Used Industrial X-ray Equipment
1990-1 - E Evolution 1200 Ton CNC Used X-ray Inspection EquipmentDie casting is a metal casting process that is characterized by forcing molten metal under high pressure into a mold cavity. The mold cavity is created using two hardened tool steel dies which have been machined into shape and work similarly to an injection mold during the process. Most die castings are made from non-ferrous metals, specifically zinc, copper, aluminium, magnesium, lead, pewter and tin based alloys. Depending on the type of metal being cast, a hot- or cold-chamber machine is used.
The casting equipment and the metal dies represent large capital costs and this tends to limit the process to high volume production. Manufacture of parts using die casting is relatively simple, involving only four main steps, which keeps the incremental cost per item low. It is especially suited for a large quantity of small to medium sized castings, which is why die casting produces more castings than any other casting process. Die castings are characterized by a very good surface finish (by casting standards) and dimensional consistency.
(HPDC) is widely used for the possibility of obtaining net to shape components of complex geometry and thin wall thickness at high production rates. However, a number of parameters exists, which, if not adequately determined and adjusted, result in a decadence of quality of the die cast part. Common defects in manufactured parts are shrinkage cavities, cold fills, oxide films, dross, entrapped air bubbles. One of the major source of defects in HPDC is air entrapment in the melt during the filling stage of the die, but a detrimental effect can also come from defects generated in the shot sleeve before and during the injection process. Defects can make the tensile behaviour of casting alloys unpredictable. Castings with thin sections, like those produced by HPDC technology, are vulnerable to the effect of defects since a single macrodefect can cover a significant fraction of the cross-section area. Even high integrity castings are expected to contain defects and thus it is important to predict their effect on final mechanical properties of the material.
Industrial Radiography is the use of ionizing radiation to view objects in a way that cannot be seen otherwise. It is not to be confused with the use of ionizing radiation to change or modify objects; radiography's purpose is strictly viewing. Industrial radiography has grown out of engineering, and is a major element of nondestructive testing. It is a method of inspecting materials for hidden flaws by using the ability of short X-rays and Gamma rays to penetrate various materials.
Shrinkage as molten metal cools during the manufacture of die-castings, can cause non-homogeneous regions within the work piece. These are manifested, for example, by bubble shaped voids or factures. Voids occur when the liquid metal fails to flow into the die or flows in too slowly, whereas fractures are caused by mechanical stresses when neighboring regions develop different temperature gradients on cooling. Other possible casting discontinuities include inclusions or slag formation.
Light-alloy castings produced for the automotive industry, such as wheel rims, steering knuckles and steering gear boxes are considered important components for overall roadworthiness. To ensure the safety of construction, it is necessary to check every part thoroughly.
Radioscopy rapidly became the accepted way for controlling the quality of die cast pieces through visual or computer-aided analysis of X-ray images. The purpose of this non-destructive testing (NDT) method is to identify casting discontinuities, which may be located within the piece and thus are undetectable to the naked eye.
(sources: Wikipedia, Domingo Mery, Giulio Timelli, Franco Bonollo)