Safety on Plastic Injection Moulding Machines

Plastic injection moulding safety: danger zones

Plastic injection moulding safety starts with thinking of the machine in zones. An injection moulding machine is at the same time a large press, a heater operating at high temperature, a high-pressure hydraulic system and often a robot cell. Machines with clamping forces of tens of tonnes at automotive suppliers in Bursa have the same danger zones as machines in small packaging workshops; only the scale changes.

Zone	Main risk	Basic protection
Mould area	Hands, arms or body being trapped as the mould closes	Interlocked safety gate, mechanical safety device on large machines
Clamping unit and toggles	Access to the moving platen and toggle links	Fixed guards
Ejector and core movements	Unexpected movement with the gate open	Limited speed and hold-to-run control in setting mode
Nozzle and barrel	Hot melt spatter, burns, electricity at the heaters	Nozzle guard, thermal protection, insulation
Feed hopper and dryer	Hot surfaces, dust, filling at height	Closed feeding, safe access
Hydraulic system	High-pressure oil jets, slippery floor	Hose maintenance, leak checks
Robot and part removal area	Being struck by the robot arm, trapping	Fencing, interlocked gate, area scanner

Two zones in the table are often overlooked on site. The first is the hydraulic system: high-pressure oil spurting from a worn hose can penetrate the skin, and oil accumulating around the machine is the most common cause of slips and falls. Including hoses in the maintenance plan, cleaning up leaks at the end of the shift and placing a drip tray under the machine are simple but effective measures. The second is the feed hopper: on large machines, people climb on top of the machine to fill the hopper. A platform with guardrails or a vacuum feed system instead of a ladder reduces both the risk of falling and granule dust.

In robot cells, the risk arises from the machine and the robot each being considered safe separately. When the cell gate is opened, both the robot and the machine must stop, restarting from outside must be prevented while someone is inside the cell, and the robot must move only at low speed in teach (programming) mode.

How does the injection moulding machine gate interlock work?

The current safety standard for the design of injection moulding machines is EN ISO 20430:2020, which replaced the old EN 201. The details of the standard concern the manufacturer; the principle you need to know as an employer is this: the gate giving access to the mould area prevents the closing movement through more than one channel, independent of each other. A typical machine has switches monitoring the gate position in the electrical circuit, a valve cutting off the closing movement in the hydraulic circuit and, on large machines, a mechanical safety device that physically prevents closing while the gate is open. Which channels are present is stated in the machine’s user manual.

Annex I of the Regulation on Health and Safety Requirements for the Use of Work Equipment requires guards to be robust and designed so that they cannot easily be removed or rendered inoperative (2.8.1). Annex III requires every piece of work equipment to be visually inspected and its functions tried by its operator before starting work, and this to be recorded (1.3).

The gate interlock test the operator carries out at the start of the shift:

With the gate open, give the mould close command; the machine must not move.
Repeat the same test with the gate left half open.
Open the gate during the closing movement; the movement must stop immediately.
On large machines, visually check that the mechanical safety device engages when the gate is opened.
Repeat the same test for the rear gate and the robot cell gate.
Record the result on the shift check form; on a single negative result, do not run the machine and call maintenance.

Crushing between mould halves: the most common scenarios

Crushing between mould halves mostly happens not during production but at these moments:

Removing a stuck part: The operator reaches over the top of the machine or from the rear without opening the gate. Top and rear access points must also be closed or interlocked.
Setting and mould trials: The setter tries the ejector or core movement with the gate open. In setting mode, movements must be made only at low speed and with a hold-to-run control.
Whole-body access: On large machines a person can get into the mould area. Additional measures are needed to prevent the machine being started while someone is inside (personal lock, detection inside the area, the gate not being lockable from inside).
Robot cell: The gate used to enter the area where the robot picks parts must stop the robot and the machine together.

For the general logic of guard types, see our guide to machine guards.

Nozzle, hot plastic and burns

The barrel and nozzle operate at hundreds of degrees, depending on the type of polymer. There are three sources of burn risk:

Purging: When cleaning the barrel, molten plastic spurts from the nozzle. Purging should be done with the nozzle guard closed, and the operator should use a face shield and heat-resistant gloves.
Moisture and degradation: Moisture in insufficiently dried granules can turn to steam and make the melt spatter. Some overheated polymers give off irritant gases; for example, PVC releases hydrogen chloride when it degrades. Check the barrel temperature and residence time when changing material.
Hot surfaces: The mould, the hot runner system and heater bands. The Regulation requires measures to prevent workers approaching or touching parts of equipment at high temperature (Annex I, 2.10).

In addition, the junction boxes and cables of barrel heater bands carry a risk of electric shock; their covers must not be left open. The choice of personal protective equipment must be based on the risk assessment.

Injection mould change step by step

A mould change is riskier than routine production: heavy loads are lifted, the machine is operated outside its normal safety cycle and there is often time pressure. The Regulation requires maintenance work to be carried out with the equipment switched off, its energy disconnected and all movements stopped (Annex I, 2.13). An example mould change instruction:

Plan the mould change; determine the weight of the mould, the lifting points and the sling required in advance.
Move the barrel to a safe position, switch off heaters if necessary and mark hot surfaces.
Stop the machine; isolate, lock and tag the electrical and hydraulic energy. If there is a hydraulic accumulator, release its pressure.
Disconnect water, oil and hot runner connections; clean up spilled liquid immediately.
Lift the mould only by its own lifting points, using a sling and crane of suitable capacity; no one must stand under the load.
After fixing the new mould, check the clamping elements.
Make the first closings at low speed and low pressure, in setting mode.
Do not move to production without testing the guards and the gate interlock.

If the mould change is a job in which more than one team works at the same time or that requires work at height, linking it to the permit-to-work system is good practice.

Periodic inspection, maintenance and training

The injection moulding machine does not appear as a separate row in the periodic inspection tables in Annex III of the Work Equipment Regulation (the machine tools table lists equipment such as presses, lathes, milling machines and saws). Under Annex III, equipment not specified in the tables or standards is inspected at the intervals and to the criteria laid down by the manufacturer, if any, and otherwise according to the risk assessment (1.4). For inspection reports on equipment whose inspection is not mandatory because it is not in Annex III, the format and ISG-KATİP (the Ministry’s online OHS registration system) contract requirements do not apply (Art. 7/6).

This does not mean that there is no equipment subject to mandatory inspection around the machine. In injection moulding halls, the following are typically subject to periodic inspection at least once a year:

Cranes, hoists and lifting gear used for mould changes; slings and lifting accessories
Compressors and compressed air receivers
Internal electrical installation and earthing
Forklifts and pallet trucks used to move raw materials and products

For intervals and who carries out the inspection, see our guide to periodic inspection intervals; planning the inspections is within the scope of our periodic inspection service.

On the training side, two subjects stand out. Row 62 of the Annex 1 list of the vocational training regulation is “moulding of plastic materials and manufacture of plastic articles”; those who will work in these jobs must hold a vocational training certificate appropriate to the job before being hired (details). In addition, under the 2026 training regulation, the topic of job- and workplace-specific risks is delivered face to face in hazardous and very hazardous workplaces; the gate interlock test and the mould change instruction should be practised at the machine in this part.

Checklist

The deficiencies we most often find in injection moulding halls during site inspections are bridged rear gate switches, machines where only the front gate is tested, moulds carried on forklift forks, face shields not used during purging and oil accumulating around machines. The list below covers all of these deficiencies:

The gate interlock on every machine is tested and recorded at the start of each shift.
Top, rear and robot cell access points are closed or interlocked.
The ban on bridging is in writing and enforced.
Purging is done with the nozzle guard closed and a face shield worn.
The mould change instruction includes energy isolation and lockout steps.
Periodic inspections of the mould crane, slings, air receivers and electrical installation are up to date.
Operators’ vocational training certificates are in their personnel files.

In our OHS specialist service, we follow these checks machine by machine during site rounds. For sector-specific risks, see our chemicals and plastics and automotive supplier industry pages.

Frequently Asked Questions

Is periodic inspection of an injection moulding machine mandatory?

The machine does not appear as a separate row in the Annex III tables; the inspection interval is set by the manufacturer’s instructions or, failing that, by the risk assessment. However, the lifting equipment, compressed air receivers and electrical installation used with the machine are subject to periodic inspection at least once a year.

How often should the gate interlock be tested?

Annex III requires work equipment to be visually inspected and its functions tried by the operator before each start of work. For the gate interlock, this is a test carried out and recorded at the start of every shift.

Does an injection moulding operator need a vocational training certificate?

Row 62 of the Annex 1 list of the vocational training regulation covers the moulding of plastic materials. If your workplace is in the hazardous or very hazardous class, the operator actually doing this work must hold a vocational training certificate appropriate to the job.

What should be done first for a hot plastic burn?

The burned area is cooled immediately with clean, cool running water; plastic stuck to the skin is not forcibly removed, and medical help is sought. First aiders need to learn the response method through hands-on practice in training.