Workflow from finished design backwards to manufacturing the parts

nyholku

I'm not a professional ME so bear with me.

When I design a 'machine' I work from concept to the final functional design. But then I need get the parts made so how am I expected to go about that?

For example I design some part that has all the final dimensions but I want to get it cast so I need to produce the 'as cast' part and drawings.

When I start the 'machine' design I have very little idea how a part will actually me produced and even if I did I would have to / want to design the part 'as machined' and without regards to the cast dimensions etc.

What would be a good workflow?

konstantin_shiriazdanov

When designing a certain part you should already keep in mind its production tecnology, if you have doubts about certain technology you make several iteration of design corresponding to different production technologies of the parts to take a desigion.

For a question about as cast/as machined problem - you design a final shape of as machined part, but keeping in mind that it was made by casting, so you need to take care about all the casting slopes, fillets, wall thicness, parting plane. And then you make a copy of that part and add machining allowances to the surfaces that need to be machined. So you get two parts - one for assembly and machining process and one for casting technology development.

TimRice

For this sort of as designed vs as manufactured part representation you should consider using Onshape's branching feature. You can model the as designed part and create a version when you meet the design criteria. You could then branch from this version and add the parting line, drafts, etc to make the as manufactured part. This will allow for quick visualization while maintaining design intent for both representations of the part.

bradley_sauln

To add to what @konstantin_shiriazdanov and @TimRice mentioned. You are now at the Design for Manufacturing (DFM) phase. Depending on the company/industry/workflow this is either done at the same time as the initial product design or done as the next step. 

Outside of working in Onshape there is a lot to be considered depending on the manufacturing process. If you want to dive deep into this a good starting point is with Dragon Innovations DFM course which goes through what to consider for several manufacturing processes: http://blog.dragoninnovation.com/category/design-for-manufacturing-course/

nyholku

Thanks everyone for your insights. My needs are modest, at work all the 'real' ME is done by real MEs!  

My needs are mostly related to my spare time activities designing model engineering stuff where I usually start my designs from the functional/requirement view point with little consideration on how I'm actually going to produce the parts. In model engineering one often has the choice of either casting or simulating castings with other fabrication methods and this where my question stemmed from and to me it looks like branching is something I will try. 

But having said that also 'at work' I see that we often design the 'machines' with little regard to how they are manufactured and then we design the parts for manufacturing often starting with say machining from billets and later converting to castings as we grow more confident that the design is good and the product volumes are there. 

So my amateurism aside I think this is an important workflow question for pros too.

Thanks again.