Tube Bending Machine RFQ Checklist: 15 Inputs Suppliers Need

Use this tube bending machine RFQ checklist to prepare a clearer inquiry before you compare equipment suppliers.

Requesting a tube bending machine quotation involves more than sending a tube diameter and asking for a price. Your supplier needs enough information to evaluate the machine, tooling, controls, automation, sample trial, and acceptance requirements.

A complete RFQ helps you avoid an oversized machine, missing tooling, unclear automation costs, and disagreements during final acceptance. This guide explains the 15 input groups suppliers need and the 14 quotation items you should ask them to confirm.

What Should You Send Before Requesting a Tube Bending Machine Quote?

Before you contact a supplier, prepare as much of the following information as possible:

2D drawing or 3D STEP file
Drawing revision and issue date
Material grade and material condition
Tube form, such as round, square, rectangular, or special profile
Outside diameter and wall thickness
Center line radius, or CLR
Number of bends
Bend sequence and bend direction
Rotation angle between bending planes
Tube-end orientation
Straight lengths and cut length
Critical dimensions and tolerances
Surface and forming requirements
Production volume and changeover frequency
Automation, factory, and acceptance requirements

You can begin an initial discussion with a sketch, sample photo, or physical tube sample. However, accurate machine and tooling recommendations usually require a drawing, material information, and representative samples.

For general machine-selection logic, you can also review how to choose a tube bending machine.

1. Part Drawing, Revision, and File Format

A tube bending machine supplier needs to understand the finished part, not only the raw tube.

Your drawing should show:

Tube diameter or complete cross-section
Wall thickness
Bend locations
Bend angles
Center line radius
Straight lengths
Tube-end direction
Critical dimensions
Dimensional tolerances
Profile tolerances
Surface requirements
Cutting position
End-forming requirements
Datum and measurement references

A 2D drawing is usually enough for an initial machine and tooling review. A 3D STEP file becomes especially useful when your part has several bends, different bending planes, complex end orientations, or tight tool-clearance requirements.

Drawing revision control

Include the following information with your drawing:

Part name
Drawing number
Revision number
Issue date
Customer approval status
Description of recent changes

Without revision control, a supplier may quote against an outdated geometry. A small change to a bend location, CLR, or end orientation can affect the CNC program, tooling, cycle time, and final acceptance process.

2. Datum, Bend Sequence, and Tube Orientation

Complex tube parts need more than overall length information. You also need to define how the part should be measured and how each bend relates to the previous bend.

Datum

A datum can use:

Starting tube-end center
Tube centerline
Clamping reference
Fixture locating face
Coordinate origin
X, Y, and Z directions

For example:

Datum A: starting tube-end center X = 0, Y = 0, Z = 0 mm

This example should be adapted to your own drawing. It is not a universal measurement system.

Bend sequence

A multi-bend part should identify the sequence clearly:

Bend 1 → Bend 2 → Bend 3 → Bend 4

Bend sequence affects:

CNC programming
Tube rotation
Tool clearance
Clamp access
Part handling
Cycle time
Potential interference between completed bends and the machine

Bend direction

Use a defined system such as:

Left / Right
Clockwise / Counterclockwise
CW / CCW
Direction viewed from a specified end
Direction based on the 3D coordinate system

Avoid using “left bend” without explaining which end of the tube the operator should use as the viewing reference.

Tube-end orientation

Also specify:

Starting tube-end direction
Final tube-end direction
Tube-axis direction
End-feature orientation
Required XYZ orientation
Orientation of holes, slots, flares, or formed ends

Tube-end orientation matters when the part will be assembled into a larger product or handled by a robotic system.

3. Material, Tube Form, OD, and Wall Thickness

A tube bending machine RFQ should identify the material and tube geometry together. One parameter cannot replace the others.

Material grade and condition

Provide:

Material type
Specific grade
Temper or material condition
Hardness, when relevant
Applicable material standard
Welded or seamless condition
Surface treatment, if applicable

Typical examples may include:

304 stainless steel
6061-O aluminum
C12200 copper
Carbon steel
Brass

These examples describe how to fill in an RFQ. They do not mean that every machine model has the same verified range for every material.

Material condition affects:

Forming force
Springback
Work hardening
Cracking risk
Tool wear
Surface quality
Required process adjustment

Tube form

State whether your part uses:

Round tube
Square tube
Rectangular tube
Oval tube
Special profile
Multi-chamber extrusion
Non-symmetrical profile

Special profiles need additional information, such as:

Cross-section drawing
3D model
Wall distribution
Critical orientation
Required support direction
Allowable profile deformation

Outside diameter and wall thickness

Provide the complete tube size, for example:

OD 38 mm × wall thickness 1.5 mm

You should also specify:

OD tolerance
Wall-thickness tolerance
Tube length
Incoming material variation
Weld seam position, if relevant

OD and wall thickness influence:

Machine size
Bending force
Die dimensions
Clamp selection
Mandrel requirement
Wiper-die requirement
Pressure-die support
Risk of wrinkling or wall thinning

You can review Zhuoran’s CNC tube bending machine range and NC tube bending machine range when comparing general machine categories. Final suitability still needs to be confirmed against your complete part data.

4. Bend Radius, Bend Count, and Part Geometry

Center line radius

Provide the center line radius, or CLR, for every required bend.

For example:

OD 38 mm CLR 57 mm CLR/OD = 1.5D

A small CLR usually places greater demands on:

Tube support
Mandrel position
Wiper-die adjustment
Pressure-die control
Lubrication
Material stability
Springback compensation

A larger CLR may reduce forming difficulty, but it does not automatically guarantee a defect-free part.

If your part uses more than one bend radius, list each radius separately.

Number of bends

State:

Total bends per part
Bend angle for each bend
Distance between bends
Bend radius for each bend
Whether bends are in one plane or several planes

Example:

Bend 1: 45° Bend 2: 90° Bend 3: 90° Bend 4: 45°

Straight lengths

Provide the straight length:

From the tube end to the first bend tangent point
Between adjacent bend tangent points
From the final bend tangent point to the tube end
Between cut points and formed ends

Short straight sections can affect:

Clamp length
Die engagement
Tool interference
Feeding stability
Minimum usable tube length
Part unloading

Cutting position and end requirements

If your process includes cutting, specify:

Developed length
Cutting datum
Cutting allowance
Final cut length
Required end-face condition
Burr limit
Chamfer
Deburring
Flaring
Expansion
Reduction
Flanging
Sealing or joining requirements

Cutting and end forming may be completed on the same production line, but the exact configuration depends on the product and process sequence.

For tooling-related details, see pipe bending machine tooling.

5. Production Volume, Changeover, and Automation

Production information helps suppliers determine whether you need a standalone CNC machine, an automated machine, or a customized processing line.

Production data

Provide:

Parts per day
Parts per month
Working shifts
Batch size
Product mix
Changeover frequency
Target cycle time
Required uptime
Expected future volume

For example:

Target output: 1,000 parts per day Working pattern: two shifts Product mix: three tube sizes

This is a project input example. Actual machine capacity must be evaluated against the drawing, tooling, number of bends, loading method, unloading method, inspection requirements, and changeover time.

Optional automation features

Our tube bending machines can be equipped with optional automation features, including automatic loading, automatic feeding, automatic tube rotation, automatic cutting, automatic unloading, robotic handling, inline inspection, NG (non-conforming part) sorting, and integrated production line control.

These functions can be configured individually or combined into an automated production line based on your tube specifications, part geometry, production volume, and quality requirements. Specific configurations are subject to technical evaluation and are not included as standard features on all machine models.

Standalone machine

A standalone machine may be suitable when you:

Process multiple tube sizes
Produce smaller batches
Change products frequently
Need flexible operator control
Prefer manual loading and unloading
Need a lower level of line integration

Automated machine

An automated machine may be suitable when you:

Produce a stable product family
Need automatic feeding
Need automatic tube rotation
Want to reduce manual handling
Need repeatable production
Have a defined loading and unloading method

Customized production line

A customized line may combine:

Raw material storage → Automatic loading → Straightening → Feeding → Cutting → Bending → Tube-end forming → Unloading → Inspection → NG sorting → Finished-part collection

Not every project needs every module. Additional operations may include:

Chamfering
Punching
Flaring
Reducing
Welding
Marking
Vision inspection
Laser measurement
MES or PLC integration

6. What Should Be Included in a Tube Bending Machine Quotation?

A complete quotation should identify what is included, what is optional, what is excluded, and what remains subject to technical evaluation.

Ask the supplier to confirm each of the following 14 items.

No.	Quotation item	What the supplier should confirm
1	Main machine	Model, axes, working range, machine layout, and basic functions
2	Control system	Controller, programming method, operator interface, and program storage
3	Tooling	Bend die, clamp die, guide die, pressure die, and related tooling
4	Mandrel	Mandrel type, size, quantity, installation, and adjustment
5	Wiper die	Wiper-die type, size, quantity, and application
6	Pressure die	Pressure-die specification and drive method
7	Multi-stack tooling	Number of layers, radius range, and changeover method
8	Automatic feeding	Feeding device, feeding method, and feed-length control
9	Cutting	Cutting method, blade or tool, cut tolerance, and end quality
10	Unloading	Push-out system, chute, rack, gripper, or robotic handling
11	Installation and commissioning	Installation, setup, commissioning, and trial operation
12	Training	Operation, programming, tooling, maintenance, and safety training
13	Sample bending trial	Sample quantity, trial conditions, inspection, and report
14	Transportation and packaging	Packing method, transport responsibility, unloading, and delivery scope

Do not compare machine prices until you know whether both suppliers have quoted the same scope.

For example, one quotation may include the mandrel and wiper die, while another may list them as separate options. One supplier may include sample bending, installation, and training, while another may exclude them.

Ask suppliers to label each item as:

Included
Optional
Not included
To be confirmed

7. Tooling, Mandrel, Wiper Die, and Multi-Stack Requirements

Tooling should be selected from your actual tube and part requirements.

A typical tooling system may include:

Bend die
Clamp die
Guide die
Pressure die
Mandrel
Wiper die
Anti-wrinkle die
Multi-stack tooling
Lubrication system
Tool-change components

Mandrel

A mandrel can support the tube from the inside during bending. It may help control deformation when you have:

Thin wall
Small CLR
Tight ovality requirements
High appearance requirements
Sensitive materials
Complex bend geometry

A mandrel is not automatically required for every product.

Wiper die

A wiper die can help control material flow at the inside of a bend. It may be considered when the part has:

Thin wall
Small CLR
High wrinkling risk
Strict appearance requirements
Difficult material behavior

Pressure die

A pressure die supports the tube and helps control material movement during the bending operation. Its selection depends on the tube size, material, bend radius, tooling arrangement, and process requirements.

Multi-stack tooling

Multi-stack tooling may be useful when you need:

Several bending radii
Multiple tube sizes
Fewer tool changes
Short distances between bends
Higher flexibility within one setup

Your RFQ should specify whether you need one radius, multiple radii, or multiple product specifications in the same production program.

8. Tolerance, Surface Quality, and Acceptance Criteria

“High precision” is not a complete acceptance requirement. You should define the measurement item, tolerance, unit, datum, and inspection method.

Dimensional tolerance

Dimensional requirements may apply to:

Straight length
Feed length
Bend position
End-point location
Installation hole position
Distance between bends

Example:

Straight length: ±0.5 mm

This is an example drawing requirement, not a universal machine guarantee.

Angular tolerance

Angular tolerance should use degrees:

Bend angle: ±0.5°

Angle accuracy and linear accuracy are different measurements. Do not write only “±0.1” without a unit.

Profile tolerance

Three-dimensional requirements may include:

GD&T profile tolerance
Tube centerline deviation
End-point position
Relative datum position
XYZ coordinate tolerance

Example:

Tube centerline profile tolerance: 1.0 mm relative to the specified datum

Surface and forming quality

Your acceptance requirements may cover:

No visible cracks
No serious scratches
No unacceptable die marks
No excessive drag marks
No obvious wrinkles
Controlled ovality
Controlled wall thinning
Required surface roughness
Appearance approval against a reference sample

You can use tube bending tolerances as a related technical reference when defining the inspection section of your RFQ.

FAT, SAT, and sample acceptance

A practical acceptance process may include:

Drawing review → Tooling proposal → Initial trial → Parameter adjustment → First-article inspection → Repeatability verification → Cycle-time check → Final acceptance

Your technical agreement should identify:

Sample quantity
Test material
Tooling used
Measurement equipment
Dimensional requirements
Appearance requirements
Repeatability requirements
Cycle-time requirements
Safety-function checks
Acceptance documents

A tube bending sample service can help confirm difficult geometries before final equipment approval.

9. How to Compare Tube Bending Machine Supplier Quotes

Use a configuration table to review the equipment scope instead of comparing only the total machine price.

Configuration item	Zhuoran proposal
Machine model	DW38CNC–DW168CNC series; the suitable model is selected according to the actual tube part requirements.
Working range	Determined by the specific machine model. Tube outside diameter, wall thickness, center-line radius (CLR), material, and part geometry must be evaluated together.
Control system	PLC or industrial CNC control system; the specific functions depend on the machine configuration.
Tooling included	Bending die, clamp die, and matching tooling; the exact supply scope is stated in the quotation.
Mandrel	Optional; selected according to the actual forming requirements.
Wiper die	Optional; selected according to the actual forming requirements.
Pressure die	Configured according to the bending system and tooling requirements.
Multi-stack tooling	Available for machine models configured for multi-stack tooling; tooling dimensions are customized according to the customer’s product requirements.
Automatic feeding	Automatic feeding is a standard configuration on CNC machine models.
Cutting	Optional; a cutting module can be integrated, or a separate tube cutting machine can be configured.
Automatic unloading	Optional; an automatic unloading mechanism or robotic handling can be configured.
Sample trial	Arranged according to the project agreement; the sample quantity and inspection criteria are confirmed by both parties.
Installation	The service scope and on-site installation requirements are confirmed according to the project.
Training	Operator and maintenance training are defined according to the agreement between both parties.
Warranty	The warranty period, coverage, and exclusions are confirmed in the quotation or technical agreement.
Delivery	Lead time and applicable Incoterms are stated in the quotation.
Exclusions	Extra tooling, automation equipment, transportation, installation, and other excluded items are clearly listed in the quotation.

A useful quotation should also explain:

Recommended machine model
Maximum working range
Recommended working range
Tooling configuration
Automation scope
Sample trial conditions
Expected changeover method
Site requirements
Installation scope
Training scope
Warranty
Delivery
Excluded items
Items still requiring technical confirmation

10. RFQ Submission Template

You can use the following template when contacting a tube bending machine supplier.

Project name:

Part name:

Drawing number:

Drawing revision:

Drawing issue date:

Material:

Material condition:

Tube form:

Outside diameter:

Wall thickness:

Wall thickness tolerance:

Center line radius:

Number of bends:

Bend sequence:

Bend direction:

Rotation angle:

Tube-end orientation:

Straight lengths:

Developed length:

Cutting position:

Cutting method:

End-forming requirements:

Critical dimensions:

Dimensional tolerances:

Profile tolerance:

Surface requirements:

Production volume:

Working shifts:

Changeover frequency:

Target cycle time:

Automatic loading requirement:

Automatic feeding requirement:

Automatic tube rotation requirement:

Automatic cutting requirement:

Automatic unloading requirement:

Robotic handling requirement:

Inline inspection requirement:

NG sorting requirement:

Factory power and air conditions:

Available installation space:

Requested quotation scope:

Sample trial requirements:

Final acceptance criteria:

Attachments:

Attach the following whenever possible:

2D drawing
3D STEP file
Tube sample
Product photos
Material certificate
Reference sample
Current inspection report
Production target
Layout drawing

11. When Should You Request a Sample Trial?

A sample trial is especially useful when your project includes:

Small CLR
Thin-wall tubing
High surface-quality requirements
Multiple bends
Three-dimensional geometry
Special profiles
Multiple materials
Tight ovality requirements
Strict profile tolerance
Complex tube ends
Automatic loading and unloading
Inline inspection
A customized production line

A machine data sheet may show the nominal working range, but it cannot replace a practical trial when the part has difficult geometry or tight quality requirements.

Zhuoran can review whether a CNC machine, tooling package, or customized straightening, cutting, and bending line is more suitable for your project. A technical review should use the actual tube, drawing, sample requirements, and production target.

For complex projects, you can also review Zhuoran’s custom tube bending engineering service.

Frequently Asked Questions

What information does a tube bending machine supplier need for a quotation?

You should provide the drawing, material grade, tube form, OD, wall thickness, CLR, bend count, bend sequence, production volume, tolerances, end requirements, automation needs, and acceptance criteria.

Do I need both a 2D drawing and a 3D STEP file?

A 2D drawing is useful for dimensions and tolerances. A 3D STEP file helps suppliers evaluate spatial rotation, tube-end orientation, complex profiles, tool clearance, and three-dimensional inspection requirements.

Why are OD, wall thickness, material, and CLR all required?

These parameters work together. They affect forming force, springback, tooling, mandrel requirements, wrinkling risk, wall thinning, and the machine’s suitable working range.

Do all tube bending machines include a mandrel and wiper die?

No universal statement should be made for all machine models. Mandrel and wiper-die requirements depend on the tube, material, wall thickness, CLR, appearance requirements, and allowable deformation.

Are automatic feeding, cutting, and unloading standard features?

Automation depends on the machine configuration and project requirements. Automatic loading, feeding, rotation, cutting, unloading, robotic handling, inspection, and NG sorting may be configured separately or combined into a production line.

What should be included in a tube bending machine quotation?

Ask the supplier to confirm the main machine, control system, tooling, mandrel, wiper die, pressure die, multi-stack tooling, feeding, cutting, unloading, installation, training, sample trial, transportation, and packaging.

How should I define tube bending tolerance?

Define the measurement item and unit separately. Linear dimensions use millimeters, bend angles use degrees, and 3D profile requirements should identify the datum and inspection method.

When should I request a sample bending trial?

Request a trial when you have a small CLR, thin wall, complex 3D geometry, special profile, strict appearance requirement, tight tolerance, difficult material, or an integrated automation project.

Can Zhuoran evaluate a customized tube bending production line?

Zhuoran can review a customized solution based on your tube specifications, part geometry, production volume, quality requirements, and requested process modules. Final configuration requires technical evaluation.

What should be included in the final acceptance criteria?

Acceptance criteria may include dimensional inspection, angle, bend position, ovality, wall thinning, surface quality, repeatability, cycle time, safety functions, and compliance with the approved drawing and technical agreement.