ElectroSpark Deposition - Impregnation of steel tools with tungsten carbide

Aegis recommends and distributes impregnators manufactured in the USA by the Rocklin Manufacturing CoModel 850

.... buy your own unit or make a test using our Rockliniser

The process of ElectroSpark Deposition results in the impregnation of one metal or alloy into the surface of another metal, often a piece of tooling or a machine component. As Materials Technologists, we are usually interested in appying a very hard material, such as Tungsten Carbide into the edges and faces of steel tools, giving them a much greater surface hardness and resistance to abrasion, whilst retaining the strength and toughness of the underlying material. Applied to localised areas on the cutting, relief or forming edges of tools, the treatment gives dramatic improvement in life between regrinds, greatly increasing production efficiency and saving on tool cost.


Fact:- Appropriate use of the Carbide Impregnation Process can increase Tool life by up to 1000%! Want to know how? Read on...

Carbide impregnators are currently used by hundreds of Companies to their great benefit on the following applications:-



The process involves creating a series of explosive sparks between a conductive workpiece and the deposition electrode. The spark is generated by discharging a capacitor which has been charged by a direct current. The discharge results in the impregnation of small particles of Tungsten Carbide, or whatever material the electrode is made of, into the workpiece.

Continuous sparking and traversing a tungsten carbide electrode over a small area produces a top layer of Tungsten Carbide of pre-determined thickness on the workpiece. Once the area is covered no further deposit or build-up occurs, unless the 'energy' control on the unit is turned up, when a thicker layer will result.

The process is quick and can be done in situ if necessary.

Using a tungsten carbide electrode, the surface produced has the hardness of Tungsten Carbide, 70-76Rc, and is part of the base material, therefore it cannot flake or chip off. Although the spark is hot, the process is effectively "cold" and does not affect the temper or toughness of the base material.

The depth of carbide impregnated into to the surface to be treated is determined by the amount of energy in the sparking process. This is preset on the Impregator, and determines the thickness of the layer being deposited. Going back over a coated area more than once does not build up an uneven coat, but does tend to densify the layer previously deposited, as well as ensuring that no areas remain untreated.

Depending on the model of impregnator selected, it is possible to deposit a layer of Tungsten Carbide up to 0.25mm thick, which, having a slightly rough surface, helps to retain lubricant especially in deep draw and bending tools.

Carbide Impregnation treatment will not turn a high-speed tool into a carbide tool, but will give improvement to its abrasion resistance and therefore its life.

Rocklin have 50 years experience of making ESD impregnators, which are known as "Rocklinizers". The range available today comprises 3 models designed to fulfil all the needs of a modern toolroom. They range in weight from 4.5 Kg for the "Micro" (smallest), to approx 12 Kg for the model 850 and 16 Kg for the 950 (most powerful). All models can be supplied for use with 220-240v power supplies. The Micro model is portable for in-factory use when powered from its built in Li-ion battery, or can be connected to mains electricty for continuous use.

Model 950Model 850Micro
The most powerful model is the 950 which can deposit over 0.25mm of hardmetal onto the toolsurface. click for brochure.

Such a great thickness is not normally needed, so the Model 850, also coming with a rotary applicator, will do 90% of toolroom jobs. click for brochure.

The Micro impregnator is ideal for use in the factory for applying material to tools which are already set for use. It is particularly effective when applying a thin layer of carbide underneath punching die cutting lands, the extra roughness on the relieved surface retaining the punched slugs in the die. It provides a certain cure to the vexing problem of slug retention and tool smashes. click for brochure.

Rocklin's 500 modelIf you would like to find out what Rocklinising can do for you, we can do sample parts here in Bewdley so long as the required deposition is within the capabilities of the Rocklin 500 model, which has a maximum deposition thickness of around 0.05 mm for tungsten carbide onto steel. We own one of these (now superceded) impregnators, which we use for customer trials. If the trial is successful, we occasionally rent out this machine to toolrooms for to verify the process prior to machine purchase. Please contact us before sending in samples for test.

Aids Carbide Hardedge UnitUntil 2001 we were selling the "Hardedge" unit (pictured right) for this purpose, which was a British designed and built machine, proven by decades of useage around the world. However, all good things come to an end, and the owner of the producing company decided to retire, leaving noone to continue supplying and supporting the units. Then we met the Rocklin Manufacturing Co and realised that while Hardedge had been selling well in Europe and Asia, "Rocklinizers" had been selling even better in the USA and had even developed new capabilities that Hardedge didn't have, such as the ability to deposit Titanium Carbide onto tungsten carbide tooling and build up worn steel parts with "Rockhard" electrodes.

Different thicknesses of Carbinite carbide, next to my ballpoint: click for the linked pageWe also work with another US company who does not supply impregnators, but can do Impregnated coatings on a subcontract basis - also having the ability to deposit significantly thicker coatings than a Rocklinizer can, up to 0.4mm thickness (0.016"). They can also coat much bigger areas than would be addressed with a Rocklinizer - and can even coat down the inside of steel tubes, if that is required. The very thick coatings tend to be extremely rough - as shown in the photo on the left.

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