What does blending mean in scrap trading?
Blending means combining several scrap lots of different chemical composition into one delivery or batch so that the mix meets a given target analysis – for example a melt shop's specification for nickel, chromium and molybdenum, including upper limits for tramp elements.
The method comes from foundries and steelworks, where the furnace charge is calculated before melting (in German: Gattierung). In the trade with stainless and high-alloy scrap, the same calculation decides whether a delivery is within specification – and how much high-grade material it takes.
The calculation behind it: the blend analysis
The analysis of a blend is the weighted average of the individual analyses. For each element, the content of every lot is multiplied by its weight; the sum is divided by the total weight.
| Lot | Weight | Ni | Cr | Mo |
|---|---|---|---|---|
| Lot A | 12.0 t | 8.1% | 18.2% | 0.3% |
| Lot B | 6.0 t | 10.4% | 16.9% | 2.1% |
| Lot C | 2.0 t | 12.5% | 17.0% | 2.6% |
| Blend | 20.0 t | 9.23% | 17.69% | 1.07% |
Worked example with freely chosen figures. Nickel: (12.0 × 8.1 + 6.0 × 10.4 + 2.0 × 12.5) ÷ 20.0 = 9.23%.
With three lots and three elements, a spreadsheet will do. With dozens of items in stock, 22 elements and limits for each of them, it becomes a job for the ERP system – especially as every booked blend changes the stock.
Then there is melting loss: the share of the material that is lost during melting. It belongs in the calculation as soon as weight and analysis are turned into a value.
How blending works in MARS-ERP
Analysis at goods receipt
The chemical analysis is recorded for every receipt item – 22 elements, including Ni, Cr, Mo, Ti, W and Co.
Set the target analysis
You define the analysis the blend has to meet.
Calculate the blend
MARS calculates the blend from the items available in stock and shows the blend analysis and weight.
Simulate
Items and quantities can be changed; the blend analysis is recalculated without anything being booked.
Book
The blend leaves as a delivery to the customer or stays in your own stock as a new batch. The batch carries the blend analysis, its origin and the value of its components; melting loss is taken into account.
Prove the origin
From every batch and every delivery back to goods receipt and supplier – and from goods receipt forward to batch, delivery and customer.
What changes in day-to-day business
- The blend analysis is available before material is moved – not only after the finished delivery has been analysed.
- The specification is checked before loading, not after the complaint.
- Stock and stock value stay consistent because the blend is booked directly from stock.
- When asked what a delivery consisted of, there is a documented answer.
Which materials?
All materials that are traded by analysis: stainless steel scrap (for example grades 304 and 316), nickel-based alloys and superalloys, cobalt, titanium, tungsten and molybdenum alloys. The analysis in MARS-ERP covers 22 elements, including Ni, Cr, Mo, Ti, W and Co.
Frequently asked questions
What is the difference between blending and blend analysis?
Blending is putting the mix together from several lots. The blend analysis is the result: the calculated chemical composition of the mix, weighted by the quantities of the lots.
How is a blend analysis calculated?
As a weighted average: for each element, the content of every lot is multiplied by its weight, and the sum is divided by the total weight.
Can a blend stay in stock?
Yes. In MARS-ERP a blend can be booked into stock as a new batch instead of leaving as a delivery. The batch carries the blend analysis and the record of its origin.
Can you prove what a delivery consisted of?
Yes. The traceability record leads from the delivery via the blend and its components back to the goods receipts – across several levels if necessary.
Which package includes blending?
Blending is part of the Enterprise package, together with the 22-element analysis.