How to choose a tandem press brake: the definitive guide

When we talk about tandem press brakes, we refer to a particular configuration that involves the connection of two machines into one, but there are also solutions that combine three bending machines (tridem) or 4 bending machines (quadrem).

In this type of configuration, the machines can have the same length and the same nominal bending power or different lengths and nominal bending powers can be provided.

What are the characteristics to consider when choosing a tandem configuration? Let's find out together in this complete guide.

What are tandem press brakes?

When two press brakes are used in tandem, a single CNC controls both machines. However, each machine can also be used independently for added flexibility

What are tandem bending machines used for?

To bend long profiles, it is not necessary to have a large bending machine. Sometimes it is enough - and much more beneficial - to choose a tandem configuration, because it allows for greater versatility and productivity.

Specifically, tandem bending machines can be used in synchronised or single mode. In the first case, both machines can be programmed by the numerical control of the master machine, which sends the signals to the secondary machine, allowing synchronized management with a single CNC.

It is crucial that both machines are perfectly calibrated, as any problem on one machine will affect the operation of both. In any case, machine builders already prepare the optimal configuration of the machines during assembly, so if the operator follows all the instructions given during installation, it is very difficult for problems to arise in the future.

In the case of separate use of the machines, each machine is independent, equipped with its own photocells and a safety guard. With this solution it is possible to carry out different processes in each machine, with the advantage of optimizing production in the best possible way. In fact, many metalwork fabrication, in addition to the bending of heavy and long profiles, supports the bending of shorter pieces. Moving a huge machine to bend smaller profiles would be costly in terms of time, energy and productivity. With a tandem setup, however, you can easily switch to single mode and operate each machine completely autonomously. 

So that's one of the great advantages of the tandem setup! We'll talk about the other benefits - and limitations - in a moment, but first we'll focus on some equally important aspects.

What processes can be done?

Most of the bending that requires a tandem configuration concerns long sheets that require high powers.

The processed products belong to the most varied sectors, including: industrial bodywork, trailers, agricultural equipment, aircraft parts, modular spaces and storage solutions.
Most tandem bending machines have deeper recess dimensions (e.g. around 1000 mm) in order to allow more agile bending of wide profiles. To enable this, machine tool manufacturers such as VICLA design a larger, thicker and more solid structure that can compensate for the increased stresses that result from having a larger groove. 

Another interesting aspect is that, compared to a large bending machine, tandem bending machines generally do not need a pit for the lower bench housing

What are the characteristics to consider when choosing a tandem?

When choosing a tandem configuration, it is important to consider the bending force: it is widely believed that using two bending machines in combination allows you to double the bending force at every point of the machine, but this is a mistake. The total force, given by the combination of the force of each machine, applies only in the case of bending along the entire length.

Let's take a concrete example. Let's take two bending machines of 4 meters and 250 tons each. In a tandem configuration, the total force is equal to 500 tons, but only if you are working on a profile that requires the entire length. On the other hand, in the case of a shorter profile, for example less than 4 meters, the total power will be 250 tons!

Another aspect to evaluate is the configuration: tandem bending machines allow you to have almost the same customizations as a single bending machine, with one caveat: while, for example, it is possible to have a different number of axes for each machine, the configuration of the stomp and the bench, for obvious reasons, will necessarily have to be identical in both machines.

Here is a list of the customizations you can do:

• Oversized recess
• Increased stroke
• Larger opening
• Intermediate heights
• Clamps for all types of tools
• Sheet metal escorts
• Motorized front supports
  

What are the advantages of tandem compared to using a single machine with the same length and power?

When choosing whether to have a tandem, it is important to consider the following advantages:
Flexibility: we have repeatedly specified the great versatility of a tandem, but it is worth repeating it once again. Such a configuration allows two machines to be used together or separately, with the great advantage that a workshop does not need to equip itself with additional machines. It also allows you to adapt to business changes effectively, always ensuring future business options.

Last, but not least, is the speed of execution: thanks to the reduced size, the bending machines configured in tandem are more streamlined in movements than a larger bending machine and this allows to obtain a fast work cycle. 

Lower risks: buying a tandem allows you to halve the risks compared to buying a large bending machine, which will be more exposed to the risk of production stoppages. In a tandem, on the other hand, it will still be possible to produce parts on the working machine.

Lower ancillary costs: Before purchasing, it is always important to evaluate all the costs related to the new project. How do transportation costs differ for one large machine compared to two smaller machines? Will special permits be required? Will additional foundation preparation work be required for one type of configuration over another? Understanding all the associated costs is the only way to accurately calculate your return on investment.

What are the limitations of a tandem?

We often talk about the benefits, but little about the limitations.

Let's look at some factors that can influence the decision to buy a tandem:
We have already said that the versatility of tandems consists in being able to bend long pieces without having to equip themselves with imposing machines that require more space and additional bending at the foundations. However, it's worth noting that a tandem setup still has limitations. One of them is related to the recess: although it is possible to increase the depth, it could still interfere with the bending of certain parts.

Another consideration is the cost of the machine. Depending on the case, buying a large car can prove to be more expensive than choosing a tandem, however, the opposite is also true. In fact, a tandem consists of two machines and therefore each component is doubled (two CNCs, 4 cylinders, etc.). This does not mean that a tandem is less convenient than a single car, but it is certainly one of the many aspects to consider when buying.

Now let's see what the other criteria are to consider before buying a machine.

What criteria should be adopted when purchasing a new machine?

Before proceeding with the purchase of a tandem or a large bending machine, it is essential to consider all the variables at play, first and foremost your production needs.

What are the processes you need to do? How much do they cost you? What is the level of sustainability in continuing to process the parts through the current production process?
These are fundamental questions to pay close attention to.

How to achieve higher productivity and save costs? What are the markets that offer the latest products? What are the changes in the production field in recent years? Buying tandems seems like a serious financial solution. Start with a clear estimate of the status of your work and get the answers to questions about how to increase the productivity of your operations and get the most profit possible.

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