Description
Magnetic particle testing for eligible SAG mill liner components supplied to an approved inspection specification.
SAG mill liner magnetic particle testing (MT) is a nondestructive examination used to identify relevant surface and near-surface indications in ferromagnetic components. For a drawing-based liner order, EB China can review buyer-specified MT coverage, procedure, acceptance criteria, personnel requirements and reporting before quotation.
This page describes manufacturing quality control for supplied liner parts. It does not advertise field inspection crews in the United States or any other destination country, and it does not replace an operating-mill condition assessment.
Applicable material first
MT requires a ferromagnetic test surface. Material grade and magnetic suitability must be confirmed before the method is specified.
Acceptance criteria by contract
A test method does not by itself define what is acceptable. The drawing or purchase specification must state the applicable criteria.
Traceable report package
Part identity, examination area, procedure, results, disposition and personnel evidence should match the agreed order scope.
What magnetic particle testing can and cannot show
Magnetic particle testing creates a magnetic field in the examination area and applies a suitable detection medium. A discontinuity that interrupts the field can produce a particle indication. The method is commonly used to find surface-breaking and some near-surface discontinuities in ferromagnetic material, particularly crack-like indications.
MT is not a universal “casting quality certificate.” It does not replace chemistry, heat treatment, hardness, dimensions or visual inspection. It is not intended to characterize deep internal volume in the same way as a selected ultrasonic or radiographic examination, and it is not applicable when the material is not sufficiently ferromagnetic.
| Question | MT contribution | Separate evidence still required |
|---|---|---|
| Are relevant surface or near-surface indications present? | Examines defined ferromagnetic areas using the agreed technique and procedure. | Acceptance criteria, indication evaluation and disposition. |
| Does the liner match the ordered alloy? | MT does not identify chemical composition. | Heat/batch traceability and chemistry or material certificate. |
| Does the liner fit the mill? | MT does not verify outline, hole pattern or interface dimensions. | Drawing revision and dimensional inspection record. |
| Is the internal section free from every possible defect? | MT sensitivity is concentrated at and near the surface. | Engineering review of whether another NDT method and acceptance basis are required. |
| Is the part approved for service? | MT supplies one item of inspection evidence. | Final release against the complete purchase specification and approved disposition. |
Standards and acceptance criteria must be separated
A recognized practice can control how the examination is performed, but the buyer still needs to specify the product-specific examination areas and acceptance criteria. For general industrial work, examples that may be referenced by contract include ASTM E3024/E3024M and ISO 9934-1. The contract should identify the required edition instead of relying on a web page title.
ISO 9934-1 states general principles and does not define product acceptance criteria. Personnel qualification requirements are also a separate purchase decision; where relevant, buyers may specify a scheme such as ISO 9712 or another contract-approved employer/certification practice.
Important: EB China will not infer an acceptance limit from the words “MT required.” The RFQ should state the governing document, edition, examination stage, coverage, technique, personnel requirement, report format and acceptance/rejection basis. Any repair and re-examination route must also be agreed.
Define the MT scope by liner position
SAG mill liners contain geometry changes, holes, lifting or handling features, ribs, transitions and high-stress interfaces. A blanket statement such as “100% MT” can still be ambiguous unless the drawing identifies the surfaces and whether inaccessible areas are included. A position schedule should connect each part number to its examination scope.
| RFQ field | What to define | Why it matters |
|---|---|---|
| Part identity | Mill, liner position, part number, drawing and revision | Links the report to the supplied component. |
| Material and condition | Specified grade, heat-treatment condition and confirmation of magnetic suitability | Determines whether MT is technically applicable. |
| Examination stage | For example, after an agreed manufacturing stage and before coating, where specified | Prevents surface condition or later processing from making the record ambiguous. |
| Coverage | Whole accessible surface or clearly marked critical zones | Defines what the report actually represents. |
| Procedure | Referenced standard, written procedure, technique and detection medium | Controls repeatability and review. |
| Acceptance | Permitted/rejectable indication criteria and engineering disposition authority | Separates detection from the accept/reject decision. |
| Records | Report, part photos, indication records, personnel evidence and traceability | Allows the buyer to verify the released scope. |
Typical pre-shipment documentation package
The exact package depends on the contract. A practical liner QA package can combine the MT record with the other evidence needed to release the parts:
- approved drawing, part list and inspection/test plan reference;
- heat or batch identification and material documentation;
- heat-treatment and hardness records where required;
- visual and critical-dimensional inspection results;
- MT procedure and report identifying method, coverage and result;
- personnel qualification evidence when specified;
- indication photographs or sketches and disposition records where applicable;
- re-examination record after an approved repair, if the specification permits repair;
- final part marking, quantity reconciliation and packing evidence.
MT, PT, UT or RT: do not select only by abbreviation
| Method | General purpose | Selection question |
|---|---|---|
| MT — magnetic particle testing | Surface and near-surface indications in suitable ferromagnetic material | Is the material magnetic, and are the relevant surfaces accessible? |
| PT — penetrant testing | Surface-breaking discontinuities on suitable nonporous surfaces | Is MT unsuitable, and can the surface be properly prepared and examined? |
| UT — ultrasonic testing | Selected internal or planar discontinuities where geometry and material permit | Can the component geometry and microstructure support a qualified technique? |
| RT — radiographic testing | Selected internal density/volume changes using an approved radiographic technique | Are section thickness, access, sensitivity, safety and acceptance criteria defined? |
The responsible engineering organization should select the method, coverage and acceptance basis for the actual liner material, geometry and consequence of failure. Multiple methods may be required; none should be promised as a substitute for a complete specification.
Information required for a SAG mill liner QA quotation
- liner arrangement, part drawings, revisions, position list and quantities;
- material grade, manufacturing route and heat-treatment requirement;
- applicable MT standard and edition or buyer procedure;
- examination stage, accessible coverage and critical-zone drawing;
- acceptance criteria, repair policy and re-examination requirement;
- personnel qualification, witness or hold-point requirements;
- required report fields, photographs, language and final document format;
- other material, hardness, dimensional or NDT records required for release.
For complete liner supply rather than inspection documentation alone, review SAG Mill Liners for Mining Grinding Equipment. Buyers can also use the pre-shipment inspection checklist, quality-control overview and certificate page when preparing the supplier-document package.
Request SAG mill liner supply with MT documentation
Send the liner drawings, material specification, quantities, MT procedure or standard, coverage, acceptance criteria and required records. EB China will confirm the manufacturing and inspection scope before quotation. Overseas field inspection is not included unless separately and explicitly agreed in writing.
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