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Sodick is smooth operatorwhen it comes to surface polishing
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July 2007
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The electron beam Pika PF-32A surface finishing machine from Sodick has the ability to give components a mirror finish and reduce hand polishing by passing a 60 mm diameter electron beam over work-pieces or moulds situated within its work zone.
The Sodick PF-32A is supplied as standard with an NC controlled table measuring 1500 by 1600 by 800 mm that can accommodate a total load of up to 1000 kg. Maximum work-piece dimensions are 300 mm wide by 200 mm deep x 100 mm high. Table travel in the X and Y-axis is 300 mm and 200 mm, respectively.
The PF-32A offers production engineers a completely new alternative, electron beam machining (EBM), a process positioned between EDM and hand polishing that, without altering geometry or harming accuracy is several hundred times faster than electrical discharge machining or traditional hand polishing process, even when processing large surfaces.
Implications for industries such as optical, medical and microelectronics are considerable with respect to the cycle time saving that is offered by the groundbreaking PF-32A. Mouldmaking companies that machine precision dies to extremely high tolerances will also find significant advantage in the elimination of post-machining ‘benching’ operations.
Another area of potential is shaping the surfaces of die-cast components produced using EBM-finished tools. This is because the EBM process can be applied to depths up to 10 mm, even in areas where it is difficult to apply an electron beam, such as vertical walls for example. Furthermore, thanks to the "closed” amorphous (glass-like) surfaces generated by EBM, the tools also enjoy excellent protection against corrosion and wear thereby extending die life significantly.
Amorphous metal surfaces contain atoms that are arranged randomly, in a similar fashion to liquids, whereas ordinary metal surfaces consist of regularly arranged crystallised particles. Metals that feature crystallised structures and surfaces tend to corrode because of inherent particle lines and depositions. As amorphous structures are free of such defects and feature chemical uniformity, the corrosion resistant and water repellent properties of the slippery, sheen-like surfaces produced by EBM are extremely good.
The fact that surfaces can be made amorphous using EBM also has many more advantages. For instance, the release of plastic moulded products from dies processed by the Sodick Pika PF-32A is made easier. With many modern mould shops operating at annual volumes well into seven figures, every fraction of a second that can be cut from cycle time amounts to a real impact on profitability and throughput. Importantly, press die friction is also reduced hence instances of clogging caused by stray residue are significantly less frequent.
In testing, EBM smoothed a surface produced by EDM with a maximum peak to valley measurement of 6 µm, to less than 1 µm. Another EDM sample surface with a maximum peak to valley measurement of 20 µm was reduced to less than 3 µm following EBM exposure.
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Author
Andrew Allcock
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