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The Magnetfinish range of machines has been designed to finish all types of cutting tools, improving tool lifetime and performance under heavy cutting conditions.

The Magnetfinish technology has been developed to increase tool lifetime.

The process polishes the flutes on all types of HSS and Carbide rotary tools such as endmills, form cutters and drills, provides conditioning or edge honing of the cutting edges (micron rounding of the edge) and is also used to polish profiles on taps and coated cutters.

This is said to result in a superior chip flow, leading to the increased productivity of the tool.

The surface finishes on the tool flutes that are generated by the Magnetfinish process are of the order of 0.02um Ra.

These fine finishes are said reduce the subsequent friction caused by chips running through the cutting tool flutes by 50 per cent.

This results in faster and smoother chip evacuation that allows faster feeds to be used, speeding up cycle times during milling and drilling operations.

The tools’ primary cutting edges are machined to allow a defined and reproducible radius of between 3 and 50um to be created.

This edge-preparation process can increase the lifetime of tools such as ball-nosed end mills by a factor of four and allows more consistent machining results to be achieved.

The Magnetfinish process is based around two rotating magnetic heads, between which a layer of processing powder is placed.

The powder is made up of magnetic and abrasive compounds.

The magnetic compound is used to hold the abrasive compound within the magnetic field that is generated by the rotating magnetic heads and then the abrasive compound itself performs the cutting function to the surface of the cutting tool.

The thickness of the processing powder is between 5-7mm and this allows 50 layers of powder grains to contact the surface to generate the fine surface finishes and radius edge forms that are required onto the cutting tool.

Because the powder is constantly refreshed during the Magnetfinish process, 100 per cent reproducible results are said to be guaranteed across large batches of tools.

A typical deep hole carbide drill of 6 x 180mm in length can be machined in 20sec, with the average machining time for smaller tools being in the region of 5-10sec.

Magnetfinished milling cutters are especially effective when used for hard milling applications, such as those used for producing very fine milled finishes on moulds that then require little or no hand polishing.

For the cutting tool to achieve an effective chip load, the associated feed rates and spindle speeds must be much higher than those normally applied in traditional milling.

The higher feed rates also make it possible to complete a much larger number of passes across the workpiece more quickly than with traditional methods.

The combination of light cuts at very high feed rates makes it possible to remove steel in the hardened state with small-diameter, fine-radiused tools said to generate surfaces that approach the quality of those that are often finished polished by hand.

A variety of Magnetfinish machines are available from small and cost-effective manually loaded machines for low-batch production through to large, automated cells with a capacity to automatically load cutting tools for processing from 240 station magazines.

The entry-level manually loaded MF61 machine has a general capacity for cutting tools from 0.1 to 20mm in diameter and for tool lengths of up to 300mm.

It is equipped with a simple laser-based safety curtain to allow for parts to be manually exchanged at ease without the need to constantly open and close a door.

Tools are manually loaded and unloaded to a centrally positioned pneumatic gripper unit that will accept cutters of various diameters and lengths.

This machine in the automated MF61A version can be specified with an optional 45-position automatic part loader.

Both machine versions are operated by a touch-panel operator control screen and all tool data can be stored for subsequent recall.

It is possible to mix different types and sizes of cutters within the optional auto-loader, with the entire batch of cutting tools then being processed without any operator involvement.

Both variants are very compact machines, requiring the minimum of floor space for installation near to adjacent cutter grinding cells.

Dorman Machine Tools

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