What should an electrical thermography survey cover in a plastics injection moulding factory?

The incoming supply, main switchboard and the panels that feed every press: machine isolators and cabinets, barrel heater zone controllers, mould temperature controllers, chillers, dryers and granulators. Survey with the presses on a normal production cycle, record what each machine was doing, and compare heater zones and phases with their matching neighbours, not with a fixed limit.

A moulding shop is full of heat that has nothing to do with the electrics. A good survey keeps that out of the findings and concentrates on the connections and components that carry the current.

What to include

Intake and LV main switchboard, including power factor correction where fitted.
Distribution to the shop floor: busbar or cable feeds and each press’s local isolator.
Press electrical cabinets: main contactors, pump motor drives or starters, and the heater zone control.
Mould temperature controllers and hot runner controllers.
Ancillaries: chillers, material dryers, granulators, loaders and robot panels.
Compressed air plant (see compressed air plant).

Heater zones: compare zone with zone

Barrel heater bands are switched on and off by solid-state relays or contactors to hold each zone at its set temperature. The relay heatsinks run warm by design, and a zone that is switching on and off will not hold one steady temperature. So each zone’s terminals and switching device are compared with the matching zones on the same press, and with the same zone on a matching press, while the heaters are switching. The report records which zones were on at the time of the image.

Process heat is not an electrical finding

The barrel, nozzle, hot runner manifold and mould are hot because the process needs them hot.
Hydraulic oil, heat exchangers and chiller pipework carry process heat.
Bare metal and shiny surfaces reflect that heat, so a reading on them can be misleading.

None of these is reported as an electrical fault. The findings that matter are connections and components reading warmer than their matching phase, zone or machine on similar load.

Timing

Survey on a normal production run, with the presses cycling. Avoid the first hour after a cold start, when every heater zone is running flat out to reach temperature, and avoid mould changes, when a press is idle. Presses that are not running on the day are listed as not imaged under load. If the shop has a planned shutdown, survey before it so the findings can be dealt with during the stop (see before or during a planned shutdown).

What the report gives you

Each finding is located by press, cabinet, circuit and phase, with a thermal and visual image pair, the measured temperature, where it was taken, the difference in °C from the matching reference, and what the machine was doing at the time. We deliver reports the same day. Ti inspects and reports; your maintenance team or contractor investigates any finding with the equipment isolated.

Why survey under load

On a London data centre build, commissioning thermography by our team found 16 busbar sections reading above 80 °C under test load, the highest 103.5 °C at a tap-off unit. Different site, same principle: connections only show their condition when they carry current (see busbar thermography at commissioning).

Frequently asked questions

Do presses need to stop?

No. The survey needs them running. Cabinets are opened one at a time by your authorised person (see who opens the panels).

Can drives on electric presses be surveyed?

Yes, while running. Drive heatsinks are expected to be warm; the incoming and outgoing connections are what get compared.

How often should a moulding shop be surveyed?

Most factories build it into annual PPM, with an extra survey after new presses or a change to the supply (see annual PPM thermography).