An irregular component with multiple bore systems required a reference strategy that connected its internal geometry, center positions and angled features.
The documented production route used OP10 and OP20 as two independent 4-axis setups, including rotary indexing at 60° and 180°. The case follows how the locating strategy was carried from the first setup into the second.
Jinhua-owned product photograph, approved for anonymous case use.
01 · Case overview
Case Overview
The starting component was a cast aluminum alloy blank, followed by CNC machining. This case focuses on milling, boring and indexed access to related features.
Starting geometry
Irregular casting with multiple bore regions
Actual route
OP10 first 4-axis setup → OP20 second 4-axis setup
Indexed positions
60°, followed by 180° in the second setup
Inspection evidence
Checks specified; measured results not supplied
02 · The starting challenge
Why This Casting Was Difficult to Machine
The challenge began before the complex bores were machined: stable machining references first had to be established on an irregular cast-aluminum blank.
Repeatable location could not be assumed from every as-cast surface. The setup had to select a supporting bore and planar contact, manage the allowance left for machining, and provide references that later operations could inherit. This describes the locating problem; it does not assign a measured accuracy level to the supplied casting.
A defined starting location
The initial fixture instruction combines rough-bore support with planar seating. Its purpose is to locate the blank before milling and boring create the next features.
Connected feature geometry
Internal steps, adjacent bores and an angled communicating hole depend on more than their individual sizes. Their reference and orientation relationships drive the route.
03 · Casting to machining references
Establishing Machining Datums on an Irregular Casting
The first setup aligns the rotary fixture and supports the component through a rough bore, with a specified planar face seated against the fixture. A rough locating bore is a starting fixture contact; it is not treated as an already verified finished bore datum.
The retained documentation does not establish when the starting planar reference was originally machined. The narrative therefore begins with its specified use for location, then follows the machined profile and step references named for the second setup.
The term machining reference here describes the physical locating strategy. It does not certify the final part's formal datum alignment or a fixture-repeatability result.
04 · First independent setup
OP10 — First 4-Axis Machining Setup
OP10 was the first actual 4-axis production operation in the documented route. The retained instructions specify rotary-fixture alignment, rough-bore support and planar seating before face, step and outer-profile milling and through-bore machining.
The operation also specifies a closely controlled center-position relationship between paired circular features, with a CMM check in the inspection plan. Conflicting source tolerances are intentionally not published here.
That relationship is part of the process-control story. A prescribed circle-center check is not automatically a measured distance between finished bore axes.
05 · Second independent setup
OP20 — Rotary Indexing at 60° and 180°
OP20 is a second, independent setup. Its locating instruction changes to an exterior profile and step face, requiring the reference relationship to be carried into the new fixture location. The documented work includes internal bore milling and boring, stepped geometry, grooves and formed profiles.
The second setup used controlled rotary indexing to reach features that could not be produced from a single machining orientation.
Index to 60°. The confirmed production sequence rotates the fixture to the prescribed machining position for the angled feature, respecting the instruction's rotation-direction note.
Machine the communicating through-hole. The process instruction specifies a drilled cross-hole communicating with an adjacent bore system. It also defines its relationship to the bore axis and planar reference; numerical details requiring reconciliation are withheld.
Subsequently index to 180°. From the prescribed starting reference, the confirmed sequence presents the opposite side for remaining face, shoulder and step machining.
Process evidence: The retained process records document 60° and 180° indexing positions; they are process positions, not measured angular acceptance results.
06 · Geometry that works together
Multi-Bore & Angled Feature Relationships
The manufacturing difficulty was not the number of holes alone, but the relationship among their axes, center positions, angular orientation and the machined datum system.
The source drawings and process instructions connect multiple bore systems, stepped internal geometry and the cross-hole's communication with an adjacent bore. Multi-bore aluminum casting machining therefore calls for a coordinated reference strategy across the internal features and the indexed approach directions.
Real product view of the bore regions. The source records establish the feature relationships; the photograph supplies visual context.
07 · One reference strategy across two setups
Datum Transfer Between Setups
OP10 and OP20 use different locating descriptions. Controlled transfer means re-establishing the prescribed contact and orientation strategy when the component moves to the second setup, so later machining remains tied to the intended reference relationships.
Rotating the component to the specified machining positions allowed the angled cross-hole and opposite-side features to be addressed within that reference strategy. The fixture's signed rotary zero, exact contact crosswalk and achieved repeatability remain subjects for technical verification.
Abstract process/reference flow. Boxes describe operations and reference transfer; no customer geometry is reproduced.
08 · Confirmed plan, no recorded achievements
Inspection Strategy
The process documentation specifies dimensional checks and selected CMM checks within the plan for critical bore, positional and angular relationships. The standalone geometric frames require a confirmed feature-to-method mapping; the cards do not establish a measured result for each frame.
Dimensional and bore checks
Calipers, bore gauges and depth checks are prescribed for selected sizes, bores and steps. Nominal dimensions and checking limits are requirements.
Selected CMM checks
The plan names CMM inspection for the paired-circle center relationship and the combined angled-hole/offset instruction. It does not supply a completed CMM report.
Profile and cross-hole checks
Profile measurement, groove checking and a plug gauge appear for selected features. Their presence in the plan does not prove acceptance.
Result boundary
The retained actual-result cells are empty. Bore conformance, position, perpendicularity and angular achievements remain unverified.
This case does not present unrecorded GD&T results as measured production achievements. The inspection plan is confirmed; achieved results are not verified.
09 · What the route demonstrates
What This Case Demonstrates
This example of 4-axis machining cast aluminum parts shows a manufacturing route organized around reference establishment, multi-bore relationships and two independent setups. Angled hole CNC machining is integrated into the second setup through the confirmed rotary-index sequence.
The case supports a specific process account for an irregular casting. It does not establish a general Jinhua tolerance, angular-accuracy or process-capability guarantee.
10 · Related CNC capabilities
Related CNC Capabilities
For a project with similar multi-bore or angled-feature relationships, review the relevant manufacturing and inspection scope:
CNC Milling — milling, boring and indexed access to related features
CNC Machining Hub — coordinated machining scope and project requirements
Share a controlled drawing, the casting condition, critical datum relationships and inspection requirements. These inputs help define the machining and verification scope for your component.
