Scrap, Waste & Yield Optimisation for Metals Manufacturers

Every offcut in your skip represents raw material you paid for but will not recover — at least not at full value. Scrap sold for recycling typically returns 40p in the pound. That is a 60% loss on every tonne that goes into the bin instead of into an order.

Industry best practice targets a scrap rate of 2.5%. Many manufacturers operate between 3% and 8%. At scale, the difference between 2.5% and 5% scrap is not an abstract number — it is millions of pounds in lost gross margin annually.

GoSmarter’s Cutting Optimiser uses mathematical optimisation to calculate the most efficient way to cut your stock to meet your orders. In a two-week production trial with Midland Steel, it reduced scrap rates by 50%.

This hub explains why scrap happens, how optimisation addresses it, and what GoSmarter’s approach looks like in practice.

Why Scrap Happens in Long Product Manufacturing

The cutting stock problem

In long product manufacturing — rebar, structural sections, beams, tube, pipe, bar stock — the fundamental challenge is this: you buy material in standard lengths, and your orders require non-standard lengths.

A stock bar is 12 metres. A customer order requires 3.2 metres. If you cut four pieces of 3.2m from the 12m bar, you have 0.4m of offcut. That 0.4m goes into the skip.

This is unavoidable at the level of a single cut. But across hundreds of orders and thousands of cuts, the total offcut generated is highly sensitive to how you sequence and combine the cuts.

The wrong cut plan: 8% scrap. The right cut plan: 2.5% scrap. Same orders, same stock. The difference is entirely in the planning.

Why manual planning does not find the optimal answer

The number of ways to combine 50 orders across 200 available bars is not something a human can evaluate by hand. Even an experienced production manager building a cut list from intuition and experience will leave scrap on the floor that a good algorithm would have recovered.

This is not a criticism of the production manager. It is mathematics. The search space is too large for manual evaluation. The optimal — or near-optimal — answer requires an algorithm.

Where the real waste comes from

Beyond the fundamental cutting stock problem, additional scrap sources include:

Off-spec offcuts

Offcuts that are too short to use for any current or likely future order. These go straight to scrap rather than back into stock.

Untracked offcuts

Offcuts that could be used for future orders but are not tracked systematically, so they get lost, damaged, or forgotten in the corner of the bay.

Grade mismatches

Material cut for a job that later gets cancelled or changed, leaving cut pieces that are not compatible with other open orders. If the grade or length does not match anything else in the queue, the material becomes scrap.

Poor bundle selection

When multiple heats or bundles of the same nominal grade are in stock, the choice of which bundle to use for which order affects both traceability and waste. Using the shortest bars for the longest cuts, or mixing heats unnecessarily, adds avoidable waste.

How Mathematical Optimisation Solves the Cutting Stock Problem

The cutting stock problem is a well-studied class of mathematical optimisation problem. It asks: given a set of required lengths and quantities, and a set of available stock lengths, what is the minimum-waste combination of cuts?

GoSmarter’s Cutting Optimiser solves a real-world version of this problem that goes beyond the textbook formulation:

What the GoSmarter algorithm considers

• Open orders — all orders in the system with their required lengths, quantities, grades, and specifications
• Live inventory — available stock bars with their actual lengths (not nominal), grades, heat numbers, and certificate status
• Grade and spec matching — the algorithm only uses bars that are certified to the required grade for each order; it does not mix incompatible heats
• Minimum offcut length — configurable; offcuts below the minimum are treated as scrap, offcuts above it are tracked for reuse
• Priority ordering — urgent or high-value orders can be prioritised so they are fulfilled with the best material
• Multi-day planning — the algorithm can plan across a production window, not just a single day’s orders

What the output looks like

The Cutting Optimiser produces a cut plan that tells you:

• Which bar from your inventory to use for each cut
• What lengths to cut from each bar, in what order
• What offcut remains from each bar (and whether it meets the minimum threshold for tracking)
• The scrap percentage for the plan
• Estimated material consumption vs. available stock

The plan is presented in a format your floor team can work from directly. It is exportable to PDF for printing or to CSV for feeding into other systems.

Overriding the algorithm

GoSmarter does not tell your production manager what to do. It gives them the best starting point the algorithm can produce. From there, they can override any cut, move material between orders, change sequencing — whatever their experience and judgment tells them is right. When they make changes, GoSmarter recalculates the scrap impact in real time.

The Midland Steel Case Study

Midland Steel is a UK rebar manufacturer. In a two-week production trial with GoSmarter:

• 734 tonnes of steel optimised across 193 jobs
• 2.5% initial scrap reduction versus baseline
• Trial ongoing, moving toward more advanced constraint modelling

“Smart technology can directly contribute to reducing carbon emissions in steel manufacturing. By integrating AI and digital tracking tools, we have significantly improved efficiency while aligning with our sustainability goals.”

— Tony Woods, Managing Director, Midland Steel

That quote came off the back of the 2.5% scrap reduction and the 734-tonne optimisation trial described above. For Midland Steel, fewer offcuts meant fewer emissions, lower CBAM exposure, and a direct improvement in gross margin. At current scrap steel prices, that represents a significant and immediate gross margin improvement.

Beyond Scrap: Yield, Offcuts, and CBAM

Yield optimisation

Scrap reduction is one side of the yield equation. The other is ensuring that the material you produce is correctly matched to orders — no over-cutting, no under-specification, no rework.

GoSmarter’s optimiser reduces both waste (excess material cut) and rework (material cut to the wrong specification) by ensuring every cut is planned against the actual order requirements, matched to the correct certified material.

Offcut tracking and reuse

GoSmarter includes an offcut tracking capability. When a bar produces an offcut above the minimum usable length, GoSmarter records it in inventory as a trackable item, with its heat number and certificate linked. When a future order has a requirement that the offcut can fulfil, GoSmarter includes it in the optimisation as available stock.

This turns what would otherwise be scrap into recoverable inventory — reducing raw material purchases and improving overall yield.

CBAM and carbon costs

Under the EU’s Carbon Border Adjustment Mechanism, imported steel is priced for its embedded carbon. Scrap is doubly costly under CBAM:

1. The raw material wasted in scrap still contributed to your imported steel’s carbon footprint
2. The lower yield means you need to import more steel to fulfil the same orders — increasing your CBAM exposure

GoSmarter addresses this by:

• Reducing scrap rates through optimised cutting
• Extracting carbon equivalence (CEQ) data from mill certificates automatically, providing the data needed for CBAM reporting
• Tracking yield by job and period so you have the evidence base for your CBAM calculations

For the finance and sustainability perspective on scrap and CBAM, see: CBAM Explained: The Financial Case for Cutting Scrap.

Scrap and Yield Metrics You Should Be Tracking

If you are not tracking these, you cannot improve them.

Scrap rate

Definition: total scrap weight as a percentage of total material consumed.

Formula: (scrap weight ÷ total material consumed) × 100

Target: ≤ 2.5% for rebar and long products.

What to watch: scrap rate by product type, by operator, by period. Spikes indicate process problems. Steady improvement indicates the optimiser is working.

Yield percentage

Definition: sellable output weight as a percentage of total material consumed.

Formula: (saleable output weight ÷ total material consumed) × 100

Target: ≥ 97.5% (the inverse of a 2.5% scrap rate).

Offcut recovery rate

Definition: the percentage of offcuts (above minimum length) that are subsequently used in production rather than scrapped.

Target: > 80%. If offcuts are being generated and not reused, your offcut tracking or planning process needs attention.

Material cost per tonne of output

Definition: total material purchase cost divided by saleable output weight.

Why it matters: this is the metric that connects scrap rate to gross margin. A 1% improvement in scrap rate typically translates to a 0.5–1.5% improvement in gross margin percentage.

Practical Steps to Reduce Scrap in Your Business

Step 1: Measure your current scrap rate

If you do not know your current scrap rate, find out. Weigh the scrap you generate over a week and compare it to the material you consumed. The result might be uncomfortable. That is useful information.

Step 2: Understand where the scrap comes from

Is it from cutting (offcuts)? From rework (mis-cut material)? From cancelled orders (cut material with no home)? Each source has a different solution. GoSmarter’s reporting helps you see the breakdown.

Step 3: Optimise your cut plans

Replace manual cut list building with GoSmarter’s Cutting Optimiser. The first time you run it, you will almost certainly see a lower predicted scrap rate than your current process delivers. Run it for a week and compare actual scrap against the optimised plan.

Step 4: Track and reuse offcuts

Set up GoSmarter’s offcut tracking. Every offcut above your minimum usable length is recorded in inventory with its heat number and certificate. When future orders can use those offcuts, the system includes them automatically.

Step 5: Review weekly

Scrap reduction is a continuous process. Review your scrap rate weekly. Look for spikes — they indicate something went wrong. Look for trends — they tell you whether your improvements are sticking.

Frequently Asked Questions

Related Resources

• Production Planning Solutions — GoSmarter’s cutting optimisation and production scheduling capabilities
• Inventory Management Solutions — how smarter inventory control connects to yield improvement
• GoSmarter for Metals Operations — the full toolkit overview
• AI for Metals Manufacturing — how AI applies across the metals industry
• Spreadsheet-to-System Planning for Metals — replacing manual planning with live systems
• Midland Steel Manufacturing Case Study — 50% scrap reduction achieved with GoSmarter’s Cutting Optimiser
• GoSmarter Cutting Optimiser product page — features, pricing, and free trial
• Smart Cuts, Less Scrap: A 1D Cutting Stock Problem — the mathematics behind the optimiser
• CBAM Explained: The Financial Case for Cutting Scrap — the financial and carbon case for scrap reduction

GoSmarter is made by Nightingale HQ, a UK-based AI company building practical tools for metals manufacturers since 2018.