Diagnostic workflow when a die starts losing tolerance

The press goes last in the triage because press diagnostics are expensive in downtime and the answer is rarely the press if the prior steps have not produced a finding. When it is the answer, the indicators are usually:

Ram alignment under load. A press that aligns within spec on a static check but goes out of alignment under tonnage is a real failure mode. The diagnostic requires a load cell or dynamic alignment fixture and a press service technician. Symptoms include uneven flash distribution, accelerated wear on one side of the die that does not match the lube or thermal pattern, and a tonnage trace that has changed shape over thousands of hits.

Slide parallelism. The slide and bolster should remain parallel within the press manufacturer's spec under load. Parallelism drift over thousands of hits is a known wear mode on mechanical presses with worn gibs or slides. The shop signal is a die that is wearing harder on one corner than the others with no process explanation.

Tonnage monitor calibration. If the tonnage signature is the trigger for the triage but no other variable has changed, the question is whether the tonnage signature actually changed or whether the tonnage monitor drifted. Calibration on a tonnage monitor on a busy press is often overdue by months.

Bolster condition. Wear or deformation in the bolster surface that the die bolts to. Less common than slide or ram findings, but real, especially on older presses that have run heavy dies for years.

The press goes last because diagnosing it well requires a service call, a tonnage load cell, and several hours of press downtime to do correctly. That cost is justified after the prior steps have ruled out the cheaper causes. It is wasted if it is the first step.