3D Printing Glossary for Buyers and Engineers
This glossary explains the 3D printing words you meet when you order parts. It is written for engineers, buyers, and plant ops teams. Each term gets a plain answer first, then why it matters for your part.
Process and Machine Terms
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 largest space a printer can build inside. Our machines print parts up to 220 mm on a side. That is about 8.6 inches. A bigger part gets split into pieces, or it moves to a large-format run.
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 how wide one printed line of plastic ends up. 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.
Design and DFM Terms
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 how thick the outer shell of your part is. The printer builds that shell from lines called perimeters. Two or three lines is normal. We flag walls under about 1.6 mm.
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.
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.
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.
File Format Terms
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 go to a person, not the instant price engine. Send one for review and we price it within 4 business hours.
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.
Quality and Tolerance Terms
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.
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.
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. The bond between layers is weaker. So a part holds up side to side, but splits easier layer to layer.
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 the weak axis in every FDM part. Hotter plastic and slower speeds bond better. Wet filament bonds worse.
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.
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.
Material Property Terms
Tensile strength
Tensile strength is how hard you can pull on a part before it breaks. It is listed in MPa. Our PETG and PLA sit near 50 MPa. PA-CF is our strongest at about 80 MPa. TPU is about 35 MPa.
Why it matters for your part: A printed part will not hit these numbers 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 heat a part can take under load before it bends. It is closer to real life than Tg, since the test adds weight. PLA is about 57 C. PETG is about 73 C. ABS is about 98 C. PA-CF is about 140 C. The materials page lists all five 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.
Buying and Production Terms
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 prices it within 4 business hours.
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 2 to 5 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 production run service.
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.
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
Unit price is what one part costs, and tooling cost is what the mold to make it 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.
Common questions
- What tolerance can FDM hold?
- A typical FDM tolerance is plus or minus 0.5 percent, with a floor near plus or minus 0.5 mm. That is typical, not a promise. Heat, shrink, and the way a part sits all move the number. Flag the few sizes that matter most and we hold those closest.
- What is the difference between STL and STEP?
- An STL is a triangle skin of your part, and a STEP file holds true curves. STEP is easier to edit and better for tight shapes. STL and 3MF get an instant price on upload. STEP files go to a person, who prices them within 4 business hours.
- How does infill change strength and price?
- More infill puts more plastic inside the part. That adds strength, weight, print time, and cost. Less infill saves money and prints faster. Tell us how the part gets loaded and we set infill to match.
- Why is a 3D printed part weaker in one direction?
- Printed parts are built from stacked layers, and the bond between layers is the weak spot. Each plastic line is strong along its length, so the part splits easier across the layers than along them. This is called anisotropy. Tell us where the load goes and we turn the part to fight it.
- What does DFM mean for a 3D printed part?
- DFM means 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 quick checks. Most flags are advice, not a stop sign.
- When should I use 3D printing instead of injection molding?
- Use printing when the count is low, the design may still change, or you need parts this week. Molding wins at high counts, once the tooling is paid off. Printing has no mold to wait on and no tooling bill.
- Do I pay a setup or tooling fee?
- No. There is no NRE, no tooling, and no minimum order. You pay per part. One test part and a full run both work.
- How long does a 3D printing order take?
- Most orders ship in 2 to 5 days. We print in the USA and ship inside the country, so customs never holds your parts. A file that needs a human quote is priced within 4 business hours.
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