When deciding which Press Brake will meet your metal bending needs, there are a range of different factors to consider due to the great variety of sheet metal characteristics and options available. Let’s take a look at 5 of the critical questions you should ask yourself before investing in a new Press Brake for your fabrication shop.

1. What type of material do you need to bend?

Start by thinking about the metal bending projects you will be taking on and which type of metal will be used. You need to consider all the specifications of your metal and finished parts in order to choose the right press brake for the job including:

  • the maximum thickness and length of the metal you’ll be working with
  • the flange lengths required
  • any particular characteristics which need to be taken into account when calculating a bend

The aim of the game is to invest in the machine with the shortest worktable and lowest tonnage while ensuring it will be able to accomplish the processing task at hand. If you choose the wrong machine you will responsible for higher manufacturing costs so it is critical that you evaluate your production needs carefully.

Acra Press Brake.docx

Durma AD-S Series CNC Synchro Press Brake

2. Which is the best machine to handle your tonnage?

One of the most important factors to consider when purchasing a new brake is the tonnage, that is the bending force or capacity of the press brake. In general, the thicker the material the more tonnage required to bend it. Softer metals such as aluminium require less tonnage compared to materials like high-strength steel. To calculate tonnage you also need to factor in length, the width of the die opening (smaller Vees mean higher tonnages) and the process (air bending requires less force than bottom bending and coining).

To work out the tonnage required by your job you can consult a press brake air-bending tonnage chart like the one supplied in Durma’s Press Brakes product specifications pdf (refer to page 7).

Please note: you should always oversize the press brake capacity by around 20 – 30% with respect to your data in order to allow for the variability in the characteristics of the metal and so that you are not in danger of working to the limits of the machine’s capacity.

3. How much deflection is likely to occur?

You also should consider the amount of deflection likely to occur in a particular machine.

Normal deflection is the amount of deformation of the press brake ram and bed that occurs naturally under a load. Under the same load, a longer machine will have greater deflection in the bed and ram than a shorter machine. For the shorter machine, that means less shimming is required to get decent parts.

Acceptable industry stress standards for materials is 8.5 kg/mm2 stress. All Durma machines are required to meet a value of 5-6 kg/mm2 . These stringent standards reduce deflection and improve frame durability and the capacity to hold tolerances over long periods of heavy use. All incoming plates must meet Durma’s strict standards and requirements. Durma’s high frame rigidity and robustness ensure long-term accurate bending.

4. What is the inside bend radius of your parts?

If you can calculate bend allowances, outside setbacks and bend deductions accurately you are much more likely to being a good part the first time around. However, in order to achieve this you need to consider every factor in the equation including the inside bend radius. The smaller the inside bend radius, the greater the flexibility of the material.

The inside bend radius differs according to the method of bending on a press brake. If you can determine the precise bend deduction required for a particular radius, you can facilitate manufacturing and reduce the number of inherent mistakes.

In you are bottom bending or coining, use the punch nose radius as the inside bend radius in your bend deduction calculations. But if you are air bending, the inside bend radius is calculated as a percentage of the die opening.

For the lowest required tonnage, you should aim for an inside radius greater than metal thickness and air bend where possible.

5. Do you have the right tooling?

They type of tooling you’ll require will depend on the materials you will be bending. It’s important to select the tooling which will achieve the strongest tooling profile that is most suited for your metal fabrication project. Having said that, you must take care not to exceed the tooling or press brake load limits.

If you intend to use your current tooling with your new press brake, you should check that your tool is compatible and in good condition. When inspecting for wear you must measure from nose to shoulder on the punches and from shoulder to shoulder on the dies.

For assistance with choosing the right press brake for your metal fabrication needs, contact our friendly team today on 03 9794 6675.

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