SOP: the rule set
An SOP explains the process at department or facility level. It answers what the organisation does, who is responsible, and what approvals or records matter. It is written for supervisors, quality, and auditors, not for someone tightening bolts on Line 3.
- Audience: supervisors, managers, auditors
- Content: responsibilities, process flow, references to standards, approval signatures
- Example: 'SOP-042: Line Changeover Procedure' — defines who approves, what gets checked, and what records are required
WI: the station-level how-to
A work instruction is the step-by-step guide at a specific station. It answers how to do the task, with numbered steps, critical parameters, photos, and pass/fail cues. It is written for the person doing the work.
- Audience: operators, technicians, assemblers
- Content: numbered steps, photos, critical parameters, tool lists, safety warnings
- Example: 'WI-042-A: Conveyor Belt Tensioning — Line 3' — step-by-step with photos and torque specs
How they fit together
In a healthy hierarchy, the SOP explains the process and responsibilities, while the work instruction shows how a specific task is performed at the station. They should reference each other without collapsing into one giant hybrid document.
- Quality manual > SOPs > Work instructions — each level adds operational detail
- An SOP may reference multiple work instructions for different workstations or product variants
- Both must be under revision control — updating an SOP may trigger work instruction revisions
Why mixing them fails
The common failure mode is one document trying to be policy, procedure, training pack, and workstation guide at the same time. Operators skip the policy language, managers skip the line detail, and nobody gets a document that fits the job.
- Mixing policy language and step-by-step instructions in one document confuses both audiences
- Putting work instructions in the SOP makes the SOP too long — operators will not read a 30-page document
- Not linking them: if the SOP changes, the work instructions must be reviewed for impact
How RevQR fits the hierarchy
RevQR can manage SOPs and work instructions as separate controlled documents, but its strongest fit is line-side delivery of work instructions. Keep the hierarchy clear: SOP for the process, WI for the exact task at the station.
- Create separate documents for SOPs and work instructions with independent revision sequences
- Use QR delivery primarily for work instructions at the workstation; share SOPs where supervisors and quality teams review them
- If your process requires named acknowledgement, track it by document type and audience