News - Technical Articles

Changing Times Challenge Black Oxide Users To Operate Differently – Five Finishers With Varying Needs Discover A New Single Solution

Can times get any tougher on manufacturers with hot oxide finishing lines? High energy requirements to operate these lines are being challenged and must be conserved. Pollution controls get more restrictive. Worker safety must be guarded at all costs. Manufacturing lead times continue to get shorter. The process itself must be made faster and easier to operate.

As the saying goes, you can't fight city hall. If it isn't the government telling you to change your ways, it's the boss. Finishers have to use less energy. The line must be non-polluting. It can't be anything but safe for operators. Line turnaround of parts must be faster while the job of running it must be easier. Above all, finishing has to add value and make a profit. Tall order, isn't it?

Traditional hot oxide and room temperature blackening have been around for years. Both have distinct advantages and disadvantages when it comes to profitability, pollution, worker safety, energy consumption, process speed and ease of operation. However, in today's changing and heavily regulated manufacturing environment, alternative processes are now often the corporate mandate.

Manufacturers with finishing needs are finding a better way with a new process positioned in the middle of the spectrum between traditional hot oxide and cold blackening. It's called Tru Temp® and the process forms a black magnetite finish, equal to or better than hot oxide, on all iron and non-stainless steel parts. What's so unique about Tru Temp is that it operates 100° cooler than ordinary hot oxides and contains no heavy metals so waste treatment is not a problem.

Quality Is Very Consistent For Mate Precision Tooling, Minneapolis, Minnesota

As a leader in the manufacture of punch press tooling, finish quality and appearance is critical. Mate has traditionally depended on outside hot oxide vendors to satisfy its quality requirements. But when it went to a 24/7 operation, outside suppliers couldn't turn around tool components fast enough to meet its shipping requirements. To achieve the desired quality and avoid shipping delays, Mate installed a 100 gallon in-house Tru Temp system.

"Finish quality is very consistent," reports Jerry Keene, line operator. "We finish tool components as needed in minutes so there's no shipping delays from outside suppliers. The line works great and the process is very straightforward and easy to maintain." Like many manufacturers needing part finishing, Mate Precision Tooling would not install an in-house finishing system of any kind that posed pollution or operator hazards. Because the Tru Temp system contains no heavy metals, waste treatment is not a problem and operators can work the Tru Temp line without fear of chemical boil-over or toxic fumes.

Precision Tooling finishing line
in house Tru Temp finishing

Precision Tooling finishing line operator Jerry Keene (left) reports consistent black oxide finish quality on its tool components (right) using in house Tru Temp to replace outside hot oxide vendors.

American Hofmann, Lynchburg, Virginia, Increases Product Value With Tru Temp

An in-house Tru Temp finishing system replaced outside blackening and reduced lead time on part finishing from two weeks to one day, according to Joe Rice, production manager for this manufacturer of balancing systems. Rice says that "value is very important in today's manufacturing environment and Tru Temp definitely adds value. Tru Temp allows us to keep control of the process so we don't have to depend on someone else. It's inexpensive and allows us to control quality and costs."

The Tru Temp blackening reaction takes only 6 to 10 minutes compared with 20 to 40 minutes for ordinary hot oxide. As American Hofmann experienced, the entire process is shorter and the work flows through faster, resulting in lower labor costs. Since labor is the largest single cost factor of any blackening system, overall finishing costs are reduced significantly.

Electrical Power Consumption Reduced Dramatically At Sanford Metal Plating, Sanford, Maine

"Our old hot black oxide tank, with all its heaters, accounted for 30 percent of my shop's electrical usage," reports Matt Fischer, owner. "With Tru Temp, there has not only been a dramatic reduction in electrical usage but part quality is also very high and predictable. Castings come out an attractive black instead of red and we don't have salt leaching problems anymore. Our customers are very pleased with the quality."

Salt bloom (leaching) is very common with traditional hot oxide. The hot oxide bath is very viscous and difficult to rinse off. Blind holes and recessed areas often form white salt blooms that can destroy the value of the finished part. As Sanford Metal Plating experienced, Tru Temp is much cooler and operates at a much lower concentration so it rinses freely thereby eliminating any chance for salt bloom. Castings and powdered metals turn out a rich black.

oridinary hot oxide
Tru Temp

Unwanted salt bloom (left) occurs because ordinary hot oxide doesn't rinse cleanly. When Tru Temp is used (right) a cooler, lower concentrate is employed. It rinses easily avoiding salt buildup, resulting in an attractive black finish that won't turn reddish.

Convenience Is The Primary Benefit For Allset Precision, Chandler, Arizona

Having an in-house line keeps costs under control, reports Dean Mortimore, president and owner of this precision machining company. "We used to send parts out for blackening. The finisher was 20 miles away, which caused delivery problems along with inconsistent quality and high costs. We blacken about four days a week so having an in-house line costs less and the quality is higher. Our customers have been very happy with what we produce."
The Tru Temp process meshes easily with a company's quality and inventory systems, as Allset Precision discovered. Control over quality, scheduling and cost of finishing is retained in-house. Operators like it too because there is no boil-over or splattering problems.

Turns Out Black Cutting Tools In A Short Time At Carolina Specialty Tooling, Icard, North Carolina

.5 micron thick satin coating

Tight tolerance parts such as routers and cutting tools are finished quickly with a protective 0.000020" (0.5 micron) thick satin coating that has a black appearance using the Tru Temp process.

This manufacturer of router bits and cutting tools reports that it likes its Tru Temp system's ability to turn out quality black parts quickly. "We run the line almost every day," reports Tim Weaver, plant manager. "We haven't had any customer complaints – it does the job without problems. Our operators got up to speed on it very quickly."

The Tru Temp process is designed for long bath life without the need for routine dumping. Solution monitoring and control is simple, as done at Carolina Specialty Tooling, using an easy color change test that indicates proper concentration level. This contributes to a short learning curve for the operator. There is no need for waste treatment equipment with the company's new installation. This is true in most sewer districts. – the rinse waters are considered to be sewerable as non-hazardous effluent. For this reason, the initial capital investment is only half that of other blackening processes.

Each of these examples demonstrate how one finishing solution can help manufacturers profit from today's economic and environmental demands.

Learn More