3D printing and CNC machining are effective methods for producing initial parts. When a program requires hundreds or thousands of identical parts, injection molding generally offers a lower cost per part, consistent dimensions from part to part, and the use of the production material. This page describes the advantages of transferring a part to injection molding and the process Future Micro Mold follows to do so.
01
The cost of a printed or machined part remains roughly constant whether ten or ten thousand are produced, because each part requires its own machine time and handling. A mold requires a greater initial investment; thereafter, each part is produced in a single press cycle. As quantity increases, the cost of the mold is distributed across more parts and the cost per part decreases.
02
Every molded part is formed in the same steel cavity, so the thousandth part matches the first. Printed parts can vary with layer height, build position and resin curing conditions. On its micro press, Future Micro Mold holds molded features to ±10 µm. Where a feature requires a tighter tolerance, it can be machined: Future Micro Mold holds ±1 µm on machined features.
03
Most 3D printers process dedicated printing materials, such as photopolymer resins and PLA or PETG filament. Molded parts can be produced in PEEK, Ultem, LCP, COC and other production grades, which carry the thermal, chemical and mechanical ratings listed on a product data sheet. A part that has been qualified in a printing resin has not been qualified in the material that will be sold.
04
A printed part is built in layers and is weakest at the bond between them. It may fracture along a layer line under a load that the same geometry would withstand if molded. A molded part is a single continuous body of material. Its weak points are the weld lines and the gate, and their locations are determined during mold design.
05
A molded part reproduces the finish of the cavity in which it is formed, whether polished, textured or matte. Layer lines, support marks and tool marks are absent, so fewer finishing operations are required and the labor content of each part is reduced.
06
Thin walls, small holes, snap fits and molded-in metal inserts are all formed in the same cycle. On a machined part, each of these features may require an additional setup or operation. The Future Micro Mold press accommodates shot weights from 0.004 g to 2.5 g, so very small parts are produced on equipment designed for them.
| Method | Setup | Cost per part | Materials | Best for |
|---|---|---|---|---|
| 3D printing | None; parts are printed directly from the CAD file | Constant; each part requires its own print time | Printing resins and filaments | Evaluating size, fit and ergonomics while the design is evolving |
| CNC machining | Programming and fixturing for each part | Constant; each part requires its own machine time | Metals and plastic stock | Metal parts, the tightest tolerances and small batches |
| Injection molding | A mold, produced once | Decreases as quantity increases | Production plastics, including PEEK, Ultem, LCP and COC | Hundreds to millions of identical plastic parts |
Further detail is available in the design guide, including sink marks and tolerances.
Before a production mold is cut, Future Micro Mold can produce prototype parts from temporary tooling. Temporary cavity inserts cost less and require less time to manufacture than hardened steel, which reduces the cost of identifying a problem and revising the design.
Cavity inserts are printed in resin and run on the injection molding press. A printed insert produces 10 to 1,000 parts, depending on the plastic. Of the two methods, it is the faster to produce, and it is well suited to an initial evaluation of molded parts.
Cavity inserts are machined from aluminum, which can be cut more quickly than hardened steel. An aluminum insert produces hundreds to a few thousand parts, which is sufficient for test builds and pilot production.
In both cases, the parts are produced on the injection molding press. They therefore exhibit the gate, weld lines and shrinkage of a molded part, none of which a printed or machined part can reveal.
Prototype tooling requires 3 to 5 weeks, or 2 weeks on an expedited schedule.
01
A STEP file is preferred. A drawing is helpful where certain dimensions are more critical than others. Future Micro Mold provides a quotation and a tooling recommendation within 48 hours.
02
Before any steel is cut, an engineer reviews the part for draft, wall thickness, sharp corners, undercuts and gate location. Parts designed for printing frequently require minor revisions at this stage, when changes are least costly.
03
If the design requires further verification, Future Micro Mold can supply printed or machined prototypes, or molded parts from temporary tooling. Prototypes ship within 14 days.
04
The interval from concept to cavity is 30 days. This includes the design review, mold-flow simulation, mold construction, first shots and first-article inspection.
To begin, submit a request for quotation or discuss the part with Marve. The materials page describes the plastics Future Micro Mold processes.