OT- Q for the engineers... 'flat' knurled finish?
Turbo Mini Forums

So I have a potential application where I need a steel plate that contacts an alloy surface, and is sheared against, and needs greater clamping pressure to generate the friction to stop relative movement than is available with the fasteners / thread depth available.

Don't suggest dowels, better bolts, etc - these have all been exhausted. this is a piece of steel that once assembled to the alloy housing, will never need to be removed

I'm actually thinking of a kind of shallow knurled finish that can be applied to the surface on the plate, such that when it is clamped up, it becomes less a pure friction generated by the clamping of the bolts, but more a positive lock, as the plate moves and deforms the softer alloy to conform to the shape of the serrations.

I 'think' this is what some of the rear camber brackets have - but can't find any decent 'close up' pictures of these...

Can anyone shed light on what this process might be called? I've searched for 'flat knurling, plate knurling, plate serration, etc. without success.

Edited by TurboDave16V on 30th Sep, 2008.

I think the rear camber brackets are serrated plate on serrated plate so the two positvely interlock with each other.

Would there not be an issue with steel and alloy to be fixed together as you describe due to corrosion of the disimilar metals?

Found this...

"Yeah, you can roll a knurl on a surface ("flat" or "face" knurling). If
you're going to do a lot of it, it really should be done with a special
rolling machine. But for "now and then" applications it is routinely done
in a vertical mill (Bridgeport). They chuck the knurling tool into the mill
spindle, press it down against the workpiece and then crank the bed back and
forth, while the tool remains stationary. The knurling wheel is set a
little deeper with each stroke until you get the desired pattern. I believe
you can use the same wheels as for rotary knurling, but you might need a
special tool holder that can be chucked into the quill. "

It is a bodge,but you say you will never need to dismantle it again so what about Loctite -or deliberately set up some corrosion between the alloy and steel -you know how that binds them together ! Not an elegant solution but pragmatic, eh ?.

hmmm,

i think this could give problems by causing mis alignment as you cant garentee uniform deformation of the alluminium.

is this in an area that may get hot? pssibly ruling out loctite/adhesive?

maybe a heavy circular lay on the steel part would help clamp against the aluminum?

Well, the part is internal to a trans so not an issue, and loctite is a no-no. We're looking at a cutter lay, but rolling a single serration rather than a full cross might be just as good (force is in same plane) and cheaper...

Oh well, it's over to the manufacturing guys now. Cheers for the suggestions guys.

Old school shaping m/c with a course feed and a fine tool will give the desired surface finish. Better than a knurling roller in a mill anyway.

Why not just use a bonding agent?

AlexF

Bonding agents would be ok as long as they are able to withstand the heat of the oil warming up, and indeed the oils themselves - some oils will eat away at the bonding agent casing premature failure.

Anyhow, in order to achive any sort of mechanical bonding between the 2 materials is going to need a fairly deep groove or knurl, to achive it with a knurling tool in a mill will more than likely break the tool as your going to need a fairly deep one to achive any bite on the alloy - which whilst its softer than the steel isn't that soft.

Now in an ideal world you would machine a set of v.grooves into both surfaces, add a smidge of oil and bob's your uncle job done, the oil would cause a near vacumn between the 2 and only need fasteners to stop it sliding apart.

Slightly more difficult on gearbox internals tho!

Your best bet (on the cheap) will be to mount the plate on a mill and then tilt the head over to around 45 degrees and using a straight cutter, machine v grooves across the plate so you end up with the following across the plate :- vvvvvvvvv, which provided the tips are sharp enough should bit into the alloy.

Only other way would be to make the plate from alloy as well, the braze or tig it together.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Arr I see - I was thinking of A-series parts LOL

AlexF

Post resurrection. Im looking to do the same on something, mainly cosmetic rather than practical. But has anyone ever used one of these??

Its a checkering file.

Edited by MikeRace on 22nd Sep, 2015.

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

to add to this, bmw suspension bolts have steel washers, when they mate to an aluminium surface the washers have 4 lightly raised ridges at 12,3,6 and 9 o'clock that dig into the aluminium and (i presume) greatly increase the load the joint can take in sheer

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Can you coat the steel components? We make our own cutting tools and spray tungsten carbide onto the surface as a rough cutting face. Once it's on it has to be ground off and the finish is we get is like a 120grit finish so it will certainly dig into the surface it is clamped against.

https://www.facebook.com/pages/Fusion-Fabri..._homepage_panel

www.fusionfabs.co.uk



1/4mile in 13.2sec @ 111 terminal on 15psi

Its purely to achieve the look on the trigger plate.

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

The way I would make that would be to start with a flat oval plate, roll the "knurl" onto it, then press it to form the curve in the face.

Yeah the curve isnt that important yet, how do I roll it on pal?? Would it be a miller?

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

Yes I would say that would be easiest, put a knurl tool in the vertical chuck somehow, press uit down on the plate then move the bed back and forth to roll the pattern into it.

Nice one pal "CARRRLLLLL!"

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/