Page 234 - Threading_Handbook

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GRADES AND MATERIALS
4
Cutting Material Grades and Engineering Materials

4.1 Tool Material Grades for Indexable Inserts and Solid Tools

The indexable inserts and solid carbide tools for thread production are produced from
different tungsten carbide grades. The grade is defined by a combination of substrate type,
coating type and post-coating treatment. If the indexable insert or solid carbide tool is not
coated, then the grade will be defined by substrate type only.
ISCAR’s products for threading are made from cemented carbide. Cemented carbides are
very hard materials, and therefore, can cut most engineering materials that are softer.
In most cases, to improve performance of thread cutting products when applied to
machining a specific class of materials, the indexable inserts and solid carbide tools are
coated. One of the most common methods of coating is by physical vapor deposition (PVD).
PVD coatings have a wide distribution in indexable thread turning inserts and thread a solid
carbide tools because they leave the cutting edges sharp.

PVD coatings are applied at a relatively low temperature (about 500°C).

Nano layered PVD coating

PVD coatings were introduced during the late 1980’s. With the use of advanced
nanotechnology, PVD coatings performed a gigantic step in overcoming complex
problems that were impeding progress in the field. Developments in science and
technology brought a new class of wear-resistant nano layered coatings. These coatings
are a combination of layers having a thickness of up to 50 nm (nanometers) and
demonstrate significant increases in the strength of the coating compared to
conventional methods.

SUMO TEC technology

SUMO TEC is a specific post-coating treatment process developed by ISCAR.
The treatment has the effect of making coated surfaces even and uniform, minimizing
inner stresses and droplets in coating. In CVD coatings, due to the difference in thermal
expansion coefficients between the substrate and the coating layers, internal tensile
stresses are produced. Also, PVD coatings feature surface droplets. These factors
negatively affect a coating and therefore shorten insert tool life. Applying SUMO TEC
post-coating technologies considerably reduces and even removes these unwanted
defects and results in increasing tool life and greater productivity.

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