What is additive manufacturing?

Additive manufacturing builds a part in layers from a digital file. No tool gets cut first. A machine reads the file and stacks material one thin layer at a time. It is the opposite of machining, which cuts a part out of a solid block. It also needs no mold. So a run of one costs about the same per part as a run of a hundred.

When is additive manufacturing cheaper than injection molding?

At low and mid volumes, because there is no tool to pay for. Molding needs a tool cut and paid for before part one exists. That cost then spreads across the run. Additive skips that step. Once the volume is high enough to pay off the tool, molding takes over on cost per part.

Is additive manufacturing the same as 3D printing?

Yes. Both names describe building a part layer by layer from a digital file. Engineers and buyers use the formal term in their paperwork. 3D printing is the everyday name. The term covers a whole family. FDM, resin printing, powder bed fusion, and metal printing all count.

Which additive process should I use for production parts?

For working plastic parts in low to mid volume, FDM is the usual answer. It is the process we run. SLA suits fine detail and smooth faces. SLS and MJF suit complex nylon parts that need no supports. Metal powder bed suits metal shapes a mill cannot reach. Match the process to the part, not to what a vendor happens to own.

Can additive manufacturing be used for end-use parts?

Yes, and it is a large share of what we print. Brackets, boxes, jigs, fixtures, guards, and spare parts all ship as finished goods. The design has to respect the process. That means sizing walls right, aiming the layers across the load, and using metal inserts where threads are needed.

How do I evaluate a 3D printing service?

Start with the price. Can you get a real one without a sales call? Then look at the file check. Does the vendor flag problems before you pay? Then look at the numbers. Real MPa and C figures beat vague strength talk. Last, ask if the price holds, where the parts are made, and whether one file can scale from one part to a thousand.

What are the limits of additive manufacturing?

It loses to molding at high volume. It cannot hold a tight bore without a second step. It is capped by the heat limit of the plastic, which is about 140 C for our strongest one. Printed parts are also weaker between layers than across them, and they carry light layer lines. We do not print metal.

Additive manufacturing: when it beats machining and molding

By the 3D Printer on Demand team · Updated July 2026

Additive manufacturing builds a part in layers from a digital file. No tool gets cut first. For a buyer, the useful question is not what it is. It is when it wins. Additive wins when the run is small, the shape is complex, the design is still moving, or you need parts in days instead of weeks. Molding wins once volumes get large enough to pay off a tool. Machining wins on tight bores and metal. This page lays out where each line crosses.

When additive beats machining and molding

Three things decide it: how many parts you need, how fast you need them, and how settled the design is. Nothing else moves the answer much.

Additive has no tool to pay for. That is the whole story on low volume. Part one costs about what part one hundred costs. Injection molding runs the other way. A tool has to be cut and paid for before part one exists, and that cost then spreads across the run. The more parts, the less each one carries.

So there is a crossover point. Below it, additive is cheaper and much faster. Above it, molding pulls ahead and never looks back. Where the point sits depends on the part, but the shape of the trade is always the same.

Additive, CNC machining, and injection molding compared on the factors a buyer weighs.
	Additive (FDM)	CNC machining	Injection molding
Tooling cost	None	None, but setup per part	A tool, paid before part one
Time to first part	Ships in 2 to 5 days	Waits on machine time	Weeks for the tool
Cost per part at 10	Low	High, setup dominates	Very high, tool not paid off
Cost per part at 100,000	Flat, never drops much	Still high	Lowest by far
Cost to change the design	Edit the file, reprint	New setup, often a re-cut	New tool or a tool change
Complex shapes	Nearly free	Expensive, some are impossible	Limited by how the tool opens
Tight bores and flat faces	Needs a second operation	Best	Good
Metal parts	Not on FDM	Yes	No, that is casting

The three questions that pick the process

Run a part through these three and the answer usually falls out on its own.

How many do you need this year? Under a few thousand plastic parts, additive is normally the cheaper path once you count tooling.
Is the design final? If a change is still likely, tooling is a bet. Additive lets you keep changing the file for free.
How fast do you need it? Additive puts real parts in your hand in days. That alone decides plenty of programs.
Two more that matter less often: does the part need metal, and does it need a bore held tighter than about half a percent? Both push toward machining or a second operation.

Which additive process fits which job

Additive is a family, not one machine. The processes differ enough that picking wrong costs real money.

We run FDM, and we say so plainly. When another process fits your part better, we will tell you that instead of selling you the one we have.

The main additive processes and the work each one suits.
Process	How it builds	Suits	We run it?
FDM	Melts plastic and lays it in lines	Functional plastic parts, jigs, housings, low-volume production	Yes
SLA and DLP	Light hardens liquid resin	Fine detail, smooth faces, patterns and models	No
SLS and MJF	Fuses nylon powder in a bed	Complex nylon parts with no supports needed	No
Metal powder bed	A laser melts metal powder	Metal parts with shapes a mill cannot reach	No

How to evaluate a 3D printing service

Most print services look the same from the outside. A logo, an upload box, and a promise. Here is what really separates them. Run this list on any vendor you look at, including us.

Can you get a real price without a sales call? An instant quote tells you the vendor trusts its own numbers.
Does it check the file before you pay? A service that flags thin walls and broken meshes up front is a service that has seen parts fail.
Does it name its process and materials with real numbers? Vague strength talk is a warning sign. Ask for tensile strength in MPa and a heat limit in C.
Does the price hold? A quote that moves after you order is not a quote. Ours is held for 30 days.
Where are the parts made? US production means no customs step and a shorter, more predictable lead time.
Can it go from one part to a thousand on the same file? If a pilot run means starting over with a new vendor, it is not a production path.
Does it tell you what it cannot do? A vendor with no published limits has limits you will find out about later.

What additive cannot do

Being straight about this is the fastest way to save you money. Additive is not the answer to everything, and a service that says it is has something to sell.

It does not beat molding at high volume. Once a tool is paid off, molded parts cost far less each.
It does not hold a tight bore on its own. Plan on reaming, a bushing, or a press-fit insert. See our tolerances guide.
It is limited by heat. Our top material, PA-CF, holds shape to about 140 C. Past that you need a different process.
It builds parts that are weaker between layers than across them. Design and print angle have to account for that.
It leaves layer lines. They are cosmetic on most parts, and they matter when a face has to seal.
We do not print metal, and we do not hold any process certification. If your part needs either, we will say so.

How additive fits an engineering program

In practice, buyers do not pick additive once. They use it in stages, and the stages carry a program from a sketch to a shipping product.

First comes the prototype. One part, printed to check size and fit, so the mistakes get found while they are still cheap. Then the fit test, where the printed part goes into the real assembly with the real hardware around it.

Then the pilot run. Ten to a hundred units for a demo, a trial install, or a first customer. This stage used to force an early tooling call. Additive takes that pressure off.

Then bridge production. You ship real product while the tooling decision waits for real demand data. Plenty of parts never leave this stage, because the volume never gets high enough to justify a tool. That is a fine outcome, not a failure.

One rule carries across every stage: design the part for the process before the first print. A change to the file costs nothing. The same change after a tool is cut costs weeks. Our design guide and our 7 design checks cover wall thickness, layer direction, and the clearances FDM can hold.

Our prototype service covers the front of that path, and our production service covers the back of it.

Cost and lead time in practice

Price here is one flat number per part. The per-part price steps down at 10, 50, 250, and 1,000 units, and the quote page applies the right tier the moment you set a quantity. The tiers are on our pricing page.

That price holds for 30 days, so a number you pulled last week still stands when the purchase order clears. No repricing.

Lead time is 2 to 5 days to ship, made in the USA. No customs step and no overseas transit window to plan around.

PLA and PETG price instantly on upload. For ABS, PA-CF, TPU, or a volume run, send a quote request with your file and target quantity, and a real person replies within four business hours.

How your parts get made here

We run FDM in our own US production. A nozzle melts plastic filament and lays it down line by line. Each line cools and bonds to the one under it. Do that a few thousand times and the part is done.

Five materials cover nearly every job that comes through. Here are the numbers that decide which one.

The five FDM materials we print, with the numbers buyers ask for.
Material	Strength	Holds shape to	Typical use	Quote
PETG	50 MPa	73 C	The default for working parts	Instant
PLA	50 MPa	57 C	Visual models and indoor fixtures	Instant
ABS	40 MPa	98 C	Heat, impact, painted parts	Human
PA-CF	80 MPa	140 C	Structural and load-bearing parts	Human
TPU	35 MPa	80 C	Gaskets, pads, flexible parts	Human

Quick takeaways

Additive has no tooling cost, so part one and part one hundred cost about the same each.
Molding wins once the run is big enough to pay off a tool. Machining wins on metal and tight bores.
Three questions pick the process: how many, how fast, and how settled the design is.
FDM suits functional plastic parts, jigs, housings, and low-volume production. That is the process we run.
Judge a print service on whether it prices without a sales call, checks your file, publishes real numbers, and holds the price.
Additive fits a program in stages: prototype, fit test, pilot run, then bridge production while the tooling call waits.
Parts here ship in 2 to 5 days, made in the USA, at one flat price per part held for 30 days.

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Common questions

What is additive manufacturing?: Additive manufacturing builds a part in layers from a digital file. No tool gets cut first. A machine reads the file and stacks material one thin layer at a time. It is the opposite of machining, which cuts a part out of a solid block. It also needs no mold. So a run of one costs about the same per part as a run of a hundred.
When is additive manufacturing cheaper than injection molding?: At low and mid volumes, because there is no tool to pay for. Molding needs a tool cut and paid for before part one exists. That cost then spreads across the run. Additive skips that step. Once the volume is high enough to pay off the tool, molding takes over on cost per part.
Is additive manufacturing the same as 3D printing?: Yes. Both names describe building a part layer by layer from a digital file. Engineers and buyers use the formal term in their paperwork. 3D printing is the everyday name. The term covers a whole family. FDM, resin printing, powder bed fusion, and metal printing all count.
Which additive process should I use for production parts?: For working plastic parts in low to mid volume, FDM is the usual answer. It is the process we run. SLA suits fine detail and smooth faces. SLS and MJF suit complex nylon parts that need no supports. Metal powder bed suits metal shapes a mill cannot reach. Match the process to the part, not to what a vendor happens to own.
Can additive manufacturing be used for end-use parts?: Yes, and it is a large share of what we print. Brackets, boxes, jigs, fixtures, guards, and spare parts all ship as finished goods. The design has to respect the process. That means sizing walls right, aiming the layers across the load, and using metal inserts where threads are needed.
How do I evaluate a 3D printing service?: Start with the price. Can you get a real one without a sales call? Then look at the file check. Does the vendor flag problems before you pay? Then look at the numbers. Real MPa and C figures beat vague strength talk. Last, ask if the price holds, where the parts are made, and whether one file can scale from one part to a thousand.
What are the limits of additive manufacturing?: It loses to molding at high volume. It cannot hold a tight bore without a second step. It is capped by the heat limit of the plastic, which is about 140 C for our strongest one. Printed parts are also weaker between layers than across them, and they carry light layer lines. We do not print metal.