Ensuring the Quality of Critical Components During Manufacturing

The reliability of industrial equipment depends directly on the quality of its mechanical components.

Girth gears, pinions, trunnions, shells, mill heads, mill bottoms, tyres, rollers and other large mechanical components are subject to stringent requirements regarding manufacturing quality, geometry, surface finish and metallurgical integrity.

Depending on their design, dimensions and operating conditions, these components may be manufactured by casting, forging, fabrication and welding, or machining.

Manufacturing inspection and monitoring help ensure that each stage of the process complies with the drawings, technical specifications and contractual requirements, while also enabling potential manufacturing deviations to be detected at an early stage.

With over 25 years of experience in industrial inspection and non-destructive testing (NDT), DIAG METAL provides its expertise to help clients define appropriate inspection requirements during project preparation and secure every stage of the manufacturing process through to final component acceptance.

Inspection Begins During Project Preparation

Component quality cannot be assessed solely at the end of the manufacturing process.

For large mechanical components subjected to significant operating loads, inspection requirements must be defined at the early stages of the project, taking into account the component’s function, manufacturing process, and dimensional, geometrical and metallurgical characteristics.

DIAG METAL draws on its experience to help clients establish the project’s inspection framework, including:

Dimensional and geometrical characteristics to be inspected;
Applicable tolerances;
Surface finishes and roughness requirements;
Hold points and inspection points;
Inspections to be performed at each manufacturing stage;
Required non-destructive testing;
Validation of weld repairs;
Material and heat treatment requirements;
Documentation and records to be provided by the manufacturer.

This preparation helps align the requirements of the client and manufacturer from the outset and reduce the risk of non-conformities that could result in component rejection during final inspection.

Inspection of Cast Components

Many large mechanical components can be manufactured by casting, including trunnions, mill bottoms, mill heads, girth gears, tyres, rollers and various other cast components such as housings and frames.

Manufacturing inspection may cover material compliance, monitoring of the various manufacturing stages, dimensional and geometrical characteristics, surface finish, machining operations, non-destructive testing, any required repairs and final component compliance.

For a cast trunnion, for example, inspection is not limited to identifying potential internal or surface indications. Diameters, concentricity, runout, drilled holes and the surface roughness of bearing contact surfaces can also be checked in accordance with project requirements.

Similarly, surfaces intended for seals or sealing functions may require specific surface finish inspections.

The objective is to verify both material integrity and the dimensional, geometrical and functional conformity of the component.

Inspection of Forged Components

Forged components are used in a wide range of mechanical applications requiring high levels of strength and integrity, including pinions, gearbox planet gears, tyres, rollers and other critical mechanical parts.

Forged pinions, for example, are components for which manufacturing inspection must take into account material quality, final geometry and the various stages of metallurgical processing, including carburising and quenching.

Inspection may cover the forging process, machining operations, dimensional and geometrical characteristics, non-destructive testing, heat treatments, hardness, any required repairs and final component compliance.

Heat treatment is a particularly important stage in the manufacture of certain forged components. It can directly affect their mechanical properties and performance in service.

Inspection activities may include verifying heat treatment requirements, checking process parameters against specifications, reviewing heat treatment records, checking hardness and examining the results of post-treatment inspections.

Following heat treatment and machining, the component’s dimensions, geometry and functional characteristics can also be verified to ensure compliance with project requirements.

Inspection of Fabricated and Welded Components

Some large components can also be manufactured through fabrication and welding, including shells, girth gears and various mechanical assemblies or associated structures, such as housings and frames.

Inspection may cover joint preparation, materials used, welding operations, assembly geometry, distortion, final dimensions, non-destructive testing, heat treatments where required, any necessary repairs and final compliance with drawings and specifications.

Dimensional and geometrical inspection of fabricated assemblies is particularly important. Distortion caused by the manufacturing process must be assessed to ensure it remains within the limits permitted by the design requirements.

For fabricated shells and girth gears, controlling overall geometry, alignment, diameters and functional characteristics can be essential to ensure correct installation and proper operation of the assembly.

Where specified, inspection may also cover post-weld heat treatment and verification that it complies with the applicable requirements.

Inspection Tailored to Each Component

Given the considerable dimensions of these mechanical components and their often one-off manufacturing, each part has its own characteristics, functions and manufacturing risks.

Their inspection requires in-depth knowledge of the relevant manufacturing processes. Drawing on its experience across these processes, DIAG METAL is an established specialist and trusted partner in this field.

Independent Expertise for Your Projects

Engaging DIAG METAL gives clients access to an independent technical perspective on the manufacturing of their components.

Our more than 25 years of experience in inspection and non-destructive testing, combined with our expertise in metallurgy, casting, forging, welding, and dimensional and geometrical inspection, enable us to assess each component as a whole.

We do more than simply determine whether a characteristic complies with requirements. We also seek to understand:

Why a particular characteristic is critical;
Which parameters could cause deviations;
What impact those deviations could have on equipment performance;
Which inspections are appropriate for detecting them;
How potential causes can be eliminated where possible;
How to address confirmed non-conformities.

This approach turns inspection into a valuable tool for controlling and securing the manufacturing project.

Do You Have a Manufacturing Project?

DIAG METAL can support you with manufacturing inspection and monitoring of mechanical components for rotating industrial equipment, including kilns, dryers, mills and granulators.

Our scope includes mill heads, trunnions, tyres, rollers, shells, girth gears, pinions, gearboxes and other large mechanical components.

We provide dimensional and geometrical inspection, metallurgical expertise and non-destructive testing, tailored to the requirements of each project.

Put more than 25 years of specialised experience to work on your next manufacturing project.