I'm doing this one anonymously.
Our company manufactures some kind of machines and also has a software department, which I'm part of. Our philosophy is mostly to have in-house software and components of the machine instead of third-party where reasonable, so we can quickly implement customer requirements.
Most recently, there has been a decision to implement a small Manufacturing resource planning system (with Bill of materials, Material requirements planning, Capacity planning, etc, all integrated with our machines.
In a nutshell, the customer will enter all of his worker schedule, different manufacturing operations and their capacities, transportation capabilities between them, operations in order and time required for manufacturing a certain item or assembly, deadlines for the internal orders, etc. and then the system will tell the customer a production plan - what the operators at any mfg. post are supposed to do, with reports on over- and under-capacity, time estimates, and so on.
I suppose there is also a vision that we'll make this software universal to be able to adapt to different customer requirements, so we'll sell a lot of them.
We're trying to add value to the machine, so the customers will only need to buy this stuff from us and won't need to pay some big software house tens/hundreds of thousands for a real ERP. We'll be mostly selling this to smaller companies (tens of employees), which cannot afford a real ERP and will have all of the of benefits of automated production planning for a fraction of the cost.
But I have a sinking feeling that there is a reason on why this kind of software does cost so much instead of the common greediness of the suppliers - it is complex, takes time to develop. I'm also worried about the "garbage in, garbage out" factor - that the system will not be able to produce any reasonable output unless the inputs are almost perfectly correct, and I'm not sure you can enforce this level of bureaucracy and overhead in smaller companies.
The powers that be think that all parts of this system are manageable (and have already drawn user interface mockups for the screens) and there will be no problem. Maybe I'm the one overestimating, but I don't know... We already have a small part of this implemented and it took about 2 years to get it to acceptable level.
My biggest concern is the underestimation of development time for this kind of system. In reality, we have about 3 developers, one under a part-time contract, and we'll maybe hire one more full-time developer, so about 3 and a half guys in total. No one has any prior experience with something of this scale, we'll have a lot more data, we'll need more customization options, bigger databases and better algorithms so there will be traps waiting around everywhere.
Is all of this unreasonable? How should I voice my concern to my superiors? Will opposing this kind of project look bad and make me seem unwilling or afraid?