A quick price enquiry can be a single sentence: “can you make this part for us?” For a dependable quotation on demanding metal components, that is often not enough.
Material, quantity, tolerances, surface finish, welding requirements and documentation can all change the route through production considerably – and with it the price. The more complete the technical information, the better it can be judged:
whether the part can be made at all
which processes are needed
which operations have to be planned in
which tests are necessary
how reliably cost and delivery time can be calculated
A good manufacturing enquiry therefore describes not just the geometry but the result wanted.
What belongs in a manufacturing enquiry as a minimum?
For many parts, six basic details are enough to begin with:
drawing or CAD data – what is to be made?
material – what is the part to be made from?
material thickness or starting stock – which dimension is intended?
quantity – one-off, prototype or small batch?
surface finish – what execution is expected?
delivery date – when is the part needed?
For simple parts that is already enough for a first assessment. More complex assemblies call for further detail.
STEP, DXF or PDF – which file format for what?
Different kinds of data do different jobs.
STEP
STEP data suits three-dimensional parts, assemblies, complex geometries, folded parts, housings, hoppers and transitions, and welded assemblies particularly well. The 3D model makes the geometry and the relationships between features quick to grasp – for complex parts, STEP is often the most valuable basis for the technical review.
DXF
DXF data is widely used for two-dimensional profiles: laser cut parts, stampings, flat sheet metal parts, outlines and hole patterns. A DXF file can serve directly as the starting point for programming, but it carries far less information about the finished part than a 3D model or a technical drawing.
PDF drawing
A technical drawing stays important even where 3D data exists. It carries what a CAD model alone does not state unambiguously: tolerances, fits, surface finishes, welding symbols, critical dimensions, inspection characteristics, notes, material and revision. Model and drawing complement each other – they do not replace each other. For demanding components, STEP plus a PDF drawing is often the ideal combination.
And DWG?
DWG files can also hold drawings or profiles; whether they are usable for production directly depends on the system and the content. For data exchange with as little friction as possible, STEP for 3D, DXF for 2D profiles and PDF for drawings and specifications are usually the most practical.
State material and starting stock unambiguously
“Stainless steel” or “aluminium” is often not enough for a dependable enquiry. A specific designation is better – 1.4301, 1.4404 or 1.4462, say – or a clearly specified aluminium alloy including its delivery condition. Materials differ in:
weldability
formability
strength
corrosion resistance
surface behaviour
price and availability
A change of material can change the whole manufacturing process. The starting stock matters just as much: 2 mm sheet, 60.3 × 2 mm tube, section, round bar, woven wire mesh or perforated sheet. On assemblies, these details should be clearly allocated to the individual items. Materials at stainlesstec
Quantity changes the manufacturing strategy
Whether a part is made once or a hundred times makes a considerable difference to the economically sensible approach:
one-off – flexibility usually comes first.
prototype – one more question: are design changes to be expected later?
small batch – fixtures, programmes and optimised operation sequences start to pay.
repeat part – existing production data may be reusable.
The enquiry should therefore not state only the current quantity: if further quantities are foreseeable, that is worth saying too. Small batches & bespoke work
Tolerances: as tight as necessary
Very tight tolerances raise both production and inspection effort, so not every dimension should be toleranced as tightly as possible just in case. The question is: which dimensions really are critical to function and assembly? Those should be clearly marked – the manufacturer can then aim processes and checks squarely at them. Uncritical dimensions can be covered by suitable general tolerances.
3D data contains no tolerances
This is easily overlooked in data-driven manufacture: a CAD model has geometrically exact dimensions, while real production always has tolerances. Without a drawing or a separate specification it is often unclear:
which dimension is critical
what deviation is permissible
which fit is required
what flatness is demanded
which positional tolerances apply
“The dimension is in the STEP model” therefore does not answer the question of permissible deviation. Manufacturing limits & data
Describe surfaces unambiguously
“High-quality finish” or “neatly ground” leaves a great deal of room for interpretation. Specific details are better:
grit size
roughness value Ra
direction of grain
visible face
product-contact surface
pickled
passivated
anodised
coated
untreated
Where different surfaces carry different requirements, they should be marked up on the drawing.
Mark the visible faces
On housings, covers and high-grade stainless parts especially, it helps to know: which surface will the end user see? That bears on material handling, protective film, bending sequence, weld position, finishing and assembly. A face defined as visible is treated differently from the outset than an inner face that will later be hidden. Segregated stainless production
What should be stated for welded assemblies?
For welded structures, further information helps:
welding process, where specified
type of weld
weld size
weld position
continuous or intermittent
visible weld
product-contact weld
ground or as-welded
requirements for the weld root
testing requirements
standards to be applied
Where no particular solution is prescribed, it can be worth leaving the manufacturer some latitude in how the welding is carried out. Welding processes compared
Assemblies need parts lists
Where several individual parts are involved, an unambiguous parts list becomes especially valuable. Where possible it should carry:
item number
designation
drawing number
revision
material
quantity per assembly
bought-in parts, where applicable
That is what ties drawings, CAD data and individual components together unambiguously.
Don’t forget the revision status
One of the most unpleasant situations in manufacturing: the part is made correctly – but to the wrong drawing. Technical documents should therefore carry an unambiguous revision status. Where changes are made, it should be plain to see:
which version is current
what has changed
from which order the change applies
On recurring small batches in particular, controlled revision status is fundamental. Production data has to be not only correct – it must also be clear which data is the correct data.
Further details for pressure and process components
For vessels, pipe assemblies and other process components, further details can be decisive:
medium
operating pressure
maximum allowable pressure
operating temperature
design temperature
volume
connections
cleaning requirements
product-contact surfaces
the rules to be applied
tightness requirements
testing
Without this information a pressure- or process-relevant component often cannot be assessed dependably. AD 2000 HP 0 explained
Food and pharmaceutical applications
For parts with demanding hygiene requirements, further details may be needed:
Testing, too, bears on effort and on the quotation. Possible requirements are:
dimensional inspection
flatness check
tightness testing
pressure testing
visual inspection
penetrant testing
other non-destructive testing
electrical testing of an assembly
documented acceptance
The same goes for documentation – depending on the project, material certificates, test reports, welding documentation, measurement records, certificates, conformity papers, traceability and acceptance documents may all be required.
Documentation does not start costing effort at despatch – it shapes how production is organised. Where a test is mandatory, it should therefore be named in the enquiry. Quality & certifications
Delivery date, packaging and despatch
There is a difference between “as soon as possible” and “by 15 November at the latest, for the plant shutdown”. A clear date helps judge whether material procurement, production, testing and any external operations can realistically be planned in.
For delicate or large parts, logistics can matter as well – high-grade visible faces, large vessels, complex assemblies, delicate flanges, international despatch, or particular corrosion and surface protection. Where there are special requirements, they belong in the enquiry.
Does an enquiry have to be fully designed?
No. In early project phases that is not always possible, and an enquiry may well contain open points. What matters then is to distinguish three categories:
fixed – this requirement has to be met.
provisional – this may still change.
open – feedback from production is wanted here.
That transparency helps more than apparently complete data that is then changed several times over.
Where can the manufacturer help?
A manufacturing business can often advise on:
bend radii
tool access
how to split a part up
weld position
material thicknesses
operation sequences
surface finishes
economic batch sizing
That is not taking over design responsibility; it is a manufacturability review from the production side. On bespoke work especially, agreeing these things early avoids needless effort.
Common mistakes in enquiries
“stainless steel” with no material number – too vague for many applications.
a STEP file only, with no drawing – geometry is there, but tolerances and technical requirements are missing.
no quantity – an economic manufacturing strategy can hardly be settled.
no surface finish – on stainless steel in particular this makes an enormous difference to effort.
no revision status – the risk of making the part to an outdated version.
“all dimensions very precise” – leads to needless production and inspection effort.
mentioning testing only after the order – can change the costing and the process considerably.
Checklist for a good manufacturing enquiry
Information
Simple parts
Complex assemblies
STEP/CAD data
recommended
yes
PDF drawing
recommended
yes
DXF for cut parts
if available
if available
unambiguous revision
yes
yes
material
yes
yes
material thickness
yes
yes
quantity
yes
yes
tolerances
relevant dimensions
yes
surface finish
if relevant
yes
welding requirements
if relevant
often
parts list
–
yes
test requirements
if relevant
often
documentation
if relevant
often
delivery date
yes
yes
The ideal combination of data
For demanding parts, a very good enquiry often comes down to a formula: STEP + drawing + specification + quantity.
STEP shows the geometry.
the drawing defines dimensions, tolerances and technical requirements.
the specification describes material, finish, testing and any special stipulations.
the quantity largely decides the economic manufacturing strategy.
For assemblies, a parts list completes that basis.
Why both sides gain from it
A good manufacturing enquiry does not only lead to a quotation faster. It also makes for:
fewer queries
more dependable prices
more realistic delivery times
better comparability between quotations
fewer misunderstandings
fewer changes during production
greater process reliability
Good data does not save paperwork. It saves uncertainty.
From enquiry to manufacturing process
At stainlesstec, customer data is reviewed technically in production planning and then turned into machine programmes and operation sequences. If you already have a specific design, you can send us STEP data, the drawing and the key technical requirements straight away.
Send us your drawing or CAD data by email – together with material, batch size and your requirements. We will come back to you with a sound assessment.
