A roll forming machine that stops in the middle of production is one of the most common problems on the shop floor. Sometimes an alarm pops up on the screen. Sometimes the machine simply stops responding.

The usual reaction is to hit reset over and over. That occasionally works, but it often hides the real cause or makes things worse. The good news is that most sudden stops come from a handful of causes, and checking them in the right order usually finds the problem within minutes.

This guide walks through a practical sequence, from the easiest checks to the harder ones.

• Start by reading the alarm. The screen message, PLC indicators, and drive fault codes are your best clues.
• Most sudden stops trace back to emergency stops or safety circuits, power or overload protection, hydraulics, sensors or encoders, and material jams.
• Lock out the power before you inspect anything inside the machine.
• If the same fault keeps returning, the root cause has not been fixed. Do not rely on repeated resets.

1. Press the emergency stop to halt all motion.
2. Before reaching into the machine or touching moving parts, switch off the main power and apply lockout/tagout.
3. Confirm the hydraulic system is depressurized before working on it.
4. Never bypass a safety switch or protective device just to get the line running.

The touchscreen message, PLC fault lights, and VFD error codes carry the most useful information.

• Photograph or note the alarm text and the time it appeared;
• If several alarms appear, the earliest one is usually the cause and the rest are knock-on effects;
• Match the code to the alarm list in your manual.

If an alarm clears after a reset, that does not mean the problem is gone. Find the cause first, then reset.

When the machine shows no reaction at all, start here.

• Is any emergency stop button pressed or not fully released?
• Has a guard door, light curtain, or limit switch been triggered?
• Are emergency stop wiring connections loose or cables damaged?
• Has someone bumped the stop button near the control panel?

A surprising number of mystery shutdowns turn out to be a stop button or limit switch that was never fully reset.

• Is the main switch or circuit breaker tripped?
• Is three-phase voltage normal, with no missing phase, low voltage, or large fluctuations?
• Has a thermal overload relay or motor protector tripped?
• Is the VFD showing overcurrent, overload, overheating, or undervoltage?
• Is there a burnt smell, hot component, or loose wiring in the cabinet?

If a breaker or overload relay keeps tripping, do not force it back on. Look for an overloaded motor, a short circuit, or a mechanical jam.

Cutting, following, and feeding often rely on hydraulics. A typical symptom is a main drive that runs while the cutter does not move, or motion that is weak and slow.

• Is the oil level sufficient?
• Is oil temperature too high (common in summer) or too low (cold starts in winter)?
• Is the pump running normally, without unusual noise?
• Is system pressure reaching the set value?
• Is the solenoid valve energized and switching? Is the coil overheated or burnt out?
• Are there leaks in hoses and fittings, or a clogged filter?

If the problem appears around a seasonal change, pay extra attention to oil temperature and oil grade.

The machine measures length with an encoder and confirms cutter position with proximity and limit switches. If any of these fail, the controller loses track of what is happening and stops.

• Are encoder connectors and cables loose or damaged?
• Is the encoder wheel slipping on the sheet, causing inaccurate length readings?
• Are proximity or limit switches covered in oil or metal dust, or have they shifted position?
• Do the sensor indicator lights behave normally?
• Are any cables being pulled, pinched, or rubbed, causing intermittent faults?

Alarms that come and go are usually caused by poor connections or wiring, so check connectors and cable routing first.

• Has the coil run out or reached its tail end?
• Has the strip drifted and pushed against a guide, causing a jam?
• Has the decoiler stopped, or is tension abnormal?
• Is there a sheet end or foreign object lodged between forming rolls?
• Do the chain, gears, or bearings make unusual noise or run hot?

If you see sheet piled up or stuck, cut the power before clearing it. Never pull on it by hand.

If everything above looks normal, move on to the controls:

• Were length, speed, or quantity settings changed recently?
• Is communication normal between the PLC, touchscreen, and drives?
• Is there moisture or dust inside the control cabinet?
• Have any program settings or parameters been lost?

This step is best handled by an electrician familiar with the machine or by the manufacturer's technical team, to avoid changing critical parameters by mistake.

1. Read and record the alarm;
2. Check e-stops, guards, and limit switches;
3. Check power and electrical protection;
4. Check hydraulics: oil level, temperature, pressure;
5. Check sensors and encoders;
6. Check material and mechanical jams;
7. Check parameters and the control system.

Following this sequence, most faults can be located on site. Whatever remains is the point to call the manufacturer.

Get in touch with the machine supplier's technical team if:

• The same alarm keeps returning and you cannot find the cause;
• The fault involves core components such as the VFD, PLC, or servo;
• The problem looks like an internal failure in the hydraulic pump or valve block;
• You notice a burnt smell, smoke, or obvious electrical damage.

Preparing the following in advance can save a lot of back-and-forth:

• Machine model and serial number;
• A photo of the alarm screen or fault code;
• What the machine was doing when it stopped (material, speed);
• A list of checks you have already done;
• A short video of the machine or the affected area.

• Before each shift: check oil level, oil temperature, e-stop buttons, and sensor surfaces;
• Weekly: clean cabinet filters, and wipe oil and metal dust off the encoder and proximity switches;
• Monthly: check terminal tightness and look for oil seepage at hose fittings;
• By season: warm up in winter and control oil temperature in summer, as covered in our guide to winter and summer operation;
• Keep a fault log: record the time, symptom, and fix for every stop so recurring issues stand out.

Can I just reset the alarm and keep running?

It is better to find the cause first. If the cause remains, the machine will likely stop again, and continuing may cause further damage.

Can I raise the breaker rating if it keeps tripping?

No. The breaker is protecting the wiring and motor. Investigate the cause, such as an overloaded motor, a short circuit, or a mechanical jam, rather than raising the setting.

Why does my machine fault randomly with different alarms each time?

This usually points to loose connectors, poor cable contact, or contaminated sensors. Focus on terminals, the encoder, and limit switches.

If the cutter will not move, is the hydraulic system always at fault?

Not always. Besides the pump and solenoid valve, a faulty limit switch, encoder signal, or control parameter can also stop the cutter. Check oil level, pressure, and the solenoid light, then move on to the electrical side.

How should I describe the problem to the manufacturer?

Share the machine model, a photo of the alarm, the conditions before and after the fault, and the checks you have done. A short video helps a great deal.

A sudden stop is not always a major failure. In most cases the cause is a stop button that was not reset, tripped electrical protection, abnormal oil level or temperature, a dirty sensor, or a material jam.

Remember the sequence: read the alarm, then check the safety circuit, power, hydraulics, sensors, and material, and look at parameters last. Combine that with daily checks and a simple fault log, and unexpected stops will become much less frequent.

If you run into a problem you cannot solve with our equipment, send us your machine model, alarm screenshot, and a description of the issue, and our technical team will help you work through it.