Supplier Data Exchange Across Two CAD Systems
A program team spans a mold maker using one CAD system and an OEM using another. The OEM sends native part models plus a STEP export. The mold maker returns tooling designs as STEP and PDF drawings. On the last program, a cooling-line change was made in the mold maker's native model but not reflected in the STEP sent to the OEM, and the OEM's simulation used the old cooling layout. The error was found only at tryout. This program has a 14-week tool build, three design reviews, and a contractual requirement that the OEM approve all cooling changes before they are cut. The team wants a data-exchange protocol that prevents a repeat.
1. Design a data-exchange protocol that prevents the cooling-line failure, naming the specific controls and who owns each.
Read the worked answer
The failure was not a format problem; STEP carried the geometry fine. It was a change-control problem: the authoritative model and the exchanged model diverged, and nobody compared them.
Protocol controls:
- Single source of truth per discipline. The mold maker owns the tooling model; the OEM owns the part model. Each exchange is stamped with a revision and a date. Owner: mold maker for tooling, OEM for part.
- Geometry comparison on receipt. The receiving engineer overlays the incoming STEP against the previous revision and signs off that only intended changes are present. Owner: receiving engineer, within 2 working days.
- Change request tied to geometry. Any cooling change gets a numbered request with before/after images and a simulation impact statement. No cutting until the OEM approves in writing. Owner: mold maker raises, OEM approves.
- Review gate checklist. Each of the three design reviews has a fixed checklist including cooling layout, and the checklist is signed by both parties.
- Archive every exchange with its revision so a simulation can always be traced to the exact geometry used.
The key control is the geometry comparison, because it catches divergence regardless of who forgot to notify whom.
2. How should the team handle the fact that the OEM's simulation may lag the mold maker's latest geometry?
Read the worked answer
Lag is inevitable when two organizations work in parallel, so the goal is to make lag visible and bounded rather than to eliminate it.
Approach:
- Define which geometry the simulation must use. Simulation results are only valid for a stated revision, so every simulation report carries the tooling revision it was run against.
- Set a staleness rule: any simulation older than the latest approved cooling revision is flagged as indicative only and cannot be used to approve a cut.
- Sequence the work so simulation runs after each approved change, not continuously. With three design reviews over 14 weeks, there are natural sync points.
- Use a shared change log visible to both parties, listing revision, date, what changed, and whether simulation has been rerun.
Risk if ignored: the OEM approves a cut based on a simulation of older geometry, and the mismatch surfaces at tryout, which is exactly the prior failure. The cost of the staleness rule is a short wait at each review; the cost of skipping it is a tryout delay measured in weeks.