I often get the question of how to make a manufacturing line run high-quality and cheap, especially from startups early in developing their hardware products. In the chaos of launching a product, things are unexpectedly breaking, the cost of the parts is too high, and it’s hard to figure out what to fix first.
To get to a smooth, low-cost build, aim for improvement in this order:
- Consistent
- Quality
- Cheap
1) Consistent
It’s hard to pinpoint the root cause of issues if you don’t know how your product was built.
If you don’t yet have process controls, assume that every product is being built differently in important ways that you haven’t yet discovered will cause problems. Different part batches have different issues, different assemblers will build differently, and some may forget fixes and regress to old techniques.
Standardize the process and control the variables you can so that every device comes out as close to the same as you can.
This can include:
- Writing work instructions and checklists for how to build the device
- Building a bill of materials with supplier part numbers
- Making drawings for custom parts with
- Setting up a production area with the right tools and consumables
In particular, pay attention to:
- Any adhesives/threadlockers/fluxes, in particular around surface preparation, mixing process, and post-cleaning
- In-process tuning or calibration methods
- Wire twisting, routing, and fastening
- Building and flashing instructions for code
- Any tests run on built devices
- Any reports of issues in the field with as much detail as you can capture
Try not to get too bogged down in fixing all the issues at this stage - just try to write down the process as it is right now.
2) Quality
Once you have consistent outputs from your build process, you can spot consistent issues and pinpoint their root causes.
This can include:
- Collecting together field issues to understand the root cause
- Returning and tearing down failed devices to understand the cause of the failure
- Cycle/torture testing hardware to uncover failure modes
When you understand the root cause of a failure mode, you can now:
- Fix the issue
- Build the process controls to ensure it stays fixed
This could include:
- Redesigning components to fix design issues
- Redesigning components to make assembly errors impossible (Poka-yoke)
- Adding engineering performance tests for all new designs
- Adding critical dimensions or parameters on drawings and manufacturing files
- Creating incoming inspection procedures for parts
- Adding in-process or post-build inspection steps or measurements with checklist steps
- For critical checks that can only be tested destructively, doing process validation to ensure the output is always good
- Warning: process validation is expensive and painful, avoid it if you can
3) Cheap
When you have both consistent high quality and the process controls to prevent and detect issues, then you have the tools to cost-reduce the assembly while keeping the risk of new issues low.
Put candidate cost-reduced components through the same inspection, build, and performance tests as your current process. If they pass all of the tests, then you can launch to production.
Conclusion
There’s a lot more to be said on how to bring up a manufacturing line, but prioritizing by “consistent, quality, cheap” can help get you to stable production quickly.
Having issues on your hardware launch? Drop me a note on any channel in my Find Me Online page - happy to help however I can!