Prototype and Low Volume

Die Cast Prototypes

A high-pressure die casting prototype die is often the best approach if you want the same properties, alloy, geometry, etc., that will be in place for production.
Prototype die casting dies can be produced in shorter lead times and at less cost because they can utilize standardized components (such as an existing die base), and pre-hardened, uncoated tool steels. The tool will not last as long, and the die will not run as efficiently as a typical production die, but this is a non-issue when you only need a small number of parts (1,000 or less). Design changes can be made faster and at less cost with a prototype die than would be the case on a custom, hardened/coated production die. Parts made with the prototype die are generally hand-cleaned of flash, avoiding the lead time and cost of a trim die.

3D Printed Prototypes

The technology of 3D Printing enables the production of rapid prototypes in durable ABS plastic, directly from STL design files. Fused Deposition Modeling (FDM_) parts are built and bonded, extruded layer by layer, from 3D computer data.

An FDM machine can produce geometrically complex shapes to tolerances of ±0.005 in. (±127mm).

Because of its strength, the ABS plastic part can be evaluated rigorously for form and fit and used in many functional tests.

Most 3D-printed processes have difficulty reproducing very tight toleranced features, such as sections containing ribs, bosses, and holes; however, CNC machining can be performed on the strong FDM ABS part to the required critical specifications.

FDM prototypes are generated on every new die casting project to expedite production and shorten total lead times by providing advanced models to all departments involved. These multiple FDM models help assure that die designs result in first-piece success and aid in the simultaneous construction of die cast tooling, trim dies, machining fixtures, finishing masks, and any required sub-assembly gauges or fixtures.

Machined Hogouts

Advantages:

• Very low or no upfront tooling costs.
• Ideally suited for low volumes.
• It can be done in a variety of alloys.
• Very tight tolerances can be achieved.
• Short lead times.

Considerations:

• Highest cost option, especially for complicated geometries.
• It does not replicate a higher volume process that may have broader tolerance requirements.
• Does not replicate the surface finish of a die cast or investment cast part.
• Some geometries, such as curved surfaces and radii, are more challenging to machine.

Gravity Cast Prototypes

Sand casting, investment casting, and rubber plaster-mold castings are gravity cast processes used to prototype a die casting design.

Sand Casting

• Advantages: Sand Casting has low upfront tooling costs and is ideally suited for volumes of up to 2,500 pieces. This manufacturing process offers the ability to cast thick wall sections and internal cored features and can be cast in various ferrous and non-ferrous alloys. Sand Castings typically have short lead times. Tight tolerances can be easily achieved through machining.
• Considerations: Compared to die casting, sand casting is harder to apply a surface finish to. Small holes and tight tolerance features will need to be machined. Achieved as-cast tolerances are not as tight as those for die casting or machined hog outs.

Investment Casting / Rubber Plaster Mold

• Advantages: Investment Casting (Rubber Plaster Mold) generally has lower upfront tooling costs than die casting and is equally suitable for applying a surface finish. Investment Casting provides the ability to cast complex geometries in a variety of non-ferrous alloys with a short lead time.
• Considerations: Tooling costs are higher than sand castings or machined hog outs. Tight tolerance features and holes will need to be machined.

Spin Casting

Advantages:

• Ideally suited for small, zinc parts.
• Very low initial tooling costs.
• Ability to produce complex geometries.
• Short lead times.
• Variety of zinc alloys available.

Considerations:

• Only available for zinc.
• Tight tolerance features will require machining.

Contact Chicago White Metal for more information about die cast prototyping for your project. You can email sales@cwmtl.com or call (630) 595-4424.