Why Do Forgings Fail Inspection?
Rejections cluster into five categories, and four of them are preventable by process control rather than by more inspection. Knowing which category dominates tells you where to fix the process.
Forgings fail inspection for five reasons: dimensional non-conformance from die wear or shrinkage errors, hardness outside the specified band, surface defects such as laps and scale pits, NDT findings including internal bursts, and incomplete documentation.
- Dimensional
- Die wear, mismatch, shrinkage error
- Hardness
- Furnace control, grade hardenability
- Surface
- Laps, scale pits, handling damage
- NDT
- Bursts, surface cracks
- Documentation
- Missing or incomplete records
Why Do Forgings Fail Inspection? at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- Dimensional and hardness failures dominate rejections
- Die wear causes progressive dimensional drift
- Laps and cracks cannot be reworked
- In-process control prevents most rejections
Dimensional and Hardness Rejections
Dimensional failures usually trace to die wear, incorrect shrinkage allowance or mismatch between die halves. Hardness failures trace to furnace control, incorrect tempering temperature or a grade that lacks hardenability for the section. Both are process problems with recorded causes.
- Die wear and mismatch cause dimensional drift
- Shrinkage allowance errors are systematic
- Hardness failures trace to furnace control
- Section size can defeat a grade's hardenability
Surface, NDT and Documentation
Surface rejections come from laps, scale pits and handling damage. NDT rejections come from internal bursts or surface cracks. Documentation rejections — missing certificates, unmarked heat numbers, incomplete reports — are entirely avoidable and yet common.
People also ask
What causes hardness to fall outside specification?
Incorrect tempering temperature, furnace control drift, or specifying a grade whose hardenability cannot develop uniform properties through the section size.
Are dimensional rejections the supplier's fault?
Usually yes, from die wear or mismatch. Occasionally the drawing specified a tolerance no forging process can hold, which should have been flagged at quotation.
How is inspection failure prevented?
By in-process control at each stage — billet weight, forging temperature, die condition, post-heat-treatment hardness — so drift is caught while it costs a die adjustment rather than a batch.
Topics covered on this page
- inspection failure
- die wear
- hardness band
- lap
- NDT rejection
- documentation
- in-process control
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
What is the most common reason forgings are rejected?
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Dimensional non-conformance from die wear, followed by hardness falling outside the specified band.
Can rejected forgings be reworked?
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Dimensional oversize can sometimes be machined. Laps, cracks and undersize dimensions cannot be recovered.
How do you prevent inspection failures?
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In-process control — billet weight, temperature, die condition, hardness after heat treatment — rather than relying on final inspection to catch problems.