Surface treatments extend tool life.

Even though tooling performance goes more than skin deep, a little bit of surface modification can do a lot to help your molds run longer and better. These modifications can make tools harder or enhance release capabilities, according to Larry Campbell, engineering director at General Magnaplate, a coating supplier in Linden, N.J. Magnaplate has dealt with tough applications - including long, zero-draft parts in which molders have all but eliminated use of release agents after applying the right coating to the tool surface.

Here's a look at some of the most recent advances in mold coatings, ion implantation, and ion nitriding that can keep your tooling in peak form.

SLICK AND NO STICK

General Magnaplate has a new self-lubricating, longer-lasting coating for tool steels. The company now offers its HTR dry-lubricant coating in conjunction with the Plasmadize family of thermally sprayed ceramic or metallic coatings. The resulting non-porous surface boasts a dynamic coefficient of friction (COF) as low as 0.12. It survives operating temperatures up to 500 F and offers wear resistance at least on par with chrome plating or electroless steel, according to Campbell.

Synergistically combining two different coating methods a thermally sprayed substrate with a lubricant infusion - the new HTR Plasmadize treatment is said to be suitable for both injection molding and extrusion tool components. It's available in thermally or electrically conductive and non-conductive versions.

DIAMOND-COAT YOUR MOLDS

A new "diamond-like carbon" (DLC) coating that promises to be comparable in cost to established vapor-deposition coatings has been developed by Southwest Research Institute (SwRI) of San Antonio, Texas. Applied at low temperatures by ion-beam deposition, DLC coatings offer low friction and wear-fighting properties. They have a COF below 0.1 under dry-sliding conditions. SwRI has developed a patent-pending bond coat to address adhesion problems associated with DLC coatings.

In other news, SwRI recently upgraded its ion-beam capabilities with a 120-kv plasma device for nitrogen-ion implantation. It enables treatment of surfaces up to 4 sq ft or batches of up to 100 parts. Ion implantation is not a coating process; it hardens the tool steel by bombarding and impregnating the surface with nitrogen ions, explains Dr. James Arps, SwRI research scientist. Because there's no surface build-up or significant heat involved, the method makes no dimensional changes or thermal deformation.

ION NITRIDE FOR STRENGTH

Another ion-implantation process comes from the from Dicer Corp. of Haverhill, Mass. Its proprietary IonLast ion-nitriding process for case-hardening ferrous metals has mainly been used to treat cutter blades. It is now being offered as an alternative to higher-temperature gas nitriding for injection tooling components, says company president Bob Vogel.

IonLast takes place in a vacuum chamber heated to 700 F, where parts are exposed to a hydrogen-ion plasma followed by a plasma of nitrogen and hydrogen. Parts end up nitrided to 65-72 Rc hardness.

Dicer also claims to boost fatigue strength by up to 40% because the diffusion of nitrogen into the metal matrix creates high residual compressive stress to counteract the load stresses that cause fatigue. By controlling part temperature, treatment time, and the plasmas' electrical characteristics, IonLast can custom tailor the surface hardness and case depth. IonLast can serve as a base for corrosion-resistant surface treatments such as TiN and TiC.