Wire EDM cuts large workpieces faster

Larger wire-EDM machines are intended for users machining larger and heavier workpieces at faster cutting speeds, with excellent surface finish and lower operating costs.

Market-leading EDM specialist - Charmilles - part of AgieCharmilles GF is launching its new high-performance Robofil 640 CleanCut wire EDM machines into the UK.

The new machines, part of Charmilles' already incredibly-popular and highly-successful CleanCut range of machines (Robofil 240 CC/ Robofil 440 CC), provide customers with the same high levels of performance - cutting speeds, accuracy, surface finish etc.

- on larger and heavier workpieces.

Charmilles' CleanCut technology is used extensively in the mould tool and die sector - and increasingly in the manufacture of precision parts and components.

The introduction of the new 640 CC machines satisfies a market demand and is aimed at customers machining larger and heavier workpieces (1300 x 1000 x 510mm in size and 3000kg weight) who also require fast cutting speeds (500mm2/min), excellent surface finish (Ra 0.2 micron) and lower operating costs.

The new machines are packed with performance-enhancing machining technologies (over 50 different technologies) which provide users with the optimum EDM wire cutting solution - irrespective of the material being machined or the type of wire (special or inexpensive) being used.

** Lifetime accuracy - the 640 CC machines provide users with high precision.

The machines are rigid and stable.

Their mechanical design features an independent fixed table (where the work piece is machined) and a polymer concrete frame.

Polymer concrete is 25 times more effective than cast iron in absorbing heat - and also provides superior electrical insulation.

(Cast iron machines can be prone to current leakages which in turn can cause corrosion).

Positional accuracy is further guaranteed with the 640 CC's linear glass scales which enable the actual movement of the slide to be checked directly - and which also eliminate accuracy errors associated backlash, expansion and wear of the ball screw.

** Machining productivity - the 640 machines are equipped with the powerful Charmilles CleanCut digital spark generator which enables users to realise all the benefits from totally submerged EDM machining - even on tall parts (up to 510mm).

The generator, using the most advanced and powerful electronic components and anti-electrolysis technology - means faster and more accurate EDM machining and the elimination of the re-cast layer.

The CleanCut generator creates high intensity and perfectly calibrated sparks.

Whatever the material being machined (steel, carbide, titanium, PCD etc) or the quality of surface finish required the generator (and machine) is able to deliver.

Owing to the creation of high-intensity sparks - removal rates up to 500mm2/min during roughing operations can be obtained - and, due to the generator's frequency finish settings, the need for certain machining operations (finishing passes) can be reduced or eliminated altogether.

** Application benefits - irrespective of whether the 640 machine is being used to manufacture complex components or tools - users can experience the following benefits.

* EDM machining steel - reduction/elimination of the re-cast layer ensures surface integrity and less time devoted to secondary operations to remove it.

* EDM machining titanium - prevents oxidation and 'blueing' of titanium plus eliminates pollution of the surface (caused by copper or zinc deposits).

* EDM machining carbide tools - no degradation of the cobalt binder means better quality and longer tool life.

* EDM machining PCD/tungsten carbide tools - anti-electrolysis technology means sharper, solid and more durable cutting edges to be machined.

** Improved functionality - the CC generator ensures the rapid filling and emptying of the dielectric work tank (it takes less than 30 seconds to completely submerge a 200mm-high part) - making the CleanCut machines the most productive on the market.

To increase the functionality and capability of the machines still further - the 640's feature Charmilles-patented 'Quadrax' technology.

Quadrax, employing the principle of crossed double guidance technology on the machines X, Y and U, V axes - enables customers to cut tapers of +/-45 deg (whatever the height of the part - up to 510mm) and therefore increases the application potential of the machines.

Productivity is further enhanced by the 640's re-threading capabilities which provide users with superior process reliability - especially during unattended and lights-out operations.

These capabilities include the following.

* Automatically detecting the absence of a threading hole - if a pre-hole has been forgotten or is not in the correct position - the machine will move automatically to the next designated pre-hole position and begin machining thereby ensuring continuity in production.

* Submerged threading/re-threading - threading/re-threading of all wires (0.33mm - 0.10mm diameter) can occur even if the tank is full or partially full due to powerful and accurate suction in the lower head.

This means that users do not need to wait until the tank has been emptied or filled to perform threading functions.

Charmilles has introduced ICP (Integrated Collision Protection) on its CleanCut machines.

With ICP customers need not worry about collisions caused by programming errors or incorrect manoeuvres - because the integrated system detects any abnormal mechanical movement and stops the machine before any damage to the workpiece or wire guidance system occurs.

** Improved control - the 640 machine is equipped with the powerful CT - Millennium control and user-friendly EXPERT software systems.

The control is based on the Windows operating system and has a 10GB hard disk, PCMCIA port for a flash memory card and CD-ROM drive.

The Windows operating system makes managing programs and technologies simple and easy to use - and a DSF (Dynamic Screen Function) helps the operator with job set ups, machining parameter and technology selection via visual prompts and animated displays.

The machines' EXPERT systems help speed up the whole EDM operation.

* CT-EXPERT - selects the most appropriate machine settings, suggests the optimum wire, automatically calculates the off-sets and creates a command program linking and all the machining phases.

* PROFILE-EXPERT - automatically adjusts the machining parameters and wire tension during changes in direction during roughing operations.

During finishing operations - automatic adjustments to the advance speed are made to ensure perfect contour accuracy and fine detail realisation.

* PILOT-EXPERT - optimises machining speeds depending on the shape of the part and the machining difficulty.

So, for example - when the height of the part changes the spark power is automatically adjusted to achieve optimal speed without wire break.

* TAPER-EXPERT - enables high accuracy machining of tapers (0 - 30 deg).

It corrects the position of the wire with the angle of cut in real time.

Said Peter Pearce, Charmilles product specialist: "The new 640 CleanCut machines give customers the very best in EDM performance - quality, accuracy, surface finish, machining flexibility and process reliability - when manufacturing large parts.

The success we have had with our 240 and 440 CleanCut machines in the past make us extremely confident about the future sales performance of the new 640.

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