Riskin offeres the following casting techniques :

* milling : low volumes ( from 1 piece ) with high precision (+/- 0,01 mm )

* sand casting : low volumes ( from 1 piece ) with low precision (+/- 0,50 mm )

* centrifugal casting : medium volumes ( from 50 pieces ) with a low precision ( +/- 0,5 mm )

* high pressure die casting : high volumes ( from 250 pieces ) with a high precision ( +/- 0,3 mm )

* Several different coatings and after finishings ( wetpaint, powdercoating, anodising, impreganting, ... )

Depending on the technical and economical needs of your product, we will suggest a technique, material and production process. With our extensive know how we will not only try to save you money but to increase the quality of the part.

High pressure die casting

The main benefits of high pressure die-casting are :

 

• Die casting is an economical process offering a broader range of shapes and components than any other manufacturing technique.

• Parts have long service life and may be designed to complement the visual appeal of the surrounding part. Designers can gain a number of advantages and benefits by specifying die cast parts.

• High-speed production – it provides complex shapes within closer tolerances than many other mass production processes.

• Little or no machining is required and thousands of identical castings can be produced before additional tooling is required.

• Dimensional accuracy and stability - Die casting produces parts that are durable and dimensionally stable, while maintaining close tolerances.

• They are also heat resistant.

• High strength and low weight - Thin wall castings are stronger and lighter than those of other casting methods.Plus, because die castings do not consist of separate parts welded or fastened together, the strength is that of the alloy, rather than the joining process. The low weight not only saves on the metal cost, but also on general transport costs In some markets this is a must such as in the automotive industry.

• Multiple finishing techniques - Die cast parts can be produced with smooth or textured surfaces and they are easily plated or finished with a minimum of surface preparation.

• Simplified Assembly - Die castings provide integral fastening elements, such as bosses and studs. Holes can be cored and made to tap drill sizes, or external threads can be cast, as can slots, etc …

• Interchangable Inserts - The same part can me casted with different bran names,logos, serie numbers, without having to make ...additional tool invesments, or without engraving costs.

• Fast, large & flexible delivery - It is ideal to produce large amounts of perfectly equal products in a minimum of time. ( of some products we produce 30 000 pieces a day on a single machine ). Saving you high stock costs, transport and logistical costs; as making quick efficient deliveries of large unexpected orders possible.

• Tool life – The tool life is extremely long ( up to 400 000 shots in some cases )

• Combination casting : Because of its high perfect degree, two or more materials/pieces can easy be casted upon or on each other.Lowering or eliminating the final cost of the product treamandously.

• Rapid and flexible delivery: customers require less or no stock.

Die casting versus. other casting processes:

• Die casting vs. plastic molding :	Die casting produces stronger parts with closer tolerances that have greater stability and durability.
	Die cast parts have greater resistance to temperature extremes and superior electrical properties.
• Die casting vs. sand casting :	Die casting produces parts with thinner walls, closer dimensional limits and smoother surfaces.
	Production is faster and labor costs per casting are lower. Finishing costs are also less.
• Die casting vs. permanent mold :	Die casting offers the same advantages versus permanent molding as it does compared with sand casting
• Die casting vs. forging :	Die casting produces more complex shapes with closer tolerances, thinner walls and lower finishing costs.
	Cast coring holes are not available with forging.
• Die casting vs. stamping :	Die casting produces complex shapes with variations possible in section thickness.
	One casting may replace several stampings, resulting in reduced assembly time.
• Die casting vs. screw	Die casting produces shapes that are difficult or impossible from bar or tubular stock, ..
• machine products :	while maintaining tolerances without tooling adjustments. Die casting requires fewer operations
	and reduces waste and scrap.

Choosing the proper alloy :

Each of the metal alloys available for die casting offer particular advantages for the completed part.

• Aluminum :	These alloys are lightweight, while possessing high dimensional stability for complex shapes and thin walls. Aluminum has good corrosion resistance and mechanical properties, high thermal and electrical conductivity, as well as strength at high temperatures.
• Pewter :	This alloy offers high density and are capable of producing parts with extremely close dimensions. It is also used for special forms of corrosion resistance.
• Zamak : .	These alloys offers high ductility, high impact strength and is easily plated. Zinc is economical for small parts, has a low melting point and promotes long die life.
• Lead :	This mettal offers a high density, heavy weighted pieced that are extreemly economical.
	For more detailled information, please click alloys in our menu

Die casting process :

The basic die casting process consists of injecting molten metal under high pressure into a steel mold called a die. Die casting machines are typically rated in clamping tons equal to the amount of pressure they can exert on the die. Machine sizes range from 10 tons to 4000 tons. Regardless of their size, the only fundamental difference in die casting machines is the method used to inject molten metal into a die. The two methods are hot chamber or cold chamber. A complete die casting cycle can vary from less than one second for small components weighing less than an ounce, to two-to-three minutes for a casting of several pounds, making die casting the fastest technique available for producing precise non-ferrous metal parts.

History :

The earliest examples of die casting by pressure injection - as opposed to casting by gravity pressure - occurred in the mid-1800s. A patent was awarded to Sturges in 1849 for the first manually operated machine for casting printing type. The process was limited to printer's type for the next 20 years, but development of other shapes began to increase toward the end of the century. By 1892, commercial applications included parts for phonographs and cash registers, and mass production of many types of parts began in the early 1900s. The first die casting alloys were various compositions of lead, but their use declined with the introduction of aluminum alloys in 1914. Magnesium, zinc and copper alloys quickly followed, and by the 1930s, many of the modern alloys still in use today became available. The die casting process has evolved from the original low-pressure injection method to techniques including high-pressure casting — at forces exceeding 4500 pounds per square inch — squeeze casting and semi-solid die casting. These modern processes are capable of producing high integrity, near net-shape castings with excellent surface finishes. N.V. Riskin was the first company in the world to diecast pewter on a high pressure die casting machine, back in 1967.

Die construction :

Dies, or die casting tooling, are made of alloy tool steels in at least two sections, the fixed die half, or cover half, and the ejector die half, to permit removal of castings. Modern dies also may have moveable slides, cores or other sections to produce holes, threads and other desired shapes in the casting. Sprue holes in the fixed die half allow molten metal to enter the die and fill the cavity. The ejector half usually contains the runners (passageways) and gates (inlets) that route molten metal to the cavity. Dies also include locking pins to secure the two halves, ejector pins to help remove the cast part, and openings for coolant and lubricant. When the die casting machine closes, the two die halves are locked and held together by the machine's hydraulic pressure. The surface where the ejector and fixed halves of the die meet and lock is referred to as the "die parting line." The total projected surface area of the part being cast, measured at the die parting line, and the pressure required of the machine to inject metal into the die cavity governs the clamping force of the machine.

Hot chamber machines :

Hot chamber machines are used primarily for zinc, copper, magnesium, lead and other low melting point alloys that do not readily attack and erode metal pots, cylinders and plungers. The injection mechanism of a hot chamber machine is immersed in the molten metal bath of a metal holding furnace. The furnace is attached to the machine by a metal feed system called a gooseneck. As the injection cylinder plunger rises, a port in the injection cylinder opens, allowing molten metal to fill the cylinder. As the plunger moves downward it seals the port and forces molten metal through the gooseneck and nozzle into the die cavity. After the metal has solidified in the die cavity, the plunger is withdrawn, the die opens and the casting is ejected.

Cold chamber machines :

Cold chamber machines are used for alloys such as aluminum and other alloys with high melting points. The molten metal is poured into a "cold chamber," or cylindrical sleeve, manually by a hand ladle or by an automatic ladle. A hydraulically operated plunger seals the cold chamber port and forces metal into the locked die at high pressures.

Automation and quality control :

Modern die casters as Riskin use a number of sophisticated methods to automate the die casting process and provide continuous quality control. Automated systems can be used to lubricate dies, ladle metal into cold chamber machines and integrate other functions, such as quenching and trimming castings. Microprocessors obtain metal velocity, shot rod position, hydraulic pressure and other data that is used to adjust the die casting machine process, assuring consistent castings shot after shot. These process control systems also collect machine performance data for statistical analysis in quality control.

Die casting design :

Die casting is one of the fastest and most cost-effective methods for producing a wide range of components. However, to achieve maximum benefits from this process, it is critical that designers collaborate with the die caster at an early stage of the product design and development. Consulting with the die caster during the design phase will help resolve issues affecting tooling and production, while identifying the various trade-offs that could affect overall costs. For instance, parts having external undercuts or projections on sidewalls often require dies with slides. Slides increase the cost of the tooling, but may result in reduced metal use, uniform casting wall thickness or other advantages. These savings may offset the cost of tooling, depending upon the production quantities, providing overall economies. Many sources are available for information on die casting design, including textbooks, technical papers, trade journals and professional associations. While this section is not intended to provide a comprehensive review of all the factors involving die casting design, it will highlight some of the primary considerations.Of course Gieterijen Riskin is always available, and ready to give you the expertise advice of over 50 years that you need. Not only increasing your quality and efficiency, but also saving you money.