Choosing the right 3D printing supplier can be the difference between a smooth project and costly rework. Whether you need a single prototype or a production run, clear questions up front save time and money. Use this checklist as a practical guide to evaluate suppliers on capability, quality, traceability, and service. The goal is to help you decide with confidence and avoid surprises during production.
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Before You Contact a Supplier
Be prepared before you pick up the phone or send a request for a quote. Define your goals and priorities. Know the intended use of the part, required mechanical or thermal properties, target tolerance band, expected volumes, and acceptable surface finish.
Prepare clean files and reference documents. Typical file formats are STL or STEP. Include drawings for critical dimensions and callouts for functional surfaces.
If regulatory compliance matters, list the standards up front. A clear project brief makes it easy for a supplier to respond accurately and speeds up meaningful dialogue.
Questions about Capabilities and Experience
Start with capabilities and experience to find a good technological fit.
1. Which 3D printing technologies do you operate, and which do you recommend for my part and volume?
2. How many years of experience do you have with parts like mine?
3. Can you show examples or case studies of similar projects and provide client references?
4. What certifications does your facility hold for quality or industry sectors such as aerospace or medical?
5. What is your production capacity and typical lead time for small and medium runs?
6. Do you have separate production cells for prototyping and production to avoid cross-contamination?
Suppliers who can present recent examples and references are easier to trust. Certifications indicate process discipline, but always ask how the certificate maps to the specific services you need.
Questions about Materials and Traceability
Materials determine part performance. Make materials a central part of the conversation.
1. Which materials do you stock, and which grades do you source from qualified manufacturers?
2. Can you provide material data sheets and certificates of analysis for material lots?
3. Do you support traceability from material lot to finished part, and can you supply traceability documentation?
4. How do you store sensitive materials, and what are your shelf life controls?
5. Do you offer industry-specific material grades, such as medical-grade or aerospace-qualified materials?
6. What is your policy for substitution if a specified material is not available?
A supplier that maintains lot-level traceability and can show certificates is more reliable for regulated or safety-critical parts. If traceability is required, place it in the contract.
Questions about Design for Manufacturability and Part Preparation
Design matters for additive manufacturing. Good suppliers add value by helping you optimize parts.
1. Do you provide design for additive manufacturing feedback, and at what stage?
2. Can you recommend orientation and support strategies to reduce post-processing and improve strength?
3. What minimum feature sizes and tolerance bands can you reliably achieve for my selected technology and material?
4. Do you perform file checks and repairs for issues such as non-manifold geometry or wall thickness problems?
5. Do you offer secondary services such as adding datum features or machining critical surfaces?
6. How do you document recommended changes and obtain approvals before production?
A supplier that proactively suggests manufacturable alternatives and documents those suggestions reduces iteration cycles and improves outcomes.
Quality Control and Inspection Questions
Quality control separates a competent supplier from a great one. Ask for specifics rather than generic assurances.
1. How do you calibrate and maintain machines, and how often?
2. What in-process monitoring do you use, such as process data logging or build environment controls?
3. Which inspection methods do you offer, including caliper inspection, coordinate measurement machine, optical scanning, or X-ray CT for internal defects?
4. Do you provide first article inspection reports, and what is included?
5. What sampling plans do you use for production runs, and how do you determine acceptance criteria?
6. How do you record and share inspection data, such as measurement reports and traceable certificates?
7. What is your nonconformance handling process, including quarantine, root cause analysis and corrective action?
8. Can you accommodate customer-specific inspection or test protocols?
Ask for a sample inspection report so you know what documentation you will receive. Suppliers that can attach measurement data to specific part serial numbers make downstream troubleshooting much faster.
Post-processing and Finishing Questions
Post-processing can be the majority of labor for some parts. Clarify what is included and what costs extra.
1. Which post-processing services do you offer, such as support removal, sanding, tumbling, dyeing, painting, plating, heat treatment or machining?
2. How do post-processes affect critical dimensions, and how do you control for distortion?
3. Can you meet surface finish specifications and provide before and after photos or samples?
4. What are the lead time and cost implications for each finishing option?
5. Do you use subcontractors for specialized finishing, and how do you control quality when work is outsourced?
6. Are there limitations to combining certain finishes with specific materials?
If a supplier will subcontract finishing, ask for the subcontractor's details and their qualifications. Where dimensional stability is critical, get agreement on who is responsible for final tolerances after finishing.
Packaging, Shipping, and Logistics Questions
Packaging protects precision parts during transit. Logistics can affect delivery dates and cost.
1. How will parts be packaged to protect precision surfaces and fragile features?
2. Do you label parts with part numbers, serial numbers and inspection status?
3. What are your typical lead times for standard and expedited orders?
4. What shipping carriers do you use, and do you offer insured shipping for high-value orders?
5. How do you handle international shipments and customs documentation?
6. Can you provide consolidated shipments for multiple part numbers or blanket order fulfillment?
Ask for photos of sample packaging and a description of your shipping workflow. For critical assemblies, request palletization or special handling instructions to be written into the order.
Pricing, Contracts, and Lead Time Transparency
Transparent pricing and clear contract terms prevent disputes.
1. How do you calculate price including machine time, material, labor for post-processing, inspection and shipping?
2. Do you offer volume discounts, and how are break points defined?
3. Are there setup or first article fees, and how are sample costs handled?
4. What are your payment terms, and do you require deposits for new customers?
5. How do you handle change orders, and who signs off on scope changes that affect cost?
6. What are the warranty and liability terms, and how do you handle defective deliveries?
Request a breakdown of estimated costs for a sample part and ask for a written quote with validity dates. Clear change order procedures reduce bill disputes.
Communication, Project Management, and Service Level
Good communication matters as much as technical competence.
1. Who will be the point of contact, and what is their role?
2. What is the typical response time for technical and commercial inquiries?
3. Do you provide an online portal for order tracking and file management?
4. How do you handle escalation if issues arise during the build or delivery?
5. Will you provide regular progress reports for production runs and expected checkpoints?
6. How do you manage file revisions and version control for repeated orders?
A named contact and clear escalation path prevent small issues from becoming project blockers. Portals reduce email confusion and help track approvals.
Red Flags and Warning Signs
Watch for these warning signs during the evaluation.
1. Vague answers to specific inspection or calibration questions.
2. No examples or references for similar work.
3. Refusal to provide material traceability or certificates.
4. Inability to provide a sample inspection report or measurement data.
5. Lack of clarity on subcontracting and who owns the final quality.
6. Unwillingness to put key terms such as lead time, warranty or change order policy in writing.
If a supplier hesitates to share basic documentation, walk away. It is harder to recover trust after a quality failure than it is to choose a different supplier.
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