When an application complaint involves product quality or performance, the following list of questions should be considered in an effort to understand the reason and scope of the problem being experienced.  Information in RED provides insight to industrial standards and good practices. Supplying this information to Aztech QA will allow us to assist effectively. 

Who is the locknut supplier? What is the lot number? Part number?

How do you describe the problem condition?

How many parts in the lot have been used? Evaluated?

How many or what percentage of parts have the problem condition described in the complaint?
Products processed to industrial standards have an allowance for limited quantities of non-conforming parts.

What is the grade or class of the mating bolt?
The mating part grade or class should be equivalent to the locknut grade or class as indicated in the following table.

Nut Grade Bolt Grade   Nut Class Bolt Class
A 2   8 8.8
B 5   9 9.8
C 8   10 10.9

What is the finish of the mating part?
Each plating type has a unique friction characteristic and when combined with the mating part plating friction characteristics, a variety of locking torque spreads can result.  The locking product has been manufactured and tested with mating parts plated as required by the applicable locking specification.

What is the speed of the installation?
High speed installation can lead to high prevailing torque or galling issues. IFI 100/107 recommends 30 rpm max for testing purposes, as parts increase in diameter over 1” they should be assembled progressively slower.

Has the assembly process or mating part changed recently? 
Changing the application, mating part supplier, plating or installation speed can change the characteristics of the assembly.

How far down the mating part is the locknut installed?
A long rundown length, (over an inch), can lead to unpredictable prevailing torque or galling issues.

Is additional lubrication added during final application assembly?
Additional wax, oil or other compounds added before or during assembly can lead to reduced or increased prevailing torque and/or clamp load.

Are documented test reports, pictures or drawings of the nut and mating part available?

Can you send Aztech examples of the parts that are in question along with mating parts?

What is the urgency to evaluate and resolve the complaint? Should a backup order be placed now?

Who should be contacted for follow-up regarding this issue?