The recent machines supplied by Frech have the added benefit of Pre-Fill. This options allows us to send the machine piston down a pre-set amount forcing air out of the machine before the die closes. This means the only air contained in the process is the volume of air of the cavities and runner and excludes the nozzle and gooseneck feature of the machine. Running our machines with the Pre-Fill option utilised reduces total porosity in the casting by as much as 15%. On average we consistently maintain porosity at around 2.3% which is significantly below the industry average of between 3% and 5%.
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This section of a zinc diecasting shows low levels of porosity which can be achieved through correct programming and advanced machine facilities such as Pre-Filling. As part of our routine quality control we measure porosity against agreed levels with our customers to ensure each batch of castings is manufactured correctly. |
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The dark areas indicate entrapped air referred to as porosity. Excessive porosity can cause weakness in the casting and also prevent successful post casting processes such as powder coating and plating. If the casting is subjected to higher temperature over 100 deg. C the entrapped air expands and creates blisters or blow holes on the surface. |
