When a mid-market manufacturing enterprise running SAP ECC 6.0 for over twelve years decided it was time to modernize, they faced a familiar dilemma: how do you migrate a heavily customized, business-critical SAP landscape to S/4HANA without disrupting production, payroll, or customer commitments? This case study walks through how our team approached that exact challenge for a 500-user manufacturing organization across three plants.
Client Overview
The client is a discrete manufacturing organization with three production facilities, a distribution network spanning multiple states, and roughly 500 active SAP users across Finance, Materials Management, Production Planning, and Sales & Distribution. Their existing SAP ECC 6.0 environment had accumulated over a decade of custom Z-programs, workarounds, and interface points with shop-floor and logistics systems.
At a glance: 500 active users · 3 manufacturing plants · 12+ years on ECC 6.0 · FI/CO, MM, PP, SD, QM modules in scope · 9-month engagement.
The Challenge
Three concerns dominated the client's planning conversations before they engaged us:
- Custom code risk — years of Z-transactions and BAdIs needed to be assessed for S/4HANA compatibility, with many requiring remediation or full rewrites against the simplified data model.
- Zero tolerance for production downtime — with three plants running continuous shifts, any extended cutover window risked missed customer commitments.
- Data integrity across a decade of history — finance and materials data had to reconcile perfectly before, during, and after the technical conversion.
"We'd seen other manufacturers in our network struggle through failed or delayed S/4HANA conversions. Our board wanted proof of a disciplined methodology before we committed budget." — VP of IT, Client Organization
Our Approach
Rather than a big-bang rewrite, we recommended a system conversion approach using SAP's Software Update Manager, paired with our Agile Implementation Framework to manage the custom code remediation workstream in parallel. The engagement followed four core principles:
- Run the Custom Code Migration app and Simplification Item Checks early, well before the technical sandbox conversion, to surface scope accurately.
- Stand up a sandbox-to-production conversion cadence (sandbox → development → quality → production) so every fix was validated at least twice before go-live.
- Involve plant super-users from week one so process changes were validated against real shop-floor scenarios, not just documentation.
- Build a dedicated hypercare team spanning the first 30 days post go-live, with daily stand-ups across all three plants.
Migration Timeline & Phases
The 9-month engagement was structured into four phases:
- Phase 1 — Assess (6 weeks): Custom code and simplification item analysis, data quality audit, and a detailed conversion roadmap.
- Phase 2 — Prepare (10 weeks): Sandbox conversion, custom code remediation, and Fiori app rollout planning for the new UX.
- Phase 3 — Realize (14 weeks): Iterative conversion cycles across development, quality, and pre-production environments, with integration and regression testing after each cycle.
- Phase 4 — Go-Live & Hypercare (6 weeks): A single production cutover executed over a planned weekend, followed by 30 days of dedicated hypercare support across all shifts.
Results & Impact
The production cutover was completed within the planned weekend window with zero unplanned downtime once shifts resumed Monday morning. Post go-live metrics over the following two quarters showed meaningful, measurable improvement:
- Month-end financial close time reduced from 6 days to 4 days.
- Real-time inventory visibility across all three plants via embedded analytics, replacing overnight batch reports.
- Over 60% of the identified custom Z-transactions were retired entirely in favor of standard S/4HANA Fiori apps.
- User adoption of the new Fiori launchpad exceeded 90% within the first month, aided by role-based training delivered during hypercare.
Key Takeaways
For manufacturing organizations considering a similar journey, three lessons from this engagement stand out:
- Run custom code and simplification item analysis before committing to a timeline — it is the single biggest source of estimation risk in a system conversion.
- Involve plant-floor super-users early; process validation from the people who actually use the system daily catches issues that documentation reviews miss.
- Budget for a real hypercare period. The weeks immediately following go-live determine whether adoption sticks or resistance builds.
Every manufacturing landscape carries its own history of customization and process quirks — if your organization is weighing a similar S/4HANA journey, our team is happy to walk through what an assessment would look like for your specific environment.
