May Manufacturing Update: Breaking the Mold

 Instafloss Water Flosser Mold

When we set out to create Instafloss, we knew we wanted to break the mold… unfortunately we’ve broken the wrong mold.

We just got back from our trip to the manufacturing facilities in Mexico, and while 90% of the news is good, the bad news represents a pretty major delay. The short version is that just a week into our initial manufacturing run we noticed advanced wear on one of our molds and an issue with another which will require a 6 month delay.

Let’s take a closer look at the molds and parts in question:

Premature Damage to Our Cylinder Sleeve Mold

While following the QC checklist we laid out during our visit, our manufacturing partner noticed some odd defects on the surface of the cylinder liners.

damaged cylinder liner

The cylinder liner, true to its name, lines the cylinder in which the pump’s piston is pushing water. It’s important for this part to have tight tolerances while being smooth and friction free. This makes the defects seen above particularly troublesome as if we ship with these parts, your Instafloss may suffer from:
  • Noisier operation
  • Premature seal failure
  • Reduced water pressure

As soon as our manufacturing partner identified the issue we put a halt to manufacturing to sort it out. Unfortunately, this was the cause:

Damaged Mold

Pictured above is our mold for the cylinder liner after just a few dozen cycles. While readily visible even at this size, zooming in shows that the damage is extensive and deep. Our partners tell us that within just 100 more units, it’s likely the mold would be completely worn out and seized shut.

We’ve already identified the cause for this premature wear as well as two possible ways forward. If you’re reading this update on the day it’s published, you’re being made aware as soon as we had a grasp of the problem, the way forward, and its potential impact to the delivery timeline.

First let’s go over what’s causing the damage:

The science-y breakdown of why this is happening

This part, like a few others in Instafloss is made of Delrin. Delrin is a type of polymer that is noted for being “slippery” and “self lubricating”. It’s also considered to be one of the strongest plastics, with some comparing it to brass in terms of its physical properties. If you want to learn more about Delrin check out this webpage.

We chose Delrin for this and other parts on the Instafloss as its high abrasion resistance and low coefficient of friction enable Instafloss to not only be quieter, but more efficient and longer lasting.

Any material expands when heated, so when you’re making pieces out of plastic, they’re actually made a tiny bit bigger! However the Delrin this part is made of is contracting at different rates in different directions. This results in the part squeezing extra tight onto the mold, resulting in damage to both the mold and part that gets worse with each new part created.

We have high confidence in a fix and multiple options we can take.

We have at least two methods of making this part that we're going to be trying in the future, but the process of making molds takes a while, so this is the biggest single delay.

But you can rest assured. We have two possibilities for a fix. First is to investigate and tune the cooling times and ejection strategy, as well as change the tolerances slightly. This method would be the simplest fix, but unfortunately as the mold is already so deeply gouged we’ll still need to wait on new parts to be manufactured for it.

Our plan 'B' for this part is to actually also change the piston, allowing us to use two different size seals, and increase the draft angle of the cylinder liner. This is more difficult and expensive, especially since we've already bought the seals, but we are confident it would fix the issue.

How does this impact the delivery timeline?

Our molds are made of a higher grade of steel than the typical molds for ABS polymers. This makes them more difficult, or possibly even impossible to change. On top of that, the modification or creation of these molds is a more time consuming process.

Even if we go for the simpler fix, where it’s just a matter of changing cooling times and ejection strategy, we will still need to repair or replace the already significantly damaged mold, which will take around 6 months to do.

This pushes back our estimated delivery month for pre-orders to November.

Fixing an Issue Caused by Rough Handling in Transit

After shipping some manufactured Instafloss to our Miami Headquarters, as part of a handling test, we noticed an issue that affected some units. The good news is we already have a solution, the bad news is that this issue could create a cascading failure ultimately resulting in the Mid Gear breaking.

So what’s going on? Let’s take away everything we don't need and look at the parts in question:

In this video we take away all the non-essentials, imitating how the impact from the box dropping is transmitted to the gearbox and motor mount by smacking the table. The axle shifts just a little, but it's enough that you can hear everything become loose.

This axle is what the part called the 'CamGear' rides on. The Cam gear simultaneously reduces the rotational speed, turns the rotational axis by ninety degrees, and drives the rod. When the axle is loosened, the gear is able to shift vertically.

Which, at full power, will partially disengage the gear teeth, and break the "Mid Gear".

Broken Mid Gear

Notice the missing teeth on the gear above?

Why is this happening and how are we fixing it?

Well, once again this issue is with a Delrin part. Like with the cylinder sleeve mentioned above, we swapped this part from the prototype’s ABS to Delrin in a bid to make your Instafloss quieter and longer lasting. You can actually hear how much quieter this is in this comparison:

Well the same “slippery” properties that allow Delrin to operate so much quieter are the culprit for this issue. With impacts, the axle is able to shift out of alignment slightly.

We never encountered the issue previously due to the use of ABS and the fact that we never threw our prototype Instafloss units in the back of a truck before hitting every speed bump at 45 MPH. (At least this is what I like to imagine happens in order to result in packages getting so messed up before delivery.)

Luckily, the fix is simple. We'll open this hole and extend the axle through it, with a retaining clip on both sides. This requires changes to the molds though, which as you already know is a long process. It won’t impact our timeline any more than the damaged molds above, but we figured you’d appreciate the detailed look into how we’re ensuring each Instafloss received is going to be defect free.

Other Minor Changes

Since we have the time due to these required mold changes, we’re also going to be making a few small changes. These are ultimately inconsequential, but we figured we’d share anyway:
  • Color change on the “silver” part of the Instafloss mouthpiece. The silver we had selected originally isn’t metallic looking enough for our tastes.
  • Added light frosting in some locations of the reservoir and reservoir lid. All vertical surfaces will remain fully transparent.
  • Did more drop testing of units to ensure no other impact related issues pop up. Check it out, the reservoir took these tests like a champ!

The Good News

It’s always extremely disappointing for us when we have to announce a delay, however the good news is that we have some manufactured units in hand and at this point we’ve tested and worked out 90% of the manufacturing of Instafloss. There’s no other electronics or parts we need to order and each of the other 70+ parts and molds looks great and are performing very well in testing.

With this issue being addressed there’s little else that can delay the delivery of your Instafloss, and that is very exciting news that we hope isn’t too overshadowed by the delay.

5 comments

May 17, 2022 • Posted by Paul Bushow

Thank you for the detailed update, and your candor relating to the new challenges. I look forward to hearing future updates as you progress though your chosen method of improving the frictional wear and component reliability during the manufacturing process.

May 17, 2022 • Posted by Christopher

It will be nice to receive this product and get to try it out. I hope the delay is overshadowed by the quality of the product.

May 17, 2022 • Posted by Page Z Stephanie

Thanks.

May 17, 2022 • Posted by Erica

Thanks for keeping us up to date! As disappointing as a delay is, I truly appreciate the rigorous testing you’re putting everything through before they even get to us. Still looking forward to receiving my Instafloss, glad to be a part of this process, and dreaming of flossing my teeth with ease one day!

May 17, 2022 • Posted by Michael Noonan

Thanks for this update. We look forward to receiving the finished product, and thanks for you careful work to produce them fault free.

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