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Injection Molding Machine Safety Device Date:2011-12-6 0:11:55

Injection Molding machine Safety Device

To protect operators, when the machine breaks down or runs in abnormal way, safety devices described in this chapter will help you. Check these safety devices always before starting up the machine to make sure of their availability when needed. The optional safety devices as requested by customers could also be installed to machine for the purpose of protection.
Injection Molding Machine

2.1 Electric safety device

l        Safety door & safety limit switch:

The number of safety limit switch depends on the machine model and the status whether there is any hydraulic safety device.

Safety limit switch can cut off clamping circuit, for it opens with safety door to disconnect circuit to stop clamping motion. Safety door must be checked prior to each running of machine.

Ø        Trial run check

Step 1: Open the safety door;

Step 2: Choose “Manual” button in operation panel (See Chapter 5 for details);

Step 3: Press “Mold close” button for clamping;

Step 4: Clamping do not occur in normal conditions


In case of safety doors at both sides of machine, please check two sides. If clamping happens, please stop running machine and contact us for repairing promptly. We’ll come to you as soon as possible for troubleshooting. (If machine needs to be running before troubleshooting, please remind operator of potential safety risk).


Ø        Regular inspection

a)      Make sure that the safety door can open and close smoothly;

b)      Try to find what will damage safety door (such as guide way or roller);

c)      Clearly know the right matching for safety limit switch (such as screw and actuator)


a)      As safety door and safety limit switch are provided to protect operators from being injured, they could not be moved or changed in whatever way.

b)      b) In case that safety door fails to be opened/closed properly or gets into malfunction, it needs to be repaired immediately.


l        Emergency stop button

It can be used to shut down machine in case of emergency. When pressing the button, the motor is stopped by pump and the machine is shut down. Turn the button to the right for resetting.


2.2 Mechanical safety device

l        Mechanical safety device for clamping

If mold open is operated with opening of safety door, the safety pawl will automatically fall down as the scotch bar moves backwards with movable platen, it suggests the safety pawl will stop the forwarding of scotch bar even if clamping attempts to take place due to one electric or hydraulic circuit failure, which in the end prevent any clamping motion.

Scotch bar must be adjusted based on die height for your machine with the following steps:

a)        Have the scotch bar end and pawl at the same level;

b)        Safety pawl can happen to drop down at location of mold open stop for general molding or at location of clamping instantaneous stop for insert molding, then fasten the scotch bar with two locking nuts provided.


a)      Adjust the scotch bar after you’ve made sure of mold installation. For safety purpose, make sure the safety pawl can automatically drop down at the location of mold open stop with clearance being within 40mm when safety door opens.

b)      Do not attempt to move scotch bar, safety pawl or rod cover;

c)      Remember that mechanical safety device will not work when the machine is shut down before mold open motion stops!

d)     Serious hazard or failure or malfunction of machine would probably be incurred if the instructions given here is not followed.










2.3 Hydraulic safety device (Optional)

l        Door valve (Optional)

This door valve shut the clamping circuit with hydraulic pressure.


Inspection procedure:

As different machine may apply different operational mode, please see Chapter 5 for detailed operation method.

a)      Check if pushing cam of valve has pressed crown bar to the lower limit after the safety door opens.

b)      Close the safety door;

c)      Check if the pushing cam of valve happen to be at the reset location which enables crown bar of valve to return to the upper limit;

d)     Jogging Initiate hydraulic pump motor;

e)      Press “mold open” button to open the platen.

f)       Open the safety door at operational side at any position, at the same time make electric limit switch of safety door in the state of “door close”.

g)      Transfer the clamp switch to “mold close”. It shows hydraulic safety door valve works if clamping fails, otherwise the pushing cam needs to be re-adjusted and machine shall be shut down for our repairing.

h)      Ensure the personal safety of operator during inspection.