Investment Casting CNC Machining Service

Grande provides investment casting CNC machining services for custom metal components that require tighter tolerances, precision bores, threads, sealing surfaces, mounting faces and other functional features that cannot be economically controlled by casting alone.

By integrating precision investment casting with CNC turning, milling, multi-axis machining, grinding and dimensional inspection, we help OEM customers move from near-net-shape castings to finished or semi-finished components through one coordinated manufacturing route.

Send us your casting drawing, 3D model, material, critical dimensions and annual quantity. Our engineering team can evaluate the appropriate combination of investment casting and CNC machining for your part.

From Investment Casting to Precision-Machined Parts

Investment casting can produce complex shapes close to the final component geometry, but not every feature should be controlled through casting alone.

Functional areas such as bearing seats, threaded holes, sealing faces and precision bores often require secondary machining to achieve the dimensions, fits and surface conditions specified on the final drawing.

Grande combines near-net-shape casting with precision CNC machining for investment castings, allowing different features to be produced using the most suitable process.

Typical machined features include:

• Precision bores and bearing seats

• Internal and external threads

• Sealing faces

• Mounting surfaces

• Flanges

• Assembly holes

• Grooves and keyways

• Datum surfaces

• Shaft interfaces

• Mating features

• Chamfers and edge details

• Complex profiles requiring multi-axis machining

This approach helps avoid unnecessarily machining an entire component from solid stock while still achieving the precision required in critical functional areas.

Investment Casting + CNC Machining Capabilities

Actual achievable tolerances, surface roughness and machining strategy depend on material, geometry, feature size, datum structure and inspection requirements.

Why Combine Investment Casting and CNC Machining?

The objective is not to machine as much material as possible.

The objective is to determine which geometry can be produced efficiently through casting and which functional features should be finished through machining.

Reduce Unnecessary Material Removal

Investment casting produces a near-net-shape blank close to the final geometry.

Compared with machining a complex component completely from bar, plate or billet, this can significantly reduce the amount of material that must be removed for components with irregular or three-dimensional shapes.

Machine Only Critical Features

Non-critical external geometry can often remain in the as-cast condition, while areas affecting assembly, sealing, rotation or positioning are precision machined.

This creates a more efficient manufacturing route for many complex industrial components.

Improve Functional Accuracy

Critical mating features often require tighter dimensional control than the casting process alone is intended to provide.

CNC machining allows these dimensions to be controlled according to the final component drawing.

Simplify the Supply Chain

Using separate casting and machining suppliers can create additional coordination work.

When a problem occurs, it may also be difficult to determine whether the issue came from casting allowance, datum positioning, machining or fixture design.

Grande coordinates casting and machining as one manufacturing process, reducing handoffs between suppliers and helping maintain consistency from casting blank to finished part.

Machining Features We Commonly Handle

Precision Bores & Internal Features

Bores frequently determine bearing fit, shaft alignment, fluid flow or assembly accuracy.

Our machining capabilities support:

• Precision boring

• Reaming

• Internal grooves

• Bearing seats

• Concentric internal features

• Multi-diameter bores

Casting allowance and datum relationships are considered before machining begins.

Sealing Faces & Flange Surfaces

Pump, valve, instrumentation and fluid-handling components often contain surfaces where flatness and surface condition directly affect sealing performance.

These areas can be machined after investment casting to create controlled mating surfaces for:

• Gaskets

• Mechanical seals

• Flange connections

• Housing interfaces

• Pressure-containing assemblies

For related components, explore our Pump and Valve Castings.

Threads & Assembly Holes

Machined threaded features can include:

• Internal threads

• External threads

• Tapped holes

• Bolt patterns

• Stud holes

• Precision mounting holes

Hole position and datum relationships can be verified during dimensional inspection.

Mounting Faces & Datum Surfaces

Industrial assemblies often require selected surfaces to control positioning.

Grande can machine defined datum surfaces, mounting pads and mating areas while retaining the advantages of near-net-shape investment casting elsewhere on the component.

Complex Multi-Axis Features

For parts containing angled holes, curved profiles, multiple machining orientations or difficult-to-access features, 4-axis and 5-axis machining can reduce repeated setups and support more complex machining strategies.

Engineering the Casting for Machining

Reliable investment casting and machining should be planned as one process rather than treating machining as an afterthought.

Before production, our engineers can review the relationship between the casting blank and final machined geometry.

Machining Allowance

Too little machining allowance can leave insufficient material to achieve the final dimension.

Too much allowance increases machining time, tool wear and material removal.

The appropriate allowance should therefore be determined according to casting geometry, material and critical feature requirements.

Datum Selection

Stable datum selection affects machining accuracy across multiple features.

Datum surfaces are considered together with the casting structure so that the component can be located consistently during machining and inspection.

Fixture Planning

Irregular investment castings may require specialized workholding.

Fixture planning considers:

• Part rigidity

• Casting variation

• Clamping location

• Machining access

• Deformation risk

• Production repeatability

Tolerance Allocation

Not every dimension needs the same level of precision.

A practical manufacturing strategy separates:

As-cast dimensions
for geometry that can remain within investment casting capability

from:

Machined dimensions
for fits, sealing surfaces, bearings, threads and other functional features.

This helps avoid adding unnecessary machining cost to non-critical areas.