Connecting Soft goods to Plastic pieces

Hey guys, I’m a product designer with only a little experience with soft goods. I’m working on a system that is mostly hardgoods, but has a softgood element that I need to attach. I’ve done a little drawing (with any sensitive information removed) to show how the system works, and how I need to attach the softgoods. Any experience you’ve had in this area would be very helpful. I show in the section view portion of the drawing where I have the space to attach the two. Keep in mind, this only needs to hold it down, the shape of the fabric is already taken care of with internal features. I was thinking possibly glue, or heat-staking through the piece.

Any thoughts? And thanks in advance for ANY help. I’m kinda stuck.

I’m not so clear on the ask. Can you give some more general drawings/views and scale?


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Heat or ultrasonic weld will work. Ultrasonic will have a faster cycle time for production. Generally, you need to weld similar materials. But if you are using a woven as your soft good, you can melt the plastic into the weave, creating a mechanical bond.

A UV clue adhesive could also work depending on material chosen.

Die-cut double-sided adhesive is another possibility.

As others mentioned, mechanical works too - sewing, rivets, staples, nut and bolt, etc

Iab beat me to it. Those are pretty much all the ways… if you find something else let us know, you might be able to retire on that discovery :slight_smile:

Also, it goes without saying, a combination of things might be the answer. You would be surprised how many things are stitched and glued. You might need a secondary thinner fling or a “stitch trench” to thin the molded part out selectively and also provide a finished look to the stitch. Check out rubber cup soles on skate shoes for an example of this. Of course to stitch you need a way to get a machine in there…

Second serrated plastic part to snap on top of that and cover the edges?

I’m still not getting the assembly, but a few things to consider-

  1. How hard/soft the injected parts are will depend if you can stitch through it.
  2. Size of parts will also depend if you can get a sewing needle in there and how tight a curve you can make
  3. Material will depend on if you can cement it and have good bonding.
  4. You can possibly look into co-molding the fabric into the injected part (in mold insert the fabric) depending on the materials and size.
  5. A secondary part to trap the fabric between the two injected parts might be easiest. Two parts can lock together.

I suggest looking at things like snowboard bindings or backpacks for examples of hard/soft parts assembly.


That is a good mechanical lock suggestion!

always a good idea. I’d get a little budget to buy a bunch of products that solve this problem and do a little reverse engineering. Never hurts to send something like that to the factory.

Thanks for the help guys. I think I’ll look into a mechanical lock of some sort. The fabric edge does show, so I’d rather not use glue to make sure that there’s no quality issues. Plus I think a secondary plastic piece might finish it off nicely. The suggestion of looking at snowboard bindings is a good one. Thanks.

No hem?

If the plastic part is flanged you can simply rivet it to the other side (the non-sight surface).
Laser cut adhesive sheets work remarkably well.
It all depends on the mechanical requirements of the bond and substrate materials.

Laser cut adhesive sheets sounds interesting. Do you have any info on that, or is it a pretty standard process vendors would understand? Also I’m thinking more about thinning the plastic out and sewing through it as I’ve figured out some more of the details, it seems more and more possible. Are there any conventional design guidelines for tapers / wall thicknesses in plastic part design?


For molding, unless you are using a specialty resin or specialty mold, 0.010" is about as thin as anyone wants to do. Anything less is considered flash. And don’t forget your gate position should be thick to thin.

Laser cut adhesive sheet is when you want to do tens of parts. If you want hundreds of parts, I’d recommend a steel-rule die and clicker press. If you want thousands/millions of parts, I’d recommend a rotary die.

For a prototype, you can simply use Heat 'n Bond ultrahold from Hobby lobby. Laser cut to shape and iron into place, it holds with great strength.
For industrial purposes my preferred supplier is Bemis. You can sew through generic plastic at film thickness of 0.25mm. Yet you will create tears in the long term so I suggest just using holes and if you need waterproofing covering these up with glue/epoxy.