Cleaning and testing our silicone F-Tubes
This post is going to seem a bit insanely obsessive, but so be it.
Back in December, I posted a video about the new all-silicone F-shaped tubes: https://www.instagram.com/p/CIh4mSXB_eS/
This tube carries water from the water tank into two pumps (hot and cold paths).
Making a custom tube allowed us to remove a lot of other parts, improving reliability and simplifying assembly.
As you can see in the video, these tubes are made by heating soft silicone, and subjecting it to pressure. It's common, though, for little bits of silicone to be left inside, dangling but still attached.
Decent engineer Alfred Nenada built a machine to clean out those bits. Actually he built several machines, as it took a few attempts to make something that actually worked.
For example, this contraption looks impressive, but the water is sent at different pressures, depending on the position of the tube, so it didn't work well enough.
In the end, Alfred decided to clean one tube at a time. A high powered pump fires clean water at 5 bar of pressure, and the water is reclaimed through a particle filter. The high pressure swells the tubes, spotting any weaknesses or leaks. The high water flow rips out any bits of silicone that might be dangling inside the tube.
This process takes about a minute per tube. As we built around 250 espresso machines per month, it takes Alfred a half day a month, to prepare the tubes we need.
Yes, this is a bit obsessive, but if we didn't do this, we would worry about a dangly bit inside the tube shaking loose some many months later, where it would then cause a blockage, and a real problem.
And yes, we could outsource this process, but we prefer to do our own cleaning and quality-control, so that we can closely monitor what our suppliers are giving us, and not get caught unawares if their quality slips.
A “Chinese Wall” between the manufacturing and testing of a part, is a really good idea. https://en.wikipedia.org/wiki/Chinese_wall
-john
Updated 2021/04/20