This technical information has been contributed by
Dynacast Inc.

Multi Slide Diecasting Process

Die Casting

Dynacast is the world leader in precision die casting of zinc, aluminum and magnesium alloys. No other die caster can rival our international network. We operate in 17 countries through 21 locations 17 of which are manufacturing. Global compatibility in design, tooling and production, provides our customers the benefit of liaison with local operations while tool and component manufacture can occur in the best place worldwide to meet their needs.

Though Dynacast's roots lie in our proprietary multi-slide die casting process we are equally as strong in the manufacture of larger parts by conventional hot and cold chamber die casting methods. This unique full service die casting capability allows customers to leverage their global sourcing while minimizing their supply base.

Die casting is a fast, cost-effective manufacturing process for production of high volume, net-shaped, tight tolerance metal components. It has the benefit of increased quality and repeatability, often at lower costs compared to other processes.

The die casting process is the injection under high pressure into a steel mold (or tool) of a molten metal alloy, which solidifies rapidly (from milliseconds to a few seconds) to form a net shaped component and is then automatically extracted.

The die casting tool will typically produce any number of components from hundreds of thousands to millions, before requiring replacement.

Benefits of Dynacast die castings:

Multi Slide Diecasting Process

Dynacast invented the multi-slide die casting process in 1936. While the designs of our machines and process controls have evolved continuously since then, the basic principles have remained constant.

What differentiates the multi-slide die casting process from traditional hot-chamber die casting is the construction and operation of the tooling, and the die casting machine required to operate it. The global use of standards means that we are able to seamlessly transfer production of a component to any region of the world, if required by a customer.

The injection mechanism of the multi-slide die casting process is very similar to that of the traditional hot-chamber die casting process.

Traditional hot-chamber die casting uses only 2 halves of the tool, making it difficult and expensive to produce parts with complex geometries. Multi-slide tooling is designed to use 4 perpendicular slides in the tool to enable very complex and accurate castings to be produced. In some cases, up to 6 slides can be added, which may be at angles other than 90 degrees. The process is used principally for small zinc components but also increasingly for magnesium parts.

The multi-slide tool is made up of the die block, slide, crosshead and cover plate. Each die block has either a cavity and/or cores on its face, which together form the complete cavity and runner profile into which the molten metal is injected. These die blocks are mounted onto sliders, which fit precisely into a crosshead, ensuring repeatable opening and closing operations. A cover plate, bolted onto the top of the tool, holds all these components together.

Each slide is managed by our PC controller, and moves independently of the other, both during the closing and opening sequences. This provides tremendous flexibility, which ensures part integrity and prevents damage to the tool.

Ejection of the parts is achieved with an airblast, which blows the shot clear of the cavity and into a padded collection mechanism.

The machines themselves cycle at speeds of up to 75 cycles per minute (4500 shots per hour). This is achieved by using pneumatics, rather than slower hydraulics, to operate the different parts of the machine. Mechanical toggle mechanisms and hydraulic thrusters supplement the weaker locking force available with pneumatics, ensuring that the die casting tool is held together securely during the injection process.

Conventional Diecasting Process

The traditional die casting process is the injection under high pressure into a steel mold (otherwise known as a tool or die) of a molten metal alloy. This solidifies rapidly (in a few seconds) to form a net-shaped component, which is then automatically extracted.

The majority of zinc components, and non-ferrous components in general, are produced by the high-pressure die casting process.

There are two basic die casting processes, differentiated only by their methods of metal injection: hot-chamber and cold-chamber. The hot-chamber process is only used for the zinc alloys (except ZA-27) and magnesium alloy AZ-91. Aluminum can only use the cold-chamber process due to aluminum alloys eroding the immersed steel of the hot-chamber injection mechanism.

The metal injection portion of the cycle normally terminates with a sharp intensification of metal pressure. This is developed by increasing the hydraulic pressure on the plunger, forcing additional metal into the die cavity to supplement the shrinkage that takes place during solidification. It is beneficial to the extent that it promotes complete filling of the die cavity and creates a uniform metal density. Excessive intensification is undesirable, because it forces molten metal between die members, causing die wear and excessive flash, which must subsequently be removed. Dynacast finely controls this intensification to produce better quality parts.

The peak pressure multiplied by the projected area of the entire shot generates the force imposed on the machine structure. This pressure often dictates the size of the machine required to make a casting, which in turn affects the cost of the finished product. Machines are rated by the number of tons locking force capable of being developed in long-term, continuous operation. The casting is normally ejected from the die, attached to extra material. This includes the gate, runner (which may have a biscuit), any overflows and possibly flash. Collectively, all of this material (known as the shot) is then transferred to a trim die, which separates the casting from the extraneous material. This trimmed metal is subsequently recycled.

This technical information has been contributed by
Dynacast Inc.

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