Quality Control of Diamond Distribution in Cutting Tool Coating

How thermal imaging cameras ensure a homogeneous distribution of diamond granules and improve tool quality

Challenge

During the production of diamond-coated cutting and drilling tools, vibrations can cause diamond particles and carrier material to separate. Uneven diamond distribution negatively affects cutting performance and tool life, while conventional inspection methods do not provide sufficiently reliable quality control.

Solution

Optris thermal imaging cameras with microscope optics make diamond particles visible in this process due to their different infrared reflection properties. Non-contact imaging enables precise inspection of particle distribution and supports automated evaluation of the mixture before the sintering process.

Benefits

Homogeneous diamond distribution improves cutting performance and extends tool life.
Non-contact quality control detects uneven material mixtures at an early stage.
Automated image analysis reduces manual inspections and operator workload.
Reproducible quality control ensures consistently high tool quality.
Compact design and flexible interfaces enable easy integration into existing production systems.

Challenge: Uneven Diamond Distribution Affects Cutting Tool Quality

In the production of diamond-coated cutting and drilling tools, the uniform distribution of diamond particles is essential for the quality and performance of the finished products. Synthetic diamond particles are used particularly in abrasive cutting discs, concrete saw blades, and core drill bits. These particles are mixed with a carrier material and subsequently sintered onto the tool surfaces. The diamond particles enable effective material removal when machining concrete, natural stone, or bricks and contribute significantly to the cutting performance and service life of the tools.

A key challenge is ensuring that the mixture of diamond granules and carrier material is as homogeneous as possible. Due to their different material properties and densities, the components can separate during processing. Mechanical vibrations, in particular, promote undesirable segregation, causing the heavier diamond particles to accumulate in the lower part of the mixture while the lighter carrier material settles above them. This results in an uneven distribution of diamonds, which can directly affect the quality of the subsequent tool coating.

Uneven diamond distribution causes certain cutting areas to experience greater mechanical stress than others. This can lead to inconsistent material removal, increased localized wear, and reduced tool life. Reliable quality control before the sintering process is therefore particularly important for high-quality cutting tools that must meet demanding requirements for precision and durability.
Conventional inspection methods, such as weighing the granules or optical inspection using visible-light cameras, do not allow sufficiently reliable differentiation between diamond particles and carrier material. Reproducible quality control therefore requires a non-contact infrared method that visualizes the spatial distribution of diamond particles and enables the mixture to be evaluated before it is applied to the tool surface.

Thermal Imaging Cameras Enable Non-Contact Inspection of Diamond Distribution

The Optris Xi 400 thermal imaging camera (alternatively, the PI 640i thermal imaging camera) enables reliable visualization of diamond distribution by exploiting the different infrared reflection properties of diamond particles and carrier material. For this purpose, the granule mixture is illuminated using an external medium- to short-wave infrared source. The diamond particles reflect the incident radiation more strongly than the surrounding carrier material and appear as clearly distinguishable bright spots in the thermal image. Unlike conventional infrared temperature measurement, this application focuses not on determining absolute temperatures but on analyzing the spatial distribution of reflective particles.
While the PI 640 delivers particularly high image quality and detailed visualization, the compact Xi 400 offers a cost-effective solution for this type of application. Its compact design, attractive price-performance ratio, and motorized focusing are key advantages.

The Optris Xi 400 features an uncooled infrared detector with an optical resolution of 382 × 288 pixels and a spectral range of 8 to 14 µm. Combined with special microscope optics, it enables the detection of extremely small structures with a spatial resolution of up to 80 µm per pixel. This allows the reflective diamond particles to be visualized in detail within a defined measurement area. A frame rate of up to 80 Hz also enables rapid acquisition of the material distribution.

For quality control, the camera is positioned vertically above a granule tray. Before measurement, the powder mixture is leveled using a scraper to ensure a constant distance between the camera and the material surface. The infrared source positioned to the side generates the required reflections, while the Xi 400 captures a representative section of the mixture. Thanks to motorized focusing, the camera can be precisely adjusted to the material surface.

The captured infrared images are displayed and evaluated using Optris PIX Connect software. A connected image processing system analyzes the number and spatial distances of the reflective particles and evaluates the homogeneity of the mixture according to defined criteria. If insufficient mixing is detected, an additional mixing cycle can be initiated. The USB interface and process interface (PIF) allow the Xi 400 to be integrated into industrial inspection and control systems.

Improved Tool Quality Through Reproducible Quality Control

By using the Optris Xi 400, manufacturers of diamond-coated cutting and drilling tools can reliably inspect the homogeneity of their granule mixtures and systematically improve product quality. Non-contact infrared imaging makes the distribution of diamond particles visible before the sintering process, allowing insufficiently mixed material to be identified at an early stage. This helps prevent unfavorable particle distributions from being detected only after the tool has been coated.

A homogeneous distribution of diamond particles contributes to more uniform material removal and more balanced mechanical loading of the cutting areas. This can reduce localized wear and extend the service life of high-quality cutting tools. At the same time, reproducible quality control improves process reliability and supports the production of tools with consistent performance characteristics.
The compact design of the Xi 400, with a housing diameter of just 36 mm and a length of 100 mm, facilitates integration into existing production systems. Its robust IP67 housing protects the camera against external influences. Motorized focusing and flexible interfaces allow the system to be adapted to different inspection positions and production conditions. Automated image analysis also reduces manual inspection efforts and enables objective evaluation of material distribution.

The extensive range of Optris accessories provides additional optimization options. In production processes with high dust levels, an air purge system can protect the camera optics against deposits and ensure a consistently unobstructed view of the granules. Water-cooled protective housings are available for more demanding environmental conditions. An optional USB Server Gigabit 2.0 also allows the camera to be integrated into larger production systems using Power over Ethernet and a network connection of up to 100 m.