Tooling can refer to the machining of a die, tool, or mold. The mold can then be used to cast other metals/alloys that have a lower melting point than the mold material. And the design of this equipment is critical in terms of product quality, performance, and cost. They necessitate particular considerations for optimal design. The blog includes a basic yet informative aluminium die-casting tooling design guide for creating molds that are practical, efficient, and supportive.
Materials for aluminium Die Casting Tooling
Steel is the most often used die casting mold material. Though a few high-strength aluminium alloys are also used as mold materials. Based on mechanical qualities, each offers advantages and disadvantages.
Steel
H13 and P20 are two of the most often utilized tool steels in aluminium die casting. They have high hardness, stability, and polish, as well as resistance to corrosion, rust, and wear. Based on requirements, they can sustain massive manufacturing rates. Some more costly options are PAS940, Maraging 300, and Berlin Copper.
aluminium
aluminium molds are appropriate for low-volume manufacture. It offers excellent heat transmission, heat treatment, production cycle efficiency, and cost effectiveness. Mold-making materials include aluminium 7000 series alloys (7075) and 6061-T651 alloys. Despite their limited utility in die casting, they are commonly utilized for blow molds, injection molds, and structural foam molds.
Die Casting Tooling DFM
DFM, or Design for Manufacturability, is a key method for designing aluminium die casting tools. It is synonymous with manufacturing/production optimization. This focuses on ensuring that aluminium die casting molds function to specs.
These unnecessary operations might cover up to 80% of the total cost. DFM is an excellent method for reducing costs without inefficiencies prior to manufacturing. Some critical factors for die casting tooling DFM are listed below –
- Weight -More materials require more filling and solidification time, raising tooling costs. The use of hollow and pocket portions can help to reduce weight.
- Wall Thickness -A uniform thickness promotes integrity, flow, and solidification, resulting in higher quality. If the wall thickness changes, provide a gentle transition.
- Draft Angles are the perpendicular tapering of the casting surfaces to the parting line. aluminium die castings are difficult and sensitive to ejection due to insufficient draft angle.
- Parting Lines – A parting line is formed when a moving half meets a stationary half. To save tooling costs, a designer must understand the position of the line and avoid inserting metals.
- Surface Finish – For aluminium die casting, a smooth outside texture is always preferred. Specifying the roughness or finishing grade can aid in achieving a gleaming, polished, and brilliant surface.
- Ejector Pins – These pins play an important role in the solidification, shrinkage, and removal of pieces from the die. For simple and even removal, use an ejector pin on strong elements such as ribs and bosses.
- Ribs and corners are built with hollow sectional savers to provide stiffness and strength. It is recommended to use ribs rather than thickness. However, excessive use of the ribs must be avoided.
- Fillets and Radii – Radii are rounded outside edges, whereas fillets are rounded interior corners. They can promote higher integrity by facilitating seamless flow and fewer disruption.
- Undercuts – It is better to avoid these pricey additions. However, keeping the number outside helps in inevitable circumstances. Placing children under bosses might also generate problems.
- Material Flow – Metal flow difficulties may be identified via software simulation. Modern casting design relies heavily on simulation tools to achieve precision.
- Bosses are the tooling’s stand-offs and mounting points. Large fillets are required for a smooth flow and enough drafts. A consistent wall thickness is also required.
- Metal shrinkage and contraction are unavoidable. Shrinkage can be reduced by using thin sections with metal-saving cores. Additional local squeeze pins help to reduce contraction as well.
- Holes/Windows- Multiple holes and windows for electronic equipment may complicate ejection. Small yet usable apertures prevent molten metals from eventually clamping down.
Considerations for Die Casting Tooling Design in Gating and Runner Systems
A gate and runner system contains all of the entry points for molten metal into the mold. This comprises
- Basin for Pouring
- Gates
- The runner
- Risers
- Sprue
It should have no effect, splash, impurity, slag, gas, or waste. It is also preferable if the mold can be easily removed from the solid high-pressure die-casting aluminium.
Improper gating system design can result in serious flaws like as oxidation, shrinkage, porosity, and erosion. The following factors must be considered to ensure a viable design:
Freezing Period
With good control over metal flows, cavities may be filled fast while maintaining density. The riser’s liquid metal should freeze at a slower pace than casting. As a result, the riser has a longer freezing time for solidification.
Feeding Volume
For appropriate solidification, the risers must have enough capacity to fill the void. In order to freeze the cast, the metals in the risers must stay liquid. This state may be maintained by electric arcs and exothermic chemicals. The needed feed volume capacity is generally determined by freezing time and freezing demand.
Feeding Dimensions
Multiple risers will be required for large castings with intricate forms. Separate risers will feed the mold if the castings are divided into zones. These risers should be connected to the heavy solidifying part by a consistent temperature gradient.
Simulation is essential for die casting tooling.
A simulation program presents the complete casting process in virtual form. Because real prototypes of a product are relatively expensive in die-casting, software-based simulations give a quick and cost-effective option.
Advanced simulation software may evaluate a casting model’s various factors connected to product quality, such as –
- Pouring rates are used to regulate evaporation and gas porosity.
- To avoid erosion, inclusions, and entrapment, create turbulence.
- Hot points to remove any remaining molten impurities
- Thermal gradient for shrinkage, cracks, and splits
Die casting aluminium mold design problems can be avoided by accurately depicting the aforementioned factors. Changing the variables to affect the outcome becomes straightforward, effective, and instantaneous.
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