Precise Breakaway Torque DoE

[mdiv]

Hi All,

I am working on the product design of a hand-held consumer product that requires the loosening/tightening of the product by hand. I am trying to design an experiment to determine the ideal range of acceptable breakaway torque needed to loosen the product by hand and I am struggling with the best way to execute. I would like to have several samples at various, precise levels of breakaway torque and then conduct a user survey with various hand strength levels to determine the optimal, and then max breakaway torque needed to loosen the product. What device/product exists that I can use to set a breakaway torque at precise levels? The closest thing I can find seems to be twist-off or tension control bolts but those pre-set torque amounts are way too high for what I am looking for. I am looking to be able set the samples to various levels in the 1-5 N-m range. I would also like to 3D print a part to go around whatever might exist out there to make a sample of appropriate size (fits in someone's hand) when doing the experiment. Anyone have any idea on what I can use?

Thanks

 

[3DDave]

It might be easier to put the feature onto a torque sensor and then ask them to twist it as much as they feel is comfortable to do. When people loosen a cap or jar lid that's what they do - apply increased torque until the item comes loose or the person quits.

 

[EdStainless]

Aren't there ergonomic references that address comfortable torque levels?

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P.E. Metallurgy, consulting work welcomed

 

[mfgenggear]

design it like a wing nut so there is leverage. fingers tightening on a small configuration does not work.

 

[SwinnyGG]

Ergonomic data like this already exists - it's going to be a lot easier and cheaper for you to go find that data than it will be to conduct an experiment yourself.

You'll also wind up with better information.

 

[Gr8blu]

mdiv: Search engines are your friend. Here are some rough numbers to get you in the ball park.

https://www.kinexcappers.com/faq/torque-guidelines.htm

Converting energy to motion for more than half a century

 

[Tmoose]

When opening screw top plastic bottles of various beverages usually I can, but sometimes I can not.
My maximum torquage is sufficient. Some caps have such sharp serrations they are painful at hand squeezing levels too low for traction.
Some had such high installation torque my old man hand strength is insufficient for traction.

 

[3DDave]

Dang it - Tmoose I typed pretty much that and wavered off. When I get skin peeling from a sharp cap I know it's not a limitation on the hand-squeezing part of the effort. So I have Knipex pliers at the ready.