Turn green light for light turning

The latest developments in blade technology have brought unique solutions to the need for sharp and durable cutting edges. This is often the case with precision turning with low cutting parameters and small parts.
In the light turning area, due to the lighter and smaller machines and the lower power, a sharper and tougher cutting edge is required. Parts and fixtures are also more unstable, so parts can only be processed satisfactorily with sharp positive rake edges. At the same time, due to the need for competition, the machine must run continuously for a long time, usually to extend the entire shift. Sandvik Coromant calls this “green-light production”.
In order to achieve a sharper cutting edge, the previous major approach was to use uncoated blades, and in recent years only blades with thin coatings have been used. The PVD (Physical Vapor Deposition) process was originally used for smaller, solid high-speed steel and carbide tools and is now widely used for indexable inserts, especially indexable inserts with sharp cutting edges.
PVD-coated blade grades are advantageous for sharp cutting edges due to edge line strength. Coating a PVD coating with a thickness of only a few microns on a tough substrate will help maintain edge line integrity. The CVD (Chemical Vapor Deposition) process requires higher temperatures and provides the blade with several times the thickness of the PVD blade, creating a blunt edge that is not suitable for light turning.
However, CVD coated inserts also have advantages such as high abrasion resistance, thermal insulation, chemical resistance, and good volumetric strength of the insert. Recent developments in blade technology have changed the conventional sequence of CVD and PVD coating grades and introduced cutting edges for light turning.
Bottlenecks in the processing area, including light turning, are often caused by excessive downtime due to tool change, usually because the blade's edge line has not been kept intact. The solution so far has been to use a universal blade grade, finding a satisfactory compromise between wear resistance and toughness, covering a wide range of fields.
However, general-purpose tools always compromise on performance. Now, people are developing more specialized high-quality blade grades to better adapt to various applications and workpiece materials.

Reduce cutting time
GC1515 is a CVD coating grade for sharp blades. It is mainly used for light turning of steel, but it is also used for supplementary turning of stainless steel. This PVD-like blade is obtained by thin coating by a CVD process. One step is to reduce the thermal barrier. Cutting lengths in this area are generally relatively short, and the duration of cutting is not sufficient to reach high temperatures. However, the blade grade includes CVD's excellent abrasion and chemical resistance. As it turns out, it is particularly advantageous for applications where simple cutting and extra wear resistance are conducive to achieving shorter cutting times.

There is also a unique new CVD grade developed that combines the wear resistance of CVD inserts with the sharp edge toughness of PVD inserts, a development that represents a major step forward in today's lightweight turning performance.

Another important development is the development of sharper PVD grades. So far, people have been using a common PVD brand to cover a variety of processes and materials. However, the new demand of the manufacturing industry cannot be satisfied by a single multipurpose brand. Now, the ultra-sharp blades have almost no tip radius and have more optimized cutting edges. They can control chips and improve accuracy, and minimize cutting forces with minimal depth of cut and feed.

The tougher grade, GC1125, is a new generation of PVD coated insert grades that replaces the previously common grades. The main application area is limited to stainless steel light turning, but it can also be used as a supplement to steel and super alloys. It is now among the new PVD coating grades that are continuously being developed today. It is more excellent than the previous brand, mainly because it has higher toughness and can form sharper positive rake blades.

Unusual Coatings New grade PVD coated insert grades of fine-grained cemented carbide substrates provide the wear resistance and toughness required to maintain a sharp edge line during prolonged production. The GC1125 is particularly advantageous for materials that are prone to smearing such as non-wheel steel and helps prevent the formation of built-up edge.
Traditionally, CVD coatings have a thickness of more than 10 microns. Due to new developments in blade technology, the GC1515 coating is thin and only 3 to 4 microns thick. This means that the cutting edge rounding can be reduced to a lower value, making the cutting edge sharper, achieving good cutting action and chip control with a smaller depth of cut.

in conclusion:

The new generation of blade grades is to enable Sandvik Coromant to claim “green-light production” outside of scheduled downtime. Sandvik Coromant's newly developed PVD and CVD coating grades complement each other in the field of light turning.
This means that a certain degree of tool specialization has now been achieved, and with only a few blade numbers, insert geometries and correct application techniques, the desired processing results can be achieved, resulting in continuous production and maximum improvement. Predict tool life, consistent quality levels, minimal waste, and shorter cycle times.