It is easy to draw something in CAD that seems like it will work. It is another thing to design something that can be made efficiently, consistently and affordably, is easy to assemble, and keeps working.
These are short examples of fixes, product evolutions and integrations. Each one went after the root cause and replaced it with something simple that lasts. Several were done during my years as a product developer at a Connecticut contract manufacturer, before founding Atrick Design.
Robot and vacuum redesign
On the Fastcorp DIVI vending platform, the scope was to fix the fragile plastic robot and pump designs while keeping the same controls and code. The redesign moved from a DC vacuum pump and a plastic robot to an AC vacuum pump and a sheet-metal robot.
Duty cycle went from about 20% to 100%. The machine got about 15 dB quieter. Assembly and break-in issues were eliminated, and the design passed a 250,000-vend life test and certification testing. It ran at full duty cycle at full vacuum for long periods.
A machine kept having static-induced control board failures in the field. Its ground used a self-threading screw into powder-coated steel. The connection passed hipot testing at the factory but corroded in the field and left the control board exposed. The fix was a welded-in stainless screw with a braided ground strap, a connection that lasts. Together with one other fix, it eliminated the static-induced board failures.
Welded stainless ground screw.
Fasteners that kept popping out
The design used a sheet metal thickness that did not match the thread size of the available PEM nuts, so they kept popping out. The workarounds in production, tack welding them in and re-tapping the distorted threads, caused rejects and rework. The cover holes were drilled by hand and did not always line up, so a bolt started into a distorted thread would cross thread. Sometimes the bolt head snapped off, leaving the stub stuck in the nut. Other times the PEM nut popped loose with the bolt jammed in it. Then the nut just spun, the bolt could not be loosened, and the cover was stuck on. Either way, a whole treadmill could come back to the factory over one fastener.
Switching to hex-shaped rivnuts, which are easy to replace in production and in the field, lowered BOM cost, rejects, assembly time, scrap and rework substantially. In the same revision the left and right sheet metal boxes were given the same flat pattern, with a cutout that shows which way each was bent.
Before: a bolt snapped off in a distorted PEM nut, leaving the threaded stub stuck in it.After: hex rivnuts in place of PEM nuts.
Crushed foam
The original design used foam as a cushion under offset rollers, but the fasteners crushed the foam completely. The assembly went wavy, the foam squeezed out over time, assembly was difficult, and the assembly could twist. Aluminum spacers replaced the foam under the fasteners, with foam kept under the rollers for cushioning. That solved every issue and made for a much smoother run. The spacers were planned to be built into the injection molded parts to remove a part and reduce cost.
Before: foam crushed under the fasteners.After: aluminum spacers.
Fuse holders to circuit breakers
This job reduced redundant options, replaced problematic fuse holders that used hard-to-find glass fuses, and simplified assembly. Fuses were swapped for circuit breakers. Six product options became two (a 110 V or 220 V outlet), BOM cost dropped by $17, and end users no longer had to hunt for fuses. The production version used snap-in breakers to simplify assembly further and meet higher electrical safety standards.
The prototype.
Touchscreen integration
A supply partner’s touchscreen came as a bulky add-on. Its screen, circuit boards and harnessing were all reused in a new mount and housing, so the finished product sat flush and looked like it belonged.
Reused parts in the new mount.
Vacuum hose nut
A convoluted hose had to connect to a vacuum tip. The first prototype followed the hose maker’s specifications, but the hose turned out to be outside the maker’s own tolerance. A reworked thread was designed in, giving a simple, reliable connection that lets the vacuum tip and hose be replaced quickly.
The reworked hose nut.
Suspension bushings flexing the wrong way
Some manufacturers use control arm bushings that are forced to flex 90° to the direction they were designed for. They fail quickly and let suspension geometry wander as they twist and tear. Polyurethane replacements bind as the control arm moves past level and wear out fast, and unsealed spherical bushings collect water, salt and grit that destroy the joint.
The fix was to weld in a collar and press in a sealed spherical joint. It brought handling up to race-part level without the downsides, and lasted years longer than the other options, because the seals keep the grease in and the grit out while allowing the needed twist.
Collar welded into the arm.Sealed spherical joint installed.The joint in section.