Regrind Usage Control

This topic is part of the SG Systems Global plastics, resin genealogy, scrap, and cost-of-quality control glossary.

Updated December 2025 • Regrind Streams, Usage Limits, Material Families, Regrind Traceability, Resin Changeover Control, Resin Segregation in WMS, Cost of Poor Quality (COPQ), Lot Genealogy, MES, WMS, QMS • Plastic & Resin, Medical Devices, Food Contact, Automotive, Consumer Products

Regrind usage control is the set of rules, limits and system behaviours that govern how, where and how much regrind (recycled in-house scrap) can be blended back into virgin resin for new parts. It decides whether regrind is a controlled raw material with traceability and risk limits—or an uncontrolled trash stream quietly undermining mechanical properties, aesthetics and compliance. When regrind usage control is strong, you get predictable cost savings and stable quality. When it is weak, you get cheap material, expensive failures and a genealogy story nobody really believes.

“If regrind can go anywhere, at any ratio, any time, it is not a cost-saving strategy—it’s an uncontrolled experiment on your customers.”

1) What Is Regrind Usage Control?

Regrind usage control is the structured management of:

• Which internal scrap streams are ground and reused.
• How they are classified (product families, risk classes, colours, fillers).
• Where they are allowed to be blended back in and at what ratios.
• How those decisions are enforced, logged and reviewed.

It treats regrind as a defined material with its own lot identity, specifications and rules—not as “whatever is in the grinder today”. It spans physical segregation, recipe management, SPC, analytics and documentation in BMRs, DHRs and customer audits.

2) Why Regrind Usage Control Matters

Regrind is attractive: it reduces virgin consumption and apparent scrap cost. Uncontrolled, it creates hidden risks:

• Material degradation from repeated heat history (loss of impact strength, elongation, clarity).
• Contamination from foreign material, mixed resins or colour carryover.
• Regulatory issues where virgin-only, medical or food-contact requirements are breached.
• Inconsistent performance as “today’s regrind” differs from “yesterday’s regrind”.

Without regrind usage control, cost savings are often illusory: lower resin invoices offset by higher scrap, more complaints, extra testing and brand damage. With control, regrind becomes a risk-managed lever: where and when to use it, how much, and how to prove it doesn’t compromise the product or regulatory posture.

3) Relationship to Regrind Traceability & Resin Segregation

Regrind usage control builds directly on:

• Regrind traceability: Knowing which products and resin lots a given regrind lot came from, and where it was later used.
• Resin segregation in WMS: Keeping regrind streams separated by resin family, risk class and colour.
• Resin changeover control: Ensuring that regrind doesn’t reintroduce previous resins or additives into sensitive products.

Without those foundations, any “regrind usage rule” is theoretical: if you don’t know what is in the regrind, you cannot credibly say where it is safe to use. Regrind usage control assumes that regrind is itself traceable and segregated, not a universal catch-all for all scrap.

4) Defining Regrind Families & Risk Classes

A practical regrind strategy starts by defining regrind “families” based on risk and compatibility, for example:

• Medical or pharma device-grade regrind (if allowed at all).
• Food-contact regrind (per polymer and colour).
• Technical/industrial regrind (per polymer, FR vs non-FR, glass-filled vs unfilled).
• General-purpose or “internal only” regrind for non-critical products.

For each family, you define where it may be used (same product, same family, downgraded products only) and where it is explicitly banned. Many plants prohibit regrind in critical applications (implants, drug-contact, life-safety components) while using well-controlled regrind in housings, brackets or internal components with lower risk. The decision logic belongs in the QMS, not only in cost spreadsheets.

5) Maximum Regrind Ratios & Recipe Control

Regrind usage control needs numeric limits, not just good intentions. Typical controls include:

• Maximum % regrind per product or product family (e.g. 0 % for medical, 10 % for food-contact, 20–30 % for non-critical parts).
• Separate limits by layer or component in co-moulded or multi-shot parts.
• Limits on the number of “regrind generations” (i.e. how often regrind can itself be reground).

These limits must be encoded in blender recipes, work instructions and MES rules—not left to operator judgement. For critical products, use of regrind may be limited to controlled trials under validation protocols, or banned entirely with documented justification. Either way, the decision should be visible in recipes and eBMR/DHR records, not just in tribal knowledge.

6) Material Flow: Regrind Creation, Storage & Issue

Regrind usage control depends on how regrind physically moves, including:

• Where scrap is created (startup, purges, colour changes, QC rejects) and how it is sorted.
• How and where regrind is produced (granulators, central grinding) and labelled.
• How regrind is stored (Gaylords, bins, silos) with location control and segregation.
• How it is issued to presses, blenders or compounders with lot and percentage controls.

Unsorted scrap swept into a common grinder is the enemy of regrind usage control: it produces a regrind stream of unknown composition and unknown risk. Controlled regrind flows, supported by WMS and clear labelling, are what make risk-based usage limits meaningful and enforceable.

7) Regrind in MES Recipes, Blenders & Work Orders

On the shop floor, regrind usage control lives or dies in the recipe and blender logic. In a controlled setup:

• Work orders specify permitted regrind families and maximum ratios.
• Blenders are configured for specific virgin/regrind/colour ratios and locked down by product.
• Regrind issue transactions are tied to specific lots and work orders in MES.
• Any deviations (temporary changes to regrind ratio, different regrind family) trigger approvals and NC/CAPA as needed.

If operators can freely adjust regrind percentages or pull “whatever regrind is handy” into blenders, your documented regrind policy is fiction. Regrind usage control means either the system physically prevents non-compliant blends, or deviations are visible, investigated and rare—not everyday reality.

8) Impact on Quality, SPC & Cost of Poor Quality (COPQ)

Regrind usage is tightly connected to quality and cost metrics:

• Scrap and SPC signals may correlate strongly with regrind ratios, especially near limits.
• Mechanical test results and field failures may show higher risk at higher regrind percentages.
• Cost of Poor Quality (COPQ) calculations should include regrind-driven scrap, rework and complaints, not just virgin resin savings.

Regrind usage control uses these data to refine limits: some products tolerate more regrind without pain; some fail earlier than expected. A mature programme treats regrind as a design and validation variable, not a static 10 % rule carried forward forever regardless of new evidence or changing field performance.

9) Regulatory & Customer Requirements

Regrind usage is often constrained by external expectations:

• Medical, pharma and some food-contact standards effectively prohibit regrind in certain components or context.
• OEM specifications may set explicit maximum regrind percentages or require virgin-only content.
• Brand owners may restrict regrind in visible, high-aesthetic parts and packaging.

Regrind usage control ensures these requirements are encoded in product specifications, BOMs, recipes and supplier agreements—not just noted in email threads. When auditors or customers ask “what is your regrind policy on this product?”, you should be able to show a controlled document and supporting evidence from MES/WMS—not just verbal assurances that “we don’t usually use regrind there”.

10) Typical Failure Modes & Red Flags

Red flags for weak regrind usage control include:

• General-purpose grinders feeding multiple resin families into the same regrind stream.
• Regrind bins labelled only “regrind” with no indication of source product or resin.
• Operators adjusting blender ratios without recorded approvals or recipe changes.
• Complaints or lab failures where regrind ratio at the time of production is unknown.
• Quality or regulatory documents that say “no regrind used” while the plant uses regrind routinely on the same line.

These patterns are difficult to explain away in audits and are frequently correlated with “mysterious” variation in mechanical properties, colour, odour or taste. Fixing them requires both physical segregation and system-level controls—not just stronger language in SOPs.

11) Implementation Roadmap & Practice Tips

For plants bringing regrind usage under control, a pragmatic roadmap looks like this:

• Map current practice: Where regrind comes from, how it is ground, stored, labelled and used today.
• Define families & policies: Group regrind streams and define where each may or may not be used, with initial ratio limits.
• Strengthen labelling & segregation: Ensure every regrind container has clear IDs, families and lot links; align with resin segregation in WMS.
• Embed in recipes: Encode regrind ratios and allowed families into MES/blender recipes and work instructions.
• Link to QMS: Update product specs, risk assessments and validation to reflect regrind assumptions; route deviations and complaints through QMS workflows.
• Monitor & adjust: Track quality and COPQ vs regrind usage; refine limits and families based on evidence.
• Scale by risk: Start with critical products and lines, then expand or relax controls where justified by data and business priorities.

The objective is not to eliminate regrind; it is to turn it from uncontrolled noise into a governed parameter—one more dial that can be turned intelligently to balance margin, sustainability and risk.

12) Audit & Customer Expectations

Auditors and OEMs are increasingly explicit about regrind. Typical questions include:

• “What is your regrind policy for this product family, and where is it documented?”
• “How do you ensure regrind is not used in products where it is prohibited?”
• “Show us how you track regrind lots and their usage.”
• “How was regrind considered in your process validation and risk assessments?”

Plants with robust regrind usage control can answer these with controlled documents, recipes and genealogy reports. Plants without it often respond with “we try not to use much regrind” and are surprised when auditors treat that as a red flag, not a reassurance. In regulated or high-visibility sectors, you are expected to either control regrind or clearly justify why it is banned—not to ignore the topic.

13) Digitalisation & Industry 4.0 – Blenders, Sensors & Analytics

In an Industry 4.0 environment, regrind usage control can be enhanced by:

• Smart blenders that log actual virgin/regrind ratios and material sources, not just setpoints.
• Integration with a manufacturing data historian to correlate regrind usage with process conditions and scrap.
• Analytics that flag when real-world regrind usage deviates from policy, or when quality signatures correlate with specific regrind families or ratios.

But, as always, analytics amplify whatever underlying discipline exists. If regrind containers are unlabelled and blender hoppers are filled “by feel”, smart sensors will mostly record how chaotic things already are. The basics—clear families, labelling, recipes and approvals—must be in place before Industry 4.0 technology can deliver meaningful insight instead of merely documenting bad habits.

14) What This Means for V5

For manufacturers running the V5 platform, regrind usage control can be implemented as a real, enforced behaviour across MES, WMS, QMS and external tools—not just as a line in a scrap-reduction slide deck. Each V5 product plays a specific role:

• V5 Solution Overview – Positions regrind as a first-class material in the V5 data model, with its own families, lots and genealogy. The same backbone that handles resin lot traceability and end-to-end genealogy can incorporate regrind streams without separate spreadsheets.
• V5 MES – Manufacturing Execution System – Controls regrind usage at the line:
  • Work orders and recipes in V5 MES can specify allowed regrind families and maximum ratios per product.
  • Operators can be guided through regrind issue and blender configuration steps, with hard limits enforced for regulated products.
  • Actual regrind usage (from blender signals or operator entries) can be recorded into eBMRs and DHRs, supporting validation and investigations.
• V5 WMS – Warehouse Management System – Manages regrind as inventory:
  • Regrind Gaylords and bins can be created with proper IDs, families and links to source products and resin lots via regrind traceability.
  • Location rules (aligned with resin segregation in WMS) keep incompatible regrind streams separate.
  • Regrind issues to lines and blenders are tracked like any other material movement, feeding genealogy and COPQ analysis.
• V5 QMS – Quality Management System – Owns the policy and risk logic:
  • Regrind policies, risk assessments and validation reports live as controlled documents in V5 QMS.
  • Regrind-related deviations, complaints and CAPA can automatically pull genealogy, usage and COPQ data from V5 MES/WMS.
  • Change-control workflows ensure that new products, resins or OEM specs trigger review of regrind rules, not ad-hoc decisions.
• V5 Connect API – Integrates regrind usage control with external devices and analytics:
  • Blenders and gravimetric feeders can send actual virgin/regrind rates and consumption to V5 MES via the API.
  • Corporate BI or OEM portals can consume V5’s regrind genealogy and performance data without custom one-off reports.
  • LIMS and lab systems can feed regrind-inclusive test results back into V5 QMS for trend analysis and limit refinement.

In this model, the glossary concept of regrind usage control shows up as real constraints and dashboards inside V5: which regrind families exist, which products they feed, what ratios were actually used, and how that correlates with quality, COPQ and customer feedback. That makes regrind a deliberate, governed input—not a background variable that nobody can fully explain when things go wrong.

FAQ

Q1. Should every product allow some regrind usage?
No. For certain products—especially medical, pharma, high-risk food-contact and life-safety components—banning regrind is often the most defensible position. For others, controlled regrind can be appropriate. The decision should come from a documented risk assessment and customer/regulatory requirements, not solely from cost pressure.

Q2. How do we decide on maximum regrind percentages?
Limits should be based on material science, validation data and risk tolerance. Many organisations run structured trials (e.g. 0 %, 10 %, 20 %) with mechanical, dimensional and cosmetic evaluation, then set limits with safety margins. Those limits should be reviewed periodically as materials, tools and requirements evolve, not treated as permanent truths.

Q3. Can we mix regrind from different products if the resin is the same?
In general, mixing regrind from multiple products or colours increases risk. Even if the base resin is the same, differences in additives, colours, contamination exposure and degradation history make streams less compatible. A conservative approach is to keep regrind streams as product-family-specific as practical, and to document any intentional mixing in the QMS and genealogy model.

Q4. How should we handle regrind in customer and regulatory documentation?
Regrind usage should be transparent. Product specifications, technical files and, where applicable, regulatory filings should either state that regrind is not used or describe the conditions, limits and controls under which it is used. Hidden regrind usage that later emerges during a failure investigation is significantly more damaging to trust than a well-documented, risk-based regrind strategy.

Q5. What is the first practical step if our current regrind practices are informal?
Start by mapping current regrind flows and creating basic families (e.g. “PC housing regrind”, “PP cap regrind”) with simple labels and storage rules. Then pilot controlled usage and ratio limits on a small set of non-critical products, capturing quality and scrap data. Use the results to refine families, limits and SOPs, and then embed them into MES/WMS and QMS before expanding to a wider product range.

Related Reading
• Regrind & Resin Flows: Regrind Traceability | Resin Changeover Control | Resin Segregation in WMS | Resin Lot Traceability
• Quality, Cost & Genealogy: Cost of Poor Quality (COPQ) | Statistical Process Control (SPC) | Traceability & End-to-End Lot Genealogy | Batch Manufacturing Record (BMR) | Device History Record (DHR)
• 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