Posts Tagged ‘zinc alloys’
Spin Casting and Rapid Prototype Technology
Spin Casting has brought rapid prototype technology to a completely different level of production efficiency. With the capability of producing prototypes in different metals spin casting has given companies options never before experienced in rapid prototype techniques. Now with spin casting technology fragile, functional metal parts can be manufactured with rapid prototype models. Spin casting can cut production times by a considerable percentage and have prototypes available for testing the same day as production. The spin casting technology also eliminates the need for considerable post production tooling and refinishing. Spin casting technology is also easy to use with all the custom features necessary to produce even complex design specifications.
Spin Casting Fabrication Metals
Spin casting technology can accommodate a number of metals to produce fine quality prototypes that are fully functional and produced according to design specifications. Using rubber molds a variety of metals can be used with spin casting technology to produce a variety of finished products. Spin casting can produce prototypes consisting of zinc alloys which are a favorite casting metal, as these metals can accept a variety of surface finishing compounds. These alloys are commonly used in spin casting to replace aluminum, copper and low-grade steel. Spin casting prototypes are suitable for electroplating to produce the appearance of brass, silver or gold.
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Spin casting can also produce prototypes in many other types of materials as well. Using polyurethane, polyester, epoxy or wax; spin casting can produce a number of products in a variety of materials. Comparing the production cost of spin casting and traditional tooling has spin casting as the most cost effective method of production. Spin casting can produce the same products as traditional tooling and molds but for a fraction of the cost. With spin casting an additional feature is be able to control the number of items manufactured. With traditional manufacturing, single or small item orders are generally more expensive with prices decreasing as unit numbers increase. But spin casting costs remain stable throughout the production process regardless of the number of items produced making it very cost efficient.
Spin Casting Fabrication Steps
Spin casting requires the use of molds that are made from a silicone based material and can accommodate the original parts to form exact details of the models used in production. Once prepared the spin casting molds are hardened and the models are removed leaving detailed molds that will be used for prototype production. With spin casting temperatures reaching around 400C air vents are cut into molds to allow gases to escape during the production process. Spin casting uses centrifugal force to inject fabrication material into molds ensuring all details of the model are reproduced in the prototype. Spin casting allows for complete adjustment of production speeds, pressure controls and cycle times. Prototypes produced by spin casting are precision products that will meet all design specifications and tolerances.
Spin casting cuts the time needed to produce prototypes by a considerable amount and will have prototypes available for the testing phase in a shorter amount of time. Spin casting technology can support post production finishing by being able to use a wide variety of materials. Spin casting techniques are easy to use, cost effective and a time conserving technology for the production of rapid prototypes.
Writer for Objet Geometries
Posted in Jewelry | 
Tags: Casting, production, prototype, prototype models, quality prototypes, Rapid, Spin, Technology , zinc alloys | 
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The Zinc-aluminium Die Casting Alloys
The zinc-aluminium die casting alloys
New high performing zinc-aluminium ZA casting alloys (zA-8, ZA-12, ZA-27) give superior mechanical properties which designers can apply utilizing die casting technology. In general the ZA alloys are stronger, harder and offer more creep resistance than standard zinc alloys and can be used where bearing properties are important.
Aluminium alloys with 0.5-0.9% Fe content have largely replaced 1350 EC alloy for making electrical circuits because the latter continuously suffered from gradual loosening at terminals, which led to overheating. This problem has been totally removed in new conductor alloys without sacrifice of conductivity.
To get economic benefit of weight advantage of aluminium wire should be capable of attaching securely to standard fixtures without special handling techniques. But EC wire on binding screw terminals tightened to a standard torque may become loose, when the wire heats due to being overloaded. The wire gets expanded more than the Cu-alloy fixture and creeps to relax the added stress.
On getting cool it contracts to a smaller dimension, whereby the area of contact is reduced and it permits oxide to form at interface. On a subsequent current overflow, the overheating increases which leads to further loosening of wire. EC wire annealed for adequate bend ability gets sub structurally loosened at 200°C and ultimately fails due to repetitions of these cycles.
The new alloys (800 series) of 0.5-0.9% Fe have much better microstructural stability and creep resistance and, therefore, they are not prone to these failures.
While annealed to the same ductility or bend ability, the high Fe alloys are double strong. This capability has been established by practical field use of many years in USA, Europe and South Africa after these alloys were introduced in 1968.
Better and latest alloys which not only provide high integrity to terminations but are suitable for magnet wire after normal hot annealing have been made after adding a third alloy to improve its performance examples are 0.5% Fe with 0.5% Co and 0.5% Fe with 0.2-0.4% Si.
Processing and microstructure:
In continuous casting a bar of 50cm2 is made at 16 m/min on a 2.5m diameter copper wheel. The quick solidification results in a 20 μm dendrite arm spacing and eutectic red cpacing of about 0.2 μm with a supersaturation of about 0.1% Fe. These very fine particles play a significant role in giving stability to substructure while being incapable of nucleating crystallization.
The presence of sub grains has been known in hot worked aluminiums but without quantitative determinations of the dimensions or the effects on properties. As the temperature rises from 200-450°C, the cold yield strength of the hot worked product decreases greatly from the strengthening made by 97.5% cold rolling.
As has been seen in many hot worked metals, the yield strength is inversely proportional to sub grain diameter. Because the temperature is less and strain rate is high in a given pass than those in the previous one, substructure “inherited” from i.e., carried forward from, the latter is altered by dislocations to the existing walls to raise their density and by formation of new walls to subdivide the sub grains lessening their size.
Posted in Small Business |
Tags: aluminium alloys, die, Europe, South Africa, Steve Manik, sub, USA, wire, za alloys, zinc alloys |
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