Precision Machining for Heavy Industrial Components

Casting and heat treatment establish the material properties of a component. Machining establishes the dimensional accuracy of the features that determine how it fits, loads, and functions within the assembly it is part of. A planetary carrier with a bore position out of tolerance by 0.3 mm will generate uneven load distribution across the gear mesh. A conveyor pulley shaft journal machined outside the bearing seat tolerance will run hot and fail prematurely. The machining stage is where dimensional engineering becomes operational reality.

Our machining capability covers the range of operations required for mining and bulk handling components — from rough turning of large castings to finish grinding of precision bearing seats and CMM verification of complex multi-feature components. Core operations are performed in-house; extended capacity for specific operations — long-shaft turning, large-diameter boring, deep-hole work — is accessed through stable, qualified partner facilities within the SMI manufacturing network.

Turning and Boring

CNC turning centres for rotational components including conveyor pulleys, shaft journals, bearing seats, and cylindrical wear parts. Standard in-house turning capacity covers components up to approximately 3,000–4,000 mm in length and 1,500 mm swing diameter. For longer shaft components and large-diameter ring or flange turning, capacity within the network extends to 10 metres and beyond for shaft-type work.

Deep-hole boring for hydraulic cylinder bodies, long bores in structural housings, and similar components is available through network facilities with the capability and tooling for this class of work. Bore straightness and surface finish requirements for hydraulic and precision bearing applications are met as standard within these operations. Capability extends to bore lengths of several metres where component geometry requires it.

Milling

CNC milling centres for prismatic components, housings, brackets, and complex structural castings. Three-axis and four-axis work covers the majority of mining component machining requirements — face milling of datum surfaces, pocketing, slot milling, and hole patterns. Five-axis machining capability, in-house and through network facilities, handles components where tool approach angles, undercut features, or complex surface geometry require simultaneous multi-axis interpolation. Typical five-axis applications include impeller profiles, complex housing geometries, and components where re-fixturing would compromise positional accuracy between features.

Grinding

Surface grinding and cylindrical grinding for components requiring controlled surface roughness and tight dimensional tolerances on bearing contact surfaces, seal running faces, and precision mating interfaces. Grinding is applied as a finishing operation after heat treatment where the hardness of the component surface would cause unacceptable tool wear in conventional machining, or where surface finish and dimensional tolerance requirements cannot be achieved by turning or milling alone.

Dimensional Tolerances and Verification

Standard machining tolerances to ±0.02 mm on critical features as a production capability. Tighter tolerances are achievable on specific features — bearing seats, precision bores, gear datum faces — where the application requires it and the component geometry allows consistent fixturing.

Coordinate measuring machine (CMM) verification is used for:

Bore position accuracy on multi-bore components (planetary carriers, gear housings)
Geometric tolerances — perpendicularity, parallelism, runout — where functional fit depends on these relationships
First-article inspection of new components before batch production is released
Components where the client’s drawing specifies CMM report as a delivery requirement

CMM reports are generated in standard format and supplied with the delivery documentation where specified. For components with particularly complex tolerance requirements, the CMM inspection plan is agreed with the client’s engineering team before first-article production.

Machining Sequence and Residual Stress Management

For precision components — particularly those subject to heat treatment between rough and finish machining — the machining sequence is specified to manage residual stress and dimensional stability. Rough machining before heat treatment removes the bulk of material and allows stress redistribution before the thermal cycle; finish machining after heat treatment achieves final dimensions on a component whose stress state has been stabilised. For components where distortion during heat treatment is a known risk (long shafts, thin-walled housings), allowances are built into the pre-heat-treatment dimensions and verified after thermal processing before finish machining begins.

NDA and Confidentiality

Machining operations on components produced to client proprietary drawings are performed under NDA as standard. For components where the geometry itself represents intellectual property — custom impeller profiles, proprietary housing configurations, specialised wear geometries — fixturing, toolpaths, and dimensional records are handled within the confidentiality framework agreed at order confirmation. Network partner facilities used for specific machining operations are bound by the same NDA terms.

For machining enquiries, tolerance capability questions, or to discuss a specific component requirement, contact our engineering team.