IMPORTANT SAFETY MEASURES FOR INJECTION MOLIDNG MACHINE PART -1

 

The injection molding machine is equipped with a range of safety devices to provide the machine operator with maximum safety from accidents. Service, maintenance and repair work should only be carried out by personnel who are sufficiently qualified in their field and who have specific knowledge of injection molding machinery. 

Safety devices must under no circumstances be removed or rendered in-operative. Should this be unavoidable during setting or repair work it is essential first to switch OFF the mains switch 1-Q0 (this completely disconnects the machine from the mains) If the safety equipment malfunctions or a fault occurs in it, the machine must be immediately shut down and the following actions must be taken:

  Actuate emergency stop button  (Front)

  Actuate emergency stop button (Rear)

  Switch off isolator 

 Close down the cooling water supply after about 20 min.

  Inform the person in charge at once

  Before putting the machine back into operation, the causes of the fault must be fully eliminated.

  Motion No Motion Control Switch to have option for operating the machine with guard door in opened or closed condition (Optional) 

 It is strongly recommended that the safety equipment be checked periodically as per the maintenance plan.

  Any process which impairs the safety on the machine should be stopped.

  The employer must ensure that no unauthorized personnel work on the machine.

  No unauthorized conversion or modification of the safety equipment on the injection molding machine is allowed! 

Harmful fumes and Explosive decomposition 

If heated excessively, some plastics emit fumes detrimental to health. This applies in particular to Polytetrafluoroethylene (PTFE), Polyoxymethylene (POM) and Polyvinylchloride (PVC). If such fumes cannot be avoided by means of a suitable machine setting, it is advisable to use an effective extractor to draw them away.

 Certain plastics tend toward explosive decomposition due to prolonged exposure to heat. These are essentially Polyoxymethylene and PVC. Plastics which react in this way must only be processed by means of nozzles and seals which open automatically under pressure.

 Adhere strictly to the prescribed parameters of the plastics materials (in particular the processing temperature, material changeover procedure and residence time in the barrel) as per the materials manufacturers recommendations to avoid accidents due to material degradation. 

If there is an extended break in the cycle, the screw cylinder must be purged and the cylinder temperature reduced.

Four principles of safety 

1. Keep the safety gate in open condition before working with your hands on the mould 

2. First switch OFF the pump before working on the mould using your upper part of the body (above waist)

 3. First turn OFF Main Power Supply before entering in between the movable and fixed platens

 4. Keep your hands faraway from any moving parts of the Injection molding machine.

Safety Precautions

1. Connection of Power Source

Earthing for the machine: It has to be done by a qualified personnel hired by the customer and the measured resistance of earthing should be less than 1Ω typically. Circuit Breaker: circuit breaker has to be installed in the electrical line of the Injection Molding Machine. The position of the circuit breaker has to be on the power side or inside the switchboard of power supply. A medium sensitive, high speed type (100mA) circuit breaker is recommended to be installed. The fluctuation in power source voltage (input supply) has to be within 10% range of the rated value.

2. Cooling Water

The piping size has to be three times more than the required water flow. This is due to varied requirement of cooling water at different ambient temperature, water temperature, molding conditions etc., and also there will be scaling formation over a long period of time.

3. Operation and storage conditions

To avoid operation failure the following conditions must be strictly maintained

 a. Ambient temperature (operation): +15˚C ~ +45˚C (+59˚F ~ +113˚F) 

b. Ambient temperature (storage) : - 40˚C ~ +70˚C (- 104˚F ~ +158˚F)

 c. Ambient Humidity: 30%RH ~ 85% RH (No dew allowed) 

d. Hydraulic fluid temperature (operation) : +30˚C ~ +55˚C (+86˚F ~ +113˚F)

 Before operating, check whether the machine is properly attached with safety labels and the safety devices are functioning normally Do not operate the machine unless thoroughly instructed on safety rules and operations

4. Purging 

 During purging or molding material changing do injection at very less speed to prevent decomposed resin from spurting out. Stay away from the nozzle during this operation. 

5. Removal of dripping plastic melt from the nozzle

 Do not remove dripping plastic melt from the nozzle tip when the nozzle is advancing (IU forward).

6. Approaching the nozzle tip

 During barrel heating and after the set temperature reaches keep your hands and face away from the nozzle tip as gas pressure can cause molten plastic which is at very high temperature to gush out even when it is not injected Do not touch the nozzle and barrel heat shield since the surfaces are very hot under high voltage .

 Before checking any electrical parts and wiring such as heaters or thermocouple please turn OFF the power and measure the voltage at the servicing point to check that the power is OFF 

When the machine is working do not insert your hands through the injection cover (Injection side cladding) and never ever touch the moving parts of the machine.  The machine should not be operated with the injection cover and barrel heat shield in removed condition.

7. Plasticizing screw removal

 Turn OFF the power switch  before removing the screw. And never stand in the direction of removal of the screw to avoid injury if the screw flies out 5. Inspection and cleaning of the Hopper .

 Wear personal safety equipment like face, hand and arm protectors while inspecting and cleaning the hopper. Molten plastic or gases may gush out. Ensure that the set temperature of the barrel is correct for the material to be processed. Abnormal temperature may degrade the molten plastic and may cause decomposed gas to gush out Do not step on the barrel heat shield.

 The shield is only for preventing burns and electric shock. If the heat shield is damaged it can be very dangerous for the personnel who is working in the machine.