Rapid Tooling -RT Prototyping

An Application of Rapid prototyping is Rapid tooling, this an automatic fabrication of machine tools. Tooling is one of the most costly steps in the manufacturing process.

Tools are often complex and need to be wear resistant for production. To meet these requirements, molds and dies are traditionally made by CNC machining, EDM or other methods. All traditional methods are expensive and time consuming; making rapid tooling prototyping the desired alternative. Many believe tooling and design cost may be cut by 50% to 70% by using rapid prototyping.

Rapid tooling is divided in two categories; indirect tooling and direct tooling.

Indirect Tooling

Most rapid tooling today is indirect tooling. Rapid prototyping parts are used as patterns for making molds and dies. These models can be in the following manufacturing processes.

• Investment Casting –

Some rapid prototyping can be used as investment casting patterns. Patterns must retain size when heated and not crack during the finishing process.

• Injection Modeling –

A Stereo lithography machine is used to make a match-plate pattern of the desired molding. To form this mold it is plated with metal material such as nickel; then reinforced with ceramic. The two halves are separated to remove the pattern, leaving a perfect model capable to producing thousands of injection models.

• Sand Casting –

A rapid prototyping model is used as a pattern which sand mold or “casting” is built. (make the following link) Laminated Object Manufacturing (LOM) machines can be used for this process. A LOM model can produce nearly 100 sand molds.

• Vacuum Casting –

The oldest and simplest rapid tooling prototyping technique; a pattern is suspended in a vat of liquid silicon. When the material cures, the pattern may be removed. The silicon molds can produce 15 or more patterns.

Direct Tooling

To make metal tooling direct from CAD file through rapid prototyping process; is the answer to every production engineers dream.

• Rapid tool –

A process which uses SLS to sinter  poly- coated steel pellets together to produce metal mold.

• Laser Engineering Net Shaping (LENS) –          

A process that can create metal tools directly from a CAD file. This process is capable of using multiple materials, stainless steel, HSS, tungsten carbide as well as others. A laser beam melts the top layer of the part in areas where material is to be added until the part is complete. Unlike sintering, LENS does produce a solid metal part since the metal was melted.

• Direct AIM –

Another technique provided by 3D Systems of Valencia, Ca. Stereo lithography produced cores are used with traditional metal molds for injection moldings from HDPE, Polystyrene, polypropylene and ABS.

• LOM Composite –

A method of using ceramic composite material for Laminated Object Manufacturing.

• Sand Molding –

A rapid prototyping technique that constructs sand molds directly from a CAD file.