The problem
Symptom. After fourteen months and about 480,000 metres on one die set, a 2.80 mm profile wall measures 2.98 mm and a third refurbishment is booked, but the order has no replacement trigger.
What it costs. Three refurbishments have cost £2,100 against a £9,800 new die, and without a trigger the buyer keeps paying for repairs while dimensional drift threatens the window seal.
This article shows how to track wall-thickness drift, compare refurbishment with replacement cost, set a trigger and fund it through an annual die budget clause.
- 1. Wall thickness drifts after fourteen months of output
- 2. Costing each refurbishment against a replacement die
- 3. Setting a drift and refurb-count replacement trigger
- 4. Holding a transition die while the new tool is proved
- 5. Funding the trigger through an annual die budget clause
- 6. Reviewing gauge records at every scheduled shutdown
Wall thickness drifts after fourteen months of output
A 2.80 mm wall specified at ±0.15 mm now measures 2.98 mm after roughly 480,000 metres, so the die has drifted past its upper tolerance and the profile no longer seats the glazing seal cleanly.
| Sign on the line | What the record shows | Decision it forces |
|---|---|---|
| Wall at 2.98 mm | Drift of 0.18 mm past nominal | Replace or re-grind |
| Third refurbishment booked | £2,100 spent on repairs | Set a refurb cap |
| No drift clause | Trigger undefined | Dispute over who pays |
| Gauge records withheld | Trend cannot be shown | Replacement delayed |
Table 1 - Reading die wear before authorising a replacement
Need a fixed price for this profile?
Send the cross-section drawing, material, cut length and annual volume. We will review die, calibration and tolerance, then return a written tooling and production quotation.
Costing each refurbishment against a replacement die
Three refurbishments at £700 each total £2,100, and a fourth would bring the spend to £2,800 against a £9,800 replacement die. Log each gauge reading and repair date before deciding.
A five-step diagnostic sequence
- Log the gauge readings.
Record the 2.98 mm wall against the 2.80 mm ±0.15 mm specification. - Total the refurb spend.
Add three £700 repairs and price a fourth before comparing with £9,800. - Set the trigger.
Fix a 0.15 mm drift limit and a four-refurbishment cap on the die set. - Prove the replacement.
Run a witnessed first article on the new die while the old set stands by. - Fund and write the clause.
Reserve £12,000 a year and put the trigger and gauge-sharing duty on the order.
The chart below is a typical result from that measurement step. Use it to separate a design limit from a setting that can still be recovered.
Setting a drift and refurb-count replacement trigger
At 2.98 mm the drift is 0.18 mm beyond nominal, and a fourth £700 refurbishment raises cumulative repair cost to £2,800 against a £9,800 new die. These are illustrative worked values from stated assumptions, not a market survey, a quoted price or a measured series.
| Clause or parameter | Agreed value | What goes wrong outside it |
|---|---|---|
| Wall drift limit | 0.15 mm from 2.80 mm nominal | Seal fit drifts unchecked |
| Refurbishment cap | Four per die set | Repairs exceed a new die |
| Annual die budget | £12,000 provision | Replacement bought in a rush |
| Gauge record sharing | At every shutdown | Trigger cannot be verified |
Table 2 - Replacement trigger clauses for the supply agreement
Holding a transition die while the new tool is proved
Plot illustrative wall thickness against cumulative output and it crosses the 2.95 mm upper limit near 400,000 m; that crossing is the feasibility boundary a replacement trigger must anticipate.
| Option | What it fixes | Cost or trade-off |
|---|---|---|
| Fourth refurbishment at £700 | Buys a little more output | Low cost, short-lived |
| Buy a £9,800 replacement die | Restores the tolerance | High, funded by budget |
| Keep a transition die set | Covers the proving run | Low: storage of one set |
| Tighten gauge checks | Catches the next drift | Low: a shutdown reading |
Table 3 - Die options ranked by cost and delivery risk
Funding the trigger through an annual die budget clause
Order the replacement die, keep the existing set as a transition tool, tighten gauge checks to every shutdown, and run a witnessed first-article trial before the new die enters normal production.
Need the section checked before tooling?
Send us the section and the installation conditions. We will review wall balance, tolerance and fixing detail, then return a marked-up drawing with a tooling quotation.
What to send us
- Cross-section drawing with wall thicknesses
- Material and colour
- Installation temperature range
- Fixing method and run length
Reviewing gauge records at every scheduled shutdown
Write a 0.15 mm drift limit, a four-refurbishment cap, a £12,000 annual die budget and a requirement to share gauge records into the agreement, then review the figures at each shutdown.
Before you release this extruded profile
- The order fixes a 0.15 mm wall-drift limit from the 2.80 mm nominal
- A cap of four refurbishments per die set triggers a replacement review
- An annual die budget of £12,000 is reserved on the agreement
- Gauge records are shared and reviewed at every scheduled shutdown
- A transition die remains available until the new tool passes first article
Write the measurement temperature and the tolerance into the drawing; most disputes are really about how the part was measured.
When should a die be replaced?
When wall drift passes 0.15 mm or a fourth refurbishment is due; on the illustrative figures 2.98 mm against a 2.80 mm nominal already exceeds the limit.
Is refurbishment cheaper than a new die?
One £700 repair is, but a fourth brings cumulative spend to £2,800 and still leaves the drift, so the £9,800 tool eventually pays back.
What is a transition die?
The existing set kept in service while the replacement is proved, so a failed first article does not stop the line.
Why share gauge records?
A drift trigger is only enforceable if both sides see the same thickness readings taken at each shutdown.
How is the replacement funded?
Through an annual £12,000 die budget written into the agreement, so the cost is planned rather than disputed mid-campaign.
What is checked at shutdown?
The current wall thickness against 2.80 mm ±0.15 mm, the refurbishment count and the remaining budget.
Get a profile that holds its dimension
Send us the profile section, the length and the service conditions. We will review die, calibration and tolerance, then quote tooling and production with a defined measurement method.
To get an accurate quote, send:
- Profile cross-section drawing
- Material and colour
- Cut length and annual volume
- Service temperature and exposure
Why buyers work with Uplastech
ISO 9001, ISO 14001 and ISO 45001 certified. Founded in 2016, with injection moulding lines in Shanghai and an extrusion plant in Jiangsu. Moulding machines from 90T to 1100T and a maximum shot weight of 5100 g. Samples and a written quotation are available on request.
Continue reading
- Extrusion dimensional drift
- Extrusion profile tolerance
- Profile calibration and cooling
- PVC profile weathering and colour
- PVC window profile design
Ready to specify? See our plastic profile extrusion services or request a written quotation.
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