The Machine That Was Built Before the Design Review

We built a machine on a tight schedule. The design review (a meeting where the team checks the design) got skipped — “we’ll review it during build.” On the floor, problems surfaced: a cylinder that didn’t reach its stroke, a sensor in a spot the operator couldn’t adjust, a wire that pinched. Each fix cost time. We retrofitted: a longer cylinder, a relocated sensor, a cable guide. It took two extra weeks. The mistake was skipping the design review. A 2-hour review meeting would have caught most of these on paper (before cutting metal). The mistake was thinking the review was a delay. It’s cheaper to fix a drawing than a built machine.

Machine design review is a structured check of the design before it’s built. It catches problems on paper. This article covers the checklist.

What Is a Design Review?

A design review is a meeting (or a structured check) where the design engineer walks through the machine with the team (mechanical, electrical, controls, safety, manufacturing). The team checks the design against a checklist. Problems are found on paper (not on the floor). They’re fixed in the CAD model before machining.

The design review isn’t optional — it’s part of the process. Skipping it saves a day on paper, but costs weeks on the floor.

The Design Review Checklist

Mechanical

  • Are all actuators (cylinders, motors) sized? (Article 53, 57, 81.)
  • Are bearings and guides sized for L10 life? (Article 51, 61.)
  • Is the frame rigid enough? (Deflection within tolerance? Article 58.)
  • Are fasteners accessible? (For maintenance?)
  • Are pinch points guarded? (Article 34, 74.)
  • Are weights within the rigging/handling limit?
  • Is there clearance for assembly? (Can you bolt it together?)
  • Are wear parts replaceable? (Bushings, wipers, belts?)

Pneumatic

  • Is the FRL sized? (Article 84.)
  • Are cylinders sized for force and stroke? (Article 53.)
  • Is there air preparation? (Filter, regulator, lubricator?)
  • Is there a soft-start/dump valve? (Article 34.)
  • Are mufflers on exhausts? (Article 75.)
  • Is the tubing routed away from moving parts?

Electrical and Controls

  • Is the power supply sized? (Article 57.)
  • Is the cabinet IP-rated and ventilated? (Article 35, 60.)
  • Are sensors placed adjustably? (Article 63.)
  • Is the PLC I/O count enough? (Spare I/O?)
  • Is the HMI sized for the operator? (Article 97.)
  • Is there a safety circuit? (E-stop, guard, light curtain? Article 64, 98.)

Safety

  • Is the risk assessment done? (Article 90.)
  • Are pinch points guarded? (Fence, light curtain? Article 74.)
  • Is the e-stop circuit dual-channel with monitored reset? (Article 98.)
  • Are guards interlocked? (Article 74.)
  • Is there lockout/tagout? (Power disconnect?)
  • Is the manual in the customer’s language? (Article 90.)
Category Key Check
Mechanical Actuators sized, frame rigid, wear parts replaceable
Pneumatic FRL, cylinder sizing, soft-start, mufflers
Electrical Power supply, cabinet IP, sensor access, spare I/O
Safety Risk assessment, guards, dual-channel e-stop, LOTO
Documentation Schematic, manual, CE declaration (article 90)

Process and Cycle Time

  • Is the cycle time met? (Sum of move times?)
  • Is the bottleneck identified? (Which station limits the rate?)
  • Is there accumulation? (So one jam doesn’t stop the line?)
  • Is the operator’s work balanced? (Not overloaded at one station?)

Maintainability

  • Are wear parts accessible? (Filters, brushes, seals?)
  • Is there a lubrication schedule? (Article 88.)
  • Are spares identified? (Fuses, filters, sensors?)
  • Can a maintenance person reach every component? (No hidden bolts?)

The design review rule: Do the review before machining, not after assembly. The machine that was built without a review had problems found on the floor. A 2-hour review catches them on paper. Fixing a drawing is free; fixing a built machine costs time and money.

How to Run the Review

  1. Prepare: The design engineer shares the 3D model, the BOM, the pneumatic and electrical schematics, and the cycle time calculation.
  2. Walk through: The engineer presents the machine (how it works, the flow, the actuators). The team follows along on the model.
  3. Check the checklist: Go through the mechanical, pneumatic, electrical, safety, and process items. Mark each as OK or “action.”
  4. Assign actions: Every problem gets an owner and a due date. The engineer updates the design before machining.
  5. Re-review (if needed): For major changes, a follow-up review confirms the fixes.

The Cost of Skipping the Review

Skipping the review saves a half-day of meetings. But on the floor, a single problem (a cylinder that doesn’t reach, a sensor that’s inaccessible) costs a retrofit — redesign, re-machining, re-assembly. That’s days (or weeks). The machine that was built without a review took two extra weeks. A 2-hour review would have prevented it.

The design review isn’t a delay. It’s insurance. Cheaper to fix on paper.

The Final Checklist (Print This)

  1. All actuators sized (force, torque, stroke)?
  2. Bearings and guides have L10 life?
  3. Frame deflection within tolerance?
  4. Fasteners and wear parts accessible?
  5. Pinch points guarded?
  6. FRL and soft-start in the air circuit?
  7. Power supply and cabinet rated?
  8. Sensors adjustable and visible?
  9. Spare I/O (20%) in the PLC?
  10. Safety circuit: dual-channel e-stop, monitored reset?
  11. Risk assessment done?
  12. Guards interlocked?
  13. Cycle time met? Bottleneck identified?
  14. Lubrication schedule and spares list?
  15. Documentation: schematic, manual, CE declaration?

The Bottom Line

Machine design review catches problems on paper, not on the floor. The machine built without a review had retrofits that cost two weeks. Run the review with the full team (mechanical, electrical, controls, safety) before machining. Walk the 3D model against the checklist. Assign every action to an owner. The machine that built smoothly wasn’t designed fastest — it was reviewed first. Fixing a drawing is free; fixing a built machine isn’t.