01 / Engineering review
Sheet Metal DFM Engineering Review
Before quotation, we connect the buyer drawing to cutting, bending, welding, hardware, finishing, assembly, inspection and packaging. The goal is to remove assumptions before they become sample rework or batch variation.
Scope
What the Drawing Review Is Actually For
This review is intended for OEM equipment manufacturers and system integrators sourcing enclosure bodies, control cabinets, access panels, brackets and assembled sheet metal structures. It supports manufacturability discussion; it does not replace the buyer's product engineering, electrical design or certification responsibility.
Manufacturing route
How a Review Runs From Files to Closed Open Points
- 01
Review 2D drawings, 3D models, BOM and target quantity
- 02
Mark missing material, finish, tolerance and assembly information
- 03
Check bend access, weld access, hardware position and coating masks
- 04
Agree first-piece evidence and open technical questions
- 05
Freeze the approved revision used for production
Specifications
DFM Review Scope and Output
| Input formats | PDF, DWG, DXF, STEP, IGES or SolidWorks drawings and 3D models |
|---|---|
| What we review | Geometry, datums, bend access, hole and feature spacing, tolerance stack and finish callouts |
| Process advice | Feasible process route for sheet metal and CNC; castings and other processes are out of scope |
| Cost drivers | Material utilisation, tooling, bend count, weld length, finishing and inspection requirements |
| Output | Written review notes returned with the quotation, with each point referenced to the drawing |
| Revisions | Superseded revisions withdrawn so that production always works to one controlled revision |
| Minimum order quantity | 10 pcs (large parts) / 50 pcs (medium parts) / 1,000 pcs (small parts) |
| Follow-up | Open points tracked until they are answered before tooling or production is released |
Review output
What a Drawing Review Returns
The review is not a pass or fail stamp. It is a short list of decisions, each one referenced to the drawing, returned with the quotation.
Every point we send back points at a specific view, dimension or note. Three questions are asked of each drawing: can the part be made as drawn, if not what is the smallest change that keeps the function, and what will you have to check on the first article to prove it. A review that answers those three questions is finished; one that returns general advice is not.
| Hole edges near a bend | The working rule is roughly 2.5 × material thickness plus the inside radius as the minimum distance from a hole edge to the bend line. A Ø6 hole 8 mm from a bend in 2 mm sheet is fine; the same hole 4 mm away will pull out of shape, so we return either a relief slot or a moved hole. |
|---|---|
| Minimum flange and bend radius | Short flanges distort and mark, and a radius below about 0.5 × thickness risks cracking the outside of the bend in mild steel. We say what our tooling holds instead of forming the part and sorting the scrap afterwards. |
| Tolerance the process cannot hold | A ±0.2 mm note across a welded assembly is not a sheet metal tolerance — welding moves material. We return a datum that can be measured after welding, or the one interface that should be controlled. |
| Hardware access | PEM studs and inserts need press clearance and must be set on the correct face before coating. Where spacing or direction is wrong we return a number, not a warning. |
| Finish and masking | Powder coating bridges threads and earth contacts, and galvanised parts need an explicit note where a chromium-free passivation is required for the destination market. |
| Missing information | Grade, thickness, finish, quantity and the critical characteristics. Anything absent is listed as an open point rather than quietly assumed. |
| Revision discipline | The revision the quotation is based on is stated inside the review, so prototype, first article and batch all point at the same document. |
The review returns with the quotation as written notes, so procurement and engineering read the same document: each open point, the revision it refers to, and what we need from you to close it. Where a change is unavoidable we say so before pricing, because a price built on a drawing we already know will not pass the first article helps nobody.
For the checks behind these comments, see seven DFM checks before RFQ. What the press brake can physically hold is covered under bending, material documentation under certification and traceability, and where the tooling decision falls between processes, see laser cutting versus stamping.
Engineering checkpoints
Where a Drawing Needs a Decision Before It Can Be Priced
Each point below is checked against the drawing you send. The ones that are missing come back as questions before pricing, not as assumptions after tooling.
Geometry and datums
Datums, mating faces, door gaps, mounting points and connector openings need a clear inspection basis.
Process sequence
A feature that is easy to model may become inaccessible after a bend, weld or inserted fastener.
Appearance and finish
Cosmetic faces, grinding scope, texture references and masked areas should be defined before sampling.
Revision discipline
The quotation, prototype and batch must point to the same controlled drawing revision.
Buyer input
What to Send for a Review That Says Something Useful
These are the items that make the review specific. Anything missing from the package is raised in the review rather than filled in with a guess.
- STEP or SolidWorks model when assembly fit matters
- PDF or DWG/DXF drawing with dimensions and notes
- Prototype, first-batch and annual quantities
- Material, finish, cosmetic faces and certification needs
- Buyer-supplied parts, assembly scope and destination
FAQ
Questions About the DFM Review
Which files should we send for the review?
A STEP or SolidWorks model where assembly fit matters, together with a PDF or DWG/DXF drawing carrying the dimensions, notes and tolerances. Add the BOM, prototype quantity, first-batch quantity and annual volume — a drawing that will be made in fifties and one that will be made in thousands do not get the same route.
Can you review a design that is still changing?
Yes, and earlier is cheaper. Marking a missing datum or an unholdable tolerance while the design is still open costs a drawing update; finding it after the first article costs a batch. Superseded revisions are withdrawn so production always works to one controlled revision.
Do you review parts that are not sheet metal?
The review covers sheet metal and CNC processes. Castings and other processes are outside our scope, and we say so on the review rather than pricing them anyway. Within scope we look at material utilisation, bend count, weld length, finishing and inspection requirement as the cost drivers.
What do the review notes look like?
Written notes returned with the quotation, each point referenced to a specific view, dimension or note on your drawing. A point that says “tolerance too tight” is not finished; one that says which datum can be measured after welding is. Open points stay tracked until they are answered, before tooling or production is released.
What do you actually flag in a DFM review?
Anything that would force a compromise in production: features too small or too close to a bend, missing bend relief, datums that cannot be measured, tolerances that conflict with the folded part, and finishes that cannot cover the geometry. Each point is raised before we quote, not after the parts are made.
Do we have to accept your suggestions?
No. The review is advice — the drawing is the controlling document. Where your requirement is difficult but achievable, we say what it will take on our side so you can decide whether the cost or the design change is the better trade.
Do you charge for the DFM review?
No. The review is part of preparing the quotation, and where a drawing change is needed we raise it before pricing rather than after the first article fails.
How long does the review take?
The review is issued together with the quotation, so it does not add a separate round trip to your RFQ. Projects with several drawings or a welded assembly take longer to price, and the review points arrive in the same document as the price.
Send your drawings to our engineering team and we will return a DFM review together with the quotation. Request a quote, or see the full range on custom sheet metal fabrication.
Discuss a real project
Send the Drawing, Not a Description of It
Send the drawing set and the target quantities. We will return the open points against the drawing, together with the quotation, before anything is released to production.
Payment Terms
How a project is paid for is agreed before production starts, and the structure that applies to your order is stated on the quotation and on the order confirmation, so there is no ambiguity later.
- 30% advance payment with the order and the 70% balance before shipment — our standard structure.
- 70% advance payment with the order and the 30% balance before shipment — used for some projects.
- 100% payment in advance before production starts — used for some projects.
If your finance team works to a fixed structure, say so in the first enquiry and we will confirm what applies to your order before you commit. Request a quotation.
Questions buyers ask before sending drawings
The nine questions that come up most often before a project starts, answered the way we answer them by email.
What do you need from me to quote a part?
2D drawings as PDF, DWG or DXF, or 3D files as STEP, IGES or SolidWorks, together with material grade, sheet thickness, surface finish, quantity and destination country. If the drawing is not finished yet, send a photo, a sketch or the existing part instead — we review what can be measured from it and reply with the questions that still need answering.
How long does a quotation take?
Enquiries are answered within one business day. Quotation time depends on the part. Simple components we can price straight from the drawing — laser-cut and bent sheet metal, brackets, panels, covers, machine guards — are quoted within 24 hours. Complex work such as assembled kiosks, welded frames and multi-part structures is quoted after the drawing review and process confirmation, because the scope cannot be judged from the drawing alone; the date is confirmed in our reply.
Is there a minimum order quantity?
Prototypes are made from a single piece, and small batches of 10–50 pieces are routine. Prototype, first batch and repeat volume are quoted in one staged quotation so the numbers stay consistent as the project scales. See low MOQ sheet metal fabrication.
Can you work from a sample or a photo if I have no drawing?
Yes. Send the part itself, clear photographs with a rule or caliper in frame, or a dimensioned sketch. We measure what can be measured, list the features that are still undefined, and confirm them with you before production rather than assuming them.
Will you sign an NDA before I send drawings?
Yes. If your process requires one, say so in the first message and we will confirm what we can sign before any file is transmitted. Customer drawings are treated as confidential and used only for the project they were sent for. See our NDA page.
What payment and trade terms do you work with?
The standard structure is 30% advance payment with the order and the 70% balance before shipment. Some projects run on 70% advance payment with the 30% balance before shipment, and some on 100% payment in advance before production. Quotations are issued under EXW, FOB Ningbo, CIF or DDP, whichever your logistics team already works with.
What quality documents come with the parts?
Inspection documents are agreed with the order. Reports are provided on request, and material certificates and traceability can be supplied for the grades we purchase. Tell us in the enquiry which documents your own quality system requires, and we will confirm what we can provide before you order rather than after.
Who will handle my project?
One contact from drawing review through to shipment. Violet, our sales manager, coordinates drawings, DFM questions, quotation, samples, production updates and shipping documents, so you are not handed to a different person between quotation and delivery.
Can you scale from prototype to repeat production?
Yes. Prototype quantity and expected annual volume are quoted together, so tooling, nesting and packaging are planned once and the sample and production prices stay consistent. See prototype to production quotation and sheet metal DFM engineering review.
Trade Terms and Delivery
We quote under the standard Incoterms your logistics team already works with, and build the packing and documentation around the one you choose.
- EXW — you collect from our Ningbo facility and run export clearance through your own forwarder.
- FOB Ningbo — we deliver to the vessel at Ningbo port and handle export clearance.
- CIF — we cover carriage and insurance to your named destination port.
- DDP — we handle carriage, insurance, import clearance and duties through to your door.
Send your destination country, target delivery date and preferred trade term together with the drawing. Request a quotation.
Quotation Time
We quote from your drawings. How long that takes depends on what the part asks for:
- Simple parts — quoted within 24 hours. Laser-cut blanks and bent components, supplied with complete 2D or 3D drawings. Mon–Fri, GMT+8.
- Complex assemblies — quoted after the drawing review. Payment kiosks, multi-part welded frames, enclosures with purchased hardware, or anything needing a coating or assembly trial. We confirm a quotation date once the scope is clear.
Production lead time is quoted separately, after drawing review and process confirmation. Send your drawings.
Who we quote for
Buyers in more than 63 countries and regions have sent us enquiries for custom sheet metal parts
These are markets where enquiries have reached us, drawn from our own enquiry records. We quote against the drawing, not against a catalogue, which means each enquiry is reviewed individually before a price is given.
Europe 18
- Germany
- France
- Italy
- Spain
- Poland
- Netherlands
- Switzerland
- United Kingdom
- Belgium
- Denmark
- Romania
- Czech Republic
- Portugal
- Greece
- Estonia
- Slovenia
- Ukraine
- Turkey
North America 3
- United States
- Canada
- Mexico
Asia-Pacific 13
- Japan
- South Korea
- China
- India
- Indonesia
- Philippines
- Vietnam
- Singapore
- Australia
- New Zealand
- Bangladesh
- Brunei
- Timor-Leste
Middle East 6
- United Arab Emirates
- Saudi Arabia
- Israel
- Qatar
- Oman
- Iraq
Africa 13
- South Africa
- Nigeria
- Egypt
- Morocco
- Kenya
- Ghana
- Tunisia
- Senegal
- Madagascar
- Mauritius
- Libya
- Guinea
- Djibouti
South America 6
- Brazil
- Chile
- Peru
- Colombia
- Argentina
- Uruguay
Europe & Central Asia 3
- Russia
- Azerbaijan
- Tajikistan
Pacific 2
- New Caledonia
- Northern Mariana Islands
Most enquiry origins: United States, Mexico, Germany, Canada, Russia, South Africa, Australia, Nigeria, France, Saudi Arabia, United Kingdom and Italy.
Where the enquiries come from
Counted across both of our enquiry records. Eleven repeatable sectors account for 122 enquiries; the remaining records are one-off requests that do not belong to a repeatable category and are counted separately.
- Industrial machinery & hydraulic equipment24
- Retail, trade & display equipment21
- Construction hardware & building products18
- HVAC & heat pump equipment13
- Agricultural & livestock equipment13
- Electrical cabinets, enclosures & lighting12
- Network & communications cabinets5
- Energy storage & EV charging enclosures5
- Automotive & transport5
- Medical device housings3
- Precision instruments & acoustic enclosures3
Who we work with
Our enquiries come from end manufacturers, brand owners, trading companies, purchasing agents and one-off project buyers. We are used to each of these situations:
- End manufacturers with their own drawings and an existing supply chain to compare against.
- Brand owners who need a manufacturing partner before they have a complete part.
- Trading companies who need a production partner they can audit and repeat.
- Purchasing agents sourcing on behalf of several end buyers.
- Project buyers needing one part, correctly made, without a repeat programme.
What we do not publish. We list the markets and sectors our enquiries come from because that information is useful to a buyer assessing a new supplier. We do not publish customer company names, customer drawings, part dimensions or load values. Drawings and designs are handled under NDA on request, and no customer drawing appears anywhere on this website.
Get a quote for this part
Send a drawing, or just the size and quantity. A sales engineer replies within 24 hours, Monday to Friday (China time).