I took some time off from writing as I was involved a series of development of plastic & sheetmetal enclosures for a whole lot of products with different vendors in India and China. I could appreciate the difference in the end.
We were planning to develop a plastic enclosure for a consumer product with LCD display. We got the design done by the vendor's design team in China and up front the vendor told me that unless I get the plastics made by him he will not do the tooling. Before this whole lot of people told me that you should do the tooling in China/Taiwan and get the plastic moulded here in India. Let me tell that is difficult at least in China now. Most Chinese vendors don't show interest unless there is manufacturing tied to it. They call themselves as "Solution Houses" no more design in India make in China. This is true especially for Tablets, Mobile Phones, test instruments etc.
So we decided will do the design and tooling in India. We got the basic industrial design(ID) in quick time. While the ID houses are good in aesthetics not so good in usable design. It took almost a month to get the usability in place. We took the design to the tool designer and they had a whole lot of questions even before they could quote. My learnings are;
Be sure about the volume that you need if you are not the tooling cost can go haywire. If you are not sure go in for a single cavity ( that is, you can get one mould per cycle) and redo the tooling later for volume
Beware rapid prototype it will not tell the issues in the design especially moulding related like shrink marks, milling lines etc.
Most tool designer do the tooling by experience and they don't use tools like Mould Flow. So if your plastic is complex insist on the analysis.
Only experience helps to solve post tooling mould related problems and go to a tool room that has good people.
Get your plastics done by the same vendor who does the tooling "DON'T TRY TO SEPARATE". Tool design and moulding machines are closely connected doing it two places can kill the whole project.
Plastic part is costed by weight so know the weight to get the pricing right.
Tool has life so if your volumes are high tell them upfront to use the right tool block material
Go for a toolroom which has EDM wirecut machines, Vertical Milling has limitations.
Now coming to the lessons, in China all the above issues will not crop up as they know how to do it. This is the big difference. Don't lose heart the part which we made in India costed us Rs.67 while in China it was costing 4USD ex factory (about Rs 290). Landed cost will be much higher.
So it is the patience and knowing exactly what you want will make the life easy. Interestingly we had challenge for the above part when we wanted to design silicon sleeve. Despite working with the vendor we could never get one sleeve that is close to what we can get from China! and we have to abandon the project!
Now coming to the sheet metal - while companies claim they have CNC machines to do the job the final enclosure has never never been good. While CNC helps in cutting the sheet metal parts, where most of the vendors fail is in bending, welding and finishing. No Sheetmetal vendor has understanding of Thermal & EMC/EMI issues. To address EMC/EMI issues you need partially exposed surfaces in the enclosures and that call for a different painting or power coating process. None of the vendor know this and you have to tell them. In China the vendor asks do you need FCC/CE certification? If you say yes, he designs the enclosures accordingly. If your product has to meet Global Standards please be very clear about the welding, revetting and surface finishing (painting and powder coating).
None of the designers also understand this. Trouble I am seeing is that mechanical engineers have no appreciation of electronics issues (I now realise the course I use to take on electronic packaging and how important is that!) so they just give you a drawing and not design!
When I was interacting with the Chinese vendor I never faced these issues as they could easily understand the aspects. When I checked with them they were telling me their On Job Training is what makes the difference.
If we want to create a robust eco system we need spend more time in design rather than copying ( I get requests for "Designing a copy of a sample product" as it is!).