DFM Frequently Asked Questions
Answers to the most common questions about tolerances, materials, cost, lead time and files for FDM design for manufacturing.
This page collects the questions we hear most often from engineers preparing a part for FDM production, grouped by topic. It is meant as a quick reference alongside the more detailed guides in this library, not a replacement for them. If a question is not answered here in enough depth, the linked guide covers the underlying reasoning.
Tolerances and fits
Tolerance questions come up on nearly every quote request, usually because a drawing was toleranced for a different process. As a starting point, expect roughly plus or minus 0.2 mm on PLA, PETG and carbon filled grades and plus or minus 0.3 mm on ABS, ASA and PC, with sliding fits needing 0.2 to 0.4 mm of diametral clearance.
Materials and mechanical properties
We work with roughly 20 engineering filaments, from PLA and PETG for general purpose parts to PA12-CF, PPA-CF and PC for demanding structural or thermal applications. The right material depends on load, temperature, chemical exposure and whether the part needs to match a certified flame rating such as UL94 with PC FR.
Cost and lead time
Cost is driven mainly by print height in the chosen orientation, then by material volume and manual post-processing. Lead time is typically 2 to 4 working days for samples and 4 to 15 working days for series, depending on quantity and post-processing.
Files and CAD preparation
STEP is the preferred format because it preserves exact geometry, but STL, 3MF, OBJ and IGES are all accepted up to 200 MB. Parts should be modelled with wall thicknesses and features already sized for FDM rather than left at defaults from another process, since we work faster and cheaper on a file that already reflects good practice.
Quality and repeatability
Repeat orders are produced from a locked process: the same material, orientation, layer height and post-processing steps validated in the first batch. Any later change to the CAD file triggers a re-check before it goes into full production, since even a small geometry change can shift wall thickness or clearance at a critical feature.
Frequently asked questions
- What tolerance can I expect on an FDM part?
- Roughly plus or minus 0.2 mm on PLA, PETG and carbon filled grades, and plus or minus 0.3 mm on ABS, ASA and PC, measured on typical part sizes as printed.
- What is the maximum part size you can print in one piece?
- Approximately 250 by 250 by 250 mm. Larger parts are split into sections and joined after printing.
- What file formats do you accept?
- STEP, STL, 3MF, OBJ and IGES up to 200 MB. STEP is preferred because it preserves exact geometry for review.
- How long does a sample take to produce?
- Typically 2 to 4 working days, depending on part size, material and current queue length.
- How long does a production batch take?
- Typically 4 to 15 working days depending on quantity, material and the amount of post-processing required.
- Is there a minimum order quantity?
- No, quantities from a single unit up to several thousand are possible.
- Which materials do you offer?
- Around 20 engineering filaments including PLA, PETG, ABS, ASA, PC, PC FR, TPU, PA6, PA12, PA12-CF, PPA-CF and PC-ABS.
- Can FDM parts be flame rated?
- Yes, PC FR is available with UL94 flame rating for applications that require it.
- What layer heights do you print with?
- 0.10 to 0.30 mm, with nozzle sizes of 0.4 mm and 0.6 mm depending on the part's detail requirements.
- What is the minimum wall thickness you recommend?
- For structural walls, 2 to 4 mm depending on the material and load. Thinner walls are possible for non-structural cosmetic features.
- Do you help optimise a design, or only print the file as given?
- We assess every part from a manufacturing point of view and typically suggest changes to geometry, orientation, material or tolerances before production.
- Can you match an injection molded part's properties exactly?
- Not exactly, since FDM parts are anisotropic and molded parts are not, but a redesigned FDM version can meet the same functional requirement.
- Can you machine a feature after printing?
- Yes, for critical bores or flat faces we routinely combine printing with light machining or reaming as a post-process step.
- Do you offer threaded inserts?
- Yes, heat set and press fit threaded inserts are a standard part of our post-processing options.
- How do you determine part orientation?
- We weigh strength requirements against the load direction, expected surface quality on visible faces, and print time, then choose the orientation that best balances all three.
- What happens if my part has overhangs?
- Overhangs steeper than roughly 45 degrees need support material unless the geometry is redesigned to self-bridge. We flag these during review.
- Can you print snap fits reliably?
- Yes, provided the arm thickness and root radius are sized for the material's real flex modulus rather than copied from a molded design.
- Is FDM suitable for parts exposed to outdoor UV?
- ASA is the standard choice for outdoor UV exposure due to its weather resistance, generally preferred over ABS for that use case.
- Can FDM parts handle sustained high temperature?
- PC and PPA-CF handle higher sustained temperatures than PLA or PETG, but no FDM material matches metal at continuous high heat. We size the material to the real operating temperature.
- What is the difference between a prototype and a series part in your process?
- A series part goes through a locked process: validated material, orientation, layer height and post-processing, repeated consistently, whereas a prototype may still change between iterations.
- Do you provide a pilot batch before full production?
- Yes, for quantities above roughly 100 units we recommend a pilot batch of 10 to 20 parts to validate fit, strength and cycle time first.
- Can two printed parts be bonded together?
- Yes, split parts are commonly joined with adhesive bonding or mechanical fasteners at a joint line chosen away from critical load paths.
- What surface finish can I expect as printed?
- Visible layer lines at the chosen layer height are normal. Bead blasting, sanding or vapour smoothing on compatible materials can improve finish where needed.
- Can you help decide between FDM and CNC machining?
- Yes, we consider quantity, tolerance requirements and load case, since FDM tends to win at low volumes and CNC at higher volumes with tight tolerances across many features.
- Do you keep my CAD files confidential?
- Yes, files submitted for quoting or review are handled confidentially and used only for the purpose of assessing and producing your part.
- What is the smallest feature you can print reliably?
- With a 0.4 mm nozzle, features around 0.8 mm and larger print reliably. Finer details may need a smaller nozzle or a design change to thicken the feature.
- Can you print parts that need to mate with metal components?
- Yes, we account for the metal part's actual dimensions and tolerance when sizing the FDM mating feature, and can add metal inserts where wear or load requires it.
- What information do you need to give an accurate quote?
- A STEP file, the required quantity, the intended material or application requirements, and any critical tolerances or surface requirements.
- Can existing prototypes be optimised before going into series?
- Yes, this is one of the most common requests we receive and usually the point where the biggest cost and reliability gains are found.
- Do you support parts with multiple materials in one assembly?
- Yes, different components of an assembly can be printed in different materials and joined mechanically or with adhesive after printing.
Have your part reviewed before production
Send us your CAD file together with the application, load and operating conditions. We review geometry, orientation, material and tolerances and come back with concrete change proposals and a quote.
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