IQC vs IPQC vs FQC vs OQC in Aluminum Die Casting

By Haijiang Lai

Owner at YongZhu Casting

As a supplier of aluminum casting since 2004, if you have a project need to get off the ground. Contact us today, or Mail: yongzhucasting@gmail.com

In aluminum die casting, quality control is not one single “inspection step.” It is a chain of checkpoints that prevent defects, control process drift, and reduce shipment risk. The four most common checkpoints you’ll hear are:

IQC: Incoming Quality Control
IPQC: In-Process Quality Control
FQC: Final Quality Control
OQC: Out-going Quality Control

These checkpoints apply to both automotive die cast parts and general industrial die cast parts, because die castings are almost always used for assembly with other components.

Quick Answer and Comparison Table for IQC IPQC FQC OQC

Quick answer

IQC checks incoming materials and outsourced components before they enter production.
IPQC checks and controls the process during die casting and machining to catch problems early.
FQC confirms finished parts meet final acceptance criteria before packing or shipment release.
OQC verifies shipment readiness and consistency, including packaging, labels, quantity, and documentation, often with final sampling checks.

Item	IQC Incoming Quality Control	IPQC In-Process Quality Control	FQC Final Quality Control	OQC Out-going Quality Control
Where it happens	At receiving, before production	During die casting and downstream processes	After production is completed	Right before shipment and dispatch
Main purpose	Stop bad inputs from entering the line	Control variation and catch defects early	Final product acceptance	Reduce shipment risk and ensure shipment consistency
Typical checks	Certificates, batch ID, material grade, insert/fastener dimensions, appearance	First article, patrol inspection, parameter change checks, key dimensions, visual defects	Visual standard, key dimensions, functional or fit checks if required	Packaging, label, quantity, mix-up prevention, final sampling verification
Frequency	By batch or lot	First article + by time interval + after changes	By lot, often by sampling plan and CTQ level	By shipment, carton, pallet, and sampling plan
Owner	Incoming inspector, supplier quality, purchasing coordination	Process QC, production, process engineering support	Final inspectors, quality team	Outgoing inspector, warehouse, shipping coordination
Records	IQC report, incoming NCR, quarantine tag	IPQC inspection record, first article report, process NCR	FQC report, final acceptance record	OQC report, packing list check, shipment release record
What it catches best in die casting	Wrong material grade, inconsistent inserts, wrong fastener spec, missing documents	Process drift, porosity trend, cold shut risk, flash trend, dimension drift	Appearance grade failures, machining dimension out-of-spec, final fit issues	Mix-up, wrong label, missing parts, wrong carton, documentation mismatch

Where These Checks Happen in Aluminum Die Casting Production

A simple workflow view makes the roles clear:

Incoming materials and outsourced parts arrive
IQC confirms the incoming lot is acceptable
Melting and holding
Die casting production
Trimming and deburring
Machining or secondary operations
Surface treatment or cleaning if required
FQC confirms finished-part acceptance
Packing and labeling
OQC confirms shipment readiness and shipment consistency
Dispatch

Many factories combine FQC and OQC into one station, but the goal is different:

FQC is about product acceptance
OQC is about shipment risk control

What Is IQC in Die Casting Incoming Material Inspection

IQC is the “gatekeeper” that protects your die casting process from unstable inputs. In die casting, incoming items are not only raw metal. They include anything that can change quality downstream.

What counts as incoming items for aluminum die casting

Common incoming categories include:

Aluminum alloy ingot or return material: grade, batch traceability, supplier certificate
Inserts: threaded inserts, steel bushings, pins
Fasteners and assembly-related components: screws, springs, washers if supplied with the casting
Outsourced processes or parts: plating parts, purchased machined parts, purchased subcomponents
Packaging materials: trays, foam, cartons, label rolls
Consumables: release agent, cleaning chemicals, cutting fluid, if controlled by your plan

Typical IQC checks

A practical IQC checklist usually includes:

Document check: COA or material certificate, lot number, supplier info
Identification check: label, batch ID, grade marking
Appearance check: contamination, rust on inserts, damaged packaging
Dimension check: key dimensions on inserts or outsourced parts
Sampling rule: by lot size and criticality level

IQC outputs and decisions

IQC does not only “pass or fail.” Typical dispositions are:

Accept and release to production
Quarantine for further evaluation
Reject and return to supplier
Conditional acceptance with documented deviation approval

Records often include an IQC report and an incoming nonconformance record with quarantine status.

Die casting example

If incoming inserts vary in dimension or hardness, the casting may pass visual checks but fail later during machining or assembly. IQC is the cheapest place to stop that cost.

What Is IPQC Full Form and What Is Checked During IPQC Inspection

IPQC full form is In-Process Quality Control. It is the checkpoint that prevents small process drift from becoming a full-batch problem.

In aluminum die casting, IPQC is not only measuring parts. It also includes verifying process conditions at the right moments.

IPQC checkpoints during die casting

A practical IPQC plan typically includes:

First article inspection after setup, mold change, or restart
Patrol inspection at a fixed time interval
Change-point inspection after parameter changes or material changes
Key process monitoring based on your control plan

Common die casting IPQC focus areas:

Visual defects: flash, cold shut marks, surface sinks, blister risk signs
Key dimensions: critical holes, datums, mating surfaces
Process conditions: mold temperature, injection stages, holding pressure and time, cooling balance
Trend checks: “is the process drifting,” not only “is this one part OK”

IPQC checkpoints during machining and secondary operations

For machined die cast parts, IPQC usually includes:

First piece approval for each machining setup
Tool offset confirmation and periodic checks
Critical dimension checks such as position, coaxiality, hole size, flatness
Deburring and cleanliness if the part goes into assembly

How often should IPQC inspection be done

Instead of a fixed answer, factories usually set frequency by:

CTQ level: higher criticality means more frequent checks
Process stability: new mold, new operator, or new alloy batch often requires tighter checks
Change triggers: any restart, repair, or parameter adjustment should trigger additional checks

IPQC records that make sense for buyers

A buyer-friendly IPQC record often includes:

part number and revision
lot and machine ID
inspection item list and measurement results
sampling size and frequency
inspector sign-off and time stamp
disposition and corrective actions if out-of-spec

Die casting example

If the mold temperature drops or venting performance changes, you may see a rising risk of cold shuts or porosity. IPQC helps you detect the trend early, adjust, and verify before a large amount of scrap is created.

What Is FQC and What Is the Final Acceptance Criteria

FQC is the “final product acceptance” step. It is performed when the product is finished and ready to be released as conforming.

When FQC happens

FQC is typically done:

after die casting and any required machining
after surface treatment if surface treatment is part of customer requirements
before packing, or sometimes after packing depending on the product and packaging style

Typical FQC checks for aluminum die casting parts

FQC often includes:

Appearance grading based on an agreed standard
Key dimension confirmation based on drawing CTQs
Functional or fit checks if specified
Reworked part verification using stricter rules

Final acceptance criteria

Final acceptance criteria should be clearly defined as:

what is considered a defect
what is a minor vs major defect
acceptance by sampling plan and CTQ level
criteria for 100 percent screening when required

FQC outputs

FQC normally produces:

an FQC report or final inspection record
a clear lot disposition: release, rework, scrap, hold for review

What Is OQC and What an OQC Report Usually Includes

OQC is the last step before shipment. It focuses on shipment risk and consistency, not only part quality.

What OQC checks in practice

OQC usually verifies:

packaging: correct tray, foam, carton strength, moisture protection if required
labels: correct part number, revision, lot, quantity, barcode
quantity: per carton, per pallet, total shipment
mix-up prevention: no wrong parts mixed, no mixed revisions
documents: packing list alignment, inspection documents if requested
final sampling: optional cross-check sampling for confidence

What an OQC report includes

A practical OQC report often contains:

shipment number, part number, revision
batch and lot traceability details
sampling plan and sampling quantity
check items: appearance, dimensions, packaging, label, quantity
photo records if needed
result and final shipment release sign-off

Die casting example

Even if the product is good, a shipment can be rejected for wrong labels, wrong carton count, or mixed lots. OQC is designed to prevent those expensive, avoidable issues.

FQC vs OQC What Is the Difference for Buyers

FQC and OQC are both “late-stage checks,” but they are not the same.

FQC answers: “Are the finished parts conforming to the specification?”
OQC answers: “Is this shipment correct, consistent, and low-risk for receiving and assembly?”

A buyer typically benefits from separating them when:

there are multiple part numbers or revisions in the same shipment
packaging and labeling requirements are strict
there is a higher risk of mix-ups
the customer requires specific shipment documentation

If a factory combines them, it is still fine as long as the plan clearly covers both acceptance and shipment consistency.

Which Stage Catches Common Die Casting Defects Better

This table helps you see where each checkpoint is most effective.

Common issue in die casting projects	Best checkpoint	Why
Wrong alloy grade or wrong batch	IQC	It must be stopped before melting and production
Insert dimension variation or wrong insert spec	IQC	Bad inserts can create hidden assembly failures
Porosity trend increases	IPQC	Porosity risk often changes with process conditions; early control saves scrap
Cold shut or misrun trend	IPQC	Often linked to temperature, speed, venting, and fill behavior
Flash increases over time	IPQC	Can indicate die wear, alignment, or parameter changes
Machining dimension drift	IPQC and FQC	IPQC catches drift early; FQC confirms final acceptance
Surface scratches or appearance grade failures	FQC	Often seen after handling or post-processing
Wrong label, wrong carton quantity, mixed lots	OQC	Shipment consistency and traceability are OQC’s core job

How to Set Sampling Frequency Without Over Inspection

A good plan balances cost and risk. Over-inspection wastes time. Under-inspection creates customer problems.

A practical way to set inspection effort is:

Define CTQ levels
- CTQ dimensions and safety-related items get tighter checks
- non-critical features get normal sampling
Use first article as a stability gate
- always perform first article after setup, restart, mold change, or parameter change
- do not rely on patrol inspection alone
Increase checks at change points
- change points include: new lot of material, tooling maintenance, process adjustment, operator change, shift change
Use sampling plans for stable processes
- for stable processes, sampling is efficient
- if instability appears, move to tighter sampling or temporary 100 percent screening until corrected

This approach is common in both automotive and industrial programs because it scales with risk.

Are You Looking for a Reliable Aluminum Die Casting Supplier

If you are sourcing aluminum die cast parts for assembly, what you usually need is not only “we inspect.” You need proof that the process is controlled and shipments are consistent.

For projects on casting-yz.com, we can support buyer-friendly evidence such as:

incoming inspection and batch traceability records
in-process inspection records and first article verification
final inspection acceptance records
outgoing shipment checks and OQC-style release records when required
photos, labels, and packing consistency checks for shipment risk control

If you want, send your drawing and quality requirements. We can align an inspection plan with your CTQs, appearance standard, and shipping documentation needs.

FAQ

IPQC full form is clear, but what should an IPQC inspection checklist include for die casting?

A practical IPQC inspection checklist for aluminum die casting is usually built in three layers:

Setup / change-point checks (every start-up, restart, die change, or parameter change): first article sign-off, key process settings confirmation, and “go/no-go” items tied to CTQs.
Patrol checks (time-based checks for stable production): visual defect watch (flash, cold shut marks, sinks), plus a short list of key CTQ dimensions.
Reaction plan (what to do when something is abnormal): stop or continue criteria, quarantine rules, who must approve release, and what verification is required after adjustment.

Buyers trust IPQC more when the checklist includes change triggers and a clear reaction plan, not only measurement items.

IPQC meaning often includes “process control” — how do factories set patrol frequency without wasting labor?

Most factories don’t use one fixed frequency for every part. A realistic approach is to set frequency by:

CTQ risk level (higher criticality = higher frequency)
process stability (new die, maintenance, new operator, or new alloy lot = tighter checks)
change triggers (any restart, die change, or parameter adjustment should trigger extra checks)

A common practice is to combine first article + patrol inspection + change-point inspection, and tighten temporarily if a trend appears (dimension drift, increasing flash, or rising defect rate).

IQC meaning in die casting — what should you verify on incoming alloy documents to prevent wrong-grade risk?

For aluminum alloy incoming control, the most important IQC goal is traceability and consistency, not only appearance. Common verifications include:

alloy grade matches the purchase requirement
heat/lot number on the COA matches the physical labels
supplier name, batch ID, and quantity are consistent
segregation rules for different lots (to avoid lot mixing during production)

Wrong-grade or mixed-lot risk is one of the most expensive issues to fix later, so strong COA-to-lot binding is a buyer-friendly IQC practice.

FQC meaning vs OQC meaning — when should a factory separate FQC and OQC instead of combining them?

Separating FQC and OQC is especially helpful when shipment risk is high, for example:

the shipment includes multiple part numbers or revisions
labeling and packaging requirements are strict (barcode, customer label format, special carton marks)
mix-ups are costly (assembly lines depend on correct revision and traceability)
customers require specific shipping documentation or photo evidence

In short: FQC confirms part acceptance, while OQC confirms shipment correctness and consistency.

OQC inspection — what shipment problems does it prevent beyond part defects?

OQC inspection is designed to prevent “delivery failures” that can cause customer rejection even when parts are good, such as:

wrong label or wrong revision label
mixed lots in the same carton or pallet
wrong quantity per carton or per pallet
incorrect packing method that increases transit damage
mismatch between packing list, carton labels, and traceability information

These are common high-cost issues for both automotive and industrial programs, so OQC focuses on shipment risk control.

OQC report — what fields make it buyer-auditable and traceable?

A buyer-auditable OQC report commonly includes:

part number and revision, plus PO or shipment reference
lot/batch traceability that links the shipment to production lots
sampling plan name and sample size
checklist items (appearance, key dimensions if required, packaging, labels, quantity)
inspector name, date/time stamp, and release sign-off
photo evidence when customers require it

The “auditable” value is mainly from traceability fields + clear release sign-off, not from long text descriptions.

“FQC meaning” implies final acceptance — when do die casting factories move to 100% inspection?

100% inspection is typically a temporary containment action, not a normal long-term plan. It is commonly used when: