The laser has been readily accepted as a tool for treating metal surfaces with a view to improving wear. Ionbond offers this technology from our laser surface treatment center in Nurnberg, Germany, which carries out laser surface treatments for customers located throughout Europe, including a number of tier one automotive suppliers.
The advantages in certain applications are localized treatment and minimal heat input resulting in reduced distortion, rapid quench rates and fine microstructures. The economical aspects are a high throughput and product quality.

Laser surface treatments can be divided into processes involving solid state transformations and melting processes. To the former category include martensitic hardening, tempering and shock hardening, while melting processes include remelting, alloying, cladding and dispersion hardening.

The most commonly used process is martensitic transformation
hardening and is applied to carbon steels and cast irons.

Application of the laser beam rapidly raises the surface temperature (at up to 1000K/s) such that a thin layer is converted into austenite. Removal of the energy results in self-quenching by conduction of the heat into the relatively cool bulk, thereby producing a rapidly cooled surface layer and transformation of the austenite into martensite. It is important therefore that the steel be in the appropriate condition (quenched and tempered) and that the process conditions are carefully selected.

The principle requirement of laser hardening is the improvement of wear resistance. Abrasive wear is reduced due to laser hardened surfaces exhibiting higher hardness than the abrasive medium, while adhesive wear can also be influenced due to a reduction in the coefficient of friction. Laser hardening can also improve the fatigue characteristics of surfaces due to an increase in the compressive stress which shifts the load bearing capacity to a level higher than the applied Hertzian stress.

Typical applications are as follows:

Sheet metal forming tools
Sheet metal forming tools are in widespread use in industry. All contact surfaces with the sheet materials can suffer from wear, particular in the radius regions where high contact pressures and sliding occur. These areas can be hardened using flame or induction although distortion or reliability are often a disadvantage.

Laser hardening is ideally suited to the hardening of the contact surfaces where the precise application and fast treatment times lead to minimum heat input reducing distortion to a minimum. Parts up to 5m long can be hardened with tracks up to 25 mm wide and case depths up to 3 mm. The flexibility of laser hardening allows a wide variety of tool shape to be hardened.

Laser hardened sheet metal forming tools:

Forming die hardened on folding radii	Laser hardened forming knives	Forming die hardened on folding radii

An increasing application of laser beam hardening is the treatment of plastic injection moulds. Typical tools, either as segmented or monolithic form, can weigh up to ten tons or more. During service, the high injection pressures (~ 1000 bar) can result in high wear on the entry and sealing faces particularly when the plastic contains abrasive media. Wear of these regions results in parts with burrs on the edges and this often requires tedious removal by hand.

The requirement for an every increasing service life demands a hardening of these edges. Many suppliers employ flame or induction hardening although these techniques do not always bring the desired results and for difficult geometries are limited in their application.

Laser hardened plastic injection moulds:

Large plastic injection mould for automotive part	Radiator cover injection mould	Hardened sealing edge on textured tool

Ionbond offers its laser services from following coating center:

Ionbond Germany - Nürnberg
Allersberger Strasse 185
DE-90461 Nürnberg
Tel. +49 911 478 03 65
Fax +49 911 478 03 66
Email infolas@ionbond.com