What to send a China rotomold supplier (STEP, IGES, DWG or sketch) and what Luban Rotomold returns: a quote, 1-3 samples, dimensional report, sign-off.
The short version: To get a China OEM mold for rotomolding quoted properly, send a 3D file (STEP or IGES), a 2D drawing (DWG or PDF) or, if you have neither, a hand sketch, together with quantity, material and the faces that matter. Luban Rotomold in Dongguan states that it returns a preliminary quote within 24-48 hours, builds a 3D concept model when there is no CAD, and after the mold is made sends 1-3 samples per design with a dimensional report and photos. Production starts only after your written sign-off, and mold adjustments are free if a sample deviates from the specification.
Most first conversations about rotomolding tooling start with price, but a price is only as good as the information behind it. A supplier quoting from one photo and a rough size has to guess the wall thickness, material, finish and volume, and those guesses are built into the number you receive.
This guide covers the information exchange on an OEM rotomold: which files and specifications to send, how to mark what matters on the part, what a supplier such as Luban Rotomold returns at each stage, and what your written approval should record. Lead times and minimum orders are covered in a separate guide. Here the focus is on what goes back and forth.
What files does a China rotomold supplier need to quote an OEM mold?
Luban lists the formats it accepts as STEP, IGES, DWG, PDF and a hand sketch, and its FAQ asks for 3D drawings in STEP (STP) format together with an estimated order quantity. Each format carries different information. The table shows, as general practice, what a supplier can read from each one and what to send with it.
| Format | What it carries | Good for | Send alongside |
|---|---|---|---|
| STEP (.stp / .step) | Solid 3D geometry in a neutral format that most CAD systems can export | Mold design, volume and weight estimates, parting line planning | A 2D drawing with critical dimensions and tolerances |
| IGES (.igs / .iges) | 3D surfaces in an older neutral format; solids can arrive as loose surfaces | Parts modeled in older CAD systems | A STEP export if your system can make one, plus the 2D drawing |
| DWG | 2D views and dimensions, sometimes 3D | Tolerances, notes and section views | A 3D file, or enough views to model the part |
| PDF drawing | A dimensioned 2D drawing, not editable geometry | Critical dimensions, tolerances and surface notes | The 3D file the drawing was made from |
| Hand sketch, photos or a physical part | Shape and intent, plus the key dimensions you write on it | Early concepts and replacing an existing part | Overall size, target wall thickness, quantity and use |
If you can, send a 3D file and a 2D drawing together. The 3D file gives the shape; the 2D drawing tells the supplier which dimensions matter and how tightly. Name files with the part number and revision, and say in the email which revision is current. A frequent cause of rework at the sample stage is a supplier working from an outdated revision, or from a model that carries no tolerances at all.
Can you order a rotomolding mold with only a sketch or an existing part?
Yes. Luban states that if you have no CAD file, its engineers will build a 3D concept model from reference photos, a hand sketch or a written description with key dimensions, and its FAQ also accepts physical samples and reference products. The concept model becomes the basis for both the mold design and the quote, so a good sketch pays back directly. A useful sketch package includes:
- Overall length, width and height, plus every dimension that must fit something else.
- Photos of an existing part from several sides, with a ruler or tape measure in the shot.
- The target wall thickness, or the load and impact the part has to take.
- Openings, threads, mounting points and where metal inserts are needed.
- Which faces the end user sees and which are hidden.
- Quantity for the first order and an estimate per year.
Confirm what "free" covers: Luban's process page describes the 3D concept model as free when no CAD is available, and the initial consultation as free and without obligation. Its FAQ adds that the concept model is included at no additional charge when tooling goes ahead. Ask in writing whether it stays free if you decide not to order the mold.
What belongs in the RFQ besides the drawing?
The drawing fixes the shape. The rest of the request tells the supplier how the part will be made and used, which is what the price really depends on. The table below works as a one-page RFQ sheet: fill in your own answers in place of the examples and send it with your files.
| Item | Example of a useful answer | Why the supplier asks |
|---|---|---|
| Part name and revision | Tank housing, part number and revision letter | Ties the quote to one version of the design |
| Volumes | Pilot batch quantity, then a yearly forecast | Sets the part price and how the tooling cost is spread |
| Material | UV-stabilized LLDPE, or "must hold diesel" if the grade is open | Sets material cost and, as general practice, the shrinkage the mold is sized for |
| Wall thickness | Nominal wall, thicker at mounting points | Drives part weight and cycle time; Luban sets it within 3-18 mm without a new mold |
| Critical dimensions | Marked on the 2D drawing with tolerances | Shows where tight control is needed; Luban states ±1% or better on high-tolerance OEM work |
| Cosmetic surfaces | Top and front faces visible, base hidden | Decides where the parting line and trim marks may fall |
| Surface finish and logo | Textured outside, logo recessed on the lid | Both are cut into the mold, so they must be known before machining |
| Color | A RAL or Pantone reference | Color masterbatch is mixed into the material, so it runs through the wall |
| Inserts and openings | Threaded inserts on the base, two cut-outs on one side | Inserts are placed in the mold before each cycle; openings are usually cut afterwards |
| Secondary operations | Trimming, drilling, foam filling, assembly | Each one adds labor to the part price |
| Use conditions | Outdoors in full sun, contact with chemicals, temperature range | Guides material grade and UV stabilizer choice |
| Destination | Port or delivery address, shipping mode, documents required | Packing and paperwork are quoted with the parts |
How do you mark cosmetic and functional surfaces on the drawing?
A rotational mold opens along one or more parting lines, and that seam leaves a line on the part. The supplier has to decide where it goes, where any flash is trimmed and which faces carry the texture. If you do not say which faces matter, those choices are made on manufacturing grounds alone. Mark the part in four ways:
- Cosmetic faces: seen by the end user. Note the finish you want, such as textured, sandblasted or high-gloss polished, and that no parting line or trim mark may fall there.
- Functional faces: sealing faces, mating faces and mounting pads. Give the dimension, flatness or tolerance that matters, and say whether a parting line there is acceptable.
- Hidden faces: inside or underneath. Mark them as free for the parting line, vents and trim marks.
- Logo, text and inserts: give position, size and whether a logo is raised or recessed, and dimension each insert from a datum the mold maker can measure. Luban cuts logos into the mold itself, so they repeat on every part.
A marked-up PDF is enough: color the cosmetic faces one way and the functional faces another, and add a short legend. It heads off a frequent argument at sample approval: whether a mark on a visible face is a defect or normal for the process.
Which plastic grade should you name, and what if you do not know?
Luban works with LLDPE, HDPE, cross-linked PE (XLPE), PVC and nylon (PA). If you already have a grade from an earlier supplier or a test program, name it. If you do not, describe the job instead: what the part holds, how much it must carry, whether it sits in the sun, what temperatures it sees and whether it touches food or chemicals. The engineers can then recommend a material and explain the choice.
A few points are worth stating up front. Luban uses UV8 or higher grade stabilizers in outdoor products and food-safe, UV-stabilized LLDPE for its cooler shells, and it lists flame-retardant LLDPE rated UL94-V0 and XLPE as upgrade options on battery enclosures. As general practice, different plastics shrink by different amounts as they cool and molds are sized with that in mind, so switching material family after the mold is cut can move dimensions. Settle the material before the CAD model is approved.
What comes back in the 24-48 hour preliminary quote?
Luban states that its engineers assess geometry, material and production volume and send a preliminary quote within 24-48 hours, and its contact page commits to a first response within 24 hours. Its value depends on the assumptions behind it, so check that it states the following:
- Which file and revision the quote is based on.
- The mold material and construction proposed.
- The plastic, nominal wall thickness and estimated part weight assumed.
- The surface finish, logo and color included.
- Secondary operations included in the part price, and any that are not.
- Tooling price and part price shown separately, with the quantity each part price applies to.
- What the tooling price covers: concept model, trial runs, samples, sample freight and adjustments.
- Payment terms. Luban's standard is a 30% deposit on order confirmation and the 70% balance before shipment, by T/T.
Compare like with like: Put each supplier's assumptions in one row of a spreadsheet before you look at the prices. Two quotes for the same drawing can assume different wall thicknesses or finishes, and the cheaper one may simply be quoting a lighter part.
What do you approve before the mold is cut?
Before machining starts, Luban's engineers model the part, flag draft angles and wall-thickness risks, and return a CAD file for your approval. This is the cheapest moment to change anything: a change to the CAD model costs an email, while the same change after machining means reworking metal. Luban's stated tooling lead time of 4-6 weeks runs from the approved drawing, so this approval also starts the clock.
Check the returned CAD file against your own drawing. Look at where the parting line has been placed, whether added draft has changed a visible face, whether sharp corners have been given radii, and whether insert positions still match your datums. As general practice, rotomolding needs generous radii and draft on deep walls, so expect some edits and agree them in writing now. Reply with an approval that names the file and the revision.
What arrives with the samples?
After the mold is finished, Luban produces 1-3 samples per design, typically 1-2 weeks after mold completion, and inspects each for dimensional accuracy, wall-thickness uniformity and surface finish. You receive a dimensional report and photo documentation. Its quality methods include ultrasonic wall-thickness measurement, dimensional CMM checks and visual inspection. Ask at the quote stage whether the physical samples are sent to you, by which courier and at whose cost. When the report arrives, check that it contains:
- Each critical dimension from your drawing, with nominal value, tolerance, measured value and result.
- Wall-thickness readings at named points, including corners and the thinnest areas.
- The sample number each reading belongs to, where more than one sample was measured.
- Photos of every cosmetic face, the parting line and any trimmed edges, taken in good light.
- Photos of inserts and openings, with a scale in the shot.
- The color compared with the RAL or Pantone reference you gave.
What should your written sign-off say?
Luban starts production only after written client sign-off, and asks you to approve a physical sample rather than a render. That sign-off becomes the reference the production parts are measured against, so make it specific. A useful sign-off records:
- The part number, drawing revision and CAD file the approval refers to.
- The sample number or numbers and the dimensional report reference.
- Any deviation you accept, with the measured value written in.
- Material, color reference, wall thickness and finish confirmed for production.
- Where the reference samples are kept: one at the factory, one with you.
- The name, role and date of the person approving.
What happens if a sample does not match the specification?
Luban's stated revision policy is that mold adjustments are free if a sample deviates from spec. It applies when the part does not match what was agreed; typical examples, as general practice, are a dimension out of tolerance, uneven wall thickness or a surface defect from the tool. Ask for a new sample from the adjusted mold, with a fresh report, before you sign off.
A change of mind is different. If the sample matches the agreed specification and you then want a new feature, a different finish or a moved insert, that is a design change, and Luban's published policy does not say how it is charged. Ask for this to be written into the quotation. Whether a sample deviates from spec can only be judged against a specification that was written down.
A vague spec weakens the free-adjustment policy: If tolerances, cosmetic faces and wall thickness were never stated, a supplier can reasonably argue that a sample meets the specification. Free mold adjustment protects you only as far as your drawing and RFQ define what a correct part looks like.
How do you send files and keep the exchange on record?
Luban's contact page asks for CAD files to be sent by email to sales@lubanrotomold.com rather than through the web form. Its English-speaking sales team also works by WhatsApp and video call, with phone and WhatsApp hours of Monday to Saturday, 9am to 6pm China Standard Time.
Whatever the channel, keep decisions in email: the files you sent, the quote revision you accepted, the CAD approval and the sample sign-off. If something is agreed on a call or in WhatsApp, follow it with a short email that repeats it. If you want to see the tool room and production line before committing, Luban welcomes buyer visits to its factory in Qishi Town, Dongguan.
Send your files for a preliminary quote
Email a STEP or IGES file, a drawing, a sketch or photos of an existing part, with quantity, material and the faces that matter. Luban Rotomold returns a preliminary quote within 24-48 hours and can build a 3D concept model if you have no CAD.
Which CAD formats does a China OEM rotomolding mold supplier accept?
Luban Rotomold accepts STEP, IGES, DWG and PDF files, and also works from a hand sketch, photos or a physical part. Its FAQ asks for 3D drawings in STEP format with an estimated quantity. A 3D file plus a 2D drawing marking critical dimensions and tolerances gives the most reliable quote.
Do I need a CAD file to order an OEM rotomolding mold?
No. Luban's engineers build a 3D concept model from sketches, photos or a written description with key dimensions. The process page describes the model as free when no CAD is available, and the FAQ says it is included at no additional charge when tooling goes ahead, so confirm the terms if you are still comparing suppliers.
How quickly does a preliminary quote come back?
Luban states a preliminary quote within 24-48 hours, after its engineers assess geometry, material and volume, and its contact page commits to a first response within 24 hours. Complete files, quantities and material information make the preliminary figure more dependable.
What documentation comes with the mold samples?
Luban produces 1-3 samples per design and inspects each for dimensional accuracy, wall-thickness uniformity and surface finish. A dimensional report and photo documentation come with them. Production starts only after your written sign-off on a physical sample.
Who pays to correct the mold if a sample is out of specification?
Luban states that mold adjustments are free if a sample deviates from spec. Changes you ask for after a sample meets the agreed specification are design changes, so ask for the way they are charged to be written into the quotation.
How do I send large CAD files to Luban?
By email to sales@lubanrotomold.com, as the website asks for CAD files to be sent that way rather than through the contact form. Name each file with the part number and revision, and say in the email which revision is current.