The title of this page really should be 'Electrode Design' rather than 'Electrode Modelling' because  electrodes need to be designed for a purpose, with thought and experience applied, rather than purely modelled from a feature or set of features.

The designer ideally should have knowledge of EDM and CNC machining as well as toolmaking experience when designing electrodes because there are many different factors to take into account. 

Some of the common things to watch out for are:

• Electrodes with too small gaps between the features making it impossible to machine.
• Electrodes with a combination of large features and small detail. - This can cause problems with EDM.
• Electrodes with no overhangs. These can cause 'feather edges' on the form being eroded.
• Insufficient support for tall thin features - causing them to bend or break.
• Collisions with either the electrode base or other form.
• Electrodes with no clear datums - Making them difficult to position.

You can be sure that any electrodes designed & modelled by us take all these factors (and many more besides) into consideration ensuring that your electrodes are trouble free every time.

2D orbiting

Another area where problems can occur, is when the EDM machine used is only capable of 2D orbiting rather than 3D.  Any radii that are not vertical on the electrode, and any steep draft angles, will not be produced at the correct size. This problem is exaggerated the larger the spark gap.  This can lead to miss-matched form, incorrect moulded products and flashing split faces.

At Alphatech we have developed a system to counteract this effect in many situations. We can employ a special machining technique that will correct the problems  caused by 2D orbits

 
Approaches to the use of EDM machining and electrodes can vary widely among different toolmaking companies. 

There is no right or wrong approach with most toolmaking companies adapting their use of electrodes to suit the type of tool they produce and the machinery and equipment they own.

Companies that employ High Speed Machining Centres with pallet changers and similar high volume EDM equipment, often prefer smaller electrodes with single or few features even though this will result in the total number of electrodes being higher. This is because they can often buy pre-mounted electrode blanks in standard sizes saving labour in making custom size blanks. The high speed machines will make short work of the larger quantities of electrodes to machine.

Small companies without  HSM equipment often prefer to make larger electrodes with as many features as possible. These can save on CNC and EDM set-up time and also are more suitable for unattended overnight running.

At Alphatech we work for companies, large and small, that use all different approaches, so we maintain a file on each company that contains all their preferences. We then refer to this file when we receive new work. This ensures that we are always working in harmony with our customers