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Limits: Lower / Target / Upper
Outputs: CTQ / Part Weight
Control: Reaction Rule
Change: Restart / Revalidation
A production control sheet freezes approved process limits and response rules after validation rather than recreating the validation study.
Production Process Control

Injection Molding Process Control Sheet: Limits, CTQ Checks & Reaction Rules

Quick answer: after process validation is complete, the production control sheet should freeze the approved molding limits, output checks, reaction rules, restart conditions, document revision, and responsible release owner into one controlled production record.

The sheet should identify the released tool and press, resin and material condition, approved target and lower/upper process limits, CTQ or part-weight checks where required, and the action to take when production moves outside the approved basis.

This page focuses on controlling validated results in production; it does not explain how the process window is developed. For the wider validation and production-release sequence, see injection molding validation and production release .

Approved Process Limits
CTQ / Output Checks
Reaction & Restart Rules
Revision & Release Owner
Document Boundary

Setup Sheet, Validation Study and Process Control Sheet Serve Different Jobs

These documents may contain some of the same molding parameters, but they are not interchangeable. The difference is whether the document starts the machine, establishes the approved evidence, or controls the validated production state.

Setup Sheet

Provides the Startup Reference

Records the nominal machine and mold settings used to reproduce an approved startup condition. It is primarily an operating reference and does not by itself establish the validated process range.

Validation Study

Establishes the Approved Evidence

Uses structured trials and measured part response to establish the supported operating range and the evidence behind the approved process basis.

Process Control Sheet

Freezes the Production Controls

Converts the approved result into controlled lower, target, and upper process limits, output checks, reaction rules, restart conditions, and revision ownership for routine production.

Boundary rule: this page begins after the process basis has been validated. For how that operating range is established, use scientific molding process-window validation .
Production Baseline

Identify the Exact Tool, Press, Resin and Revision Being Controlled

Before parameter limits are recorded, the process control sheet should define the production baseline they apply to. Identify the released part and mold revision, active cavity configuration, approved press and injection unit, resin grade and material condition, and the current document revision so later changes can be recognized and reviewed.

01 · Part & Revision

Freeze the Product Baseline

Record the part number, released drawing revision, and applicable engineering-change status so the control sheet is tied to the correct product configuration.

02 · Mold & Cavities

Identify the Active Tool State

Record Mold ID, mold revision, active cavity count or configuration, and insert configuration where those details affect the approved production baseline.

03 · Press & Injection Unit

Tie Controls to the Approved Machine

Identify the approved press, injection unit, screw or other machine configuration needed to distinguish the validated production setup from an unreviewed equipment change.

04 · Resin & Material Condition

Record the Approved Material Basis

Record resin grade and the material-condition fields required by the project, such as supplier or lot traceability and approved drying condition where applicable.

Part / Mold Revision
Mold ID / Cavity Configuration
Press / Injection Unit ID
Resin / Material Condition
Control rule: document identity also matters. The sheet should carry a controlled document number, revision, effective date, and owner so an outdated process sheet is not mistaken for the active production baseline. Detailed approval and change-control logic is handled later in this article.
Injection molded plastic parts arranged beside a precision mold and measuring tools for process control and dimensional inspection
Approved validation results should be transferred into controlled lower, target, and upper process limits rather than copied as nominal settings only.
Approved Process Limits

Record Lower, Target and Upper Process Limits from the Approved Validation Basis

A production control sheet should do more than repeat nominal machine settings. For each controlled parameter, record the approved target and the lower and upper process limits that apply to the released production baseline, together with the unit and the source or validation reference supporting those limits.

Typical fields may include melt or barrel temperature, mold temperature, injection or hold conditions, V/P transfer position, cushion, cooling time, or other project-specific variables. The exact parameters and limits should come from the approved validation evidence; this sheet does not create new limits or replace the study used to establish them.

Controlled Parameter Lower Process Limit Target Upper Process Limit Unit Approved Source / Reference
Melt / Barrel Temperature Approved value Nominal target Approved value °C / °F Validation record / approved study
Injection / Hold Condition Approved value Nominal target Approved value Project-defined Validation record / approved study
V/P Transfer / Cushion Approved value Nominal target Approved value mm / position Validation record / approved baseline
Cooling / Cycle Control Approved value Nominal target Approved value s Approved production basis
Terminology rule: use Lower Process Limit and Upper Process Limit for controlled machine or process settings unless the approved quality system defines another term. Avoid using product-specification terminology such as LSL or USL for process settings when it could confuse process limits with drawing or CTQ specification limits.
Output Verification

Tie Process Control to CTQ and Part-Weight Checks Where They Matter

A process control sheet should identify the product-output checks that confirm production remains aligned with the approved baseline. Record the characteristic, measurement method, check frequency, applicable cavity or sampling basis, and the defined limit or reference where the project requires that output to be monitored.

01 · CTQ Characteristic

Identify What Must Be Checked

Reference the drawing characteristic, CTQ identifier, appearance requirement, functional check, or other approved output signal that is relevant to production control.

02 · Measurement Method

Record How the Check Is Performed

Identify the approved gauge, inspection method, weighing method, or referenced inspection instruction so the recorded result is traceable to a defined method.

03 · Frequency / Cavity Basis

Define the Required Monitoring Basis

Record the approved frequency, sampling basis, and cavity identification where cavity-specific monitoring is required. Do not apply a universal frequency to every molding program.

04 · Part Weight

Use Weight as an Output Signal When Applicable

Where part weight is part of the approved control basis, record the target or allowable range, weighing method, frequency, and the reaction trigger for an out-of-range result.

CTQ / Output ID
Method / Gauge
Frequency
Cavity / Sample Basis
Limit / Reference
Boundary rule: this section records the approved production checks; it does not create a universal sampling plan, define full SPC methodology, or replace the project Control Plan or inspection standard. Any out-of-range response is handled by the reaction-plan logic in the next section.
Out-of-Window Reaction

Define What Happens When a Process or Output Check Moves Out of Control

A controlled process sheet should not leave the response to operator judgment alone. For each applicable out-of-window condition, define the immediate control action, the scope of suspect output, the verification needed before restart, and the authorized owner responsible for returning production to the approved basis.

Step 01

Detect the Trigger

Identify the parameter, CTQ, part-weight, alarm, or other approved signal that crossed its defined limit or requires review.

Step 02

Control Suspect Output

Hold, identify, or segregate affected production according to the approved reaction plan, including the relevant time, lot, cavity, or cycle scope where defined.

Step 03

Verify the Process Basis

Compare the current machine, material, tool state, process values, and required output checks with the approved baseline before making an uncontrolled adjustment.

Step 04

Authorize Restart

Resume production only after the required verification is complete and the responsible function or approved authority has released the process under the applicable project rule.

Trigger
Immediate Action
Suspect Output Scope
Verification Required
Restart Authority
Control rule: the reaction plan should define what must happen when an approved limit is exceeded, but it should not impose the same containment quantity, inspection frequency, or restart authority on every molding program. Those details should follow the applicable Control Plan, quality procedure, customer requirement, or approved production-control basis.
Restart & Revalidation

Separate Routine Restart from Changes That Require Revalidation Review

Not every production interruption requires a new validation study. The control sheet should identify the events that need normal restart verification and the changes that require engineering review because they may alter the approved production baseline, process limits, or product-output evidence.

Routine Restart

Baseline Is Unchanged

After an ordinary stop or planned restart, follow the approved startup checks and output verification when the tool, machine, material, and controlled process basis remain unchanged.

Change Review

Confirm Equivalent Conditions

A press, injection-unit, material, or setup change should be reviewed against the approved baseline to determine whether documented equivalence is sufficient or additional validation evidence is needed.

Revalidation Trigger

Approved Basis Has Changed

Escalate when a mold modification, cavity or insert change, resin-grade change, revised process limit, or other change affects assumptions used to approve the production process.

Performance Trigger

Control Can No Longer Be Demonstrated

Repeated drift, recurring CTQ failure, unstable part-weight behavior, or inability to reproduce the approved condition should trigger a documented review of the validation scope before normal release resumes.

Trigger Event
Baseline Impact
Verification Scope
Approval Required
Effective Revision
Decision rule: do not define every machine, material, or tooling change as an automatic full revalidation. The required scope should follow the change impact, approved equivalence criteria, customer or quality requirements, and the evidence needed to show that the controlled production basis remains valid.
Approval & Document Control

Keep One Approved Process Sheet Active Through Controlled Revision

The process control sheet should identify which version is currently authorized for production. Record the document number, revision, effective date, approval owner, and applicable change reference so operators and reviewers can distinguish the active production baseline from obsolete or superseded instructions.

01 · Document Identity

Give the Sheet a Controlled Reference

Record a unique document number or controlled identifier together with the process, part, tool, or program reference needed to trace the sheet.

02 · Revision & Effective Date

Make the Active Version Obvious

Show the current revision and effective date, and identify or withdraw superseded versions so outdated limits or reaction rules are not used in production.

03 · Approval Ownership

Record Who Authorized the Change

Identify the responsible approval function or project-defined authority for the current process-control revision rather than assuming one universal department must approve every program.

04 · Change Reference

Link Revised Controls to the Approved Change

When the approved production baseline changes, reference the applicable ECN, deviation, customer approval, or other controlled change record that authorized the revised limits or instructions.

Document No.
Revision
Effective Date
Approval Owner
Change Reference
Change-control rule: if a process-relevant change alters the approved production baseline, update the controlled sheet through the applicable change process and retain traceability to the authorization. The process-change ECN form can be used where an ECN is the required change record.
Downloadable Control Asset

Download the Injection Molding Process Control Sheet Review Checklist

Use this two-page PDF to review whether a production process sheet identifies the controlled tool, press, resin and revision; records approved lower, target and upper process limits; defines CTQ or output checks; and documents reaction, restart, revalidation and approval responsibilities. It is designed for post-validation production-control review rather than for developing the process window itself.

Production Baseline
Approved Process Limits
CTQ / Output Checks
Reaction Plan
Restart / Revalidation
Revision & Approval
Open Process Control Sheet Review Checklist PDF · v2.0 · Updated September 2026
FAQ & Production Handoff

Frequently Asked Questions About Injection Molding Process Control Sheets

These questions clarify how a controlled production sheet should be used after validation without turning the document into a process-development, SPC, or full approval procedure.

Is a process control sheet the same as a setup sheet?

No. A setup sheet provides nominal startup settings, while a process control sheet records the approved production limits, required output checks, reaction rules, restart conditions, and document-control status.

Where should the lower and upper process limits come from?

They should come from the approved validation or production-control basis. The process control sheet records those approved limits; it does not create a new process window or replace the study used to establish the operating range.

Does every press or material change require full revalidation?

Not automatically. The required response depends on whether the change affects the approved production baseline, whether equivalence can be demonstrated, and what project, customer, or quality requirements apply.

What should happen when a controlled value moves outside its limit?

Follow the approved reaction plan: identify the trigger, control suspect output, verify the current production basis, complete the required checks, and obtain restart approval from the authorized function.

Need a Review of Your Production Control Plan?

SPI can review the available process-control structure, identify missing limits, output checks, reaction rules, and revision-control gaps, and help prepare the record for controlled production use.

Review Your Molding Process-Control Plan Controlled Production Injection Molding