Gears - Surface Temper Etch Inspection After Grinding, Chemical Method

ISO 14104:2017

This document specifies procedures and requirements for the detection and classification of localized overheating on ground surfaces by chemical etch methods.

The process described in this document is typically used on ground surfaces; however, it is also useful for the detection of surface anomalies that result from post-heat treatment machining such as hard turning, milling and edge breaking (deburring) processes. Surface metallurgical anomalies caused by carburization or decarburization are also readily detectable with this process.

Some methods which have been used in the past are no longer recommended. Specifications are intended to be changed to use the methods in this document. These etching methods are more sensitive to changes in surface hardness than most hardness testing methods.

This document applies to steel parts such as gears, shafts, splines and bearings. It is not applicable to nitrided parts and stainless steels.

NOTE: This process, although at times called "nital etch", is not intended to be confused with other processes also known as "nital etch".

The surface temper etch procedure is performed after grinding and before additional finishing operations such as superfinishing, shot peening and honing.

This document explains the materials and procedures necessary to determine, evaluate and describe localized overheating on ground surfaces. A system to describe and classify the indications produced during this inspection is included. However, specific acceptance or rejection criteria are not contained.

An industry-wide survey was conducted to establish common solutions in time that were acceptable to the greatest number of users. The safety and environmental precautions were included therein for those not familiar with storage, handling, use and disposal of concentrated acids, alkalis and solvents. These precautions, however, do not supersede the latest applicable requirements.

The committee responsible for this document is ISO/TC 60, Gears, Subcommittee SC 2, Gear capacity calculation.

This third edition cancels and replaces the second edition (ISO 14104:2014), which has been technically revised. The changes of the corrected version have been incorporated as well as adoptions in the cleaning method of etching procedures shown in Tables 2 and 3.