Iscar Not a small challenge: Cutting tools for miniature dental and medical parts

Editor: Steffen Donath

The demands for miniature dental and medical components present a specific challenge for cutting tool manufacturers. Iscar has designed tools for this sector.

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Iscar has succeeded in developing highly effective cutting tools for the sector.
Iscar has succeeded in developing highly effective cutting tools for the sector.
(Source: Iscar)

The rapidly growing field of dental and medical components is driven by enterprising orthopaedic surgeons, dental professionals and medical screw and implant companies, who work in close co-operation with computer-aided design and manufacturing (CAD/CAM) software developers and dedicated machine and tool manufacturers to transform their inventions into parts that are revolutionising medical and dental procedures. Each new component demands correspondingly advanced tools and geometries to create new and complex shapes, and to ensure extreme precision and consistently excellent surfaces.

The materials used for producing medical screws and implants include titanium superalloys, although stainless steel materials are used when a special ratio of depth of cut to chip thickness is required. These materials are gummy and cause built-up edge (BUE), which tends to wear down edge sharpness, while the high temperatures generated during chip-breaking shorten tool life and damage surface quality.

Dental screws

Iscar provides dedicated cutting tools for each of the main operations involved in machining dental screws. The company has developed two options for rough OD (outer dimension) turning. The Swisscut compact tool is designed for Swiss-type automatics and CNC lathes; it reduces set-up time and enables easy indexing without having to remove the toolholder from the machine, while the inserts are equipped with chip deflectors designed specifically for machining small parts. The second option features Swissturn toolholders and offers a unique clamping mechanism to improve insert clamping and replacement on Swiss-type machines and Jetcut high-pressure coolant tools.

Chatter-free endmills are utilised for the slot milling stage to maximise the stock removal rate, eliminate vibration and reduce cycle time. The unique ground geometry provides great surface and tool life while machining at high material removal rates, according to the company.

Pentacut parting and grooving inserts perform the cut-off operations. With five cutting edges and very rigid insert clamping, Pentacut is a stronger insert for higher machining parameters, particularly on soft materials, parting of tubes, small and thin-walled parts.

Swisscut tools are used in the face and OD turning (screw head turning) operation, while the drilling operation is performed by Soliddrill solid carbide drills with 3xD and 5xD drilling depths and right-hand cut. All of the drills feature coolant holes.

The thread milling operation features Solidthread thread mills, whose short three-tooth cutting zone with three flutes and released neck between the cutting zone and the shank enable precise profiles and high performance. The extremely short profile exerts a low force, which minimises tool-bending, facilitating parallel and high thread precision for the entire length.

Solid carbide Solidmill endmills with two flutes and 30° helix medium length perform the key head milling operation.

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Femoral head

The machining required for a femoral head involves rough turning or rough grooving, semi-finish profile turning, rough drilling, semi-finish milling, semi-finish internal turning, internal grooving (undercut), cut-off, rough turning and semi-finish turning.

Isoturn turning tools may be used for rough turning. The ISO standard tools perform most of the industry’s chip removal in applications ranging from finishing to roughing. Offered in all standard geometries, the trigon (semi-triangular) turning inserts for axial and face turning feature six 80° corner cutting edges. For profile machining, Iscar provides intricate and precise V-Lock, V-shaped special profile grooving inserts for the range of 10 mm to 36 mm. Precision ground and utility Cut-Grip full-radius inserts are used for performing semi-finish turning. Sumocham drilling tools perform the rough drilling operation, offering fast metal removal and economical indexing with no set-up time. Sumocham integrates a clamping system that offers improved productivity output rates and a shank designed with twisted nozzles as well as a durable and stable body.

Chatter-free four-flute endmills are utilised for the semi-finish milling operation; the endmills feature 38° helix and variable pitch for chatter dampening with 3xD neck relief. Chamgroove internal grooving inserts are applied for semi-finish grooving. The inserts possess extremely small bore diameters starting at just 8 mm (the other diameters being 11 mm and 15 mm) and incorporate internal coolant.

Semi-finish internal turning is performed by Isoturn inserts with Swissturn toolholders, while the cut-off operation uses Do-Grip twisted double-sided parting inserts, which feature double-ended twisted geometry for no depth-of-cut limitation.

For rough turning, the Swissturn ISO standard insert range with small shank sizes is used. Also available for this operation are standard geometry inserts with precision ground cutting edges and small radii for manufacturing small and thin parts.

The semi-finish turning operation is performed using Cut-Grip inserts. In addition to the large variety of general-use precision ground and utility inserts of the Cut-grip family, there is a vast range of inserts for specific applications and materials.

The challenges and demands placed on the cutting tools needed to manufacture miniature parts for dental and medical devices is not to be underestimated, as has been shown here. But Iscar has succeeded in developing effective cutting tools for this field that adhere to high standards of quality and precision essential for medical industry applications.