Sheet Metal Fabrication

[TechWise]

I've just completed a couple of projects with mostly box section construction with a few bits of sheet welded on here and there. There was a bit of handheld plasma cutting involved and a fair bit of measuring and drilling involved. Since it's mostly repetitive parts, I'm thinking of getting future parts laser cut then CNC folded.

Anyone had that done before and have companies to recommend? Also any pitfalls to watch out for? I've been eying up fractory.com but the shipping costs are quite severe and seem to increase disproportionately the more parts I add, as though they're sending every part to a separate manufacturer. Shipping cost is currently sitting at £200 but I thought I would get a pallet sent from anywhere in the UK for half that!

I do all my design in CAD but my usual laser cutting company are asking for .pdf drawings because they don't use the same CAD package. Pretty disappointed in that as it's a heck of a lot of work to produce drawings when I really ought to be able to hand over a .step file.

 

[SuperTwo]

When we are getting stuff cut out of house we just send through PDFs of the fabrication drawings and .DXFs of the flat pattern of the parts. What software are you using?

 

[Warp Land Farmer]

@Dave W has a pal with a big laser and press break who does subcontract work.

 

[Dave W]

@Dave W has a pal with a big laser and press break who does subcontract work.

Yes. I can give you the details but again it's the haulage that might kill it unless it's pallet sized stuff

 

[TechWise]

When we are getting stuff cut out of house we just send through PDFs of the fabrication drawings and .DXFs of the flat pattern of the parts. What software are you using?

I'm using Autodesk Inventor. I usually export .dxf files for laser cutting and it's hassle free. Because I'm modelling the parts as 3D shapes, it's a bit tricky to "unfold" them to get back to the flat profile if you see what I mean. It does have sheet metal features where you start with a flat profile and start folding so it looks like I'm going to have to study that feature a bit.

I sent the salesman a list of all the file types that Inventor can export so I'll see if he gets back to me with a solution. Me making a 3D part then doing 2D drawings of it just to pay someone else to convert it to another 3D drawing seems a bit convoluted.

 

[TechWise]

Yes. I can give you the details but again it's the haulage that might kill it unless it's pallet sized stuff

The folded parts are about 1800 long by 300 wide so slightly over a standard pallet size. There's potentially quite a few little flat profiles to cut so the shipping cost wouldn't be too bad if I fill up the remaining space with smaller parts.

 

[Andrew]

Laserfab in Spalding are worth a look.

Whenever I’m dealing with formed parts I make a DXF flat pattern and a PDF drawing showing max dimensions folded and flat, as depending on CAD package you can get different end results. Takes a bit more time but only a minute or two a part.

 

[SuperTwo]

I'm using Autodesk Inventor. I usually export .dxf files for laser cutting and it's hassle free. Because I'm modelling the parts as 3D shapes, it's a bit tricky to "unfold" them to get back to the flat profile if you see what I mean. It does have sheet metal features where you start with a flat profile and start folding so it looks like I'm going to have to study that feature a bit.

I sent the salesman a list of all the file types that Inventor can export so I'll see if he gets back to me with a solution. Me making a 3D part then doing 2D drawings of it just to pay someone else to convert it to another 3D drawing seems a bit convoluted.

I also use inventor at work.
When modeling folded components you need to use the sheet metal feature from the start. You can add folds this way that will flatten and will also give you the correct size flat pattern accounting for deductions etcs (once its set up correctly that is).
If you are modelling them as solids no software package will be able to flatten them so at the moment any profiling company will have to redraw anything you send to them

 

[TechWise]

I also use inventor at work.
When modeling folded components you need to use the sheet metal feature from the start. You can add folds this way that will flatten and will also give you the correct size flat pattern accounting for deductions etcs (once its set up correctly that is).
If you are modelling them as solids no software package will be able to flatten them so at the moment any profiling company will have to redraw anything you send to them

Sounds like I need to get up to speed with the sheet metal functions then I've been playing a little bit with the stress analysis tools too to try and choose thinner sections where possible but maintaining the same strength in the direction of interest.

My degree is in electrical engineering so this is mostly new to me. It's all good fun though.

Is there such a thing as a standard chart of how tightly you can bend certain thickness sheets and how close you can put holes to bends etc? I have a whole row of holes along this piece but I'm not sure how large I need to make the flat face to make sure the holes aren't too close to the folds.

 

[SuperTwo]

Sounds like I need to get up to speed with the sheet metal functions then I've been playing a little bit with the stress analysis tools too to try and choose thinner sections where possible but maintaining the same strength in the direction of interest.

My degree is in electrical engineering so this is mostly new to me. It's all good fun though.

Is there such a thing as a standard chart of how tightly you can bend certain thickness sheets and how close you can put holes to bends etc? I have a whole row of holes along this piece but I'm not sure how large I need to make the flat face to make sure the holes aren't too close to the folds.

The best thing to do is to ask for the chart from whoever is going to fold your parts because your min fold lengths and max material thickness that can be folded will depend on what tooling they have and the tonnage of the press.
Can you give some rough dimensions for the attached screenshot? Looks to be ok but hard to know for sure.
If the holes are too close to the fold they tend to elongate into an elliptical shape.

 

[Sharpy]

Have you tried Nichol Mackay at Prestwick?

 

[I dot]

Southwest Engineering, 07748 809562, just along the road from me,has all modern kit, highly recommend him and only 30 minutes from Ayr.

 

[TechWise]

Never realised there were quite so many potential options right on my doorstep. I'll check those out.

 

[TechWise]

The best thing to do is to ask for the chart from whoever is going to fold your parts because your min fold lengths and max material thickness that can be folded will depend on what tooling they have and the tonnage of the press.
Can you give some rough dimensions for the attached screenshot? Looks to be ok but hard to know for sure.
If the holes are too close to the fold they tend to elongate into an elliptical shape.

2mm mild steel sheet. Holes are 6mm in diameter. They're just for attaching plastic panels to so the location and size aren't critical. It's also not really a problem if they get distorted a bit as a drill will be going through them to attach the panels anyway.

 

[Hjwise]

For thin stuff like that you can use an internal bend radius equal to the thickness of the material with a k factor of 0.5 and you’ll be pretty close. Solidworks can flattern a solid model.

 

[SuperTwo]

2mm mild steel sheet. Holes are 6mm in diameter. They're just for attaching plastic panels to so the location and size aren't critical. It's also not really a problem if they get distorted a bit as a drill will be going through them to attach the panels anyway.

Should be no problem folding that the only thing is that the radius on the bends will be dictated by the brake press tooling

 

[oskerb]

I've just completed a couple of projects with mostly box section construction with a few bits of sheet welded on here and there. There was a bit of handheld plasma cutting involved and a fair bit of measuring and drilling involved. Since it's mostly repetitive parts, I'm thinking of getting future parts laser cut then CNC folded.

Anyone had that done before and have companies to recommend? Also any pitfalls to watch out for? I've been eying up fractory.com but the shipping costs are quite severe and seem to increase disproportionately the more parts I add, as though they're sending every part to a separate manufacturer. Shipping cost is currently sitting at £200 but I thought I would get a pallet sent from anywhere in the UK for half that!

I do all my design in CAD but my usual laser cutting company are asking for Hongjingyuan Hardware .pdf drawings because they don't use the same CAD package. Pretty disappointed in that as it's a heck of a lot of work to produce drawings when I really ought to be able to hand over a .step file.

Just wondering who on here does sheet metal fabrication? You know making panels for vehicles on cars and hvac and stuff. would like to get into it a little. Just wondering what special tools do u need to do so and for those who own a business what is a majority if your work?

 

[Mc115reed]

Just wondering who on here does sheet metal fabrication? You know making panels for vehicles on cars and hvac and stuff. would like to get into it a little. Just wondering what special tools do u need to do so and for those who own a business what is a majority if your work?

When I did my fabrication apprenticeship for the sheet metal section the only tools we had was, a pencil, paper, cardboard, 3 different length rulers, a big set of dividers, a punch, 3 different hammers, calk, a calculator, radius finder and a lot of patients
The workshop had all the modern toys but for the first few months everything was done on the anvil and vice then we moved up too a hand folder, when I finally got a job in sellafield they had a press break that would bend 100mm thick steel too a perfect right angle and it was actually a pretty tight bend aswell!