How to set up an old press brake

Let’s discuss where to start in order to use such a press as efficiently as possible. First, find the operating manual. If it is not available, try to find it online. Then review it and study the machine itself, making sure that its components are properly adjusted. The guide rails may be loose or worn. Check the connection of the braking unit and make sure it works as intended. If the ram needs to make three revolutions before stopping, something is wrong.

Check the mechanical condition of the press brake. Any issues may lead to safety problems. If everything is satisfactory, begin preparing the press working area—the ram and the table.

Remove the crosshead, take a fine file, and dress it as well as the surface of the table. By doing this you remove burrs and protrusions that have appeared over years of use, rather than modifying the machine.

Clean out the slot in the crosshead where the die locating tang is inserted. Also, if you find clamping screws on the table, remove them. Leave four—two on each end of the table.

Remove all clamps from the ram. Clean their surfaces and sand the bottom side. Before reinstalling the clamps, find a magnetic base and a dial indicator. Assemble them and take readings between the table and the ram. Now move the magnetic base and indicator along the entire length of the table, observing the readings. You will see them change slightly, responding to surface roughness. The readings should not increase as you approach the center of the table and then decrease. If the readings increase in the center of the ram, the press brake clearly has ram problems—it is bowed. Even if you adjust the center, the press brake will never work accurately and needs repair until the table is machined flat.

If the indicator readings increase or decrease as it moves from one end of the table to the other, the ram is not balanced and this must be corrected. You should move the indicator and magnetic base from end to end of the table and make sure the readings remain constant.

After this inspection, clean the entire machine, wipe it down, and lubricate it where necessary.

Tool preparation

Inspect all tooling. Clean it and grind off any burrs and scratches that could affect performance. Look for worn radii relative to the rest of the tool and set it aside—it can no longer be used for bending.

Next, inspect the S-shaped tooling with a straightedge to see if it is bent (springing). Place the straightedge against the back of the tool; if it can rock slightly, it is bent and should not be used. The center of the radius of the thin section will not match across different sections of the same set, which is dangerous. Bent tooling is weak and has a high probability of breaking and causing injury.

Setting initial coordinates

How does axis offset affect setup? Significantly. When tooling is installed on a press brake, differences between tools cause the radius center to shift along the press X-axis, changing its relationship to the backgauge position.

The radius of the punch tip forms the bend line at its center—set the gauges or calibrate them relative to this center. There are two ways to do this: one for manual or fixed gauges, and another for simple powered ones.

Begin by bringing the ram to the center of the lower “dead zone,” its lowest point. Then adjust the opening for the die and punch, leaving enough space to position the tooling correctly. Manually clamp the punch in the ram, center the die as closely as possible, and clamp it. Then seat the die and punch in the press under light load.

Using the adjustment mechanism, raise and lower the punch into the die space and observe whether it moves. If it moves, the punch is not centered. Adjust it and check again, bearing in mind that adjusting one end affects the other, and several attempts may be needed before the tooling is properly aligned. Do not skip this step. Tooling must be centered, especially for coining and bottoming operations.

Setting manual backgauges

Measure the full width of the die—not the opening, but the entire tool length—and divide it by two. Then add this value to the distance from the edge to the bend line. Set a combination square to this value. For example, if the total die width is 2 inches and the flange is 3 inches, set the combination square to 4 inches.

Place the square against the die and, holding it in position, move the gauge to the end of the square; lock it in place. Do this for both gauges. Note that for safety reasons this is best performed by two technicians.

Now your two gauges are set to size. However, remember that this setup is rarely perfect, and several test bends will be required to refine the results—that’s just how it works.

Setting a mechanical backgauge

If you are setting a mechanical backgauge for planed or precision tooling, first physically retract the backgauge, move it fully to the end of its travel, and lock it there. Then locate the gauge block.

Set the digital indicator to the distance from the center of the V-profile of the gauge block to the end of the gauge, and move it to that value. Both blocks will fit snugly between the die and punch under very light load. Now physically move the gauges to the ends of the gauge blocks and lock them. The backgauge is now calibrated relative to the bend center, and even a simple controller can move it accurately.

It should also be noted that, although not always possible, you should always try to program the forming sequence so that movement is directed toward the centerline. This way the mechanical backlash works for you rather than against you.

Author: Steve Benson, The Fabricator

IMA Information:

• Using older machines in production, even after taking the measures described in the article, may still present certain difficulties. Sometimes it is impossible to increase productivity without additional investment. Italian Machinery Association is ready to help you solve your problems in various ways.
• If you are interested in other materials on bending, we recommend the following articles:

Step bending increases press brake productivity

Automation to improve bending operations

4 tips to improve press brake performance

• If it is time to expand or upgrade your production capacity, you can always contact IMA to purchase a new press brake from a reliable Italian manufacturer. The range of press brakes from association members in our catalog can meet the needs of any manufacturer—from small subcontractors or individual producers to large-scale automated plants.
• In some cases, the productivity of machines installed in production can be significantly increased by equipping them with new high-quality tooling of one of the popular styles. Explore the press brake tooling offerings from the Italian Machinery Association.
• Do you need repair services, installation, machine restart, or operator training? The IMA service department has extensive experience and knowledge to solve any problem.
• Do you have other questions or needs? Contact us immediately by phone or email, or visit any of our representative offices.