Die casting is actually a metal casting method that is characterized by forcing molten metal under high pressure into a mold cavity. The mold cavity is generated using two hardened tool steel dies that have been machined healthy and work similarly to aluminum die casting parts during the process. Most die castings are manufactured from non-ferrous metals, specifically zinc, copper, aluminium, magnesium, lead, pewter and tin-based alloys. Based on the type of metal being cast, a hot- or cold-chamber machine can be used.
The casting equipment along with the metal dies represent large capital costs and that has a tendency to limit the process to high-volume production. Output of parts using die casting is relatively simple, involving only four main steps, which ensures you keep the incremental cost per item low. It really is especially designed for a big number of small- to medium-sized castings, this is why die casting produces more castings than any other casting process. Die castings are characterized by a good surface finish (by casting standards) and dimensional consistency.
Two variants are pore-free die casting, that is utilized to eliminate gas porosity defects; and direct injection die casting, that is utilized with zinc castings to reduce scrap and increase yield.
Die casting equipment was invented in 1838 when it comes to producing movable type for that printing industry. The very first die casting-related patent was granted in 1849 for a small hand-operated machine with regards to mechanized printing type production. In 1885 Otto Mergenthaler invented the linotype machine, a computerized type-casting device which took over as the prominent kind of equipment within the publishing industry. The Soss die-casting machine, manufactured in Brooklyn, NY, was the initial machine to be sold in the open market in Canada And America. Other applications grew rapidly, with die casting facilitating the development of consumer goods and appliances by making affordable the production of intricate parts in high volumes. In 1966, General Motors released the Acurad process.
The key die casting alloys are: zinc, aluminium, magnesium, copper, lead, and tin; although uncommon, ferrous die casting is likewise possible. Specific die casting alloys include: Zamak; zinc aluminium; water proof aluminum enclosure to, e.g. The Aluminum Association (AA) standards: AA 380, AA 384, AA 386, AA 390; and AZ91D magnesium.F The following is an overview of the advantages of each alloy:
Zinc: the easiest metal to cast; high ductility; high-impact strength; easily plated; economical for small parts; promotes long die life.
Aluminium: lightweight; high dimensional stability for complex shapes and thin walls; good corrosion resistance; good mechanical properties; high thermal and electrical conductivity; retains strength at high temperatures.
Magnesium: the simplest metal to machine; excellent strength-to-weight ratio; lightest alloy commonly die cast.
Copper: high hardness; high corrosion resistance; highest mechanical properties of alloys die cast; excellent wear resistance; excellent dimensional stability; strength approaching those of steel parts.
Silicon tombac: high-strength alloy made from copper, zinc and silicon. Often used as a replacement for investment casted steel parts.
Lead and tin: high density; extremely close dimensional accuracy; employed for special sorts of corrosion resistance. Such alloys are not found in foodservice applications for public health reasons. Type metal, an alloy of lead, tin and antimony (with sometimes traces of copper) can be used for casting hand-set key in letterpress printing and hot foil blocking. Traditionally cast at hand jerk moulds now predominantly die cast once the industrialisation of the type foundries. Around 1900 the slug casting machines came on the market and added further automation, with sometimes lots of casting machines at one newspaper office.
There are numerous of geometric features that need considering when creating a parametric style of a die casting:
Draft is the level of slope or taper presented to cores or other aspects of the die cavity to enable for convenient ejection of your casting from the die. All die cast surfaces which are parallel to the opening direction of the die require draft for the proper ejection from the casting through the die. Die castings which feature proper draft are easier to remove from the die and bring about high-quality surfaces and more precise finished product.
Fillet will be the curved juncture of two surfaces that would have otherwise met with a sharp corner or edge. Simply, fillets could be included with a die casting to eliminate undesirable edges and corners.
Parting line represents the idea where two different sides of the mold combine. The position of the parting line defines which side of your die will be the cover and the ejector.
Bosses are included with die castings to provide as stand-offs and mounting points for parts that must be mounted. For optimum integrity and strength from the die casting, bosses will need to have universal wall thickness.
Ribs are included with a die casting to offer added support for designs which need maximum strength without increased wall thickness.
Holes and windows require special consideration when die casting because the perimeters of such features will grip towards the die steel during solidification. To counteract this affect, generous draft needs to be included with hole and window features.
The two main basic types of die casting machines: hot-chamber machines and cold-chamber machines. These are rated by just how much clamping force they could apply. Typical ratings are between 400 and 4,000 st (2,500 and 25,400 kg).
Hot-chamber die casting
Schematic of your hot-chamber machine
Hot-chamber die casting, often known as gooseneck machines, rely upon a swimming pool of molten metal to give the die. At the start of the cycle the piston of your machine is retracted, that enables the molten metal to fill the “gooseneck”. The pneumatic- or hydraulic-powered piston then forces this metal out of the die casting parts to the die. The benefits of this system include fast cycle times (approximately 15 cycles one minute) along with the comfort of melting the metal in the casting machine. The disadvantages of the system are that it is limited to use with low-melting point metals and this aluminium cannot 21dexupky used since it picks up some of the iron whilst in the molten pool. Therefore, hot-chamber machines are primarily used in combination with zinc-, tin-, and lead-based alloys.
These are generally used once the casting alloy should not be employed in hot-chamber machines; such as aluminium, zinc alloys by using a large composition of aluminium, magnesium and copper. The procedure for such machines get started with melting the metal within a separate furnace. A precise quantity of molten metal is transported towards the cold-chamber machine where it can be fed into an unheated shot chamber (or injection cylinder). This shot is then driven in to the die by way of a hydraulic or mechanical piston. The greatest drawback to this system is the slower cycle time due to the have to transfer the molten metal through the furnace towards the cold-chamber machine.