A press brake can have a great appearance when performing a 10 minute demonstration.

The more useful test is started several hours later.

At this point the machine has already gone through numerous strokes, hydraulic temperatures have fluctuated, and the operators have had time to load various parts and production has been ongoing to demonstrate weak positioning, deflection or setup practices.

This should be the setting when evaluating an industrial CNC Press brake machine.

When it comes to factories producing the same sheet metal again, the most significant thing is not “Is it possible to bend this plate?”

Will it continue to make the same acceptable part throughout the shift without continually having to be corrected?

It is the difference between a press brake demonstration and press brake used on industrial production.

It is critical that an industrial machine be predictable when under load.

The repeated loading of the ram, tooling, bed and frame is the issue with industrial bending.

The mechanical structure, if it is not predictable, CNC accuracy will not be able to compensate completely by itself. However, with a lack of structural deflection control, the controller could order the same ram position and still have a different actual bend.

A rigid welded frame is therefore of practical importance because it is a more stable reference for repeated bending.

APEX hydraulic press brake machine is said to be based on high rigidity welded frame, and also has synchronously hydraulic control to perform repeated production.

This is more significant as the length of the brackets increase, or as the forces to be bent increase.

Industrial capacity does not necessarily equate to “more tons.”

It should mean that the structure is in working order and it has a fixed behavior when these tons are repeatedly applied.

Production Requirement	What to Evaluate	Useful Evidence
Repeated Bending	Ram and angle repeatability	Parts measured across a production run
Long Workpieces	Deflection control	Left / center / right angle check
Multiple Shifts	Hydraulic and thermal stability	Results after extended operation
Complex Parts	Positioning flexibility	Multi-bend sample test
Frequent Production	Setup recovery	Stored program and tooling record
High Utilization	Service accessibility	Maintenance points and service plan

If there is a need to check for accuracy, it should be done throughout the shift, NOT just in the first part.

The first approved component is an indicator that the setup is capable of functioning.

It currently does not provide an indication of the stability of the process.

If parts are being produced in industry, check parts throughout the run:

• first approved part;
• early production;
• In the middle of the batch;
• later production;
• final part.

Always measure the critical flange dimensions and bend angles in the same manner.

If corrections are being made repeatedly as production is made, determine what has changed rather than assuming that this is a normal operator production.

It can be a material change, tooling, hydraulic effects, positioning, temperatures, etc., – not only CNC program.

However this type of process monitoring shouldn’t be so difficult if your industrial CNC press brake is configured correctly as the position of the machine, the movement of your backgauge and the bend corrections are controlled and not recreated manually.

What Changes During Production	What to Record	What to Check Next
Bend angle gradually changes	Angle by batch position	Material, tooling, temperature
Center angle differs from ends	Three-point angle measurement	Crowning and alignment
Flange dimension varies	Backgauge result	Gauge reference and positioning
More corrections are needed later	CNC offset history	Process drift source
Cycle time increases	Time by operation	Handling and positioning
Unplanned stop occurs	Fault and operating hours	Maintenance history

The principle of crowning is to keep the middle of the part honest.

A long bend will expose issues which might not be apparent in a short sample.

The machine structure and tooling system under bending load will have deflection. If not compensated for, the two ends of a long workpiece might reach the desired angle, while the center is different.

This is why crowning should be given more attention in the industrial use.

APEX’s CNC hydraulic press brake configurations include a programmable V-axis crowning system as well as synchronized Y1/Y2 control. Servo controlled backgauge axes can be used on the same platform to position complex parts.

On a production manager’s agenda, however, the result is the most important factor and the specification “CNC crowning” is not of great concern.

Pick a real long piece and measure it at several points across the piece; and ask:

What is the amount of angle variation from the left to center to right?

The option list isn’t as meaningful as that test.

The Ram moving faster isn’t the only way Cycle Time is reduced.

Approach speed, working speed and return speed are often factors that industrial buyers consider.

Those numbers are relevant but the ram stopwatch should not stop.

Within a bending cycle, there can also be:

Positioning→ bend→ repositioning → bend again and again→ unloading→ inspection.

If the time spent by operators on finding references and repositioning workpieces is more than the time spent on bending, then increasing the speed of the ram will not help to improve production output.

Programmable backgauges and multi-axis positioning are helpful at this point.

For more complex multi-step work, APEX’s high accuracy CNC press brake is able to accommodate servo controlled backgauge axes and graphical programming and bend-sequence simulation.

Hence, for industrial production, the productivity of a machine should be measured in terms of number of acceptable finished parts per hour (not strokes/minute).

This number contains the actual factory.

CNC Control should minimize what has to be decided at the Machine.

Production press brake should not need operators to “relearn” a press brake set-up each morning.

After validation of a process, it is important that as much useful information as possible be retained in the program: the bend sequence, backgauge positions, ram settings and tooling information and corrections that were verified.

Graphical CNC systems also assist operators in understanding the complicated sequences prior to the part reaching the tooling.

But that doesn’t rule out operator skill.

It alters the location of the application of that skill.

Knowledgeable operators can save time by eliminating the need to repeatedly tweak a known job and can devote more time to validating new parts, improving setups and solving some of the more unusual production issues.

This doesn’t just mean simpler programming. This is an improved utilization of production knowledge.

Industrial Reliability = Including the Time Between Batches

A press brake is considered to be making a profit when it’s available for production.

Which means that access for maintenance, hydraulic state, lubrication, tooling checks and basic machine checking are not afterthoughts after installation, but rather part of the purchasing conversation.

Operators should have an established pattern of checks to be made:

• tooling condition;
• Condition and temperature of the hydraulic oil;
• any unusual noise or leakage;
• backgauge positioning;
• RAM and TOOLING ALIGNMENT;
• safety devices.

By understanding how a press brake works, maintenance and production teams also can determine if the problem is a programming one or one related to the press brake’s mechanics or hydraulics.

Typically the most successful maintenance event will be the one that is performed between orders and not the one that is performed in the middle of an urgent batch.

Purchase on the day you do have!

Describe the one normal production day before determining an industrial press brake.

• What is the length of time that the machine is working?
• Which materials do you get the most?
• What is the turnover rate for jobs?
• What is the maximum length regular bend?
• Which parts have the most critical tolerances?
• What is the number of operators using the machine?
• What are some of the jobs that need to be repeated?

These questions are a far better machine specification than a tonnage and/or working length alone.

A CNC press brake machine is a production system, which is used in the industry. There has to be more than one amazing test piece for it, its frame, hydraulics, CNC control, backgauge and even operator workflow to play their part.

The main thing should not be that the machine should start off the shift accurately.

It should still be ‘predictable’ close to the end of the change.

FAQ

Q1. So, what makes a CNC press brake suitable for an industrial production?

Good capacity, sturdy construction, repeatable ram control, good positioning and a CNC system that allows for repeatable production are all factors that lead to the suitability for industry. As well as the bend accuracy of a single bend, long term stability is also important.

Q2. On an industrial CNC press brake machine, why is it important that the frame is rigid?

There is bending load on the frame in each stroke. Too much or irregular deflection of the structure can be a factor in the angle change, particularly with longer or higher force bends.

Q3. Is it necessary to do CNC crowning on an industrial press brake?

Not all of the small parts need be paid the same. Crowning is particularly useful for long workpieces and when workpieces require a high level of consistency of their angles, where machine deflection is important.

Q4. What are good productivity indices for press brake?

Inspect acceptable finished parts for a realistic production time. Consider positioning, handling, multiple bends, inspection and setting up in addition to the bending stroke of the machine.

Q5. What information should a factory provide before selecting an industrial CNC press brake?

Materials, thickness range, maximum regular bend length, typical batch sizes, tolerances, hours of operation per day and representative drawings. All this information allows for a better match of machine capacity and control configuration to actual production.