3D Printing Glossary for Buyers and Engineers

FDM

FDM is 3D printing that melts plastic and stacks it in thin lines. The letters stand for fused deposition modeling. A hot nozzle draws each layer. The next layer melts onto the one below it. It is the only process we run, and you can read how we use it on our FDM printing service page.

Why it matters for your part: FDM prints in real engineering plastics, so the part works, not just looks good.

Build volume

Build volume is the biggest space inside a printer where a part can be made. Our machines print parts up to 256 mm on a side. That is about 10 inches. Very large parts in some materials get a quick review first. A bigger part gets split into pieces.

Why it matters for your part: Check your longest side first. It is the fastest way to know a part fits, and it is check one of our 7 design checks.

Nozzle diameter

Nozzle diameter is the width of the hole the melted plastic comes out of. A wide nozzle lays down more plastic each pass. That prints faster and stronger. A narrow nozzle prints finer detail and takes longer.

Why it matters for your part: A detail thinner than the nozzle cannot print. Keep small features at 1.2 mm or more.

Extrusion width

Extrusion width is the size of one printed line of plastic. The nozzle sets it, but it is not the same number. A squashed line spreads a bit wider than the hole it came from.

Why it matters for your part: Walls sized to whole lines print clean. Odd sizes can leave a gap inside the wall.

Layer height

Layer height is how thick each printed layer is. We run 0.20 mm as our standard. Thin layers look smoother and take longer. Thick layers print fast and show more lines.

Why it matters for your part: Layer height trades finish for time. Most working parts are fine at 0.20 mm.

Print orientation

Print orientation is the way your part sits on the bed while it prints. It changes strength, finish, and support needs all at once. We pick the angle that holds the part straight and strong. The design checks page shows the same part in four angles.

Why it matters for your part: Tell us which way the part gets loaded. We aim the layers to take that load.

Support material

Support material is scrap plastic printed under the parts of your model that hang in open air. A printer cannot print on thin air. Supports prop up steep overhangs. We snap them off after the print. Our guide to 3D printing supports shows how to design past them.

Why it matters for your part: Supports cost time and plastic, and they leave marks. Fewer supports means a cheaper part.

DFM

DFM is checking a design against the way it will really be made. The letters stand for design for manufacturing. For printing, it means thick enough walls, big enough holes, and overhangs the machine can hold. Every file you upload runs through 7 automatic design checks.

Why it matters for your part: Most flags are advice, not a stop sign. You see them before you pay.

Wall thickness and perimeters

Wall thickness is the depth of a part's outer shell. The printer builds that shell from lines called perimeters. Two or three lines is normal. We flag walls under about 1.6 mm. Our wall thickness guide lists the safe minimum by job.

Why it matters for your part: Thin walls crack. Half a millimeter more costs pennies and buys real strength.

Infill

Infill is the pattern of plastic inside your part. Printed parts are not solid. A grid fills the middle to save weight, time, and cost. More infill means more plastic and more strength. Our infill guide walks through the trade.

Why it matters for your part: Infill drives strength and price at the same time. Tell us how the part gets loaded.

Overhang

An overhang is any part of your model that leans out over open space. Up to about 45 degrees, a layer can rest on the one below it. Past that, it droops and needs support. Our design rules guide covers the 45 degree rule in more depth.

Why it matters for your part: Turn a sharp overhang into a slope and the support goes away.

Bridging

Bridging is printing a flat span across a gap with nothing under it. The nozzle pulls a hot line from one wall to the other. Short bridges print clean. Long ones sag in the middle. Our guide to supports and bridges shows the safe span length.

Why it matters for your part: Make a wide flat roof into an arch. It prints better and skips the support.

First layer

The first layer is the plastic laid straight onto the print bed. It holds the whole part down. If it does not stick, the print fails. A flat face sticks best.

Why it matters for your part: One flat face on the bed is the cheapest way to make a part print right.

Raft

A raft is a flat pad of plastic printed under your part. The part builds on the pad instead of the bed. It adds grip for shapes with a small footprint. We peel it off after.

Why it matters for your part: Rafts eat extra plastic and time. Most parts do not need one.

Brim

A brim is a thin skirt of plastic printed around the base of your part. It is like a raft, but only around the edge, not under the whole part. It pins the corners down so they cannot curl.

Why it matters for your part: Brims help tall skinny parts and big flat ones. We add one when the shape asks.

Warping

Warping is when a part curls or lifts as it cools. Hot plastic shrinks a little on the way down. Big flat parts pull hardest at the corners. ABS warps most. PETG stays flatter.

Why it matters for your part: For a big flat part, PETG is often the safer pick.

STL

An STL is a 3D file that draws the skin of your part out of triangles. It is the most common file in printing. It holds shape only. No units, no color, no notes. Upload one to the instant quote and you see a price in seconds.

3MF

A 3MF is a newer print file that packs shape, units, and color into one zipped file. Because it carries units, scale mix-ups are rare. We turn your 3MF into an STL on our side. The price still shows up right away.

Why it matters for your part: Export a 3MF when your part has to land at the exact size you drew.

STEP

A STEP file is a CAD file that stores true shapes instead of triangles. Curves stay curves, so nothing is chopped into flat faces. It is the best file to send when a shape may need an edit.

Why it matters for your part: STEP files get an instant price now. We turn your STEP into a printable mesh right in your browser, then price it on the spot. Upload a STEP file to try it. If a file will not read, we give it a fast review. A person reviews your request and follows up by email.

Mesh and manifold

A mesh is the triangle skin of your model, and manifold means that skin is fully closed. Closed means no holes, no flipped faces, no loose edges. Software needs a closed shape to tell inside from outside. An open mesh can print wrong.

Why it matters for your part: We check this on upload. If your mesh has a hole, we can repair it. Just ask.

Slicing

Slicing is cutting your 3D model into flat layers a printer can build. Software does it in one pass. It maps the path for every line of plastic. It also sets supports, infill, and speed.

G-code

G-code is the list of moves a printer runs to build your part. The slicer writes it. Each line tells the machine where to go, how fast, and how much plastic to push. You never touch it. We handle that step.

Tolerance

Tolerance is how far a finished part may drift from the size you drew. For FDM, a typical figure is plus or minus 0.5 percent, with a floor near plus or minus 0.5 mm. That is typical, not a promise. A tight fit needs a test part first. Our guide to FDM tolerances lists the drift by feature.

Why it matters for your part: Flag the few sizes that really matter. We hold those closer than we hold all of them.

Dimensional accuracy

Dimensional accuracy is how close the printed size lands to the drawn size. Tolerance is the rule you set. Accuracy is the result you get. Heat, shrink, and print angle each move it a little. See the numbers by feature in our FDM tolerances guide.

Why it matters for your part: Holes often print a touch small. Plan a test fit on parts that mate.

Anisotropy

Anisotropy means a printed part is stronger in some directions than others. Each plastic line is strong along its length, and the bond between layers is usually weaker. How much weaker depends on the material and the machine: published figures range from about 12 percent of the in-plane strength to nearly 90 percent. Our design rules guide covers how to aim the layers against the load.

Why it matters for your part: Tell us where the load goes. We turn the part so the layers work against it.

Layer adhesion

Layer adhesion is how well each layer sticks to the one under it. It is usually the weaker axis in an FDM part. Hotter plastic and slower speeds bond better. Wet filament bonds worse. Our material comparison shows how each of our five plastics bonds between layers.

Why it matters for your part: Wall thickness and print angle help this more than any machine setting.

Post-processing

Post-processing is any work done on a part after it leaves the printer. That covers pulling supports, sanding, painting, drilling, tapping, and setting inserts. Some of it is built in. Some shows up as its own line on a reviewed quote.

Why it matters for your part: Ask for it up front. Added later, it can push your ship date.

Tapped holes and heat-set inserts

Tapped holes and heat-set inserts are the two ways to put real screw threads in a printed part. Tapping cuts threads into the plastic itself. An insert is a brass sleeve pressed in with heat. Brass takes many more screw cycles than plastic. Our guide to threads and fasteners covers both in full.

Why it matters for your part: If a screw comes out more than a few times, use an insert and leave the right size hole.

Tensile strength

Tensile strength is how hard you can pull on a part before it breaks. Published strength figures do not rank cleanly across the five materials we print. Manufacturers measure different things, and two products sold under one polymer name can disagree. PA-CF is our pick when a part carries real load, though published figures do not put it ahead of PETG or PLA on every test. TPU is measured on a different standard again. The material properties reference lists the published figures with their test method.

Why it matters for your part: A printed part will not hit the same rank in every direction. See anisotropy above.

Glass transition temperature

Glass transition temperature is the point where a plastic starts to go soft. It is often shortened to Tg. The part does not melt. It turns rubbery and loses its stiffness. PLA softens early, which is why a PLA part can droop in a hot car.

Why it matters for your part: If your part sees heat, start with ABS or PA-CF.

Heat deflection temperature

Heat deflection temperature is the warmth a loaded part can take before it bends. It is closer to real life than Tg, since the test adds weight. We rank our five core materials from most heat to least, rather than publish one number for each, since filament brands vary. PA-CF holds the most heat, then ABS, then PETG, then PLA. TPU varies widely by product, from below PLA to above PETG depending on which one you buy. The material properties reference shows the published figures at both test loads. The materials page lists them side by side.

Why it matters for your part: Match this to the hottest spot your part will live in.

Hygroscopic

Hygroscopic means a plastic pulls water out of the air. Wet filament pops and hisses in the nozzle. That leaves rough, weak parts. Nylon is the thirstiest. PETG drinks some too.

Why it matters for your part: We dry filament before a run, so you never have to think about it.

UV resistance

UV resistance is how well a plastic holds up in sunlight. Sun makes many plastics fade, chalk, and turn brittle. PETG and ABS do better outside. PLA does poorly.

Why it matters for your part: For an outdoor part, pick the plastic first, then the color. Black holds up best.

Annealing

Annealing is baking a printed part in a low oven to make it stronger. Heat lets the plastic settle and bond better between layers. It can add heat resistance too. The catch is that parts shrink a little.

Why it matters for your part: Ask before you count on it. A tight-fit part can drift out of tolerance.

RFQ

An RFQ is a request for a quote that you send to a shop. You send files, quantity, material, and dates. The shop sends back a price and a ship date. Most parts here skip that step, since the price shows up the moment you upload.

Why it matters for your part: Use a review request for bulk runs, odd plastics, or big parts. A person reviews your request and follows up by email.

MOQ

MOQ is the smallest order a shop will take. Molders set high ones, because the tooling has to be paid off. We have no minimum. One test part and 10,000 parts both work. See how our pricing works.

NRE

NRE is the one-time setup bill a shop charges before it makes your parts. The letters stand for non-recurring engineering. It pays for tooling, fixtures, and program setup. Molding carries a big one. Printing carries none here.

Why it matters for your part: No NRE means you can order 10 parts to test a design without a setup bill.

Lead time

Lead time is how long it takes from order to parts in your hands. Most of our orders ship in 3 to 5 business days. We print in the USA and ship inside the country, so customs never holds your parts. More on that in our buyer FAQ.

Low-volume production

Low-volume production is making real parts in small counts, not just prototypes. Think 50 to 5,000 units a year. Printing fits well here, because there is no tooling to pay off first. See our low-volume production guide.

Why it matters for your part: You can change the design between runs and pay nothing to retool.

Bridge production

Bridge production is printing real parts while you wait on a mold to be built. Tooling takes weeks or months. Printing lets you ship and sell in the meantime. Teams also use it to hold a launch date after a late change. Our low-volume production guide covers bridge runs in detail.

Why it matters for your part: It buys time, so you do not have to freeze a design too early.

Unit price vs tooling cost

Tooling cost is the price of the mold, and unit price is what one part costs. Molding has a low unit price and a big tooling bill up front. Printing has a higher unit price and no tooling at all. Where they cross depends on your count.

Why it matters for your part: Compare total cost, not the per-part number. Our pricing page shows what a printed run costs.

Injection molding

Injection molding is shooting melted plastic into a steel mold to make the same part again and again. It is the cheapest way to make a lot of one part. The catch is the mold. It costs a lot, it takes weeks, and each change costs more. Our service comparison covers where each one wins.

Why it matters for your part: At high counts, molding wins on unit price. Below that, printing skips the wait.