Metal Blackening Article

Process Speeds Metal Blackening

User… CTS repairs and refinishes toolholders, tapholders, collet chucks, milling cutters, removable and indexable carbide inserts, drills, taps and dies.

Operation… After returning damaged tools to their original specifications, the company blackens them.

Problem… About a year-and-a-half ago, CTS became very concerned about the bottleneck it was experiencing during the metal blackening process. The room temperature blackener it had been using for 10 years wasn’t measuring up to the company’s standards. After blackening, the tools sat overnight and were rubbed down the next day. Half of the black oxide would rub off and the tools had to be put through the process a second time.

Solution… CTS decided to seek a new supplier. As a result, CTS switched to EPI’s metal blackening process. Rebuilt tools are placed into a surface-preparation tank containing EPI’s E-Prep 255, which makes the steel surfaces receptive to the blackener. Immersion time is about 5 minutes, then the tools are rinsed with cold water and immersed in a tank containing the Insta-Blak 333 blackening solution for 2 to 4 minutes. Then, the tools are rinsed with cold water and dipped in a solution of E-Tec 503, a water-displacing, rust-preventive oil that protects the blackened finish.

Benefits… The new blackener produces a rich, deep, uniform blackness on a variety of materials and does not rub off like the previous blackener. Tools now require only one trip through the blackening solution.

Room Temperature Blackening Process Adds Value For Metal Finisher

Since 1945, Metal Improvement Company (Milwaukee, Wisconsin), a wholly owned subsidiary of Curtiss-Wright Corporation, has specialized in providing shot peening services to a range of industries including aerospace, automotive, chemical, marine, agricultural, mining and medical. The process of shot peening improves fatigue properties of metal parts and provides resistance to stress corrosion cracking. Common applications include gears, springs, shafts and other components that are prone to high cycle fatigue.

This operator is blackening small parts in a slowly rotating acid-resistant plastic barrel. An overhead manual hoist moves the barrel from tank to tank through the line.

As a value added service to its customers, Metal Improvement recently installed an in-house, room temperature blackening system for use on their iron and steel parts. “By bringing the black oxidizing and blackening process in-house and not having to send parts out, it’s given us greater convenience, and we’re obviously able to save a lot of time,” says Jeff Olwig, production manager. “We’re also able to maintain greater control over the quality of our parts, which was another important factor for us.”

After researching suppliers of room temperature blackening processes, Metal Improvement selected Electrochemical Products, Inc. (EPI)(New Berlin, Wisconsin) to manufacture and install its system. “Since EPI specializes in both hot and cold blackening processes, we felt comfortable that they could recommend the best method to fit our particular needs,” says Mr. Olwig. “They also provided us with finish sample parts so we could better compare the processes.”

EPI customers have access to technicians, chemists and chemical engineers for technical advice and service — all backed by a new laboratory facility that is said to feature the latest equipment. “We’ve received outstanding technical support from EPI,” adds Mr. Olwig. “When the InstaBlak system was installed, all of our operators received comprehensive training on the process. It’s very user friendly, and the parameters for their cleaning solution, surface preparation solution and InstaBlak metal blackening solution are easy to control.”

“After comparing processes, we decided to go with a room temperature blackening system rather than the conventional 290 degrees hot black oxide process,” says Mr. Olwig. “The cold process is safer for our employees to operate and offers improved overall productivity.”

With InstaBlak, the entire blackening operation can be completed in 10 to 12 minutes versus 30 to 40 minutes with a conventional hot black oxide process. Energy savings can also be realized with the room temperature process. Also, there is no leaching out when blackening powdered metal or cast iron parts as there typically is with conventional hot black oxide process. Additionally, the InstaBlak process produces essentially no dimensional change in precision machined surfaces.

“We can blacken cold or hot rolled carbon steels, alloy steels, tool steels, as well as cast iron, forged steels and powdered metals in a single tank of room temperature blackening solution,” adds Mr. Olwig. In fact, Metal Improvement is now able to use its InstaBlak line to bring in outside blackening jobs from other manufacturers.

With the InstaBlak process, Metal Improvement is able to control the blackening solution. With other processes, the company would have had to send samples to an out-of-state lab for testing.

“With EPI, we saved 35 percent on the initial equipment and chemicals to charge the new line,” says Mr. Olwig. And, unlike hot processes, InstaBlak requires no special ventilation. “It’s so safe and convenient to use, we were able to put it right on the production floor.”

For more information about the Black Oxide Process and the room temperature metal blackening process from Electrochemical Products Inc., call (262)786-9330. You can also purchase EPi’s products online.

Reprinted from the May 2003 Modern Machine Shop Magazine, www.mmsonline.com, copyright 2003 by Gardner Publications, Inc., 6915 Valley Ave., Cincinnati, Ohio 45244-3029.