Technical & Reference Section > Tech and Restoration
??? WHITE SKYWAY WITH WIERD CIRCLES ON IT, IN THE MOULDING ???
toys19:
It's not where the plastic is injected in, that is called a gate, these can be found on the inside edges, see photo below.
If you are sure they are marks in the part from the mould tool and not the results of the application of stickers then its possible is that these are ejector pin marks (See piccy below). There a few present on all of my tuff's. An ejector pin is used to push the wheel out of the mould tool after it has cooled, the mould tool will be in 2 halves (the line were the two halves join is also shown). There are 20 ejector pin marks on my tuff wheels, one in each corner of each section. Yours seem to be much bigger and have many many more, so I dunno if its this either.
Also it could be that these are marks from, copper cooling/heating inserts put into the mould tool. Thse are used to control the cooling rate of the part after it has been injected, which inturn will control the formation of semi crystalline regions and effect the toughness and stiffness of the wheel. But I have never ever seen this many witness marks from cooling inserts in a mould tool..
Mould tools wear over time and are replaced, also manufacturing techniques change rapidly so during the lifetime of tuff manufacturing the method will probably have been fiddled with. The earliest wheels will have been made from a mould tool that will have been experimented with an awful lot, so they may have tried changing the position of ejector pins or cooling inserts....
Are you really sure its not from stickers??? I remember some awful stick on reflectors that were about that size people used to stick them everywhere - I think they were the result sof some school road safety campaigns...
Whatever it is, I'm sure they will clean off so let us know how it turns out.
firebird4130:
I had a white skyway front wheel, had the same type of circles but all over the inside of the rim ,so the tyre covered them I thought it must be some kind of factory fault
toys19:
I reckon its defo heating or cooling inserts, once they had sussed out they needed them on the next tool they made they probably moved them to under the tyre so you cannot see them.
bmxbob:
cleaned up mags :shocked:
it was just sticker marks :-[
but there is an indented circle at the each end of every spoke, ejector pin marks :D these are the ones i was looking at and thought the rest were the same :LolLolLolLol:
anyway they cleaned up ok, now all i need is a rear white and a front yellow Tuff II :shocked:
toys19:
Quality! It's funny how the stickers seemed the same size as the ejector pin marks! The funny thing is I sent this thread to mate of mine an old injection moulding guru who has beind squishing platics for 50 odd years. He's now retired and he was all up for asking you to send him the wheels so he could tell us exactly what it was... (He's even more of geek than me) :LolLolLolLol:
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