Hmmm guess where my cars from! France! Its a Citroen C4!
And I see what you mean about stretching the panels to shape - On some panels I cant see any other way it could be done (complex shapes around wheel arches etc)
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- Thread starter Steve
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And I see what you mean about stretching the panels to shape - On some panels I cant see any other way it could be done (complex shapes around wheel arches etc)
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You are joking aren't you?
Modern paint is a lot harder, and needs less maintenance to keep it shining. In the old days when I had a red Dolomite, I would have to T cut it every 6 months, and polish it even more regularly. I had to do this if I didn't want a dull car, and it was a problem mainly because the car lived outside.
Another example is silver (or Roman Bronze) metallic Fords produced in the 70s. My dad had a new silver Granny (Sweeney MK 1
). After 3 years, the sun was bleaching the paint off the car, and was down to the undercoat. He had to have it resprayed.I think you are wrong about modern paint. Regular T Cutting, polishing and resprays are a thing of the past.
Perhaps he meant 'more recent' as in post global warming? 
Car panels have always been stretched, as you call it.
Look at the front wing on the old mini, its bulbous shape is created by drawing the metal, in a 2 stage die draw tool.
To create any car panel, other than a completely flat one, the steel must be stretched.
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I was talking solely about a paint finishes resistance to knocks.
Paints of yesteryear are better at resisting impacts.
They were allowed to contain certain constituents that are now banned, lead being one.
Paints of yesteryear are better at resisting impacts.
They were allowed to contain certain constituents that are now banned, lead being one.
Agreed, my car paint is softer and can easily scratch
It's to do with H&S paint fumesThere is only 1 reason why car manufacturers make panels in this way and that's to do with money....it's cheaper.
There will always be some stretching of the metal...it's the nature of the beast. However you contradict yourself with your second line.
a 2 stage draw tool or to give it it's more commonly used term "double action draw die" cannot work in the same way as how a stretch draw die has been made. 1 reason is the draw bead(s) on a double action draw die is designed to allow the material to flow over them as opposed to a stretch draw dies beading which is designed to hold the material hence them being called "lock beads". the second most obvious reason is the punch on a stretch die is locked in the bottom of the tool as opposed to being able to move in the top of a double action draw die and having its own ram to operate it.
I didn't want to go into this length of an answer when i quoted Steve as it's very hard to explain to someone who does not work in the industry how this process is done without physically showing them how it's done and was the reason i kept my answer to one of the material being stretched as opposed to forced into shape.
Their is no contradiction at all, a "double action draw die", as you call it Stretches the material.
I used the mini wing as an example, as I used to work on reproduction tooling for Veng.
This panel started out as CR1... 1.5 m/m, and after drawing was reduced to 0.9 m/m in places, and would even tear to a feather edge, if the steel had age hardened.
In 2001 I bought a new Bmw convertible and during the second week I had it some kids threw a HOUSE BRICK off a bridge one sunny day as I drove past with the roof down
When i pulled over I was suprised how un-damaged it was as it sounded horrible.
The cost to replace the plastic panel was a lot cheaper than if it had gone on the bootlid
Christ all mighty. That's tantamount to attempted murder. I hope they were put in prison for that.
Yeah right.
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