Drafting and order of features.

Question

I am familiar with parting lines and pull directions for molded or cast parts, but I have not had a lot of experience designing parts with draft. I have an initial concept of a part shown in the pictures. My two thoughts for the parting line would be either the top of the cylinder near the four tabs or where the slot at the bottom of the part intersects the cylinder. There is some geometry in the bottom of the slot shown in the second picture.

Besides the parting line question, I am also wondering about the order of operation. Typically rounds/radii go towards the end of the part. What about draft? Do you get a concept done similar to what I have and then add draft, or is it added up stream. This is a fairly simple part, so if it needs to be upstream, I can easily recreate the part if needed.

Thanks for suggestions and ideas,

Dale

This thread is inactive and closed by the PTC Community Management Team. If you would like to provide a reply and re-open this thread, please notify the moderator and reference the thread. You may also use "Start a topic" button to ask a new question. Please be sure to include what version of the PTC product you are using so another community member knowledgeable about your version may be able to assist.

TomD.inPDX · Answer

This is a common question for many working with molded parts.

The simple one to answer is the drafts and chamfers. Add them after drafts. All too often a feature will fail from an arbitrary round before draft.

As to parting line, this is usually driven by the design intent. With some license... I would consider the flat face on the 1st image to be the logical parting line providing flash at the assumed mating interface, in this case. Also remember to logically direction of pull for the center bore which I would probably keep with the countersink feature.

Only a few design intents would change my perspective. If the cylinder and 4 tabs were a critical mating feature, and a fillet or chamfer on that edge was desired or even critical. I would be aware that flash at the transition would be clearly visible, or would require post mold operation.

As to when to apply the draft; rarely do people think draft while modeling and they spend a lot of time after the fact to apply it. I don't know if the "dome" is sculpted or a simple round, but features like this can really slow you down when adding draft. I will do both but I like to work on primary features with draft already defined. Some things just don't lend themselves to doing this simply so those I might feature straight, consider the tooling, and add drafts at that point (before I am too committed with more dependent feature).

Sign up

Please use your PTC eSupport account.

Welcome to the PTC Community

Please use your PTC eSupport account.