Manufacturing method for this part?

[akreft]

Hi,

First time poster - hope this isn't off base.

I'm looking for a manufacturer for the product pictured below. I need to know what TYPE of manufacturing methods could be used to make this part (injection molding, extrusion, thermoforming, etc.)

It is about 21" (533mm) in diameter and about .040-.080" (1-2mm) in cross section. I don't have a material in mind. It should be roughly 70-90D, tough, and capable of stretching at least 2% without permanent deformation.

Suggestions are appreciated.

 

[Compositepro]

This appears to be a bicycle wheel rim. I am not aware of any plastic that would be suitable for this standard metal design. What plastic are you planning to use? Without knowing the material, a manufacturing process cannot be determined.

 

[akreft]

Thanks for the reply.

It's not a rim. It's a flexible element that lines the rim. It's not a structural part.

Polypropylene is my best guess. It's very tough, but flexible and elastic. Does that help?

 

[MikeHalloran]

PP doesn't readily stick to anything. ... which may or may not be an impediment to your wishes.

I'd try painting on polyurethane, in several thick coats.





Mike Halloran
Pembroke Pines, FL, USA

 

[Pud]

My question would be 'how many do you want per annum?

This will have a significant impact on process to choose.

www.tynevalleyplastics.co.uk

Politicians like to panic, they need activity. It is their substitute for achievement.

 

[akreft]

About 40,000 pieces per year.

This part does not need to "stick" to anything. It stays in place because it's diameter is slightly less than the wheel's. That's why the material requires a minimum 2% stretch without damage.

 

[RobWard]

The smallest diameter of that part needs to stretch over the largest diameter of the rim.
I'd suggest that 2% might not be enough if the picture shows a wall thickness of 1-2mm.

"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams

 

[dgallup]

Those are usually just a strip of rubber that conforms to the shape of the rim.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

 

[Compositepro]

Rob, The ID of all tires is less than the OD of their wheels and they do not stretch significantly. That is why wheels have the cross-sectional shape that they do. One side of the tire slips on first.

 

[RobWard]

Compositepro- I'm just pointing out that the 2% mentioned in the OP might be marginal when compared with the images.
It just might affect the material choice, that's all.
(I've written this post three times now and it still sounds snarky - apologies if it comes across that way - it's not supposed to!)

"I love deadlines. I love the whooshing noise they make as they go past." Douglas Adams

 

[Compositepro]

No problem. My response to you was like yours to the OP, a knee jerk reaction to a statement that did not seem quite right. You do not need any stretch to get it on the wheel. But you are correct that 2% strain to yield would tend to be a very stiff or brittle material.

 

[akreft]

I should have clarified - the part needs a MINIMUM of 2% stretch. But it turns out that is not enough. 2% is sufficient for a bicycle wheel but not a motorcycle wheel due to the taller rim flange. In reality it needs closer to 10%.

We tried a 3D printed polypropylene prototype and it broke during installation.

TPU is perhaps the obvious option, but we are hoping to avoid the high friction of that material. A harder, thinner material would make installation easier and reduce heat buildup from friction while in use.

Are there any other materials we should be looking at?

 

[Pud]

Have you looked at the polyester elastomers? e.g. Hytrel by DuPont, Arnitel by DSM and plenty of others.
They are very fluid when molten and with multiple gating are good for thin sections.

Note TPUs have a low limiting shear ratio which makes fast injection speeds and small gates a problem. Especially on softer grades.

www.tynevalleyplastics.co.uk

Politicians like to panic, they need activity. It is their substitute for achievement.

 

[akreft]

Thanks for the tip Pud!!