Plastic Lid Design

[PRuggiero]

Guys,

I am designing a small container, ~ 4" x 2" x 1.5" that can hold liquid without leaking out. This device basically consists of a base that has a lip around the perimeter and a cover which fits over that lip making a tight seal (think of a typical plastic tote you use around the house). Before the product goes into production (injection molding) we want to ensure that the seal remains tight throughout the products use (~2 week disposable). I've found plenty of documentation on press fit designs with plastic but they typically talk about a shaft in a hole. One advantage I have is that we have prototypes made of a SLA resin, but the question is how can I ensure the design is good before spending big money on tooling.

Some of the things I'm interested in:

1. What material properties play into the lid/base fit design?
Flexural modulus, flexural strength, creep resistance....

2. What's the best way to estimate the force required to make the interference

Any guidance would be appreciated.

Thanks,
Pete

 

[MikeHalloran]

Best advice I can give: Reverse-engineer similar stuff from Tupperware and Rubbermaid.



Mike Halloran
Pembroke Pines, FL, USA

 

[patprimmer]

Like Mike said.

The closer you can make the lid to circular the better, so keep the radii in plan view as big as possible.

Regards
Pat
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[telecomguy]

And no matter what you do, it will come out of the dishwasher all warped and never seal again. ;-)