A tool with a particular shape of strengths
Industrial 3D printing is sometimes described as a replacement for traditional manufacturing. In practice it is better thought of as another tool, strong in some situations and poor in others. A fair evaluation asks what a plant actually needs to make, in what quantity, and what each route would cost in time, effort and risk.
The benefits below are the ones most often cited. Whether they apply depends on the part, the process and the people involved, so treat them as questions to test rather than guarantees.
Where printing tends to help
Prototypes
A printed prototype can be in an engineer’s hands soon after the design is finished, without waiting for tooling. Several versions can be tried in succession, each one improving on the last. This shortens the loop between idea and physical test. Details of this use are covered in rapid prototyping.
Tooling, jigs and fixtures
Plants often need one-off holders, gauges, guides and assembly aids that fit a specific part. Printing them can be quicker than machining them or ordering them, and the digital file can be changed or reprinted when a design changes. Many printed fixtures are plastic and are used where loads are modest.
Low-volume and custom parts
When only a handful of parts are needed, the cost of tooling can outweigh the parts themselves. Printing has little or no tooling cost, so each part costs about the same whether it is the first or the tenth. That makes it suitable for custom items, spare parts for old equipment and short production runs.
Complex shapes
Some geometries, such as internal channels, lattice structures or combined assemblies, are difficult or impossible to make by cutting or molding. Printing can produce them in one piece. Designers must still follow the design rules of the specific process.
Spare parts on demand
A digital inventory of part files can reduce the need to store physical stock for rarely used items. This depends on having a process and material that meet the part’s requirements, and on confirming that any substitute is acceptable for the application.
Where printing falls short
- Per-part cost at volume. Unit cost does not fall much as quantity rises, while molding or stamping becomes cheaper per part at large quantities.
- Speed for large runs. A printer builds in layers, so it is usually slow compared with high-rate processes.
- Material limits. The range of printable materials is narrower than that of conventional processes, and properties may differ from the same material made another way.
- Surface finish and accuracy. Many parts need finishing or machining to reach a required surface or tolerance.
- Qualification. Parts for safety-critical or regulated uses need documented testing and process control, which takes effort.
- Post-processing and handling. Cleaning, support removal, curing or heat treatment add labor and equipment.
A hypothetical example
All numbers here are invented for illustration. Suppose a small plant needs a plastic bracket. Two options exist.
- Option A, injection molding: a mold takes about six weeks to make, and after that each bracket is produced in seconds.
- Option B, 3D printing: no mold is needed, and brackets are available within days, but each one takes about an hour of machine time.
In the first week, only option B can supply parts. If the plant needs 25 brackets in total, printing takes roughly 25 machine hours (25 parts at one hour each), which is manageable on one printer over a few days. The mold is not worth building for such a small number. If instead the plant needs 25,000 brackets, printing would take roughly 25,000 machine hours, which would tie up many machines for a very long time (25,000 hours is about 2.9 years of continuous operation on a single printer). Molding looks far better at that scale.
The break-even point between the two lies somewhere between those quantities, and where it falls depends on real mold costs, printer costs, labor and material. A sensible habit is to compare total cost of ownership across the expected life of the product, not only the first order.
A common middle path is to print the first parts while the mold is being made, then switch. Another is to print a trial version to confirm the design before spending on tooling.
Questions for an evaluation
- How many parts will be made, and how often does the design change?
- Which material properties are essential, such as strength, heat resistance or chemical resistance?
- What accuracy and finish are required, and what post-processing will be needed?
- Does a printer need to be owned, or would a service provider or rented equipment be more practical for occasional use? Questions around equipment rental apply here too.
- Who will operate it, and what skills and safety training are needed?
- How will parts be inspected, and how does this fit existing manufacturing quality control?
Small firms sometimes find printing particularly appealing because it avoids tooling investment, a theme that also appears in discussions of small manufacturer equipment. The gains are real but not automatic, and a pilot project on one or two parts is often a safer way to learn than a large purchase.
This article is general information and not engineering advice. Material properties and process capabilities should be confirmed with the manufacturer and through testing.