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Final Sample issue + Solution

Posted on April 22 2016

We've been testing the "Final" samples from the factory and they all looked great on arrival but there are issues with warping after daily use in real life scenarios. We're testing them with a variety of clothes in different temperatures to simulate the various climates they will be used in, from humid and hot to cold and dry. What we're finding is the slides permanently bend after 3-4 days and that's unacceptable.  We're working on design solutions that will solve this problem but regrettably this forces us to push our dates. Our prototypes did not have this issue as they were made with hand-filled molds and lower pressure. The chemistry of the plastic under high pressure and the antimicrobial additive is creating this new challenge.

 

The Problem

The problem lies in the fact that this is a flat piece of plastic that needs to be rigid. Most thin flat plastic parts have contours designed into them to prevent this.  We originally did this to a small extent by angling the left and right sides up several degrees, similar to a paper plate, but more defined channels and contours are now required.  Lets look at a few samples of common flat products.

The Solution

Below is a lid to a container bin. You can see the lid has 3 tiers of channeling. This channeling provides structural strength while allowing the part to maintain a thin but uniform plastic thickness.

 

The paper plate below has several features allowing an otherwise thin piece of paper to become a rigid plate. Starting from the center arrow is a contour that flares upward, which is similar to what we did with the ThreadStax slides. The "Ribs" on the outside add even more rigidity and reinforces the contour. 

Below is a top view of the slide showing the solution we're currently testing.  Highlighted in red is a new feature that will add rigidity to the slide in both directions (front to back and left to right).

 

Here is the bottom view.  Notice the channel is hollow on the bottom.  A fundamental rule to follow when designing injected molded parts is to make sure the plastic thickness is uniform throughout the part. This does two things- firstly, it keeps the slide light while providing good structure and strength to the part. Secondly, it ensures uniform cooling during the injection process to prevent future defects and warping.

Thank you for the continued support throughout this process.  Being that this is my first product, I've learned a lot that will carry over in future products in terms of design, logistics and manufacturing. This unforeseen setback in manufacturing is frustrating because I know how much you guys want this product delivered on time, but I'm 100% committed to putting out only a high quality product that will last and function flawlessly. Please know we're so close and I promise that we're working diligently to get these out to you as soon as we can.  

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