CNC Folding Services in the UK: How to Get Bent Sheet Metal Parts Right First Time

Below we explain how CNC folding works, what to think about at the design stage and what to ask a UK supplier before you place an order.

What does a CNC folding service do?

CNC folding, also called press braking or sheet metal bending, forms flat metal between a punch and a die. The machine's controller sets the back gauge and the depth of each stroke, which is what makes the result repeatable. Once a program is proven, part one hundred matches part one.

At GF Laser we run three CNC controlled Amada press brakes in Dudley, with a maximum of 220 tonnes over a 4 metre bend length. All three share the same tooling, so a high volume part can run across more than one machine when a deadline is tight.

Why should cutting and folding happen in the same place?

Every fold stretches the metal slightly. That means the flat blank has to be a little different from the simple unfolded shape, or the finished part will come out wrong. When folding and laser cutting sit in the same building, the bend is developed first and the flat blank is cut to suit.

We use Bend Cam software alongside our Amada machines to develop each fold and create a proven flat blank before it goes to the flatbed laser. The same software checks whether the part will collide with the machine. It also works out the most efficient bend sequence for parts with several folds.

There is a practical benefit too. One supplier means one order, one delivery and one point of contact if something needs to change.

How do you design a part that folds well?

Keep features clear of the bend line

Holes and slots placed too close to a fold tend to stretch out of shape as the metal bends. If a feature has to sit near a bend, it can be added after folding instead. We use our 5-axis laser cutting department to cut details like these once the folding is complete, so they hold their shape.

Check the part can physically be folded

Deep boxes and parts with many return flanges can hit the machine or the tooling partway through the sequence. Simulating the folds before cutting catches this early. On one job, a run of 6,000 defibrillator cabinet parts, we simulated every fold and checked for press brake collisions before cutting a single blank.

Think about the material

Mild steel, stainless steel and aluminium all behave differently under the press brake. Aluminium in particular folds differently from steel, so if you are switching material, a prototype is worth the small cost.

When is press braking better than press tooling?

Press brakes are a faster and cheaper route than traditional press tools for prototypes and ongoing batch work. Set up times are short, which makes them a sensible choice for small quantities of many different parts. Hard press tooling only starts to pay back at high, steady volumes.

Where a part needs a profile that standard tooling cannot form, specialist tooling can be bought in and its cost spread across the piece part price. Tooling we do not stock is generally available next day from our approved supplier. Our in-house machining department can also modify stocked tooling or make custom sections.

What should you ask a CNC folding supplier?

• What is the longest bend and the highest tonnage available?
• Can they cut the flat blanks themselves, or will you need to supply them?
• Do they simulate folds before production?
• How do they check parts during a run?
• Can they finish the parts, for example with powder coating?

Getting your folded parts made

Good folded parts start with a good flat blank, and that is far easier when one team handles both. If you have a drawing for a bracket, an enclosure or a full assembly, send it over and we will check it for folding before we price it.

Find out more about our sheet metal bending service, or send your DXF or STEP file and we will come back with a price and a date within 24 hours.

Frequently asked questions

What is the longest bend GF Laser can fold?

Our largest Amada press brake folds up to 4 metres long with a capacity of 220 tonnes.

Can I supply my own material for folding?

Yes. Material can be supplied to us on a free issue basis, or our laser cutting department can produce the flat blanks for you.

Can you fold parts in small quantities?

Yes. Press brakes suit everything from low quantity prototypes to high volume batches, because set up is quick and no dedicated press tool is needed.