Masterbatch Dosing Control

This topic is part of the SG Systems Global plastics, colour, additive dosing & recipe enforcement glossary.

Updated December 2025 • Colour & Additive Ratios, Gravimetric & Volumetric Feeders, Loss-in-Weight Feeder Calibration, Color Changeover Logging, Resin Changeover Control, SPC, BMR, DHR, MES, QMS • Plastic & Resin, Medical Devices, Food Contact, Automotive, Consumer Products

Masterbatch dosing control is the combination of recipes, hardware, software and checks that ensures colour concentrates and additive masterbatches are dosed into base resin at the correct ratios, in the correct place and time, for every shot or metre of product. It is where colour targets, UV and slip packages, anti-stats, FR systems and processing aids move from “nice formulation slides” to hard, enforced behaviour on feeders and hoppers. When masterbatch dosing control is strong, colour and performance are boringly consistent. When it is weak, every silo, shift and humidity change becomes an excuse for off-shade, brittle or non-compliant parts.

“If your colour and additive ratios depend on how many turns of a knob the last shift left, you are not running recipes—you are running superstition.”

1) What Is Masterbatch Dosing Control?

Masterbatch dosing control is the structured way a plant manages:

• Which masterbatches (colour and functional additives) are used for each product and resin family.
• The nominal and allowable range of dosing ratios (e.g. 2 % colour, 0.5 % slip, 15 % FR concentrate).
• How those ratios are delivered (gravimetric, volumetric, pre-compounded blends, manual addition).
• How actual dosing is monitored, verified and recorded during production and changeovers.

It treats masterbatch dosing as a validated control parameter, not a “move the slider until it looks right” exercise. The result is predictable colour, performance and regulatory compliance across lines, shifts and plants, instead of the usual folklore around “line 3 always runs a bit darker”.

2) Why Masterbatch Dosing Control Matters

Masterbatch dosing directly influences:

• Appearance: Colour, opacity, gloss, haze, streaking, mottling and batch-to-batch consistency.
• Performance: UV stability, antistatic behaviour, slip and antiblock properties, barrier performance, combustion behaviour for FR systems.
• Regulatory status: Migration, toxicity, heavy metal and additive limits in medical and food-contact applications.
• Cost: Over-dosing wastes expensive concentrates; under-dosing triggers complaints and rework.

Without masterbatch dosing control, every shift change, material swap or dryer tweak risks drifting outside the “sweet spot”. That ends up in rejects, brand inconsistency and difficult-to-defend device or packaging failures. With control, dosing becomes a lever to tune performance deliberately and defensibly, not an uncontrolled hidden variable in every root cause analysis.

3) Relationship to Resin, Colour & Additive Families

Masterbatch dosing is rarely one-size-fits-all; it depends on material families:

• Different base resins (PP, PE, PET, PC, PA, ABS) have different carrier compatibility and recommended ratios.
• Masterbatch families (colour, UV, slip, antistat, FR, optical brighteners) have their own dose/response curves and limits.
• Regulatory families (food-contact, medical, industrial, outdoor) impose additional constraints on additive level and type.

Masterbatch dosing control requires a clear mapping: which masterbatch SKUs and ratios per resin/product family are allowed, validated and current. That mapping must be reflected in BOMs, recipes and lab specifications—not just in an old spreadsheet on one process engineer’s laptop.

4) Dosing Equipment – Gravimetric vs Volumetric

Dosing hardware strongly affects achievable control:

• Gravimetric (loss-in-weight) feeders weigh masterbatch continuously and adjust feed to maintain targeted mass flow.
• Volumetric feeders rely on screw speed and assumed bulk density; they are simpler but more sensitive to density and flow variation.
• Manual addition (scoops, pre-mix) is highly operator-dependent and difficult to document accurately.

Loss-in-weight feeder calibration, maintenance and recipe management are critical for gravimetric systems to deliver their theoretical advantages. For volumetric setups, masterbatch dosing control needs to include density management (e.g. lot-based calibration factors) and tighter procedural controls.

5) Recipes, Ratios & Setpoint Governance

At the heart of masterbatch dosing control are recipes and limits, including:

• Nominal ratios for each masterbatch in each product.
• Permitted adjustment ranges (e.g. ±0.1 or ±0.2 percentage points, not “whatever works”).
• Controls on who may change ratios (role-based permissions) and under what conditions.
• Requirement for trials, validation and QMS approval when ratios are changed.

These rules should live in the QMS and be enforced in MES and feeder controllers. “Tuning” colour or slip by quietly nudging ratios outside these limits—or editing recipes on the fly at the machine—should be visible as deviations, not invisible “craftsmanship” that nobody can reconstruct later.

6) Startup, Changeover & Flush Control

Many dosing problems appear during start-ups and changeovers, not steady state. Masterbatch dosing control should therefore cover:

• Pre-run procedures to ensure hoppers and feeders are loaded with the correct masterbatch and purged of the previous one.
• Color changeover logging with specific focus on masterbatch change steps.
• Transition product handling—off-shade or off-ratio parts until feed stabilises.
• Checks that masterbatch feeders and tubing are correctly assigned after tool or line changes.

In uncontrolled environments, colour and additive changeovers are treated as minor tasks. In reality, they are critical boundaries where wrong materials or wrong ratios are most likely. Dosing control treats these transitions as high-risk events with specific SOPs, logs and sign-offs, not as “we’ll sort it out while we ramp up”.

7) Integration with MES, Work Orders & BOMs

To be sustainable, masterbatch dosing control must be integrated into systems, not managed by standalone feeder panels and memory:

• BOMs and recipes define which masterbatch SKUs and ratios belong to each product.
• MES uses that data to drive feeder setpoints, material calls and line-side checks.
• Work orders reference specific masterbatch and resin lots, supporting full genealogy.
• Changes to masterbatch recipes go through change control, with impact on validation and labelling assessed.

When MES is the orchestration layer, feeder settings follow the work order; when feeders are adjusted in isolation, MES and genealogy are always chasing reality instead of defining it. That gap becomes glaring when customers or regulators ask exactly what was dosed when a given lot was produced.

8) In-Process Checks, SPC & Alarms

Masterbatch dosing control requires verification, not just setpoints. This includes:

• Feeder alarms and tolerances (e.g. deviations between target and actual feed rates).
• SPC charts for colour metrics, additive-related performance indicators or feeder weight data.
• Visual checks locked into sampling plans for colour and surface, with clear acceptance criteria.
• For critical additives (UV, FR, antistat), periodic lab checks that confirm performance at the dosed levels.

These checks should be planned and recorded, not sporadic “eyes-on” reviews. When a line is run under validated dosing control, data shows both that setpoints were correct and that actual outcomes matched expectations. That dual evidence is what moves masterbatch dosing from “tribal art” into engineered control.

9) Traceability, Genealogy & BMR/DHR

For regulated or high-risk parts, masterbatch dosing is part of the record, not just an internal detail. Good practice includes:

• Recording which masterbatch lots were used on which work orders and lines.
• Documenting nominal and actual dosing ratios for each batch or time interval.
• Including masterbatch information in batch manufacturing records (BMR) and device history records (DHR).
• Linking masterbatch changes to colour changeover logs and resin genealogy.

This level of traceability is vital when investigating discolouration, premature ageing or FR performance; it also supports regulatory files that require detailed formulation and process evidence. Without it, you are effectively telling customers and regulators “we think we dosed this” rather than “we know we did, and here is the evidence.”

10) Typical Failure Modes & Red Flags

Weak masterbatch dosing control tends to show in familiar ways:

• Frequent “tweaking” of feeder setpoints based on operator opinion rather than data.
• Shared masterbatch feeders that are re-routed between lines without clear mapping or logs.
• Colour or additive suppliers blamed for variation when dosing data is incomplete or unknown.
• Different lines running the “same” product with visibly different appearance or performance.
• Recipes updated informally at the feeder or PLC without QMS awareness.

These red flags undermine both brand consistency and regulatory confidence. They also make it difficult to run meaningful trials or supplier comparisons—because the masterbatch dosing background is constantly shifting underneath the data you think you are collecting.

11) Audit & Customer Expectations

OEMs, brand owners and regulators often probe masterbatch dosing without naming it directly. Common questions include:

• “How do you ensure colour and additive levels are consistent across lots and plants?”
• “Where are masterbatch ratios defined and who can change them?”
• “Show us documentation for how you validated your dosing settings for this material and product.”
• “What happens when feeders alarm or drift? How do you assess product impact?”

Plants with strong masterbatch dosing control can show recipes, validation reports, MES records and well-defined reactions. Plants without it tend to point at a feeder, say “we set it to 2 %” and hope no one asks how they know that 2 % is accurate, recent or adequate for the claims and regulations in play.

12) Digitalisation & Industry 4.0 – Smart Feeders & Analytics

In an Industry 4.0 context, masterbatch dosing control benefits from:

• Networked gravimetric feeders with real-time monitoring, alarms and remote recipe management.
• Integration with a manufacturing data historian so dosing trends can be correlated with quality and scrap.
• Analytics that flag lines or products with abnormal adjustments or performance at given dosing levels.

However, smart feeders do not fix poor governance. If anyone can push unapproved recipes into a feeder, or if masterbatch identification and segregation are weak, all that data will mainly show how inconsistent behaviour already is. The governance and recipe discipline described above must exist first; Industry 4.0 tools then help scale and audit that discipline rather than replace it.

13) Implementation Roadmap & Practice Tips

For plants formalising masterbatch dosing control, a realistic roadmap looks like this:

• Map current state: Document masterbatch SKUs, dosing equipment, recipes and known problem areas.
• Define ratios & limits: Agree target and allowable ranges per product, resin and risk class in controlled documents.
• Clean up equipment & mapping: Standardise feeder assignments, labels and line layouts; minimise adhoc cross-feeds.
• Integrate with MES: Drive feeder setpoints and material calls from BOMs and work orders; capture key dosing events and alarms.
• Strengthen checks: Add SPC, visual and lab checks that are explicitly tied to dosing assumptions.
• Link to QMS: Bring recipes, validation, NCs and CAPA under QMS control; stop “stealth” recipe edits at machines.
• Iterate by risk: Start with high-visibility or high-risk products, then expand where benefits justify the complexity.

The end-game is not zero variation; it is a controlled, explainable relationship between masterbatch dosing, product performance and cost—backed by evidence solid enough to stand up in OEM meetings and regulatory audits, not just on the shop floor.

14) What This Means for V5

For manufacturers running the V5 platform, masterbatch dosing control can be embedded directly into how recipes, materials and work orders flow across MES, WMS, QMS and integration layers—instead of living as isolated feeder settings and local spreadsheets. Each V5 product reinforces a different part of the control loop:

• V5 Solution Overview – Positions masterbatch and additive data as part of the core V5 data model. Colour and additive masterbatches become first-class materials with their own SKUs, families, lot history and recipe roles, shared consistently across V5 MES, WMS and QMS modules.
• V5 MES – Manufacturing Execution System – Is the execution engine for masterbatch dosing control. V5 MES can:
  • Pull target ratios and allowed ranges directly from product BOMs and validated recipes.
  • Drive feeder setpoints via integrations or operator prompts, ensuring the correct masterbatch and ratio for each work order.
  • Capture key dosing events—ratio changes, alarms, colour changeovers—and embed them in eBMR/DHR records for later analysis and audits.
• V5 WMS – Warehouse Management System – Manages physical masterbatch logistics:
  • Tracks masterbatch lots and locations, aligned with resin segregation in WMS and colour-changeover rules.
  • Ensures correct masterbatch lots are staged and issued to the right lines, avoiding cross-contamination or wrong-colour events.
  • Supports controlled handling of off-shade material and scrap created during masterbatch changeovers.
• V5 QMS – Quality Management System – Owns the governance for masterbatch dosing:
  • Holds the approved recipe documents, ratio limits, validation reports and change-control records for masterbatch settings.
  • Receives NCs, complaints and CAPA that reference colour or additive issues, automatically pulling in V5 MES dosing data and genealogy.
  • Supports risk assessments and regulatory files that need clear statements about how colour and additive levels are controlled and monitored.
• V5 Connect API – Connects V5 to dosing hardware and analytics:
  • Feeds gravimetric or volumetric feeder data into V5 MES and historians, so real dosing performance is visible alongside scrap and SPC.
  • Allows external colour measurement, lab systems or OEM dashboards to push results back into V5 QMS and MES for correlation with dosing behaviour.
  • Publishes curated masterbatch dosing and performance metrics into corporate BI or OEM portals without manual data reshaping.

In practice, this means a V5 user can trace from a discoloured part or under-performing additive property back through resin and masterbatch lots, actual dosing ratios, feeder alarms and colour changeovers—and forward to affected batches and customers. The glossary concept of masterbatch dosing control becomes a concrete set of V5 workflows, configuration and dashboards that both enforce recipes in real time and make dosing history auditable when it matters most.

FAQ

Q1. Do we always need gravimetric feeders for good masterbatch dosing control?
Not always, but they make consistent control easier, especially at low ratios or when bulk density varies. Volumetric feeders can be acceptable for less critical applications if density is well characterised and dosing is backed with periodic checks. For regulated or tight-tolerance products, gravimetric systems with robust calibration and integration into MES are usually a better fit.

Q2. How tight should masterbatch dosing tolerances be?
Tolerances should be based on product sensitivity, additive chemistry and validation data. For some colours, ±0.1 % may have a visible impact; for others, wider ranges may be acceptable. Functional additives (UV, FR, antistat) often demand tighter control to guarantee performance and regulatory margins. Tolerances should be justified by data, not only by equipment capability or supplier brochures.

Q3. Can operators adjust masterbatch ratios to correct colour “by eye”?
In a controlled environment, any ratio change outside validated ranges should be treated as a deviation or formal trial—not routine practice. Adjustments based purely on visual impression are subjective and hard to reproduce. If visual corrections are necessary, they should be guided by structured procedures, limits and, ideally, colour measurement and QMS approval.

Q4. How does masterbatch dosing control relate to sustainability or PCR content?
Where post-consumer recyclate (PCR) is used, masterbatch dosing often must compensate for colour or property variability. This increases the importance of dosing control and traceability: OEMs and regulators may demand proof that final colour, UV resistance or FR behaviour remains in spec despite variable base streams. Masterbatch recipes and limits should be part of PCR-related validation and claims.

Q5. What is the first practical step if our current dosing is mostly “know-how” at the machine?
A practical starting point is to inventory current masterbatch SKUs, dosing methods and “typical” ratios for a few key products. Capture those as formal recipes, implement basic logging of setpoints and changes (even manually), and run simple trials to confirm appearance and performance at those settings. From there, integrate recipes into MES, tighten limits and add feeder integration where cost and risk justify it.

Related Reading
• Colour & Additives: Color Changeover Logging | Resin Changeover Control | Resin Lot Traceability
• Dosing & Flow: Loss-in-Weight Feeder Calibration | Powder Flowability Index | Powder Conditioning – Temperature & Humidity Control
• Quality & Records: Statistical Process Control (SPC) | Batch Manufacturing Record (BMR) | Device History Record (DHR) | Traceability & End-to-End Lot Genealogy
• Systems & V5 Platform: V5 Solution Overview | V5 MES – Manufacturing Execution System | V5 WMS – Warehouse Management System | V5 QMS – Quality Management System | V5 Connect API | Data Integrity | Change Control