GMW GMW15821 PDF

This specification covers manganese-iron phosphate coating on ferrous metal. The coating may be impregnated with oil or another supplemental coating.

Material Description. A friable manganese-iron phosphate layer on a ferrous substrate is produced by a chemical process. Subsequent treatments can be added to enhance various other properties. A code system is provided in Appendix A, Table A1 for designation of these treatments.

Symbols. Not applicable.

Typical Applications. The primary purpose of this coating is for promoting rapid break-in of moving parts without scoring or scuffing, and provides minor corrosion resistance. Typical usage is on small moving parts with low corrosion requirements, such as certain powertrain components. This coating is also used on fasteners used against powdered metal components.

Remarks.

Friction Characteristics. Use of this coating system on threaded surfaces and/or bearing surfaces of joints could affect the torque-tension relationship. It is recommended that a torque-tension study of the fastener joint be performed before releasing this finish on any new application.

High Strength/Hardness Materials. Due to the nature of the phosphating and pretreatment process, not all materials are suitable for this process. Potential failure by pitting and hydrogen embrittlement must be considered before specifying this process, especially with high strength/hardness materials (hardness above 38 Hardness Rockwell C (HRC)).

High Temperature Applications. The performance specified in this standard may not be met at elevated temperatures. Proper validation of material and process shall be performed before usage.