Prototype parts get produced by printing, casting or molding, and the decision is usually made on speed and price. That is the wrong basis for it. Each route proves something different: printing proves geometry, casting proves form in a polymer that behaves roughly like a molded part, and molding proves the actual process that will

Most molded products do not start at a hundred thousand units. They start at a few hundred, produced to prove a market, satisfy a first customer or bridge a launch, and the tooling decision made for that quantity determines whether the second order is profitable or painful. Low volume injection molding covers that range: roughly

Between the first molded sample and the production tool there is usually a gap: the design is close enough to sell, the launch date will not wait for a long tool build, and the production tool cannot be cut until the last changes are settled. Bridge tooling exists to fill that gap with parts that

The tool material decision usually arrives with a quantity forecast attached, and the forecast is usually wrong. Choosing aluminium because the first order is small, then discovering the program runs for three years, is a more expensive mistake than paying for steel at the start; choosing steel for a product that will be redesigned in

A prototype that has been printed, cast and assembled can still fail the moment it is molded, because molding introduces variables the other routes do not have: melt flow, gate position, shrinkage and ejection. Prototype injection molding exists to expose those variables before a production tool is committed. The parts are real molded parts in

The question is rarely whether a prototype mold is cheaper, because it obviously is. The question is what the program gives up by choosing one, and whether the difference matters for the quantity the product will actually run. A prototype tool delivers parts sooner and absorbs a change more cheaply; a production tool runs longer,

A black anodized batch that comes back two shades apart is one of the most common disputes in finishing, and it is rarely the finisher's fault alone. Colour in anodizing depends on the alloy, the temper, the coating thickness, the dye concentration and the sealing step, and a specification that says only "black" leaves all

Machining a plastic part is often the fastest way to get a hundred units that behave like the final product. It is also, above a certain quantity, an expensive way to avoid a tool. The comparison between machining and low volume molding is one of the most useful exercises in a product program, because it

At twenty parts, printing is usually the obvious answer. At five thousand, it usually is not. The interesting part is everything between, where the comparison depends on the part rather than on the process: the volume, the geometry, the material and whether the units have to be saleable rather than merely representative. This guide is

An anodizing order usually starts with a colour and a part, and that is where the problems begin. The coating is an oxide layer grown from the aluminium itself, so the alloy, the temper, the surface before processing and the class of coating all change the result. Two parts machined to the same drawing can