Board is bought by area and used by shape, and the gap between the two is where a fabrication operation loses money quietly. Yield is rarely anyone’s specific responsibility, which is why it tends to sit several percentage points below what it could be.
Where the waste comes from
- Blank layout. Parts placed on a sheet without considering nesting, leaving awkward offcuts that cannot be used.
- Flute direction constraints. Every blank has to run the same way relative to the flutes, which reduces the layout freedom considerably – and is often forgotten when the part is designed.
- Standard sheet sizes. A part sized without reference to available sheet dimensions wastes a strip on every sheet.
- Cutting method. A saw kerf is small; a router bit is wider; a die cut is different again. Over thousands of parts, kerf width is a real quantity.
- Defects and rework. A part that fails inspection after being cut wastes the whole blank plus the cutting time.
- Offcuts not kept. Small pieces that could serve a smaller part get binned because there is nowhere to put them.
The layout is the biggest lever
Nesting parts across a sheet to maximise yield – and, where it matters, to respect the flute direction – is the largest single improvement available, and it is done once at design stage.
Two things make it harder than it looks. The flute direction constraint fixes the orientation, so parts cannot be rotated to fit. And a part designed for a round number wastes material if the sheet is not a multiple of it.
Which leads to the practical recommendation: design the part around the sheet, not the other way round. Changing a part dimension by a few millimetres to fit the sheet exactly can improve yield substantially with no functional consequence – and it is much easier before tooling exists.
Sheet size choice
Where a part is imported or standardised, sheet size may be fixed. Where it is not, choosing sheet dimensions that are a multiple of the blank is free yield.
This is worth checking at quotation stage. Two suppliers can quote the same price per square metre and deliver noticeably different cost per part once the layout is worked out.
Dealing with offcuts
Offcuts are only waste if there is no use for them. Three measures make a difference:
- A place to keep them, organised by size. If offcuts have no home they get binned regardless of value.
- A standard small part that uses them – a spacer, a pad, a corner protector. Having something to make from offcuts turns them into material.
- A rule about minimum keepable size, so the storage does not fill with pieces too small to use.
What to measure
Yield: the area of finished parts divided by the area of board purchased. Measure it once on a representative month and you will know where you stand. Most operations that measure it for the first time find more than they expected.
Then measure it again after a layout change, so the improvement is visible rather than assumed.
The return compared with buying better
Negotiating a few percent off the board price is visible and satisfying. Improving yield by a few percent is the same saving with no dependency on a supplier’s goodwill, and it repeats on every order.
Where yield has never been measured, it is usually the larger of the two opportunities.
What we can do
We supply corrugated PP sheet cut to size, and we will look at your blank layout against our standard sheet dimensions and tell you where yield is being lost. Sometimes the answer is a small change to a part dimension; sometimes it is a different sheet size. Both are cheaper than a price negotiation and both persist.