Hobson data sheet
BUMAX Lock All-Metal Stainless Lock Nut: Data Sheet
BUMAX's two-page data sheet, distributed by Hobson, for BUMAX Lock: an all-metal stainless lock nut with a special thread profile. It explains how the thread locks, the steel grade, load distribution, a vibration test, fitting and reuse, and the standard range.
What this covers
- What makes it different
- Steel grade
- Load distribution
- Junker test
- Fitting and reuse
- Standard range
Applies to Hex Flange Nut and All-Metal Prevailing Torque Nut.
Key things to remember
The essentials from this document in plain words. Check the full document before you rely on a figure.
- All-metal lock nut made from 316L high molybdenum steel, the same steel as BUMAX 88, as standard.
- The root of the nut thread forms a wedge-shaped surface. When torque is applied the bolt thread bears against it, giving metal to metal contact with no play, and the preload is spread along the whole thread.
- In the maker's vibration (Junker) test on M8 nuts preloaded to 15kN, BUMAX Lock held better than a standard nut and a metal lock nut. The sheet says locking holds even at preloads as low as 25% of yield strength.
- It does not lock until tightened hard enough to meet resistance, so it is easy to fit, including with a power tool. It locks in one direction: fit it with the collar or flange against the joint.
- Can be locked and unlocked up to 10 times, but BUMAX recommends changing the screw after each unlocking. Suitable for surface temperatures up to about 300°C.
- The standard range is strength class 80.
Who it helps: Engineers locking stainless bolts on vibrating or corrosive equipment.
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This document is published by Hobson Engineering, who supply this range to us. We show it here in full so you can read it next to the product; the summary above is ours. Read it on this page or download the PDF. For the most current version, ask us.
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