Can various bolt grades be mixed in the same joint?
A case example: An audit rebuild schedule for 200-ton capacity, two-story-high trucks for mining operations showed that the electric motors for rear wheel drive power and braking (costing $80,000/axle), were to be assembled with SAE Grade 8 bolts. In fact, most drive motor connections were found to be Grade 5. Some even displayed a random mix of Grade 5 and 8, along with even higher grades – all on the same flange connection. All bolts were installed by an authorized rebuilder for the motor manufacturer. Problem: No matter what standard torque setting the fastener installer chose, it would be incorrect. Mixed fasteners lead to serious problems in tightening, producing incorrect clamp loads. Breakdown of these monster trucks was extremely cumbersome and expensive. The same situation deserves attention for your product as well.
