Zinc Diecasting
Zinc diecasting is the process of injecting molten zinc under high pressure into a precision, hardened-steel tool. As the zinc rapidly cools in the tool, it solidifies to take the shape of the component part designed into the tool. Fielding operates multi-slide, hot-chamber diecast machines to create high volumes of precision net-shape parts. Our machines are a mix of OEM-supplied and custom in-house designed & built hydraulic and pneumatic machines that can produce parts in a wide size range.
Net Shape Parts
Multi-slide design allows complex parts and features to be cast directly, eliminating the need for secondary machining operations.
Superior Functionality
Zinc castings offer superior performance for many applications, including EMF shielding in electronics, thermal conductivity for heat sinks, high strength performance for industrial applications, and more!
Tight Tolerance
With our experience in precision tooling, we can hold part dimensions well-within the standard +/-.005" tolerance and critical dimensions better than +/-.001" on miniature and micro castings.
Affordability
With minimal process scrap, fast cycles, minimal secondary operations/machining and tight tolerances, diecasting allows for the high-volume production of precision components at minimal piece price costs.
Repeatibility
The hot chamber process significantly reduces variability, creating dimensional repeatability +/-.0005" part-to-part
High Volume
Diecasting is a rapid, repeatable process to produce precision net-shape parts from 10K per year to 10MM per year.
Zinc Alloys
Fielding offers different zinc diecasting alloys with a range of mechanical properties best-suited for the final application. Fielding only works with certified, local alloy suppliers to guarantee correct chemical composition to ensure the final cast part is suitable for the application. We do not re-introduce/re-melt material scrap in our diecasting machines, which can introduce process variation and quality defects in the final casting. We work with our suppliers to reprocess all material scrap and return the material to alloy specifications, creating a truly green process with no zinc scrap entering a landfill.
ZAMAK Alloys
Zamak is a family of alloys most commonly used in diecasting. These alloys contain varying amounts of Aluminum (Al), Copper (Cu) and Magnesium (Mg). Fielding casts ZAMAK #2, #3, #5, and #7 alloys to provide different material properties to match your application.
EAZAC Alloy
EAZAC is a proprietary zinc alloy developed for hot chamber diecasting by Eastern Alloys Inc. EAZAC offers improved creep resistance, higher yield strength and increased hardness. EAZAC allows zinc diecastings to be used for higher temperature applications where the traditional ZAMAK alloys may cause issues due to high-temperature creep.
the Diecast Process
In the diecast process, metal is melted and injected into a hardened die (aka the "tool") which forms the negative imprint of the part. As the molten metal cools, it solidifies in the tool cavity, forming the shape of the desired part. The tool is opened and the solid metal part is ejected. The tool is sprayed with die release and closed for the next cycle to produce another part. Fielding Manufacturing operates multi-slide, hot chamber diecast machines which have the following advantages over conventional diecasting:
Multi-Slide
Conventional diecasting consists of two tool halves to fit a single-action press; similar to standard injection molding machines. The tool works in one axis when it closes, requiring complex and expensive cams and actions in the tool to produce different geometries. Multi-slide machines have up to 5 moving tool components (dies and/or cores) that come together with separate actions on the machine to create complex geometries. This allows complex part geometries to be produced in one cycle. It eliminates the need for additional actions in the tool, reducing the tooling complexity ultimately leading to a lower tooling capital investment. The separate components in multi-slide tools improve serviceability leading to less downtime, reduced tool maintenance costs, and extended tooling life.
Hot Chamber
Traditional diecasting is done with cold chamber presses; metal is melted in a separate furnace then transported (typically ladeled by an operator) into the injection unit at the machine during each cycle. This introduces variability in the process as molten metal cools and is metered unevenly before injecting into the closed tool. In hot chamber diecasting, the metal melt furnace is built into the machine and the injection unit is submerged in the molten metal where it automatically charges and consistently meters each shot to inject into the closed tool. This creates a significantly more consistent process from shot-to-shot (between each machine cycle), significantly minimizing process variation for repeatable, high precision parts.
Rapid Production
Incorporating the melt furnace and injection unit directly into the machine, allows for rapid cycles for high volume production. Depending on the part/tool complexity and the machine platform, Fielding Manufacturing produces a precision casting every 2.5 to 10 seconds. We can also employ multi-cavity tooling to exponentially increase throughput, supporting programs from 10K to 10MM parts per year.
Precision Net-Shape Parts
The consistent cycling of the hot chamber diecast process creates precision castings with +/-.0005" dimensional repeatability on critical features. Combined with multi-slide tool design, our diecast machines produce tight tolerance miniature & micro zinc castings, repeatably at volume while minimizing cost. For many part designs, multi-slide tooling can produce net shape final parts and eliminate the need for additional machining operations required by conventional tooling; a further cost savings to yield functional, quality parts for your application.
Cast Part Capabilities
We operate casting machines in 3 size ranges; 2x2", 4x4" and 6x6". These sizes refer to the L x W dimensions of the tool die face. Our machines can produce parts from a 0.5 oz. shot size up to 10 oz. For a rough approximation - we can produce parts that fit in a 1/4" cube up to a 3" cube (thinner parts can be produced up to a 5 sq. in. footprint). CONTACT US today with your design to determine if it is a good candidate for our machine capabilities.
Designing Zinc Diecastings
Zinc offers several advantages over other cast metals and is a favorable material choice in many applications. Many parts are designed or first produced using traditional manufacturing methods; machining, turning, stamping, etc. Design features tailored for other manufacturing processes may produce defect modes when diecasting. For the most robust design, always design parts for final form, fit & function in the application AND for manufacturability in the manufacturing process being used. Below are a few (though not all!) design considerations for zinc diecast parts. Please reach out to us for a free manufacturability assessment of any part design you may be considering for zinc diecasting.
the Advantages of Zinc
Zinc is stronger, stiffer and tougher than molded plastics as well as aluminum and magnesium diecastings. It holds better dimensional repeatability than other casting metals, making it suitable for tight tolerance, precision parts with high repeatability at volume. Zinc is non-magnetic and a strong EMF insulator, making it a good choice for electronic connectors, housings, shielded covers, etc. Although not as lightweight as aluminum or magnesium, zinc offer high yield strength, improved impact strength and superior torsional and bending stiffness for high-mechanical load couplers, torsional hubs, gears, etc. With a higher elongation than other cast metal, zinc castings are a good choice
for large assembly components as they work well in crimping, staking, swaging, riveting, and other secondary operations. Zinc castings can be finished in a variety of functional plate and paint options, and can achieve high cosmetic finishes with proper part, tool and process design. When casting zinc, minimal tool wear can be achieved with proper tool design and maintenance, leading to long tool life and maximization of initial capital investment.
Thin Wall Sections (Go with the Flow)
Most part design assumes a machining or stamping approach - start with a chunk of metal and systematically remove and re-shape to achieve the desired functional features. When designing for zinc castings, think flow - molten metal is flowing through the part, filling all features, then solidifying. Any restrictions or sudden changes to an even flow/fill can introduce defects when casting. When able, avoid large transitions in cross sections, use radii, avoid sharp edges and thin, blind areas. One of the advantages of zinc castings is the superior strength of the cast "skin", which is the near-surface layer. This allows us to cast thin walls, as small as .014" thick. Ribs and thin wall sections not only reduce material (cost and weight) but they can produce a better quality casting. CONTACT US for a free manufacturability assessment of your part design and let us work with you to design out defect modes and create a high quality, functional part for your application.
Tooling Considerations
Unlike other manufacturing methods, such as machining, several features related to the process and tool must be considered when designing a part. The parting line location (where moving tool components meet) must be considered as it may create a witness mark and is not preferable on sealing and/or high cosmetic surfaces. When casting, the molten metal flowing through the runner must enter the tool cavity through a gate. When the runner is removed from the casting, the gate location leaves a visible witness mark and is the most prone area to vesitge (excess material <.005") and/or micro voids (typ. <.010"). The gate must be located in an area that supports tool construction and castability, but should be kept away from functional surface and features. A knock out (KO) system is typically required to remove the cast part from the tool cavity. This is most commonly achieved with KO pins that contact the casting in key areas to eject the part from the tool die as it opens. Similar to the parting line, KO pins may leave witness marks that may cause problems on high functioning surfaces. We can work with you to understand your design and offer the best tooling configuration to design out potential defect modes. We also offer custom machining and secondary operations to achieve high quality features when the tooling design limits our ability to achieve all requirements at casting.
Final Application
The most successful projects occur when we understand the part function in your assembly and final application. Any related assembly design, mating parts and/or final performance specifications shared at initial design allows us to develop tooling and a process to eliminate potential failure modes. We use job-specific gaging for every part and design, build and implement custom functional gages to best assess performance in your application. Working with a high cosmetic application? We have visual inspection systems, sample boards, and more to ensure we are both aligned on the acceptable cosmetic standards. Our process is not just cast and ship - we handle different finishing/plating options, regularly perform secondary machining, automated inspection, assembling, kitting, and more; we design a manufacturing process unique to each part to provide value and ensure quality for your application. We also offer custom packaging solutions when there are concerns of delicate part features being damaged in transit or in storage. CONTACT US today to discuss how we can make your next project a success!
