Nondestructive testing (NDT) helps manufacturers evaluate components without destroying them. The inspection method, process stage, and acceptance criteria must match the material and customer requirements. An inspection result supports a quality decision; it is not a guarantee that a part is free of every possible defect.
Sub Source provides NDT services in Rockford, Illinois, alongside metal preparation and coating. This guide explains what to discuss with your inspection provider before sending parts for processing.
What does nondestructive testing evaluate?
NDT uses different methods to look for particular types of discontinuities. A method suited to surface-breaking cracks may not reveal internal conditions. Material, geometry, accessibility, surface condition, and the governing procedure all affect the inspection. Customer drawings and specifications should define what is required and how indications are evaluated.
Liquid penetrant inspection
Liquid penetrant testing is used to reveal discontinuities open to the surface of suitable solid, nonporous materials. Penetrant enters accessible surface openings; subsequent processing makes indications visible for evaluation. A clean, appropriately prepared surface is essential. The method does not establish the absence of internal defects.
Discuss preparation and process sequencing with the inspection team. Do not assume penetrant inspection through a finished coating can verify the underlying metal or coating adhesion. Follow the applicable inspection procedure.
Magnetic particle inspection
Magnetic particle testing uses magnetization and particles to reveal indications associated with surface and near-surface discontinuities in ferromagnetic materials. It is not interchangeable with penetrant testing, and it is not suitable for every alloy. Material suitability, access, and the specified technique must be reviewed before processing.
Plan inspection with finishing and coating
Inspection belongs at the stage required by the manufacturing plan and governing specification. Cleaning, machining, preparation, and coating can affect access to the surface being examined. Coordinate the sequence before work begins rather than treating inspection as an automatic final step after coating.
When your project also requires metal finishing, grit blasting, or coating, provide the complete process requirements so the team can review the handoffs and inspection points.
What to provide when requesting an NDT quote
Include drawings and revision levels, material and alloy, part dimensions, quantity, required inspection method, governing specification, acceptance criteria, incoming surface condition, reporting requirements, and requested delivery date. Identify any customer approval or accreditation-scope requirements that apply to your order.
If the drawing does not identify an inspection method, ask your engineering or quality team to clarify the requirement. The inspection provider needs a defined basis for evaluating and documenting the work.
Discuss your inspection requirements
Send your drawings and specifications through our quote request form, or contact Sub Source at 815-968-7800. Our team can review the requested services and discuss how inspection fits your processing needs.
Further reading: ASNT explains the principles and limitations of liquid penetrant testing and magnetic particle testing.
