation for pressure gradient as a function of radius for viscous flow between two disks? Pressure is applied at the ID and flow is outward. I'm trying to size a thrust washer to react a thrust load in a pump and I need to approximate the thrust capacity of the washer...
  13. enirwin

    Hydrodynamic Thrust Bearing

    I need to add a thrust bearing to an existing oil pump design. I would like to react the thrust with a simple thrust washer if possible to keep the cost down. I think I can approximate the thrust capacity of the thrust washer by treating it like two parallel disks with pressure applied from...
  14. enirwin

    Journal Bearing Material for Seawater Pump

    I'm looking for an acceptable material for a journal bearing for a seawater pump. Due to the size of the bearing and the radial load, the material must be able to operate at a PV of about 130,000 psi-fpm with essentially no fluid film. I'm currently using US Graphite Grade 14. My problem is...
  15. enirwin

    Graphite Bearing Material for Seawater Pump

    I'm currently using US Graphite Grade 14 as a plane bearing material in a seawater pump. My problem is that the material is hygroscopic. Over time, it swells and takes up my pump clearances. Is anyone aware of a graphite bearing material that is not hygroscopic? Thanks, Eric
  16. enirwin

    Spring Material for use in Seawater

    I'm looking for a high-strength spring material suitable for use in a seawater environment. It will be used in a seawater pump and will be in contact with Titanium and Graphite. I'm considering Inconel X-750, spring temper. Is this a reasonable choice? Is there a less exotic material that...
  17. enirwin

    Oil Reservoir Heat Loss

    I need to size a heater for a small aluminum oil reservoir. It will be operated indoors with minimal air circulation. The shape is roughly square. I need a rough approximation of heat lost to the air from the tank. Does anyone have a rule of thumb value for the convection heat transfer...
  18. enirwin

    Significant Digits

    Can Excel be formatted to display a set number of significant digits rather than just decimal places?

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