Plastic processing products are made by injecting synthetic resin into molds mounted on injection molding machines, allowing it to solidify. The injection molding process involves mold closure, injection, packing, cooling, mold release, and product separation.
After injection molding, products undergo processes such as trimming, inspection, and assembly to complete them. During these stages, there are risks such as machine jams, collisions with robots, and musculoskeletal disorders due to handling heavy objects.
▣ The hazardous factors and preventive measures for each process
1.The hazardous factors and preventive measures for raw material receiving, outgoing, and loading
| Activity | Harmful/Risk Factors | Preventive measures |
| Transportation using a forklift | – Collided with a worker while operating a forklift – Fall while operating a forklift |
– Separate entrances for transportation machinery and pedestrians are installed. – Installation of safety passageways in the workplace -Observe the speed limit within the workplace and assign a work leader or guide. -The forklift is operated by a qualified person. -Attach and maintain forklift safety devices |
| Loading raw materials into warehouse | -Collapse of raw materials due to high-level loading or damage to pallets | -High-level loading of raw materials is prohibited. -Check for damage to the pallet and improve its strength. |
| -Back pain due to manpower transport | -Use of mobile cart and transport by 2 people. -Stretching to prevent musculoskeletal disorders -Strict safety measures such as attaching stoppers to mobile cart wheels |
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| -Collided during transport using a crane | -Ensure sufficient work space -Determine a certain signal method and signal, and the driver must obey the signal. |
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| -Hit by heavy objects due to breakage of chains or wire ropes and hangers. | -Before starting work, inspect ropes and hanging devices, etc. – Complies with the hanging rope safety factor according to the weight of the hanging object. -Use auxiliary tools when guiding salvage objects -Follow safety rules when doing rope hanging work. -Entry under suspended heavy objects is prohibited. -Inspect and maintain the function of crane safety devices |
2. Mixing
| Activity | Harmful/Risk Factors | Preventive measures |
| mixer | -Back pain while inputting raw materials | -Automates raw material input work -When transporting and inserting heavy objects, two people work as a team. -Perform periodic rest and stretching |
| -Getting caught in the mixer pumper when removing foreign substances or cleaning during operation. -Getting caught due to unexpected operation during maintenance/repair work |
-Inserting raw and subsidiary materials and removing foreign substances while working is prohibited. -Install the mixer lid and install the interlocking device. -During maintenance/repair work, turn off the power, install a ‘Work in progress’ sign (tag), and install a lock on the operation panel. |
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| -High part fell during repair work | -Work platforms and safety railings are installed at the top of the facility. | |
| -Health problems caused by dust | -Wear personal protective equipment such as a dust mask. | |
| tumbler mixer | -Collision when rotating cylinder | -Touching within the operating range is prohibited, including installation of protective barriers. |
| -Musculoskeletal diseases when inputting raw materials | -Stretching to prevent musculoskeletal disorders -When transporting and inserting heavy objects, two people work as a team. |
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| -Slip and fall due to resin particles falling on the floor | -Housekeeping | |
| -Being hit by a heavy load due to damage to the crane wire rope or chain. | -Safety inspections are conducted on protective devices such as crane winding prevention devices before work. -Entry into the hazardous area below the salvage is prohibited. -Inspection of work delivery mechanism |
3.Raw material transportation and input
| Activity | Harmful/Risk Factors | Preventive measures |
| Transport of raw materials/input raw materials into hopper by manpower | -Falling when transporting raw material sacks | -Use a mobile truck and transport with a team of 2 people |
| -Injection molding machine located at a high place where raw materials contained in a bag fall while being placed in the hopper section. | -Use a designated workbench and auxiliary stand. -Uses automatic feeding device |
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| -Musculoskeletal disorders such as back pain due to carrying heavy objects | -Stretching to prevent musculoskeletal disorders -When transporting heavy objects, two people work as a team. |
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| -Dust generated when inputting raw materials in bags | -Use local exhaust or raw material recovery equipment -Wear personal protective equipment such as a dust mask. |
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| – Hit by heavy objects due to damage to crane wire rope or chain | -Conduct safety inspections on protective devices such as crane winding prevention devices before work. -Entry into the hazardous area below the salvage is prohibited. -Inspection of work delivery mechanism |
4.Injection and ejection
| Activity | Harmful/Risk Factors | Preventive measures |
| Mold mounting work using a crane | – Collision while transporting mold using crane | -Workers are prohibited from entering under suspended heavy objects. |
| -Being hit by a heavy object while transporting a mold using a crane | -Inspect and maintain the function of crane safety devices such as overload prevention and hook release device. -Check for damage to the hanging rope and comply with the hanging rope safety factor according to the weight of the heavy object. |
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| -Getting caught during mold installation work | -Find out information about the mold such as weight, size, installation decoration, etc. in advance. – Use a flexible connecting rope or crane scale between the mold hanging eyebolt and the crane hook to facilitate positioning. |
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| Nozzle and barrel replacement due to replacement of raw materials, etc. | -Burns due to contact with high temperature barrel -Burns caused by high-temperature, high-pressure molten resin eruption |
-Wear personal protective equipment such as safety glasses and face shield. -Check whether the molding resin pressure is present -Turn off the motor power during replacement work. |
| -Stuck between barrel and screw | – Comply with the specified tightening torque when tightening bolts. | |
| -Electric shock due to contact with heater terminals | -Turn off the motor power before disassembly work. -Attach the fixing cover after completing the work. |
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| Manual removal of injection molded products | -Getting caught between molds during injection and ejection operations -Damage of injection machine protection device, jamming due to removal of function -Getting caught due to malfunction during maintenance/repair work |
-Inspection, maintenance, and management of electrical, mechanical, and hydraulic safety door interlocking devices – During maintenance/repair work, turn off the motor power or the injection machine, install a lock on the operation panel, and install a ‘under inspection’ sign (tag). |
| Automatic removal of injection molded products using robots and Kinveyer | -Struck by the take-out robot | -Turn off motor power or injection machine power during maintenance/repair work. -Prohibit access when operating the robot. |
| -Getting caught in the transport conveyor | -Attach a protective cover to the conveyor power transmission unit. |
5. Finishing, inspection and assembly
| Activity | Harmful/Risk Factors | Preventive measures |
| The idea of removing unnecessary parts from products | -Cuts when working with tools such as knives | -Produce and use thought tools appropriate for the task. -Introduced automation of thought tasks |
| -Getting caught by automated finishing machines | -Protective measures are taken, such as attaching photoelectric safety devices to automation machines for sanding work. | |
| -Musculoskeletal disorders caused by simple repetitive work. | -Perform periodic rest and stretching during simple repetitive tasks. | |
| Ultrasonic bonding, manual assembly | -Getting caught during assembly work using press or ultrasonic glue machine | -Use photoelectric safety devices or two-hand operation safety devices during ultrasonic bonding work and assembly work using a press. |
6. Smash
| Activity | Harmful/Risk Factors | Preventive measures |
| Grind using a low or high speed grinder | -Getting stuck when putting ground material into the grinder | -Use an auxiliary device when adding crushed material |
| -Noise when grinding at high speed | -Wear soundproofing protective gear during high-speed grinding work. | |
| -Getting caught when inspecting or cleaning the grinder | -During inspection and cleaning work, turn off the power, install a locking device on the operation panel, and install a ‘inspection’ sign (tag). -Operation is prohibited when the protective device is dismantled. |
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| -Dust generated during grinding work | -Wear protective gear such as a dust mask. -Install covers in areas where crushed material is likely to scatter or splash. |
▣ Injection molding machine
The injection molding machine is a device used to produce molded products by injecting molten thermoplastic or thermosetting plastics, rubbers, etc., between two molds via a nozzle under pressure. The sequence of operations includes resin input (hopper), resin melting (barrel), injection (nozzle), molding (mold), and product ejection.
During these processes, accidents such as falling, electric shock, burns, and jams can occur. It is essential to ensure the installation status and operational condition of safety door interlocking devices before operating the injection molding machine and strictly manage not to release safety devices arbitrarily. In case of abnormalities during operation, always report to the supervisor and handle the situation collectively rather than dealing with it alone.
When entering the molding area of a large injection molding machine to remove foreign substances from the mold, check the status of the working platform-type guardrails and the installation of insulation caps or covers on the exposed charging parts of the barrel and nozzle. Additionally, confirm the installation status of safety guardrails (for places with a height of more than 2m) at the raw material input point in the hopper.
Avoid accessing the interior of the mold to remove foreign substances while the machine is in operation. Follow safety procedures for mold attachment, disassembly, or storage operations. During machine maintenance and cleaning, stop the operation, attach an operation prohibition tag or remove the key from the start switch, and keep it with the operator.
▣ Take-out Robots
The term “취출(取出)” means “to take out” in English, and it refers to a dedicated robot installed in the mold of an injection molding machine to remove processed plastic products. This robot is called a “취출로봇 (take-out robot)” and is equipped in most injection molding machines..
To remove molded products, there is a risk of getting stuck between the molds or being caught in the safety door of the injection molding machine when the operator partially inserts their body after opening the safety door, or if the safety features of the door are disabled or malfunction, allowing the door to open while working, leading to accidents. Additionally, there is a risk of collision if workers enter the operating area of the take-out robot.
To prevent accidents caused by power loss or pressure loss of compressed air supplied to the take-out robot, mechanisms such as descent prevention pins are installed to prevent the upper and lower moving axes from descending arbitrarily. Furthermore, position detection sensors and stoppers are installed at the ends of each axis of the take-out robot to prevent detachment.
When manually operating the take-out robot, it should be designed to require the simultaneous operation of two control switches to prevent operating errors and should be equipped with an emergency stop device.
