A garden products company was losing margin on its best-selling irrigation controller. A Design for Assembly review cut part count from 31 to 19, assembly time by more than half and unit cost by 32%.
Key numbers
A Queensland garden products company had a problem every product manager dreads. Its best-selling irrigation controller, a reliable product with loyal customers, was being undercut by competitors at price points it could not match without losing money. The sales team asked for a price cut. Engineering was asked to find the cost.
The situation
The controller had been designed eight years earlier and had served well. But it used 31 parts, including 14 screws, and a sealed enclosure that took almost seven minutes to assemble. Over the years, small changes had added brackets, spacers and clips, each sensible on its own.
What the data showed
A cost breakdown by category showed where the money really went.
Fasteners, clips and assembly labour together accounted for almost 30% of unit cost, far more than the plastic mouldings themselves. Electronics were the largest single category, but the board had grown a separate sub-board over the years that existed only because of an earlier enclosure constraint.
A Design for Assembly review asked the three classic questions of every part: does it move relative to its neighbours, must it be a different material, and must it be separate for assembly or service? Twelve parts failed all three tests, the approach described in our plastic design guidance and Design for Manufacture work.
What changed
- Enclosure redesigned with integrated snap fits and an overmoulded seal, replacing screws and a separate gasket.
- Battery compartment and mounting bracket merged into one moulding.
- Electronics board re-laid out to remove the sub-board and its connector.
- Assembly sequence redesigned so every part loads from one direction, with self-locating features.
Results
Part count fell from 31 to 19. Assembly time dropped from 412 to 198 seconds. Unit cost fell from $42.80 to $29.10, a 32% saving. On annual volumes of around 60,000 units, that is more than $800,000 a year, enough to compete on price while restoring margin.
The redesigned enclosure also sealed better, because a moulded-in seal cannot be pinched or forgotten the way a loose gasket can.
Lessons for your operation
- Mature products accumulate cost quietly. Every addition made sense at the time.
- Fasteners and assembly labour are often the largest hidden cost in plastic-intensive products.
- The three Design for Assembly questions are a fast, reliable way to find parts that should not exist.
- Redesign beats renegotiation: purchasing can squeeze a few percent; design can remove a third.
If one of your products is under price pressure, a structured design review is often the fastest route to a competitive cost.
