Discussion Overview
The discussion revolves around calculating the torque required to tighten a threaded terminal made of copper alloy, specifically focusing on the coefficient of friction between copper components. Participants explore the implications of using a coefficient of friction value of 1.0, as suggested by various sources, and its impact on torque calculations using Motosh's equation.
Discussion Character
- Technical explanation
- Debate/contested
- Mathematical reasoning
Main Points Raised
- One participant mentions using Motosh's equation and cites a coefficient of friction of 1.0 for copper-copper interactions, but expresses concern that this leads to excessively high torque values.
- Another participant asks for the pitch of the screw and the angle of contact, suggesting that these factors influence the friction calculation.
- A participant confirms the average coefficient of friction for copper as 1.00, stating that while the resulting torque may seem high, it should be considered accurate.
- Further details are provided about the screw's pitch (0.0833 inch) and thread angle (60 degrees), with a participant noting that the calculated torque of 2771 lb-ft seems too high based on the yield strength of the copper alloy.
- Questions arise regarding the realistic safety factor to apply given the high torque requirement, prompting discussions about the necessity of such loading levels.
- One participant suggests that it may be preferable to avoid designing for loading to yield and questions the rationale behind the chosen fastener size and loading requirements.
- A later reply indicates that for the calculated yield clamping force of 12315 lb force, the high torque requirement is expected, and recommends considering a lower coefficient of friction, potentially through lubrication, to reduce torque needs.
Areas of Agreement / Disagreement
Participants express differing views on the appropriateness of the coefficient of friction value of 1.0 and its implications for torque calculations. There is no consensus on the correct coefficient to use or the necessity of the high torque values derived from the calculations.
Contextual Notes
Participants highlight potential limitations in their calculations, including assumptions about the coefficient of friction, the influence of screw pitch and angle, and the implications of yield strength on torque requirements. These factors remain unresolved in the discussion.