Prehard or heat-treated
Separate the condition used for machining from the final hardness requirement. Include the permitted hardness range and verification requirement.
Metal / CNC MATERIALS
Carbon & Alloy Steel CNC Machining
Drawing-based steel parts for prototypes, small batches and repeat production. Regularly machined materials include prehardened 4140 and Q235.
CNC milling & turning · Drawing-based orders
Prehardened stock or machining before heat treatment?
The answer changes the process sequence. For prehardened 4140, state the incoming hardness requirement. If hardening follows rough machining, identify final dimensions and any grinding allowance. Q235, 4140 and a carburizing steel such as 20MnCr5 describe different material choices, not ascending levels of the same product.
01 / MATERIAL SPECIFICATION
Carbon & alloy steel grades & conditions.
Match the full designation on your drawing. Frequent machining experience, published project evidence and specifications for review are shown separately.
| Grade / designation | Experience | Include with your drawing | Inquiry |
|---|---|---|---|
| 4140 prehardened | Regularly machined | Specify the required hardness range and material standard; no universal prehard hardness is assumed. | Quote grade ↗ |
| Q235 | Regularly machined | Include the complete grade designation, quality suffix where specified, and product standard. | Quote grade ↗ |
| 1018 / 1045 | Specify for review | State the exact grade, product form and required heat-treatment condition. | Quote grade ↗ |
| 4340 | Specify for review | Include the supplied condition and final hardness requirement where applicable. | Quote grade ↗ |
| AerMet 100 | Published project | Documented hard-machining project; the case separates drawing hardness from measured dimensions. | Quote grade ↗ |
| 20MnCr5 | Published project | Documented gear project involving carburizing and subsequent operations. | Quote grade ↗ |
OUJI machining experience: confirmed by the company owner, 10 September 2026. Family-level experience does not establish a specific grade, stock condition or customer end use; see individual row and case evidence.
Listed grades do not imply current inventory. Material condition, stock form and documentation are agreed with the quotation.
02 / MACHINING REQUIREMENTS
Make the drawing ready for review.
Focus on the details that change material purchasing, the machining route and finished-part acceptance.
Process sequence
Highlight dimensions that apply after heat treatment, grinding or coating, so the complete route can be reviewed.
Surface protection
Specify coating, masking and packing requirements with the drawing. Material grade and a finish name alone do not define acceptance.
03 / PROJECT EXPERIENCE
Carbon & alloy steel in the workshop.
Read the actual machining route and evidence for each project. Requirements and individual inspection results retain their original scope.
AerMet 100 alloy steel
AerMet 100 Hard Machining: 6-Up Fixturing and a 20-Part Cutter Interval
- Project quantity
- 1,800 completed parts
- Drawing requirement
- 51–54 HRC specified on the drawing; not presented as a measured result
What this case documents
The material grade, order quantity, process sequence and observed tool-change intervals come from OUJI production records and photographs. The 51–54 HRC value is a drawing requirement, not a published hardness measurement. The CMM screen covers one randomly selected finished part and one front-side inspection program; three mapped characteristics are published from its 12-characteristic report. This does not establish batch capability, Cpk, yield, a result for the other 1,799 parts or a zero-defect result.
20MnCr5 alloy steel
Controlling Concentricity Through Carburizing and Gear Shaping on 20MnCr5 Steel
- Drawing requirement
- HRC 58–62 after carburizing
- Drawing requirement
- 0.4–0.6 mm
What this case documents
The published drawing excerpt documents these requirements and the planned route. No final hardness, case-depth or dimensional inspection report is included in the public evidence set.
ORDER DETAILS
Material, finish and documentation.
Specify the requirements together so the quoted scope matches the finished part you need.
Purchasing
Material certificates ↗
Specify the material records and traceability your order needs.
ManufacturingFinish compatibility ↗
Connect material, coating and final dimensional requirements.
SpecificationGrade cross-reference ↗
Review regional names without assuming an automatic substitute.
Finishing is coordinated through specialist partners. View surface finishing services.
What hardness does “4140 prehard” mean at OUJI?
We do not assign one universal hardness range to that label. Put the required range and material standard on the drawing or RFQ; incoming condition and any verification must be agreed for the actual stock.
Can I specify a local steel name such as A3?
Send the applicable standard or an existing material document as well as the name. A short local label is insufficient to approve a substitute. A2 tool steel and an ambiguous A3 designation should not be combined into one equivalence row.
Can the drawing call for dimensions after heat treatment?
Yes. Identify those dimensions explicitly, including the required hardness, finish and inspection stage. The AerMet 100 and 20MnCr5 cases show different process routes rather than a single route for every steel.
DRAWING TO QUOTATION
Have a material on your drawing?
Send the drawing and quantity. We’ll review the material, machining route, finish and inspection requirements together.
Response within 24 hours of receiving complete project details.
Start with what you have.
Open the full request form ↗Details already in your drawing do not need to be repeated. If a material is undecided, tell us what the part needs to do.
See our inspection approach ↗