News - Technical Articles

Safer In-House Coating Processes Reduce Cost, Improve Customer Satisfaction

Component and product coatings offering corrosion protection and aesthetic appeal have been transformed into "good guys" that no longer threaten the environment or the workers who use them.

Companies which previously jobbed out coating operations to avoid safety and environmental hazards are now finding substantial cost advantages by setting up their own coating operations using these new processes. More importantly, they also enhance their ability to satisfy their customers because part coating lead times are virtually eliminated. Many orders can literally be shipped on a same-day or next-day basis.

A Safer Coating Alternative

Tru Temp

Brake cylinders, tie rods, ball joints, pump impellers corrosion protected with a Satin Black Tru Temp coating.

One recent innovation is a patented, low temperature black coating system for iron and steel components that optimizes quality, efficiency and safety. Called the Tru Temp process, its an ideal in-house substitute for traditional (and dangerous) 290°F hot oxide processes which many OEM's shy away from. Operating at only 190-200°F, Tru Temp is safe, operator friendly and eliminates the pollution and severe hazards of the boiling tank processes.

In about 18 minutes, the Tru Temp process forms a durable, black magnetite coating of 0.000020 inch thickness – equal to that of regular black oxide. The in-house process streamlines part movement, provides better control of finished part inventory and enhances ISO accountability. Perhaps best of all, it gives the user a "same-day turnaround" capability to satisfy key customers and fill rush orders - with minimum levels of finished goods inventory.

Satisfying Mil Spec DTL 13924D and AMS 2485, the Tru Temp process contains no EPA regulated metals. Rinse waters are generally sewerable without waste treatment. Because the process requires no effluent treatment, the initial capital investment is only about half that of other blackening systems. Many parts can be processed for a chemical cost of only about 2 to 4 cents per pound.

High Quality Without Salt Bloom

Traditional hot oxide baths are highly concentrated, very viscous and difficult to rinse off. Blind holes in parts and recessed areas often form white salt blooms that destroy the value of the coated part and upset customers. Because the Tru Temp solution is much milder and cooler, it rinses freely so white salt blooms don't occur. When Tru Temp coated, castings and powdered metal parts turn out a rich black.

oridinary hot oxide
Ordinary Hot Oxide
Tru Temp
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.

Tru Temp

A turnkey finishing line can be set up and operating in about a day.

The Tru Temp blackening time of only 18 minutes, compares with the 40-60 minutes needed for traditional hot oxide. As a result, the hourly throughput of the line is much higher, resulting in lower labor costs. Since labor is the largest single cost factor of a black coating system, overall finishing costs are reduced significantly.

OEM's with existing tank lines can implement the Tru Temp process with minimal modifications or can buy an economical, pre-engineered, off-the-shelf system in a range of capacities to fit their production requirements. Customized process lines can also be developed for large volumes or special circumstances. All come with factory training for the operators with ongoing technical help available as needed.

One such system is the Birchwood Technologies, Tru Temp 100 gallon line that can be set up, ready to go, in little more than a day. The system utilizes seven individual tanks, each measuring 24 x 40 x 28.5 inches deep with a 100 gallon capacity. The complete system occupies a footprint of 4 ft. x 22 ft. and can process up to 6000 lbs of parts per shift at very low cost.

Functional Coatings For High Value Components

High value parts require corrosion protection in storage and in service. To meet this need, Birchwood Technologies has formulated a simple low temperature metal coating process for iron and steel components, with no negative environmental impact, called MicroLok® AO. This patented process provides high corrosion resistance using a non-corrosive bath and no EPA regulated chemicals.

Tru Temp

Corrosion protection on these parts includes break-in lubricity and anti galling protection.

The MicroLok AO finish is ideal for tooling and machine components, piston/cylinder assemblies, rotors & calipers, oil-field equipment - any part that does not require a black coating but does require robust corrosion protection or anti-galling properties without a dimensional change.

The MicroLok AO immersion tank process works on all iron and non-stainless steel surfaces. It forms a non-toxic aluminum oxide conversion coating that is 0.000040 inches (1 micron) thick that is tightly bonded to the part surface. It has an attractive silver-black color. When sealed with a rust preventive topcoat, the MicroLok AO coating protects parts during storage and shipping and provides break-in lubricity and anti-galling protection.

Unaffected by temperatures as high as 1400°F, the MicroLok AO finish can be used in high-heat applications and also serves as an excellent base for paint finishes or other topcoats, outperforming iron phosphate coatings.

Unlike acidic and caustic finishing processes, the MicroLok AO process uses a mild (pH 4-5) solution that contains no EPA regulated metals. Hazardous waste treatment of heavy metals is unnecessary and process rinse water is sewerable as non-hazardous effluent. The working bath operates at 150°F and does not cause a scale build-up on tanks and heaters, thereby minimizing process line maintenance.

On non-rusty surfaces, the MicroLok AO coating process requires only five steps and 16 minutes process time:
  1. Clean and degrease the parts for 5 minutes in Safe Scrub® ST biodegradable liquid cleaner at 150°F.
  2. Rinse in clean water.
  3. Apply MicroLok AO coating by immersing parts in process bath for 10 minutes at 140°F.
  4. Rinse thoroughly in clean water.
  5. Seal in appropriate rust preventive, such as Sheath® RB1 water displacing oil; or in Dri-Touch® Plus IRP3 non-tacky rust preventive. Or force dry. Or apply paint, and then cure as required. Or apply stamping lubricant.

Like the Tru Temp process, the MicroLok AO process is an easy and safe in-house coating system alternative that can streamline part movement, reduce finished inventory and enhance ISO accountability. It too can be integrated easily into an existing tank line or into a complete, off-the-shelf, pre-engineered systems designed to fit most production requirements.

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