Why a custom screw needs more than a generic torque value

Describe the complete joint

Provide the mating thread, clamped stack, bearing surfaces and intended function. Include washers, inserts and other components that affect assembly. A torque copied from an unrelated table may have assumptions that do not match this connection.

Identify the friction condition

Coating, lubrication and contact surfaces can change tightening behavior. State the supplied and assembly conditions that the design uses. Do not change a lubricant or finish solely for appearance without reviewing whether the existing tightening instruction remains appropriate.

Distinguish reference values from validation

Reference torque information can support an engineering discussion but is not a substitute for evaluating a specific joint. Agree the responsible design calculation, test or approval process. Avoid treating one successful tightening trial as proof that all production and service conditions are covered.

Record the assembly requirement

Document the tool method, acceptance criteria and any required checks with the approved part specification. If the screw or surface system changes, consider whether the assembly instruction needs review. The quotation should make clear which tests or reports are included and which require separate agreement.

Specification example

Replacing a plain screw with an integral flange changes the bearing interface. Review the joint assumptions before carrying over the original torque instruction solely because the nominal thread is unchanged.

RFQ checklist

• Mating joint and clamped stack
• Coating and lubrication condition
• Required assembly method
• Engineering validation responsibility
• Change-review and acceptance records