Hi all, I am currently doing engineering drawing for a bottle and now looking for the tolerance. Do anyone know what is the actual tolerance to prevent water leak from a bottle? Thankyou very much.
Hi Yuki, can you explain your design a bit more? What part of the bottle do you need to tolerance? Are your trying to tolerance the fit between 2 parts? The geometry & materials need to be understood by us before a tolerance can be recommended. If you could upload a sketch it would be helpful.
Hi GarethW, Hmm, it is a shampoo bottle, when we open the shampoo cap, there is a hole where the shampoo can leak out and we can use it. When we close the cap, the cap have a cylindrical shape which fit the hole and prevent the shampoo leak even if we put the shampoo bottle upside down. That is the part where i need to list the tolerance. Both material is PP, polypropylene. Is that clear? Thankyou very much for your reply GarethW
Yes - I know the kind of thing you mean. A moulded-in plug feature on the cap clicks into a hole? I expect that's probably some kind of interference fit and yes, I'm sure some fine detail and tolerancing will be involved in the design of both parts. I just had a quick look at some stuff in the bathroom and already see a few variations on this theme, they all seem to be air-tight and all have a slightly different "feel" (that will be all-important with a consumer product). Have you established how the parts will latch? Personally, I think it's difficult to recommend a tolerancing scheme without first studying the design in detail myself. I'd be inclined to take measurements from some existing products (ones I like the "feel" of) and study them close-up too to see what makes them tick. I'd then draw up sectional views and use them to come up with a tolerancing scheme. Do you have such a section view? One other thing, are you planning on making a mould tool? I'd certainly recommend trying to get prototypes made before you do this. You should also discuss the design of this latch in great detail with toolmaker & moulder. Whatever your design intent is, you need to ensure it carries through accurately to production. Shrinkage, mould flow etc. can totally screw up an otherwise brilliant design!
Yes, it is. when you close it, it will produce a "tick" sound and this is the section and detailed view. No,i am not planning on making a mould tool, just drawing the prototypes. Thankyou very much
Sir, just buy a few similar bottles from the market and measure their dimensions. Apply the usual precision moulding tolerances and you will get your answer.
I don't think you will have a specific tolerance as the click will be produced by deformation of both parts. I think the tolerance will be linked to the elasticity of your material. If your material is elastic enough then you will not have fatigue problems (we open and close very often a bottle of shampoo). Then, if you have a very thin tolerance, the risk is that it will be too difficult to open or to close this bottle...
If you look closely I think you will find that the seal is tapered (probably just the standard molding draft angle), so it closes until the taper makes contact and it seals. This will give a good seal with a much looser diametral tolerance.
