Stepped shafts
Show bearing seats, shoulders, keyways and the datum used for runout. Include the final material condition and any local hardness requirement.
Steel shafts, bushings, flanges and milled parts
Bushings and sleeves
Define the bore and outside-diameter fits together. Mark lubrication features, edge breaks and surfaces that must remain untreated.
Flanges and coupling hubs
Identify the mating face, bolt pattern, locating diameter and bore. Specify whether acceptance applies after hardening and coating.
Mounting brackets
Locate mounting holes from functional datums and identify faces that contact the assembly. Include any welding or coating after machining.
Fixture plates
Show locating holes, threaded holes and contact faces. Discuss flatness, parallelism and any finishing work after heat treatment.
Machined blocks
Supply the internal passage layout as well as the outside shape. Identify burr-sensitive intersections and the checks needed for each passage.
Choosing carbon steel or alloy steel for your parts
1020 for general engineering parts
1020 is a low-carbon steel used for general engineering components and welded structures. It is worth discussing when the part does not require the properties of a higher-strength alloy steel. [1]
- Material family
- Low-carbon steel
- What to specify
- Specify the material standard, stock form and required condition. Identify any welding, case hardening or later coating.
1045 for shafts, pins and mechanical parts
1045 is a carbon steel used for shafts, pins and other mechanical components. It can be considered for suitable flame- or induction-hardened features, with the required result defined on the drawing. [2]
- Material family
- Carbon steel with more carbon than 1020
- What to specify
- State the supplied condition and any hardness requirement. Do not treat an untreated part and a hardened part as the same specification.
4140 for specified strength and hardness
4140 is a chromium-molybdenum alloy steel used for high-strength components. Prehardened and tempered stock is available in the supply market, but the actual supplied condition must be confirmed for the order. [3]
- Material family
- Chromium-molybdenum alloy steel
- What to specify
- Give the required condition or hardness range and the governing standard. Record any additional treatment separately from the raw-stock specification.
Case-hardening steels for wear surfaces
A case-hardening grade can be reviewed when a part needs a hard wear surface and a tougher core. Bodycote lists 8620H among examples for atmospheric carburizing; the specified grade and process must suit the application. [4]
- Material family
- Drawing-specified case-hardening steel
- What to specify
- Identify the treated surfaces, case-depth definition and core requirements. Approve the exact grade rather than substituting a similarly named steel.
Need 1018, 4340, a tool steel or a grade from another standard? Send the full specification for review. Grade names, stock conditions and product standards are not interchangeable. The examples above do not confirm vetcnc inventory, material suitability or approved substitutes.
Milling and turning steel to your drawing
CNC turning for shafts and fitted bores
Use turning for cylindrical features, shoulders, bores and threads. Show any keyways, cross-holes or flats that need an additional operation. Specify runout from the actual assembly datum, not just the stock centerline.
View the Machining ServiceCNC milling for plates and housings
Use milling for faces, pockets, locating holes and mounting patterns. The review should include workholding, access, released-part flatness and whether heat treatment comes before or after the final cuts.
View the Machining ServiceCombined machining for multi-feature parts
Some parts need both turning and milling, or access to features on several faces. Discuss the actual geometry before choosing the setup; an extra axis is not a substitute for a clear drawing.
View the Machining ServiceGrinding, honing, specialist heat treatment or other secondary operations are reviewed separately where needed. Their inclusion and manufacturing responsibility must be confirmed in the quotation.
Plan steel heat treatment before finishing the critical sizes
Machine in the agreed stock condition
The order may call for parts machined from an agreed as-supplied or prehardened stock condition, with no additional hardening. Record that condition explicitly, including any hardness verification the order needs.
Quench and temper for the specified properties
Quench hardening followed by tempering is used to develop a required combination of hardness and mechanical properties in suitable steels. State the final condition and leave the process selection to a qualified review. [5]
Carburize the surfaces that need a hardened case
Carburizing adds carbon to the surface before hardening. A defined case-depth and hardness requirement is more useful than simply requesting a “hardened part”; include areas to protect and any final finishing allowance. [4]
Review nitriding or local surface hardening
Nitriding changes the surface layer, and its response depends on the steel composition. Local induction hardening is a different route. Specify the surface requirement and ask for the appropriate process to be reviewed. [7]
No heat-treatment route selected.
Confirm the material
Agree the grade, stock condition and final property requirements.
Plan rough machining
Identify stock allowance and any stress-relief step before finishing.
Complete agreed treatment
Record the treatment scope, responsible supplier and acceptance checks.
Verify the finished part
Check specified dimensions and properties at the agreed stage.
Where residual stress is a concern, stress relief may be planned after rough machining and before final finishing to reduce the risk of dimensional change. It is a separate process decision, not a blanket requirement for every part. [6]
Design details to resolve before steel machining
Long shafts and uneven sections
Identify the surfaces that must remain straight when the part is free of the fixture. Discuss support, the sequence of cuts and any post-treatment finishing before assigning tight limits.
Threads, keyways and cross-holes
Show the usable thread depth, keyway geometry, internal intersections and edge requirements. A rendered model alone may not communicate the intended fit or deburring acceptance.
Grinding allowance and protected surfaces
Mark dimensions that will be finished after treatment. Identify faces to mask or protect, and agree any allowance before starting the rough-machined part.
Welded assemblies and fitted components
Tell us whether the component will be welded, pressed into a housing or assembled with other materials. Include the service load and operating environment for an informed material review.
Which features need a closer review?
No review topics selected.
Specify steel part tolerances after heat treatment and coating
| Requirement | What to specify | What to verify |
|---|---|---|
| Shaft and bore fits | Limit sizes or fit designation, functional datum and final surface condition. | Agree the measurement stage and method, especially where grinding or plating follows machining. |
| Straightness, flatness and runout | Datum references, support condition and the feature covered by each tolerance. | Check released parts using the agreed setup, not only while clamped in the machine. |
| Hardness and treated depth | Required scale and range, test location, treated zones and the definition of any case-depth requirement. | State the method, sampling and record. Surface hardness alone is not a case-depth measurement. |
| Threads and coated surfaces | Thread standard and class, masking, coating requirement and the finished dimensions. | Identify checks after coating and any permitted allowance before the final process. |
We confirm achievable tolerances for the actual grade, geometry and treatment sequence. There is no single tolerance or hardness promise for every steel part. Put the critical limits and final acceptance condition on the drawing.
Surface finishes and protection for machined steel parts
As-machined with agreed preservation
Define tool marks, edge breaks and any local roughness requirement. Agree the cleaning and temporary protection appropriate for the part’s storage and transport.
Tell us about assembly cleanliness and surfaces that must remain oil-free.
Black oxide with a specified final condition
Include the required appearance, process specification and any sealer or preservation step. Keep dimensional acceptance separate from the visual finish.
Name the faces to protect and the treatment records required.
Plating with allowance for fitted features
State the specified plating system and any thickness requirement. Identify threads and fits to protect or check after treatment, and any required process-control or relief records.
Do not approve a coating change solely from a color or finish name.
Paint or powder coating on selected surfaces
Mark cosmetic faces, masking zones, color and acceptance criteria. Leave locating features and assembly interfaces clearly identified in the finishing instructions.
Agree which surfaces are coated and when the final dimensions are checked.
Finishes are options for review, not confirmed capabilities or corrosion-performance guarantees. Specify the service environment, governing process requirements and records before a finish is approved.
Material records and inspection for finished steel parts
Trace the material back to the supplied stock
Specify the required material certificate and how the heat or batch identity is linked to your order. An approved equivalent needs written agreement; a similar grade name is not enough.
Keep treatment records tied to the order
Define hardness checks, treated zones and any case-depth verification before production. Keep treatment records identifiable from the drawing revision and the delivered batch.
Measure the finished features
Agree which dimensions are reported, how the part is supported and the sampling plan. Separate dimensional results from material records and treatment reports.
Agree packing and arrival condition
Include protection of machined faces, separation of parts and any preservation restrictions. Identify the expected condition on arrival and how to report a discrepancy.
From steel prototypes to repeat production
Use a representative material and condition
Define what the prototype is intended to prove. Record any temporary material, finish or hardness difference so a fit-check sample is not mistaken for production approval.
Approve the treatment and inspection plan
Tie sample acceptance to the drawing revision, grade, final condition and recorded requirements. Resolve any finishing allowance or open inspection question before batch release.
Keep repeat orders on the same specification
Reference the approved files and document any change in grade, hardness, coating or packaging. Confirm quantities and records for each delivery rather than relying on an old verbal agreement.
What affects the cost of steel CNC machining?
The grade, stock condition and amount of machining
A quote should identify the actual material and starting condition. Compare stock size, removed material, setups and features against the same drawing, not just the finished-part weight.
Hardening, secondary operations and final inspection
Make treatment, grinding, coating and reporting visible in the quotation where they apply. Confirm which operations are included and which need a separate partner or review.
Sample quantities, batch size and delivery scope
Separate sample and production prices when useful. Compare the same finish, records, packing and delivery terms; a lower number is not the same scope if a required operation is missing.
Prepare your steel machining and heat-treatment requirements
Name the steel and the final supplied condition
Send the full material callout, standard and stock requirement. For treated parts, distinguish the incoming material condition from the required condition at delivery.
State hardness, case depth and final dimensions
Identify the test scale, location and range. Where a treated layer matters, state the depth requirement and how it is defined. Keep treatment instructions aligned with the dimensioned drawing.
Send a controlled set of files
Include a matching CAD model and drawing, part number, units and revision. List proposed alternatives separately and confirm that you are authorized to share the design.
Your steel parts and heat-treatment brief
This brief is a request for review, not an approved material choice, treatment instruction or purchase order.
How to start a steel CNC machining order
Send the current files
Include grade, quantity, treatment, critical dimensions and the intended final condition.
Resolve technical questions
Review material identity, machining sequence, secondary processes and the checks that matter.
Approve the quoted scope
Confirm the drawing revision, manufacturing arrangement, price, records and delivery terms.
Review the delivered parts
Use the agreed acceptance requirements and document approved changes before the next order.
Talk to Kevin about your steel machining project
I want you to know who is making your parts, what we have agreed to supply and how you can check the result. You should be able to start that conversation without first traveling to China.
Kevin · vetcnc
Our Family and Manufacturing BackgroundI have spent ten years in the CNC industry, following my father’s generation. Our family business grew through exhibitions and long-term customers. We have multiple factories in China, and I am bringing that experience online so new customers can ask practical questions directly.
When a requirement is outside our factories’ scope, we can discuss a suitable partner, coordinate the work or introduce you directly. For steel parts, that also means agreeing who handles any heat treatment, final finishing and inspection before the order is placed.
Questions about steel CNC machining
Which steel grade should I use for CNC machining?
Start with the drawing requirements: loading, wear surfaces, service conditions, any welding and the final material condition. 1020, 1045 and 4140 are different specifications, not interchangeable grades. Send the approved callout or ask for alternatives to be reviewed before you select one.
Can you review a drawing that specifies 1018, 4340 or a tool steel?
Yes. Send the exact grade, product standard, stock form and required condition. Availability and feasibility must be checked for the order; the grade examples on this page are not a complete inventory list.
Is 4140 steel always supplied at the same hardness?
No. The grade name alone does not define the final supplied hardness or mechanical properties. Specify the required condition, applicable material standard and any test requirements. Confirm these details in the quotation. [3]
Should the parts be machined before or after hardening?
The sequence depends on the incoming condition, geometry, required properties and final dimensions. A plan may include rough machining, agreed treatment and then finishing. Identify critical fits and surfaces so the sequence and any allowance can be reviewed. [5] [6]
Is case hardening the same as through hardening?
No. Carburizing is a surface-enrichment process followed by hardening, while quench-and-temper treatment has a different purpose and process route. State the required surface, core and final-property requirements rather than using “hardened” as the entire callout. [4] [5]
Can you guarantee one tight tolerance for every steel part?
No single number applies to all sizes, grades, geometry and treatment sequences. Send the critical dimensions, datums and final condition. The quotation should confirm the achievable requirements for that particular drawing.
How should I specify hardness and case depth?
State the hardness scale and range, test location, treated surfaces and any permitted untreated zones. For case depth, define the required depth and acceptance method. Agree any test pieces, sectioning or sampling with the responsible specialist.
Can you supply coated or black-oxide steel parts?
Include your finishing specification, required records, masking, preservation and final-size requirements in the inquiry. We will review the arrangement and confirm the process scope rather than assume that a finish name fully describes the requirement.
What information is needed for a steel machining quote?
Provide the CAD model and matching 2D drawing, grade and condition, quantity, treatment and finish requirements, critical tolerances and requested delivery date. List sample approvals, material records and inspection needs at the same time.
Do you accept prototype and repeat-production inquiries?
You can request a sample, pilot batch or repeat-production quotation. State the quantities and any release stages. The minimum practical quantity, cost and schedule are confirmed after reviewing the material and manufacturing requirements.
What happens when a process is outside your own factories’ scope?
We can discuss coordination with a suitable partner or a direct introduction. The production arrangement, responsibilities and commercial terms should be clear before an order is released.
Which files can I attach, and how should confidential drawings be shared?
The preview accepts PDF, DWG, DXF, STEP, IGES, SLDPRT and ZIP files up to 20 MB. Agree confidentiality and a suitable transfer method before sharing sensitive or restricted files. This design-preview form does not send any data until an actual submission service is connected.
Request a quote for your steel parts
- Matching CAD model and dimensioned drawing
- Steel grade, stock condition and material standard
- Final hardness, treated areas and case depth if required
- Finished dimensions, coating, masking and inspection
- Sample and batch quantities, records and requested arrival date
Agree confidentiality and the transfer method before sharing sensitive or restricted files.
Technical references and material notes
- Vulcan — 1020 Carbon Steel Bar — General low-carbon steel characteristics; supplier data, not vetcnc inventory.
- Vulcan — 1045 Medium Tensile Carbon Steel Bar — Carbon steel applications and surface-hardening context.
- Vulcan — 4140 High Tensile Steel — Alloy family and the importance of supplied heat-treatment condition.
- Bodycote — Atmospheric Carburising — Surface enrichment, case hardening and example grades.
- Bodycote — Neutral Hardening — Quenching and tempering of appropriate steel grades.
- Bodycote — Stress Relieving — Residual stress and placement of stress relief before final finishing.
- Ionbond — Plasma Nitriding — Surface treatment and the effect of steel alloying elements.
References support general material and process information. They are not certificates for vetcnc, approved process instructions, or evidence of supplier relationships. The drawing, applicable specification and agreed order govern the supplied parts. Reviewed September 2026.