Metal material guide
Cast Iron CNC
Machining
CNC-machined housings, bases and cast-iron components, with the iron grade, starting stock and datum scheme agreed before cutting.
Confidential enquiries. NDA available.
- Specify
- Grey iron by ASTM A48 class or named alternative
- Review
- Machining allowance and Bearing bore
- Confirm
- Final condition and acceptance records
Choose the iron type and the starting form.
Grey iron, ductile iron, a foundry casting and continuously cast bar are not interchangeable purchasing descriptions. Match the iron grade and stock route to the load, geometry and machining plan.
Machine bases and supports
Identify mounting datums and flatness. Separate the cast shape from the faces that locate the final assembly.
Housings and bearing features
Mark bore positions, wall sections and mating faces. Provide a casting drawing as well as a finished-part drawing when machining a supplied casting.
Machined bar-stock components
Compare a continuous-cast stock route when it suits the geometry. Retain the exact supplier product and required grade.
Choose the grade and stock together.
Compare the Cast Iron options below against the drawing and service conditions. Specify the complete supplier grade, condition and stock form; material examples do not establish current inventory or permit substitutions.
| Grade or stock | Why consider it | What to resolve |
|---|---|---|
| Grey iron by ASTM A48 class | A casting design that calls for a specific grey-iron class. | State the class, section requirements and finished-part acceptance; do not assume equivalence to another standard. |
| Ductile iron by ASTM A536 grade | Loaded parts requiring a defined nodular-iron specification. | Name the grade and material tests, plus any treatment or hardness acceptance. |
| Continuous-cast grey iron | Machined components suited to a named continuous-cast stock product. | Specify the supplier grade, stock allowance and required records. |
| Continuous-cast ductile iron | A stock-based route for a defined ductile-iron component. | Review section, product specification and required final properties. |
Selection examples are subject to material and drawing review. They are not an inventory list.
Already have a grade on the drawing?
Add it to your quotation checklist ↓Establish datums before removing the allowance.
The casting or bar is only the starting point. Define how the finished dimensions relate to the raw geometry, and identify the surfaces from which machining and inspection begin.
Casting variation and allowance
Provide the raw-part condition, machining stock and any supplier casting tolerances. Flag thin local sections where available material needs review.
Bores and datum transfer
Identify first-operation locating surfaces and the final datum system. Discuss how opposite faces or related bores are to be produced and measured.
Edges and casting defects
State edge condition and the acceptance process for porosity, inclusions or surface defects in functional regions. A machined surface alone is not a casting-quality certificate.
Mark critical dimensions on the drawing. Achievable tolerances, wall thickness, part size and delivery are confirmed for the geometry, material, finish and quantity in the quotation.
Define which surfaces remain raw or machined.
Machined functional faces
Specify flatness, fitted bores and roughness where required. Identify surfaces protected from paint or preservation coatings.
Paint or protective coating
State preparation, coating system and masked faces. Indicate whether raw casting texture is acceptable on visible areas.
Preservation for delivery
Define storage, rust prevention and packaging where these affect acceptance or subsequent assembly.
Inspect the iron, the casting and the finished geometry.
Material acceptance
Request the specified grade, lot records and agreed mechanical or hardness tests.
Raw-part acceptance
Define any casting inspection or defect criteria before machining. Identify who supplies and accepts the starting casting.
Finished dimensions
Set datum faces, bore relationships and final surface checks. Include the dimensional-report scope and any first-article requirement.
Three different checks.
The material record identifies the purchased stock. The inspection report checks the drawing. Application validation checks the part in service.
Review inspection requirements ↗Cast Iron machining questions.
Answers to the decisions that affect the material, drawing and finished part.
Are grey and ductile iron the same material?
No. They have different graphite structures and mechanical behaviour. The drawing and purchase order must name the required type and grade.
Can the same grade be machined from a casting or bar?
The stock route and product requirements still need review. A standard or supplier grade for one form does not automatically approve another starting form.
What drawings are needed for machining a casting?
Provide the raw casting drawing, finished drawing, available allowance, datum plan and casting acceptance requirements. Identify critical sections.
Does machining remove every casting defect?
No. Defects may remain or become exposed. State inspection and acceptance requirements for the starting casting and relevant finished surfaces.
How should painted and fitted surfaces be separated?
Mark masked bores, datum faces and assembly contacts on the drawing. Specify paint preparation and final dimensional acceptance.
What should a cast-iron quote include?
Include iron grade, stock source or supplied-casting condition, raw and finished geometry, quantity, treatment or paint, material tests and final inspection requirements.
Prepare your enquiry
Connect the iron grade, raw blank and finished drawing.
Send the CAD model and dimensioned drawing with quantities, service conditions and the requirements below. If the grade is undecided, describe the function and the constraints.
Your files stay confidential. NDA available.
Cast Iron RFQ checklist
Material: [iron type + grade + product specification] Starting part: [foundry casting / continuous-cast bar / supplied blank] Drawings: [raw geometry, finished geometry, machining allowance] Critical features: [datum faces, bores, mounting surfaces] Acceptance: [casting defects, material tests, dimensional report] Finish and quantity: [paint, preservation, lot size]
Material references & specification notes
Manufacturer information supports material selection. Use the datasheet for the exact grade, stock form and test conditions. It does not establish Prolean inventory, application approval or a guaranteed machining result.
Prepared October 2026. Final material and manufacturing requirements are agreed in the quotation.