Aortha EVA (Ethylene Vinyl Acetate) is one of the world’s most commonly used foam products in Orthotics, Prosthetics and Footwear manufacture. Tried and trusted, this truly versatile closed-cell foam is lightweight, shock absorbing and very hard wearing. Aortha EVA retains its shape well, reflects body heat and boasts an impressive life span.
This skin friendly foam is toxic-free, washable, heat mouldable, grindable and can be fine sanded to create an exceptional finish.
Aortha EVA has good thermal properties and softer grades are comfortable and unlikely to breakdown or bottom out. The MLD material has a shore A value of 35, making it a versatile choice when both comfort and low level support is required, and the neutral colour makes it ideal for top covers and linings that will be visable.
Shore A: A35
Density: 0.20 g/cm³
Sheet size: 940 x 900mm
The ideal temperature for thermo-moulding Aortha EVA depends on the material thickness and hardness.
The standard principles would be:
1. Shore A25-A35 and 15mm EVA material: 100-130ºC temperature during 30 to 90 seconds exposure.
2. Shore A50 and 15mm EVA material: 110-140ºC temperature during 30 to 120 seconds exposure.
3. Shore A65 and 15mm EVA material: 120-150ºC temperature during 30 to 140 seconds exposure.
It is important to indicate the aforementioned conditions should be adjusted according to the following patterns:
•The thinner the material the lower the temperature or the exposure timing. The only effective way to determine heating times based on variable thickness and sheet size, is to test in stages based on the above guidelines.
• The heat source is also important; a direct infrared radiation will be much more aggressive than heating a piece with a circulating air system, meaning the temperature should be adjusted accordingly. Again, test in stages as per above.
• In general, EVA copolymers should not be extruded hotter than 200°C since degradation may occur.
• Degradation products include the elimination of acetic acid, which can account for a “vinegar” odour and corrosion of some materials.