Page 40 - MetalForming August 2013

Tooling Technology
Coatings of Many Colors
Robust, long-life coated tooling, in combination with the right lubricant in the right amount, can yield top-quality parts hit after hit. Photo courtesy Phygen Coatings.
...provide solutions when tooling up to stamp aluminum and high- strength steels that are claiming increasing shares of automotive ingredients.
BY LOUIS A. KREN, CONTRIBUTING EDITOR
High Coating Adhesion Prolongs Tool Life
For its part, tool-coating company Phygen Coatings Inc., Minneapolis, MN, applies its patented FortiPhy phys- ical vapor deposition (PVD) technolo- gy to create a thin and dense nanocrys- talline coating structure onto any tool-steel substrate. Described by pres- ident Dave Bell, the process creates a higher level of adhesion than is possi- ble with conventional coating process- es. And, other processes may use a method of adhesion that, unlike Phy- gen’s, pulls carbon from the tools to help the coating stick. Doing so depletes the tools’ carbon grains, ham- pering tool life, Bell says.
“Coating adhesion is the number one factor in coating success for diffi- cult-to-form applications,” says Bell. “One manager at a major metal-stamp- ing company told me, ‘There are a lot of very hard coatings, but none of them stick.’”
Temperature also varies among the various tool-coating processes. Chem- ical-vapor-deposition (CVD) coatings
Low friction and wear resistance are two fundamental benefits brought by tool coatings. Coat- ings also prevent similar materials in the tool substrate and part material from interacting to cause tool and part damage.
The use of coatings for metal- stamping tools originally arose from the need to form stainless-steel exhaust components in automobile applica- tions. Why? When attempting to form stainless steel, chrome in the tool-steel substrate would weld to the chrome in the stainless steel, with galling occur- ring almost immediately. Coatings form a barrier to prevent this chrome-to- chrome contact.
Today, coatings can bring all man-
ner of advantages in specific metal- stamping applications, with a number of coating options available compris- ing various adhesion processes and temperatures. That said, even the best coating cannot make up for inade- quate substrate. Base tool material must be matched to its intended use, with the properties and characteristics selected to produce quality parts time after time.
In addition, the introduction of new part materials demands improved coat- ing solutions, which process experts have delivered. With exotic tool mate- rials subject to scarcity, protective tool coatings become even more critical. We explore all of these issues with lead- ing coating-solutions providers.
38 MetalForming/August 2013
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