Machining Miniature Medical Parts
Miniaturised medical devices, being intricate and precise in character, depend on cutting tools that are progressive and tailor-made to machine them competently. By Yair Selek, product manager, face grooving systems and miniature industry, Iscar
The miniature medical manufacturing industry is one of the world’s fastest growing industrial sectors and the demand continues to increase for smaller, more intricate and accurate medical industry parts. Machining intricate and minute devices, often using hard-to-machine metals such as titanium, represents a major challenge for metalworking shops, which need to develop a range of advanced capabilities to meet these specialised demands, especially when involved in small batches and prototype work.
Mindful of the specific requirements of this challenging sector, Iscar conducted numerous research and field trials to develop a new range of cutting tools for miniature parts production in the medical industry. In addition, a series of modifications were applied to existing popular tools to enable the efficient and economical machining of miniature parts.
Iscar’s expanded range of machining solutions for small scale cutting tools was made possible by developing user-friendly quick indexing inserts, suitable tool geometries, and by designing ultra-secure clamping systems.
High Pressure Coolant Channel For Grooving And Turning
Incorporating a jet high pressure (JHP) coolant channel, the GEHSR/L-JHP-SL tool family is an improved version of the popular GEHSR/L screw-clamped tools. The tools are designed for Swiss-type and screw machines.
The insert clamping system enables the inserts to be fastened using a key from either side of the tool: the torx screw is inserted on one side, while a specially designed plastic screw blocks the opposite side to prevent chip entry. If indexing is required from the other side, the screw can be switched to the opposite side of the tool.
The GEHSR/L-JHP-SL tools are manufactured in 10 mm, 12 mm and 16 mm shank sizes to hold GEPI and GEMI inserts carrying different chip former geometries, and the inserts range from 2.2 mm to 3.2 mm widths. Integrated jet high pressure coolant channels extend tool life and improve chip evacuation.
Turning small parts requires light cutting parameters, making small sized economical inserts more suitable than large inserts for this type of machining. The shorter head design of the GEHSR\L tools allows higher rigidity and improved machining stability, which enables the application of higher cutting conditions to enhance surface finish.
Enabling Deeper Machining
A new Swisscut XL line featuring up to 10 mm grooving depth capability has been designed to enable deeper machining than that provided by the Swisscut Innoval line, with the aim of reducing the number of items needed by half and cutting users’ inventory costs.
The clamping design uses a special screw that can be accessed and operated from both sides of the tool, enabling inserts to be indexed without the need to fully remove the screw.
This represents a significant improvement over existing tools, where the clamping screw must be fully removed for insert indexing and can easily fall and get lost.
Different Edge Configurations
The Pentacutline now includes 17 mm diameter Penta inserts, designed with five cutting edges for machining miniature parts with up to 4 mm maximum grooving depth capability. The inserts are produced in a range of widths from 0.25 to 3.18 mm, with different edge configurations for parting, grooving, turning and threading.
Importance Of High Accuracy And Flexibility
The growing demand for high accuracy and flexibility in clamping orientation brought about an advanced new series of tool holders developed by Iscar, the Piccoace range. Featuring a patented clamping system, the tool holders set new standards in three highly important areas – accuracy, rigidity and clamping orientation flexibility.
The tool holder is capable of fast action and very secure clamping system and it increases machining efficiency by saving time when replacing an insert, ensuring rapid indexing and guaranteeing high clamping repeatability of 0.005 mm. The wide variety of Swiss-type machines available today has increased the need for multi-orientated clamping; however most of the existing tools provide a single clamping orientation. Operators are able to install and remove the boring tool from any direction.
Increasing Tool Life
To maximise the possibilities for small scale tooling, an option is the MIFR 15 inserts and tools for face grooving up to 15 mm depths and turning operations. The 5 inserts are screw-clamped into a long pocket on the MIFHR -15 bars with very rigid clamping, enabling high machining parameters and resulting in prolonged tool life. The line also includes MIFR 15 inserts in 2.5 mm, 3 mm and 3.5 mm widths, as well as full radius 2.5 mm and 3 mm inserts made from IC908 grade.
Turning Miniature Parts
To accommodate small boring diameters, Iscar has expanded its internal turning application range by introducing new positive and negative boring tools with steel and solid carbide shank options and new small size inserts. Each of the new tools features coolant channels directed precisely to the insert’s cutting edges.
The tools carry new positive (single-sided) ground EPGT and CCGT inserts. EPGT insert has a 75 deg geometry designed for a minimum bore diameter of 4.5 mm. CCGT insert features an 80 deg geometry for minimum bore diameter of 5 mm, with shank sizes in a diameter range of 4 mm to 7 mm.
Tools for negative (double-sided) inserts D min=12 mm carry ground WNGP and DNGP inserts. WNGP has an 80 deg geometry for a minimum bore diameter of 12 mm and DNGP features a 55 deg geometry for minimum bore diameter of 13 mm, with shank sizes in a diameter range of 10 to 20 mm for forward and back turning operations.
In addition, there are also new double-sided inserts with four cutting edges present an alternative to the conventional ISO standard positive inserts with only two cutting edges. The new double-sided VNGU, CNGX, CNGG and CXMG inserts operate similarly to positive inserts with the same corner angles, providing addedadvantage of double cutting edges.
The small diameter range of the Sumocham hole-making line includes new drilling heads and tools covering diameters of 4 mm up to 5.9 mm, with 0.1 mm increments. The 4 mm to 5.9 mm drilling range is covered by four sizes of Sumocham Dcn drill bodies in 3xD and 5xD length to diameter ratios; and is designed especially for this industry. A user-friendly key was specifically developed to enable easy mounting with no set-up time.
Right Tools For The Job
The medical device and implant industries have made major and highly significant advances in miniaturising medical parts; it is up to cutting tool manufacturers to enable the realisation of these achievements by providing the tools for the job, however small.
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