SOURCING DIGEST

Multitask turning centre

In addition to simultaneous machining on the left- or right-hand spindles, a high-productivity multitasking turning machine has three highly rigid turrets for milling and turning, with ±31-mm y-axis capability on all three. Nakamura-Tome Precision Industry Company Ltd (Hakusan, Japan, www.nakamura-tome.co.jp) has designed the Super NTY3 to enable the user to optimise machining process layout by using the y-axis for machining with the upper and lower turrets at the same time. Cycle time may be reduced dramatically by machining with multiple tools simultaneously on one side or on both the left- and right-hand sides. The compact machine is designed for operator friendliness as well as productivity. With its 60° slant-bed construction, the distance from machine front to spindle centre is 572 mm.

The three 12-station turrets of the Super NTY3 provide as many as 72 tool stations for turning and 36 for driven tools. With high-efficiency motor power of 11 or 7.5 kW per spindle, the machine offers up to 22 or 15 kW of cutting power for shaft-work turning with synchronised spindles. The three milling motors can have either 7.1 or 2.2 kW of output power.

Other elements of machine construction include a servo-controlled nonlift turret, a servo-controlled tailstock function, and compensation for thermal expansion. The housing of the indexing unit on which the turrets are built has a low centre of gravity to provide high rigidity and cutting stability for turning, drilling or milling. The distances of 820 mm between spindle centres, 305 mm from upper-turret z axis origin to spindle nose and 578 mm for lower z axis stroke, provide for a wide machining range. Nanometre resolution in machine control is afforded by the Fanuc Series 31i Model A computer numerical control.

Large bioceramic bearings

A range of large-size ceramic femoral heads and acetabular cups for hip replacement surgery gives surgeons flexibility when selecting optimal joint stability for their patients.

Morgan Advanced Ceramics (Stourport, UK, www.morganadvancedceramics.com) has added a 36-mm diameter option to its implant components made of HIP Vitox alumina bioceramic. The larger diameter of the new joint bearings offers greater system strength than that provided by smaller sized products to thereby reduce the chances of joint dislocation or fracture in the period following surgery. The fact that the range of offsets extends to ±5 mm, whereas existing 28-mm products allow only ±3.5 mm, increases options during joint-replacement surgery.

The HIP Vitox bioceramic is a purpose-developed material that displays low wear compared with metal or polyethylene. It can be used in alumina-on-alumina ceramic systems or in conjunction with a polyethylene acetabular cup.

Finishing stones

Resin-based finishing tools are suitable for automated machining applications involving prosthetic implants such as artificial hip joints that need to be given an extremely smooth surface quality. The cup-shaped ultra silicon carbide wheels from Tyrolit Ltd (Crick, UK, www.tyrolit.com), for mounting on dedicated honing and polishing machines used in high-productivity orthopaedic-part production, can help shorten cycle time considerably, says the company. This is achieved by not only replacing manual lapping and minimising the incidence of necessary rework, as earlier finishing stones have done, but also by reducing the number of honing stages needed to bring the prosthesis to the polishing stage.

In automated honing and polishing operations, a succession of wheels removes the stock material in stages to prepare the hip-joint ball surface for a final polish. Finer and finer grit sizes ranging from 180 to 1500 mesh have been applied over the typically five- or six-stage process until the point is reached when a diamond paste can be employed to achieve the desired polished mirror finish. However, medical device companies have demanded shorter cycle times. Faster machine feeds and speeds can respond to this requirement up to a point, but Tyrolit concluded that reducing the number of tool changes was ultimately necessary to generate substantial savings in time and money.

The company’s new finishing tool range is designed to remove more stock at each stage while leaving the surface in a condition conducive to efficient machining in the next, finer-grit stage. This has made it possible, in one real-world application, to reduce a six-stage process taking more than 7 minutes to a three-stage process that can be completed in 3 minutes 20 seconds. Other case studies resulting in similar success have also been documented.

Surgical tools and implants

Surgical cutting instruments and accessories are machined by a company that specialises in orthopaedic implant machining and the production of tools for surgeons. Orchid Orthopedic Solutions LLC (Bridgeport, Michigan, USA, www.orchid-orthopedics.com) is a vertically integrated machining services vendor that offers capabilities in manufacturing, laser marking, cleaning, passivation, packaging and sterilisation. Projects are managed by a dedicated staff of engineers and, when the project is complete, the company can manage inventory and consignments and provide delivery with the desired frequency. Its stocking programmes are designed to relieve clients of inventory investment and ensure a high level of customer service. The company has enterprise- and quality-management systems in place to ensure that lead-time requirements are fulfilled.

The product range encompasses surgical drill bits and reamers, cutting burrs and blades; multicomponent surgical instrument assemblies; and precision machined spinal, trauma and dental implants made of stainless steel and titanium. Special processes that the company offers include laser welding, induction welding and brazing; chemical and laser etching; colour-code identification; anodising and titanium nitride, chrome and diamond coating; electropolishing; microdeburring; laser cutting; gun-drilling; multiaxis cutter grinding; and electrical-discharge machining.

The service provider maintains dedicated, manned prototype machining cells with capabilities identical to its production cells so that it can provide rapid turnaround prototypes and smooth production scale-up. Another special service is the provision of engineering support from proto-typing through to production, including help with material selection, design for manufacturability, and product performance enhancement. Custom sterile and nonsterile packaging services and labelling capabilities are also available. The firm has been supplying surgical tools for more than 25 years.

Laser cutting system

Designed for the profiling of medical implants such as stents and other precision components, a high-precision laser cutting system in an all-in-one housing employs state-of-the-art technology to cut an 8-mm-long coronary stent in reportedly less than one minute. The latest edition of the StarCut Tube system from Rofin/Baasel Lasertech (Starnberg, Germany, www.rofin.com) has a motion system based on linear-motor technology. This, together with its direct-drive rotary axis, make the system highly productive.

The sophisticated laser control unit adjusts all performance parameters of the laser source to optimally match the motion system’s travel speed. Even extremely small radii pose no problem. With its massive granite frame, the machine makes possible dimensional tolerances of a few microns with high long-term stability, reports the company.

This system allows for a choice of rod or fibre laser sources. The StarCut 18 laser with a power range of 7–25 W provides kerf widths of 18–20 µm. The new StarCut12fm fundamental-mode laser with 12-W output and the StarCut Tube Fiber with 20-W maximum power can achieve kerf widths below 15 µm. System expandability is afforded by a wet-cutting option, which is available in a four-axis version that allows nonradial cuts, and the option of adding a cutting support box for cutting sheet components with high precision.

The laser source, control, drives with supply modules, and automatic tube-loading apparatus are integrated into the StarCut Tube’s compact and ergonomically designed housing. The arrangement facilitates access to components for setup, loading and unloading.

Titanium materials

A metal materials stockist is offering titanium bar, sheet, plate, tube, wire, fasteners, fittings and open-die forging products with short lead times. Acnis International (Villeurbanne, France, www.acnis.fr) provides custom delivery and cutting services.

Characterising its activity as titanium full-service management, the ISO 9001:2000 certified supplier offers its materials expertise to the users of its products. The company can provide stainless steels and cobalt chrome alloys as well as titanium for implantable applications. In addition, it supplies special steels and coloured polyacetal copolymers for use in instrumentation. Small-quantity orders are welcome.

Swivel-head VMC

The swivel-head spindle on a compact vertical machining centre (VMC), targeted at manufacturers of medical and dental components, allows complex parts to be fully machined from plastics, stainless steel, titanium and other materials in a single setup. The FZ 08K S Tilt from Chiron-Werke GmbH & Co. KG (Tuttlingen, Germany, www.chiron.de) has a swivelling range of –20° to +115° and reportedly takes only half a second to swivel from 0° to 90°. This six-axis machining centre can be equipped with optional bar-feeding capabilities to maximise versatility. The numerically controlled (NC) swivel head enables users to produce milled surfaces and holes at every angular position, including along outer/inner contours and in tapping applications.

By including an NC linear unit with an NC vertical turning device, the machine manufacturer extends the range of application possibilities to include machining complex workpieces on six sides. This VMC’s x-y-z travel range is 18 × 10.6 × 11 in. (457 × 269 × 279 mm). Other machine features are a high-speed patented tool changer with a tool-to-tool time of 0.8 seconds and chip-to-chip time of 1.9 seconds; a rapid feed rate as high as 3000 in./min (76200 mm/min); accelerations to 2 g; and spindle speeds up to 40000 rpm. Digital drives and glass scales maximise machine accuracy.

Machine tools

A line of machine tools ranging from small turret mills to fully enclosed vertical machining centres (VMCs) and large-scale bridge mills is available from a manufacturer and supplier that places great emphasis its high standards of after-sales service, training and support. XYZ Machine Tools Ltd (Tiverton, UK, www.xyzmachinetools.com) operates five showrooms throughout the UK, in which it demonstrates all of its machinery; it can exhibit an operating ProtoTrak turret mill or bed mill at the prospective customer’s office. It provides full training in the use of its products. The service portfolio includes machine rental.

The company’s automated-product line comprises the ProtoTrak Edge and SMX turret mills with variable-speed heads and tables ranging in dimension from 42 × 9 in. to 58 × 12 in.; ProtoTrak SMX bed mills in three models with 5500-rpm spindles; a variety of ProTurn lathes suitable for small production runs; a pair of Mini Mills and the Mini Turn lathe for larger runs; a line of 8000-rpm-spindle VMCs and a high-speed VMC with a 20-hp head and a 12000-rpm spindle; a pair of rigid, durable turning centres with chuck sizes of 200 and 250 mm; XL-series lathes for large-scale turning projects; and bridge mills for handling large, awkward-to-machine workpieces. Supplementing these machines are manual turret mills, lathes and surface grinders.

Rapid prototyping services

A company that has been providing rapid prototyping services since the mid-1990s has announced the acquisition of a second direct metal laser sintering (DMLS) unit. This new machine will allow the Centre for Rapid Design and Manufacture Ltd (High Wycombe, UK, www.crdm.co.uk) to process stainless steel 17-4 and nickel-free cobalt chrome MP1.

These dense materials resist corrosion and are sterilisable. In particular, MP1 meets the requirements of ISO 5832-4 and ASTM F75 for cast CoCrMo implant alloys as well as the requirements of ISO 5832-12 and ASTM F1537 for wrought CoCrMo implants. Parts typically have tolerances of ±0.05 mm.

The DMLS additive manufacturing process produces metal components direct from a CAD model using a 200-W Yb-fibre laser and layers of fine metal powder. The CAD model is sliced into 0.020-mm layers, which are then fused together. The process enables the construction of complicated geometries including voids, tunnels and undercuts. One prominent application is the production of proto-type or one-off medical implants.

Vertical machining centre

A vertical machining centre (VMC), featuring box-in-a-box construction and proprietary drive technology to maximise machine rigidity, is designed to offer the high-accuracy performance demanded by precision machining applications such as medical device components with complex geometries. Mori Seiki France SA (Roissy-en-France, France, www.moriseiki.com) has also equipped the NMV5000 DCG machine with direct-drive motors on its b and c axes to further improve its precision. DCG stands for “driven at the centre of gravity” and signifies a technology applied to the y- and z-axis drives, whereby vibration is controlled by pushing moving structural parts by means of twin ball screws placed equidistant from the machine’s centre of gravity.

This VMC features five-axis control, but is not difficult to set up, says the company. The user’s access to the table, which was a central consideration in the machine’s development, maximises operability. The NMV5000 DCG not only performs machining that could not be done on a three-axis-control machine, but it is reportedly easy to use for milling complex workpieces. The direct-drive motors on the axes that turn the table eliminate backlash and allow precise positioning; turning is possible as well. The standard rapid traverse of 120 rpm on the c axis can increase productivity by enabling machining and turning to be performed on one centre. Options include 500- and 1200-rpm capabilities.

The latest-generation MAPPS III operating system provides support that makes five-axis machining even more efficient. Significantly reducing setup and programming times, this control offers a real-time interference checking function and provides specialised high-speed canned cycles for multiaxis machining.

Customisable wire EDM

The core features medical device manufacturers require of a wire-cutting electrical discharge machine (EDM) to meet their demands for accuracy, surface integrity, part cleanliness and repeatability are found in a wire EDM especially designed for that set of users. The Robofil 240 Med-Pack from Charmilles Technologies SA (Meyrin, Switzerland, www.charmilles.com) is highly customisable. It can accommodate a range of options that enable the machine to be tailored to a particular manufacturer’s operations. The basic machine offers smart wire threading for enhanced productivity, integrated collision protection, and linear glass scales that ensure accuracy. It can provide maximum taper cutting of 30°. An optimised filtration system keeps the dielectric fluid clean, and cutting technology designed for stainless steel and titanium further indicates this machine’s suitability for medical applications.

An optional b-axis can be added to this EDM to provide simultaneous turn and burn functionality for cutting parts such as saw guides and surgical tools. The machine can also be equipped with an automation kit that enables unattended operation through integration with a robot. Even higher levels of lights-out capability can be attained when the option of a large wire spool or Sigma organisation software is employed. A system for increasing accuracy while cutting variable taper angles is another available option. Finally, users with productivity concerns can add a high-speed generator to boost machine cutting speed and efficiency.

Fibre-optic combiners

A wide range of high-power fibre-optic combiners can be used directly in metal cutting and welding applications or to pump the latest-generation of high-power fibre-based lasers for precision marking or medical and industrial machining. Manufactured by Sifam Fibre Optics Ltd and available from the distributor AMS Technologies AG (Martinsried/Munich, Germany, www.ams.de), the newly introduced products include 6 + 1 × 1 high-power combiners with single-mode or polarisation-maintaining fibre feed-through, and combiners that feature large-mode-area (LMA) feed-throughs. The availability of LMA fibre in these combiners makes possible higher-brightness amplifier outputs with less distortion and better beam quality.

All multimode fibre combiners from this manufacturer can be supplied with as many as 19 input fibres and with larger diameter 220-µm input and 400-µm output fibres. This enables matching to a broader selection of double-clad fibres and allows the use of greater pump power so that designers can push fibre-laser and amplifier output power beyond 100 W continuous-wave.

The long-term high-power durability of these components has been proven to exceed 50000 device hours. The use of a housing designed to optimise heat dissipation helps to ensure this performance. This efficient heat management is important for enabling fibre lasers to meet demanding requirements for reliability.

CNC mill/turn centre

Even short runs of complex surgical tools, implants and other high-precision medical devices can be machined to a high surface finish cost-efficiently with a five-axis computer numerically controlled (CNC) milling and turning centre designed for the continuous production of multiple or different parts from bar stock. The fast-changeover 60-position tool magazine and trunnion swivel assembly on the compact Model MC 726 MT from STAMA Maschinenfabrik GmbH (Schlierbach, Germany, www.stama-america.com) machine make this efficiency possible. Users have reported reducing part processing times by as much as 70%, according to the machine manufacturer.

In bar-feeding applications, after the stock is fed to the rotating/swivelling-trunnion positioning element, it is drilled, milled and turned by CNC-programmed vertical and horizontal spindles. Completed pieces or piece runs are automatically offloaded by a discharge conveyor to make way for the next program.

This mill-turn centre features vertical-spindle speeds to 12000 rpm and a top horizontal-spindle speed of 5000 rpm, says the company. It can accommodate bars of stock material up to 800 mm long and 15–65 mm in diameter. Axial travels are 500 × 380 × 360 mm in x-y-z, 360° in the a axis, and 180° in the b axis. Rapid traverse is 60 m/min.

High torque 49-hp milling and 56-hp turning spindles allow machinists to process all current medical device and orthopaedic implant substrates, including titanium, cobalt chromium and nitinol. The machine features an HSK-A63 tool taper and can be supplied with an external tool magazine that enables up to 180 positions to be accommodated.

Horizontal machining centre

Flexibility and versatility are the hallmarks of a horizontal machining centre that performs grinding, milling, drilling and boring operations. Makino GmbH (Hamburg, Germany, www.makino.com) designed the G5 Grinder to enable manufacturers not only to save on capital equipment investment, but to avoid the extra setups and stack-up errors caused by having to use multiple machines for one workpiece. Additional benefits are the reduction in fixture costs that comes with five-axis capability and numerically controlled (NC) intermittent rotary dressing simplifies the manufacturing process.

The full five-axis machine includes a 0.5/1.5-second b axis for 90°/180°, a 100-rpm c axis, and a 60-tool automatic tool changer that will hold a grinding wheel as large as 220-mm diameter. A two-axis coolant nozzle enables it to accommodate variations in wheel diameter and changes in cutting direction while maintaining optimal cutting conditions. It also allows for intermittent dressing with a hydraulically powered machine feature whereby the wheel is dressed again to reestablish profile geometry on the cutting edge.

Mechanical rigidity is secured by means of stepped-column machine construction, close proximity of the ball screw to the column’s centre of gravity, and the large-diameter bearing surface of the NC rotary table. Thermal stability is a function of having an integral spindle with the cooling jacket linked to the bed temperature, a coolant chiller that maintains high-precision capability, and core-cooled ball screws in all axes, as well as using high-volume, high-pressure coolant.

Custom tube machining

Metal tubes and rods with complex custom features such as slots, notches, cross-holes and multiple angles produced by electricaldischarge machining (EDM) are manufactured for suppliers of surgical tools for minimally invasive procedures. Marshall Manufacturing Co. (Minneapolis, Minnesota, USA, www.marshallmfg.com) uses computer numerically controlled (CNC) high-precision wire EDM processes to machine the features burr-free and with a reported dimensional accuracy of 0.0005 in. (0.0127 mm). The company offers tight-tolerance part features, yet is able to create them cost-effectively in small as well as large quantities. Tubes and rods of stainless steel, titanium and other exotic metals in diameters of 0.064–1.250 in. (1.63–31.75 mm) and lengths of 0.064 in. (1.63 mm) and above can be processed.

Components can be given a variety of points and tips, including custom configurations. The company can also perform custom three-dimensional bending and contouring, threading, forming and grooving. Additional part features include swaged ends such swaged special shapes as point, chisel, hex, square, flare, and double flare; and a variety of hole configurations ranging from round to special shapes cut at various angles. The company’s full range of manufacturing processes encompasses CNC Swiss machining, grinding, knurling, milling, stamping, broaching, burnishing, induction brazing and finishing by means of heat-treating, electropolishing and plating.

Insert-clamping system

The robust T-rail interface between insert and toolholder that distinguishes a cutting system for profile machining is designed to enhance clamping stability and security and thus machining performance. The CoroTurn TR system from Sandvik Coromant Co. (Fair Lawn, New Jersey, USA, www.coromant.sandvik.com/us) is suitable for a variety of turning operations ranging from medium cutting to finishing, and can handle the operational demands of multitask machining.

The pressure exerted on tools during profiling can open up inserts when the tools use conventional clamping designs. This degrades quality and tolerances. However, this CoroTurn system employs long insert screws and horizontal and vertical rails arranged in a T to provide strong support while minimising movement in the toolholder. In addition, the inovel design features geometries optimised for effective, high-volume chip evacuation, which is a necessity for continuous machining.

Medical-alloy machining

To extend its ability to meet all customer project needs, a full-service subcontractor for medical device manufacturing has acquired computer numerically controlled and deep-hole-drilling machinery that enables it to produce proximal humeral, femoral, supracondylar, tibia, and intramedullary titanium nails and a range of titanium threaded locking screws at any level of customisation. Carniaflex srl. (Paluzza, UD, Italy, www.carniaflex.com) specialises in machining medical-grade titanium and stainless-steel alloys. The company offers services ranging from product development through to production of items such as biopsy forceps, orthopaedic components and dental and spinal implants. Included in its list of capabilities are design and engineering, prototyping, preseries and series manufacture, and attention to postproduction requirements for packaging, delivery and after-sales servicing.

Reflecting its awareness of the expectations of potential customers in the medical sector, the contractor has had its internal quality management system certified to ISO 13485 as well as ISO 9001. As evidence of its reliability and trustworthiness, the company cites the fact that it has not lost a customer in years even though patented projects pass through the plant. In-house laser marking and Class 10000 assembly and packaging facilities are available.