When we are talking about diamond grinding tools, we are not actually talking about the small machines that are used for giving these precious stones that proverbial “finishing touch”. Rather, the diamonds themselves become part of the tools – with very convincing results. In this article, we will be revealing where diamond grinding tools are used and why – and what advantages you yourself might gain from these devices.
What are diamond grinding tools?
The first thing you associate with diamonds and the picture that immediately comes into mind is one of high-quality jewellery. However, fine diamond dust, resp. industrial diamonds (also known as boart), are not used as decorative or prestigious objects. Due to their special properties, they are primarily used for producing tools. Apart from using diamonds as a cutting material for devices such as drills and milling cutters, diamond grinding tools are now also particularly high in demand.
In the latter case, fine diamond dust is applied to a grinding wheel as an abrasive, i.e. the grinding wheel is not made entirely of diamonds. This production method would be far too costly and complex. Instead, the base body consists of a carrier material to which the diamond powder is bonded. Raw materials which can be used to make the base body include metal, such as steel, synthetic resin compounds and lightweight materials – depending on the requirements and area of application concerned.
What are the advantages of diamond grinding tools?
Diamonds are a form of modified carbon which is characterized by one particular property: It is the hardest naturally occurring substance to be found. As a result, diamond grinding tools can process materials where other machines are forced to give up. The level of wear and tear involved is relatively low which means that diamond grinding machines offer a convincing advantage through their long service life.
Similar to the case of simple sandpaper, the granulation can be individually adjusted according to the requirements. It is possible to produce a very coarse diamond powder with a granulation of 1000 microns or more. Very fine variants with a diameter of only 25 microns or less are also achievable. As a general rule of thumb: The harder the surface material and the finer the desired result, the finer the diamond powder used should be.
What are diamond grinding tools suitable for?
Due to their special hardness, diamond grinding tools are in demand wherever particularly hard materials have to be processed and ground. Steel, however, is an exception. Rotating diamond grinding tools cannot be used for steel as the resulting temperatures are too high. Apart from this, the areas of application open to such tools are virtually limitless:
- Thermosetting plastics, glass or carbon fibre-reinforced, for example
- Graphite and electrocarbon
- Grey and nodular cast iron
- Cemented carbide
- Nickel and titanium-based superalloys
- Technical ceramics
- Wear protection coatings (sprayed and weld on alloys)
This makes diamond grinding tools an attractive alternative to conventional grinding tools for a multitude of industries – or even the only solution for day-to-day business, next to CBN tools. Areas that benefit from hard-wearing tools include, for example:
- Automotive industry and suppliers
- Energy sector
- Foundries (grey and nodular cast iron)
- Ceramics processing industry
- Plastics processing (GFRP/CFRP)
- Mechanical and plant engineering
- Medical technology
- Tool and mould making
- Tool manufacturing industry
What do you need to consider when using diamond grinding tools?
Diamond grinding tools can achieve great things when used in industrial applications. In order to exploit the full potential of these devices, a few points should be borne in mind when selecting and using them.
Diamond powder type
Grinding tools are either coated with monocrystalline or polycrystalline diamond powder. In the case of monocrystalline industrial diamonds, subjecting these to stress results in straight cutting edges – the diamond grain is virtually cut into slices during the grinding process. This type of industrial diamond can be produced easily and inexpensively.
The production of polycrystalline diamond powder is more expensive. However, this has one distinct advantage: When subjected to the stress of grinding, it breaks in such a way as to create new, sharp corners instead of a straight edge. This results in a kind of self-sharpening effect which allows materials – even extremely hard ones – to be processed particularly finely on a long-term basis.
Temperature management for diamond grinding tools
Generally, care should be taken to ensure that the cutting speeds selected are not too high. This is because although diamonds are considered to be highly robust, they do have their weak point. The material burns at temperatures of over 800° C. If such temperatures are reached during the grinding process, the diamond grinding tool will cease to be operational. This can be remedied by either using accordingly low speeds for dry grinding or appropriate coolants for wet grinding.
Choice of bonding
As already mentioned, diamond grinding wheels are not composed of pure diamond material but instead always consist of a combination of different materials. In the case of an electroplated bond, the metal base body is coated with a layer of diamond grains. Such grinding wheels are cheaper because the single-layer coating can be renewed over and over again as soon as it wears out. Diamond grinding tools based on a synthetic resin or metal bond function differently. Here, the diamond grains, bonding material and fillers are combined and highly compacted to form the abrasive coating. Although it is not possible to simply renew this coating, it offers convincing advantages through being highly resistant to wear and the fact that it can be optimally adjusted to meet individual requirements.
Robust helpers for the industrial sector
It is almost impossible to imagine life without diamond grinding tools when it comes to processing really tough surfaces and materials. Due to their being an extremely hard cutting material, diamonds offer convincing results where conventional grinding machines are forced to give up. And due to their durability and different manufacturing processes, diamond grinding tools are often a good alternative in the long term – with costs that are quickly amortised and convincing results on a permanent basis.