One melt, one number
When a mill or foundry melts a batch of metal, that batch is called a heat. Every heat is given an identifying code, the heat number (you will also see it called the cast number), and every bar, plate or billet poured from that melt carries it, stamped on the metal and printed on the mill's test certificate.
Everything from one heat shares the same chemistry and was tested together. So the heat number is the link between a piece of material on your rack and a specific set of results: composition, tensile strength, hardness.
Why it matters when you machine parts
If you make parts for aerospace, defence, energy or medical customers, sooner or later somebody will pick up one of your parts and ask what it is made of, and how you know.
The honest answer is a chain:
- this part came from this works order
- that works order was issued material from this batch
- this batch arrived on this delivery, with this heat number and this cert
Break any link and the answer becomes "probably". An auditor does not accept probably, and neither does a customer investigating a failure.
The day it really matters
Now and then a mill discovers a problem with a melt after the material has shipped. A notice goes out naming the heat number.
If your records hold, you can say within minutes which batches you received from that heat, which jobs they went into, which parts were made and which customers have them. You quarantine what is left and you make a short list of phone calls.
If your records do not hold, the safe assumption is that everything you made in that material, over that period, is suspect. That is a very different week.
Where the chain usually breaks
In most shops the information exists. It is just in the wrong places:
- the cert is in a filing cabinet, or an inbox
- the heat number was written on the goods-in sheet but not on the rack label
- a bar was cut, and the offcut went back on the rack with no label at all
- material was issued to a job from "the 40 mm bar", not from a particular batch
None of these is careless. They are what happens when the record is a separate job from the work.
Making the record part of the work
The fix is to make it impossible to do the job without leaving the record behind. In Amplify ERP that means:
- Every receipt becomes a numbered batch, with its heat number and its cert attached at goods-in. If an item needs a cert and none has arrived, the batch goes into quarantine and cannot be issued.
- Material is issued from a batch, not from a description. The issue is the traceability record.
- Splitting a batch keeps its identity. Move part of a bar to another location and the new batch keeps the heat number and the cert, and remembers where it came from.
- The certificate of conformity writes itself. When the job despatches, the batches, heat numbers and certs that went into it are already on the paperwork.
Nobody has to remember to do traceability. It is simply what the system leaves behind when the job is done properly.
The short version
A heat number is the identity of a melt of metal. Carry it, unbroken, from goods-in to despatch, and "what is this made of?" takes a minute to answer. Lose it once, and it can take a week.