TOOLING wear and tear, maintenance and downtime add millions to the cost of machining each year - a figure that can be significantly reduced by extending the life of cutting tools through cryogenic treatment, says Cryogen Industries co-founder, Shannon Mafodda.
Extensively used in US but still in its infancy in Australia, cryogenics is the cold or sub zero process used to increase the performance and productive life of ferrous and non-ferrous metals by as much as 300%.
While its applications vary, its most recognised application is in the area of industrial machining for the treatment of circular wet saw blades, band saw blades, high-speed steel drills and cutters, slot drills, centre drills, spiral cutters and taps.
Available in Australia through Melbourne-based Cryogen Industries, the cryogenics process is based on a predetermined thermal cycle that involves the initial cooling of tools and parts in a controlled cryogenic chamber and depending on the composition of the product being treated, a post temper thermal cycle may be applied.
The materials are slowly cooled to about -200°C and left at that temperature for a period of time after which they are allowed to return very slowly and in a controlled manner to ambient temperature.
The entire process - which takes 70-75 hours to complete - changes the structure of the material.
In ferrous metals, the treatment converts retained austenite (the softer grain structure present in ferrous metals after heat treatment) into a more durable structure known as martensite and at the same time promotes the precipitation of very fine carbides. These small carbide particles add to the wear resistance of metals.
Cryogenics is not a coating; rather it treats materials to their very core. It can be applied to new or used and dull or sharpened parts, increasing durability and reducing stress, warping and cracking - providing for enhanced performance and yielding 2-3 times the productivity of untreated materials.
"What this means for manufacturers is that they are able to have their machining centres in production for longer, dramatically reducing downtime costs associated with damaged and worn-out parts,” Mafodda said.
"In fact, overseas case studies have shown a significant 20% increase between scheduled plant maintenance and the replacement of parts."
He says downtime is largely as a result of abrasive and adhesive wear, chipping, deformation and galling of cutting tools.
"Adhesive wear occurs when the action of the tool being used exceeds the material’s ductile strength or the material is simply too hard to process, resulting in micro cracks or stress fractures.
"These micro cracks eventually interconnect, or network, forming fragments that pull out and become wedged between the tool and the work piece, causing friction which can result in a poor finish.
"At worst, this can result in catastrophic tool failure, costing thousands of dollars in machine damage and production loss or resulting in warpage and stress fractures to tool heads, decks and rotating and load bearing assemblies,” he said.
However, Mafodda cautions that cryogenic processing should not be seen as a substitute for heat-treatment. "It will not in itself harden metal like quenching and tempering and as such is not a substitute for heat-treating, rather it's an addition to heat-treating.
"Also, if a product has been poorly treated, cryogenics simply won't help.” Cryogen Industries 1300 721 490.