How is this made?
How is this made?
(OP)
Hello Everyone,
Does anyone have an idea how these are made?
http:// www.freshw atersystem s.com/popu p.aspx?src =images/Pr oduct/larg e/2615.jpg
This is made from polypropylene. I had the top part (the hexagonal nut) shaped part right in the middle separate from the rest of the filter head. Would this whole thing be injection molded or would these top pieces be added in later with some sort of plastic weld?
Thanks in advance!
Does anyone have an idea how these are made?
http://
This is made from polypropylene. I had the top part (the hexagonal nut) shaped part right in the middle separate from the rest of the filter head. Would this whole thing be injection molded or would these top pieces be added in later with some sort of plastic weld?
Thanks in advance!





RE: How is this made?
RE: How is this made?
Sorry perhaps I was not clear. I uploaded a picture of what my filter head looked like. I never used tools on it so it was not over tightened, it did not freeze and when I look closely at the fracture surface it does not seem to be a brittle fracture, I see lots of little fibers within the crack...
As if it got pulled apart over time?
RE: How is this made?
If the hex part is cracked at the base where it meets the large round cap it's a manufacturing defect (or under engineered section)
RE: How is this made?
It is under constant water pressure, perhaps over time the pressure simply forced it to let go at the weakest parts? I kept thinking that perhaps the plastic degraded over time, but I have no idea how to check for that.
RE: How is this made?
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
Chinese prisoner wins Nobel Peace Prize
RE: How is this made?
If you're just trying to make it better for yourself I'd say just reverse engineer it and have it machined from a piece of round stock and buy some tube fittings. (Look to SMC, Festo, Parker, etc) Shouldn't be a difficult task, and probably wouldn't cost a ton to do.
James Spisich
Design Engineer, CSWP
RE: How is this made?
These may also be weld or fold lines as the mould fills.
It may well be fibre reinforced PP which may explain fibrous surface at the break.
If it is straight PP if you cut off a chunk so as not to include the fittings, then drop it into a pot of water, if it floats it is straight PP. If it sinks it is reinforced (that is presuming the base resin is PP).
It is a one piece moulding.
It may have been subjected to abnormal water pressure or more likely excessive water hammer that has caused fatigue cracks.
Some chemicals can cause solvent stress cracks in the stressed areas. Cleaning or sterilisation with antibacterial chemicals might just do that.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: How is this made?
RE: How is this made?
A friend of mine has a lab and I brought it to a lab and played with my filter under a stereo microscope. I attached the picture of the fibers within the fracture surface.
This is the fracture between the hexagonal piece up top and the round top part. Does that look like a fibrous surface from reinforcement? It think it looks like some sort of environmental stress cracking? Any ideas?
RE: How is this made?
I am starting to wonder if contact with the brass fittings caused some thermo-oxidative degradation which then spread radially around the fitting due to the water pressure.
RE: How is this made?
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
Chinese prisoner wins Nobel Peace Prize
RE: How is this made?
RE: How is this made?
RE: How is this made?
Dezincification of brass can be a serious problem in chlorinated water and the zinc chloride can attack some polymers, especially acetal, but also nylon. It is not normally a problem for PP. Thermal oxidation is also not a problem for PP at temperatures water is used at without pressure. Electric kettles are very often PP.
Have you confirmed it is PP.
Have you confirmed it is unfilled or filled. SG being more or less than 1 (ie does it sink or float is by far the easiest test. It requires nothing more than a water supply and a container to hold water, ie a bucket or tub.
Why do complicated tests before the dead simple ones?
I personally cannot get a clear enough image to positively tell if there are fibres present or if the polymer is fibrillating at the break. PP is quite prone to fibrillation due to its very linear molecule.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: How is this made?
The (supposed) material of GFPP may have been glass filled rather than glass coupled.
Hoescht (aka Ticona these days) have had many water devices on continuous test (sustained pressure) for over 20 years to determine failure modes.
Imho, if I had to design parts for sustained pressure, GFPP would be way down the list...
Then as Pat implied, it may be just cr*p moulding!
H
www.tynevalleyplastics.co.uk
RE: How is this made?
Okay, maybe PP with a lot of clay filler, but the color is wrong for either neat PP or GFPP.
Mike Halloran
Pembroke Pines, FL, USA