Danaher Corporation and Cooper Industries are selling Apex Tool Group, a tool-making business they created two years ago, for about $1.6 billion to private equity firm Bain Capital LLC.

Danaher is an industrial and medical equipment manufacturer based in Washington, D.C., while electrical components and tools manufacturer Cooper is headquartered in Maynooth, Ireland, with American headquarters in Houston, Texas.

The companies announced in March 2010 that they would blend some of their tool-making businesses into a joint venture called Apex. The companies completed the deal a few months later and each has kept a 50 percent ownership interest.

Danaher officials said Apex’s sale price is subject to post-closing adjustments, but they estimate after-tax net proceeds to total about $650 million.

The deal is expected to close in the first half of 2013.