Control panel of an injection molding machine

The control panel of an injection molding machine is the operator panel: the screen and keys where the operator sets temperatures, speeds, pressures, positions and times, runs the machine in manual, semi-automatic or automatic mode, and reads alarms. It is the front end of the controller: it sends the settings to the CPU board in the electrical cabinet over a cable and shows what the machine is doing. People also say "electrical panel" for the electrical cabinet behind it, which holds the boards, the servo drive and the wiring. This page covers both.

Where the control panel sits

The operator panel is mounted on the operator side of the machine, on the electrical cabinet or on a swivel arm near the safety gate, so the operator can see the mold area while working. Functions that must act at once, such as the emergency stop, are separate hardware buttons on or near the panel, not keys on the screen.

Depending on the controller, the panel is either a display unit that talks to the CPU board in the cabinet, as in the drawing, or it contains the main processor itself. Machines use controllers from various makers; the controller model is printed on the operator panel and on the boards, and it decides which replacement panels and boards fit.

What the operator panel does

• Process settings: barrel temperatures, injection speeds and pressures, switchover and hold, screw recovery, clamp and ejector positions, and timers.
• Mold data: storing and loading the settings for each mold, so a mold change does not mean entering everything again.
• Manual operation: keys that move the clamp, the injection unit, the screw and the ejector one movement at a time, for setup and purging.
• Monitoring: actual values, cycle time, production counters, alarm messages and the alarm history.
• Diagnostics: most controllers have an input/output page that shows the state of each switch, sensor and output. It is the first place to look when one function stops working.

The electrical panel behind it

The electrical cabinet, often called the electrical panel, contains:

• the main isolator switch, and fuses or circuit breakers;
• the main CPU board, the I/O modules, the drive interface board and the power supply board;
• the servo drive, or the starter of the pump motor on a fixed-speed machine;
• contactors and relays for the motor and the heater zones;
• terminal blocks, where the wiring from switches, sensors, valves and heaters lands before it runs to the I/O modules;
• cooling fans and filters.

The electrical system guide explains how these parts work together in the cycle.

Types of operator panel

Older and simpler panels combine a display with membrane or mechanical keys. Newer panels use a touchscreen, usually with some hard keys kept for manual movements and mode selection. The display, the touch layer and the keypad membrane are the parts that wear; on some panels they can be replaced separately, on others the whole panel is changed.

Signs of a failing control panel

• The screen is dark, dim or flickering while the keys still light up or the machine still responds, which often points to the backlight.
• Keys or areas of the touchscreen do not respond, respond only sometimes, or trigger the wrong function.
• A communication alarm between the panel and the controller, or a panel that freezes and restarts.
• Settings or the clock are lost after the machine is switched off, on controllers that keep them in battery-backed memory.
• Physical damage: cracked glass, swollen or torn membrane keys, or oil inside the display.

Common causes are heat, oil mist and dust around the machine, water from cooling lines, worn keys after years of use, and a damaged cable or connector between the panel and the cabinet. A low supply voltage from the power supply can also make a healthy panel restart.

Inspecting and replacing a control panel

Work on the panel and in the cabinet is for qualified electricians, with the machine switched off at the main isolator and locked out before anything is disconnected.

1. Record the symptom and any alarm. If the panel still works, back up the mold data and machine parameters; many controllers can save them to a USB stick or memory card.
2. Note the controller model, the panel's model number and its software version, which is usually shown on the start-up screen or a system page.
3. Isolate and lock out the machine, then check the cable and connectors between the panel and the CPU board. With the machine in a safe state, the electrician can check the supply voltage at the panel.
4. Replace the panel, or the failed part of it (screen, touch layer or keypad membrane) where the panel is repairable, with one that matches the controller model and software version.
5. Restore the settings, then test every manual movement, the emergency stop and the safety gate before running production.

What to send for a replacement quote

• The machine brand, model and serial number.
• The controller model printed on the operator panel and on the boards.
• Photos of the front and back of the panel, including every label and connector.
• The software version, if the panel still starts.
• A description of the fault: dark screen, dead keys, communication alarm.

For the boards behind the panel, see the main CPU board and the other circuit boards we supply.