Rapid prototyping

Rapid prototyping is a set of technologies and methods for quickly producing a physical prototype directly from a CAD model. The goal is to test the design in the real world (shape, fit, function or ergonomics) as early as possible, before any investment in series production.

The most common rapid prototyping technologies are additive manufacturing (3D printing) processes: FDM, SLA, SLS and MJF (Multi Jet Fusion). For functional prototypes with tighter tolerances, CNC machining is used. The right technology depends on what the prototype is for, the required accuracy and the available budget.

Compared with traditional development, the main benefit is that design errors surface early, iteration cycles are short and relatively inexpensive, and the product can reach the market sooner. As a rule of thumb from practice, a flaw found on a prototype costs a fraction of what it would cost to fix after the molds or tooling have been made.

In practice, technologies are often combined: the rough form comes from FDM printing, functional parts from CNC machining, and the final appearance from manual surface finishing (post-processing).

Rapid prototyping makes sense once a CAD model exists and you need an answer to a specific question: does the part fit into the assembly, is it comfortable to hold, will it carry the load, can it be assembled without trouble? Typical uses are verifying fit before ordering molds, ergonomic models for user testing, samples for customers or trade shows, and jigs and fixtures for production.

It also suits small batches of a few parts, where making a tool would not make economic sense, and side-by-side comparison of several design variants.

A prototype made with a different process and material behaves differently from a production part. A 3D printed part has different strength, stiffness and surface quality than a molded or cast part, so mechanical test results cannot automatically be carried over to series production. Before you order, be clear about what the prototype is supposed to verify and choose the technology accordingly.

Ask your supplier about the achievable accuracy for the given part size, the print orientation and material, and whether the price includes support removal and surface finishing. The cheapest quote often means just a raw print.