Rapid Prototyping

Rapid prototyping is a technology which has developed in the last decade. Through the use of modern solid modeling CAD packages, combined with laser systems and new materials, we can now generate solid parts directly from the computer model without human interaction. In addition, these parts are generated in a matter of hours, and are accurate to a few thousandths of an inch. Compare this to handmade prototypes which can take weeks or months to create and tend to contain errors.

At MSC Technologies, we utilize the following processes:

STEREOLITHOGRAPHY - SLA

Stereolithography is a method that employs an ultraviolet laser to cure a thin layer of liquid plastic into a solid. The process operates by taking a thin layer of the light-sensitive liquid plastic and passing the laser beam over the points where the part is solid. Once a pass is completed, another layer of the liquid is added to the existing part, and the process repeats until the full part height is achieved. SLA parts are extremely accurate, and tend to have excellent surface finishes. A variety of SLA materials are available for different purposes, including waxes, plastics, and flexible elastomers. Most SLA materials do tend to be somewhat brittle, which means they break
easily, as we have proven on many occasions.

LAMINATE OBJECT MANUFACTURING - LOM

Laminate object manufacturing builds a part by taking individual sheets of paper that have a layer of glue on one side, and building up successive sections of a part. LOM is very useful for larger parts, as the process builds these much faster than the other processes. LOM is not as effective for very small parts as the flexural stiffness of the paper is usually too low for small parts. LOM parts are accurate, and very easy to sand and paint. LOM parts, if untreated will tend to absorb humidity and can crack because of it.  LOM parts also have different strengths in different directions due to the paper layers.

FUSED DEPOSITION MODELING - FDM

Fused deposition modeling is a process that most closely resembles a miniature glue gun.  In fused deposition modeling, a heat softening and curing plastic is melted in a small nozzle which puts down a very fine bead wherever the solid part is supposed to be. FDM parts have a rougher surface finish than an SLA part, but typically are stronger and more durable.

SILICONE RUBBER MOLDING/URETHANE CASTING

This is a two stage process: First, a master prototype is made by one of the above processes. This master is then used to make a silicone rubber mold. Once the molds are made, liquid urethane rubber is placed inside the mold and allowed to cure. Once cured, you have a urethane copy of your master prototype. 

The process allows the creation of a larger number of prototypes (up to about a dozen, possibly more) rapidly and accurately. Additionally, urethane castings are typically more durable than any of the master prototypes, and can be made faster and for a much lower cost.

CNC-MILLING

When a single metal part is needed, and it is too complex to fabricate by hand, we can turn to CNC milling. CNC stands for Computer Numerical Control. In this process, the computer controls the motions of a milling machine, guiding it in the fashion of the old saying "cut away everything that doesn't look like the part." While the theory is simple, the actual application is more complex.

The process yields a single part, but this part can, theoretically, be made out of anything, and if correctly made, can perform in an identical fashion as the real part. CNC parts, however, tend to take longer than the other processes, and are usually more expensive. CNC parts become more cost effective as they grow larger, and if a wider variety of materials can be used (aluminum parts typically cost less than steel).

INVESTMENT CASTING

If very complex steel parts are needed, or many steel parts are needed, in- vestment casting may be the technique of choice. Investment casting begins with a wax pattern piece, which can be made by the stereolithography process.  This pattern is coated with a very fine plaster-like material called investment.  Layers of this investment are built up until a thick layer is formed.
The wax is then melted out in an oven, leaving behind a cavity in the investment that is a perfect copy of the master part.  This cavity can then be filled with any molten material, brass, aluminum, steel, stainless steel, even exotic alloys such as inconel. Once the material cools, the investment is broken away and a finished part is left.

Investment casting can be used to make an unlimited number of parts, all of which are very accurate to the design. Investment cast parts need little to no finishing work in most applications before use.  However, investment cast parts are typically more expensive than other processes, and are limited to parts that are normally no more than 12" in any direction.