Safety Precautions for Injection Molding
Learn more about potential hazards plus the available machine and operator safety precautions.
Safety is critical in manufacturing operations, and the injection molding process presents its own set of hazards and safety concerns. High temperatures, high-pressure hydraulic circuits, and hazardous fumes all pose a risk to operators, and the popularity of injection molding provides many opportunities for accidents. There are methods to prevent safety breaches, but they all involve education on how injection molding works and where the danger lies in the process.
This article will help educate readers by detailing various safety precautions for injection molding, covering machine and operational procedures.
Below is an image of an injection molding machine as used in an industrial setting.
Plastic injection molding involves mechanical and thermal hazard sources, where users can experience burns, crushes, impacts, and other dangers. Not only do improper safety procedures jeopardize the longevity of machines, but they can also lead to operator injury, so it is essential to define a working protocol for all aspects of the injection molding process.
The American National Standards Institute (ANSI) defines a safety standard for all horizontal and vertical clamp injection molding machines in its ANSI/PLASTICS B151.1-2017 – Plastics Machinery – Safety Requirements for Injection Molding report. It defines the potential danger zones of injection molding divided into classifications defined as mechanical/thermal, electrical, and other hazards.
A summary of these potential hazard areas appears below for each classification:
- Mold Area
- Clamping mechanism area
- Core and ejector drive mechanism areas
- Nozzle area
- Injection unit area
- Feed hopper/opening area
- Heater bands/heat source areas
- Parts discharge area
- Hoses and manifolds in/around the machine
- Inside the guard and outside mold areas
- Part insert and removal areas
- Electromagnetic component disturbances
- Stored/residual energy areas
- Vapors and gasses
The standard also states that the risk responsibility of injection molding machines is attributable to multiple parties but is principally determined by whether the machine is in use or not. Existing machines in use must be kept safe by the users (manufacturing company, business, etc.), and this includes everything from installation to operation to maintenance. Responsibility for machines currently being repaired, manufactured, or upgraded is shared by both the user and the technician/repair person/service supplier.
The injection molding machine must be constantly evaluated and maintained for safety. Taking the proper precautions prevents the machine from causing harm, eliminating any primary safety issues. The list below includes the necessary considerations that should be checked by operators when examining the injection molding machine before, during, and after use:
- The machine and its platform are free of debris, past materials, oil, water, etc., and no vital safety equipment/devices are missing.
- All safety equipment (especially eye protection) is present, undamaged, and operative.
- Fire extinguishers, first aid kits, and personal protective equipment are present and readily available in needed quantities as per work staff numbers.
- The environment around the machine is clean and free of slipping hazards such as oil or water leaks on the ground.
- All tooling and equipment are in good condition (this will depend on maintenance-specific factors of your machine).
- All temperatures in the barrel, the hydraulics, and the mold are to the project's specifications and are held during a cycle.
- All pressures in the barrel and the mold are to the project's specifications and are held during a cycle.
- There are no plastic materials left inside, on, or around the machine before beginning operation, and no sprues, runners, gates, etc. within the barrel, nozzle, or mold cavity.
- All hoses and cords are fully intact with no damage to their insulation or cladding.
- All mold setup steps are followed as posted on the setup sheet/procedure before injection molding.
Ensuring that your injection molding machine is fully operational and in compliance with the above considerations is vital for safety precautions. It provides operators a primary defense against unforeseen issues and keeps equipment from prolonged states of degradation that will ultimately halt a project if left unattended.
The second (and arguably more important) half of injection molding safety relates to how the operator interacts with the machine. Operators are commonly required to open the operator’s gate and retrieve a finished part from the mold, a dangerous task if, for example, it is being done between two massive molds with the size and weight of a small vehicle, as seen in the image below.
Half of a large mold used for injection molding.
They also operate the control panel, provide manual feeding of material, as well as service and maintain the machine using lockout/tagout procedures and additional measures— all of which can expose them to risks.
With automation entering the injection molding sphere, these considerations may quickly become outdated. However, it is still important to understand the operative dangers of injection molding.
The list found below cannot encompass all considerations for every injection molding operator. Still, it does provide the general steps to ensure proper safety precautions while operating an injection mold machine:
- Before even touching the machine, all operators must be adequately trained in machine operation, workspace management, and proper lockout/tag-out protocol.
- Operators should never reach over or under machine guards, stick appendages into the hopper/granulator, or stand directly below a suspended mold.
- PPE such as safety glasses, safety shoes, and respirators (if required) should always be worn during operation, and proper lifting techniques should be learned (e.g., upright back, lift with legs).
- Operators should never free climb on the machine, horseplay around the area, or leave catwalks/railed platforms when needing to climb the machine.
- Training must be provided on the chemical hazards associated with the injection molding process, both with regard to the material and any supporting chemicals such as mold release, lubricant, etc., used in the injection molding process.
- Safety measures should not be bypassed, modified, or altered on any or all safety equipment for the sake of expediency.
- Every worker should know the location and route to fire extinguishers, fire exits, and other emergency tools.
- Operators should double-check that the nozzle tip is firmly in place and correctly centered prior to molding.
- When changing materials, operators should understand the possible chemical reactions and related issues between the two materials (some thermoplastics will produce toxic gases when mixed).
- No steel tools are to be used on the mold cores when cleaning/performing maintenance, opting instead for copper, aluminum, or bamboo tools that will not scratch the mold.
- If there is a shutdown, heaters must be turned off, and plastic in the plasticizing cylinder must not be further heated.
- Operators must remain vigilant of sharp ejector pins and corners and frayed wires near the nozzle heater bands.
- It is strictly forbidden for operators to open the safety door at unauthorized times. The front gate should have mechanical, electrical, and hydraulic devices to prevent closing when the gate is open.
- Double check that the mold is firmly aligned on the platen and the head plate.
- Report any and all issues to relevant supervisors, including open junction boxes, leaks, frayed wires, loose water, or injuries.
There are many more model-specific safety precautions to be taken—this list only provides a general overview of the minimum requirements for safety when performing injection molding. Be sure to understand the specific safety requirements and recommendations for your machine, and if you are unsure, reach out to the manufacturer or service provider for safety protocols.
This article presented a summary of various safety precautions associated with the injection molding process and the use of injection molding machines. We hope this article helped readers understand the dangers involved in this manufacturing process and how to mitigate them with maintenance, vigilance, and due diligence on the part of the operator.
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