FREQUENTLY ASKED QUESTIONS 
Why do you offer high pressure die cast for prototype aluminum and zinc parts, most companies are telling me sand cast or ‘plaster cast’ (gravity casting) is about the same.
It is possible to achieve a similar part using a gravity cast process but the part will be made of another alloy. A high pressure die cast created from your CAD data is made using the correct alloy. Most alloys used in die casting like A 380 cannot be gravity cast without a significant loss of strength. As a result, substitute alloys made for gravity casting are used like A356 with a T6 heat treat. It takes alternate alloys like A356 with a T6 heat treatment in sand cast aluminum to reach the strength and offer similar properties to die cast. For a field proven design needing less than 25 parts to supply early testing, then a gravity cast could be acceptable.
Why would I want to spend the money on a high pressure die cast when sand and plaster can be used to pass my testing requirements?
Future recommends ‘gravity’ casting for low volumes only or for ferrous castings as they cannot be die cast. A die casting for aluminum and zinc parts can actually be cheaper if you need more than 25 parts, usually it is less money if you can justify needing over 100 parts.
Properly validated testing though is a big reason to go die cast. If the design is new, a true die cast validates the alloy, its performance and if the part can be dimensionally processed as expected using as little secondary processing as possible. It is very important in today’s law suit prone society to provide properly tested parts before commercial sales or for early commercial ‘beta’ launch. If testing is required to validate your die cast part then you should test the part using the actual process (high pressure) and the correct alloy. If there are commercial field failures of the casting and legal actions are taken, your validation and durability data should show that you used the correct alloy and the same process for validation testing.
What Alloys are available to die cast?
In zinc, ZA 3, 5 and 8 are the common alloys and Future runs them all. In aluminum AA380 or AA381 are standard alloys considered interchangeable, Future uses AA380 as our standard material. A360 and A390 and A413 are available but we require a restocking fee to change our furnace over to those alloys.
What Alloy’s are available for gravity casting, like in sand or plaster casting?
Ferritic cast metals like casting grade iron or steel are typically gravity cast. Most die cast grade zinc can be gravity cast. It is important to note that sand, spin or plaster cast zinc’s strength is very different (lower) than die cast. Select aluminum alloys can be gravity cast and still produce a reasonable casting like A356 and A319. Aluminum is more difficult to gravity cast in sand because it solidifies so quickly and the pressure packing typically associated with die casting helps to add strength. For early prototype of low volumes, Investment or split mold plaster cast aluminum is also an option for low volume aluminum prototyping. Future can quote that for you to, including complete machining and inspection.
I have a new design that I know could be cast in metal cheaper than other processes like stamped steel or machined metal, how can I select a cost effective casting material and process?
Boy, that’s a big question – we can only offer you suggestions – here they are:
Do you need extreme strength?
Gravity cast iron or steel provides more strength per pound when really high strength is required though often a greater price than die cast. For medium duty to light heavy duty parts consider aluminum gravity cast permanent mold or high pressure die casting.
If you are considering aluminum, please consider the manufacturing process closely.
The debate between gravity cast permanent mold and high pressure die casting is often a volume consideration. Less dimensional parts or complex internal cores (valves) may favor permanent mold especially in lower volume. Bulky parts in low volume like truck brackets are excellent permanent mold or sand cast products. Close net shape (little machining desired) or tighter tolerance (telecom, electrical enclosure etc.) and higher volumes tend to favor die cast. Prototype and low volume should therefore be die cast if at all possible as would high volume production. Future does not provide permanent mold but this is worth exploring for applications like automotive intake manifolds or internally cored valve body. We do offer sand, plaster and select investment casting for a good gravity cast prototype or low volume cast part.
If your part requires dimensional precision and or small details, consider die cast.
Die cast was once expensive for low volume and not time sensitive – with Future, it’s not that way anymore and that is a process we worked hard to bring to market using standard tools, running in standard machines. The best reason to use die cast is the ability to avoid machining and make a great casting right out of the mold. High pressure die casting offers fast time to net shape (like injection molding) with little or no machining and we cannot stress it enough, in this legally based society, that your prototype or low volume production should be the same process as would be used throughout the product life cycle. Gravity casting is typically variable part to part and by processor thus it is tough to scale results objectively to compare to production intentions. CNC cut billet machining is typically much stronger than any casting so the error potential to be too strong or precise is also significant. We try to be objective offering many castings choices for prototype and low volume production so we sincerely ask people to process the way they would in production. Why take a chance and struggle later making expensive tool changes, product redesigns or something more serious.
O.K., so die cast makes sense for this application. Can zinc now save you money?
Have you considered zinc? Zinc is not well known because it is thought to be too heavy. Zinc is cheaper to process and tool than die cast aluminum. AcuZinc and ZA 8 are actually stronger than aluminum (except for fatigue strength). Zinc offers excellent heat or electric conduction. Zinc can be die cast thinner than aluminum to reduce weight and save money though it is still usually a heavier part than aluminum. For small parts or good thin wall designs, zinc can be a winner for the accountant and the engineer.
I only need 2 parts to provide early testing, what are my options before I invest any more money on this design.
We can CNC cut from billet or use an SLA model to create a fast pattern for sand casting.
I know sand or plaster casting is not very dimensional unless machined, what can I expect from tolerances with die casting?
Your CAD model quality helps us. Give us a CAD model with 2 degrees of draft per wall (1 degree possible in select areas). Use as big of fillets and radius corners as possible. Tolerances cannot be held in aluminum as tight as zinc. For instance zinc can be toleranced closer to an injection molding. Aluminum tolerances are not nearly that close. For either metal, expect the tolerance to be the widest where the parting or split line of the tool crosses inside the dimension call out as the die cast mold will flash along the molds split line and the dimension will grow.
What Protective Coatings or finishes can I use with a cast part?
Conversion coatings are an engineered surface treatment to stop further corrosion. This is often called a ‘chromate’ although most are considered now ‘tri valent’ in nature and more environmental. Within this family is a conversion coating called Alodine that is especially durable for aluminum and zinc. Conversion coatings offer a good value.
‘E’ coating is a thin coating that is actually attached to the part like a conversion coating. It offers incredible protection for nearly all castings. Typical color is a medium gloss black. It is most commonly used for iron, steel and aluminum. e-coat is a reasonably priced coating for excellent durability and appearance.
Power coating is a decorative process offering wide variety of colors and finishes. This process tends to be the most expensive process while offering good looks and protection.
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