Injection Molding Safety Manual

Injection Molding Workplace Hazards

Injection molding combines high temperatures, high pressures, powerful mechanical movement, stored energy, and automated equipment.

Potential hazards include:

• Moving machine components
• Clamping mechanisms
• Mold areas
• Crushing and pinch points
• Unexpected machine movement
• Hydraulic pressure
• Pneumatic pressure
• Electrical energy
• Heated barrels and nozzles
• Molten plastic
• High-pressure plastic release
• Purging operations
• Robots and automated equipment
• Mold changes
• Material-handling equipment
• Granulators and grinders
• Plastic resins and additives
• Fumes and decomposition products
• Noise
• Slips and falls
• Manual material handling

Employees should receive training appropriate to the equipment and tasks they perform.

Injection Molding Machine Safety

Injection molding machines use significant mechanical force, pressure, and heat to produce molded products.

Employees should:

• Follow manufacturer instructions.
• Operate only equipment they are authorized and trained to use.
• Keep guards and safety devices in place.
• Remain clear of moving components.
• Avoid reaching into hazardous machine areas.
• Follow established startup and shutdown procedures.
• Report abnormal machine operation.
• Stop equipment when unsafe conditions develop.

Employees should never bypass a safety device to increase production speed or simplify machine operation.

Clamping Unit Safety

The clamping unit develops substantial force to close and hold the mold during injection.

Employees should remain outside hazardous clamping and mold areas while the machine is capable of movement.

Potential hazards include:

• Crushing
• Pinching
• Shearing
• Mold movement
• Ejector movement
• Tie-bar hazards
• Unexpected cycling

Employees should never place any part of their body between mold halves unless hazardous energy and movement have been appropriately controlled.

Mold Area Safety

The mold area may contain several hazards simultaneously, including hot surfaces, moving platens, ejector systems, cores, slides, hydraulic components, and molten plastic.

Employees should:

• Keep hands clear during machine cycles.
• Use appropriate tools for removing parts when necessary.
• Avoid reaching into the mold area while hazardous movement is possible.
• Follow safe procedures for stuck parts.
• Wear appropriate PPE.
• Follow lockout/tagout procedures when required.

Production pressure should never justify reaching into an operating machine.

Machine Guarding

Injection molding machines and auxiliary equipment should have appropriate guarding for hazardous moving components.

Guards may be necessary around:

• Mold areas
• Clamping mechanisms
• Belts and pulleys
• Chains and sprockets
• Rotating shafts
• Fans
• Granulators
• Conveyors
• Other moving machinery

Employees should not remove, bypass, defeat, or modify guards without authorization.

Missing or damaged guards should be reported promptly.

Interlocks & Safety Devices

Injection molding equipment may incorporate gates, doors, interlocks, presence-sensing devices, emergency stops, or other protective systems.

Employees should:

• Use safety devices as intended.
• Never intentionally defeat an interlock.
• Report malfunctioning devices.
• Avoid modifying safety systems.
• Verify proper operation as required by established procedures.

A machine with a defective critical safety device should not continue normal operation until the condition has been appropriately addressed.

Emergency Stops

Employees should know the locations and functions of applicable emergency-stop controls.

Emergency stops should remain:

• Accessible
• Identifiable
• Unobstructed
• Maintained in operating condition

Employees should understand that activating an emergency stop does not necessarily control all hazardous energy and is not a substitute for lockout/tagout when energy isolation is required.

Lockout/Tagout

Injection molding machines and associated equipment can contain multiple hazardous-energy sources.

Potential energy sources include:

• Electrical
• Mechanical
• Hydraulic
• Pneumatic
• Thermal
• Gravity
• Stored pressure

Applicable energy-control procedures should be followed during servicing and maintenance when unexpected startup, machine movement, or release of stored energy could cause injury.

Only appropriately trained and authorized employees should perform lockout/tagout.

Stored Energy

Shutting off a machine does not necessarily eliminate all hazardous energy.

Stored energy may remain in:

• Hydraulic accumulators
• Pressurized lines
• Pneumatic systems
• Injection units
• Elevated components
• Springs
• Heated components
• Electrical systems

Employees performing servicing should verify that hazardous stored energy has been relieved, restrained, blocked, dissipated, or otherwise controlled as required by the applicable procedure.

Hydraulic Systems

Injection molding machines frequently rely on hydraulic systems to operate clamps, injection units, ejectors, cores, and other equipment.

Employees should:

• Inspect for visible leaks and damage.
• Avoid touching suspected high-pressure leaks.
• Report damaged hoses and fittings.
• Follow energy-control procedures before servicing.
• Relieve stored pressure as required.
• Keep body parts away from potential injection points.

Employees should never use their hands to search for a hydraulic leak.

Pneumatic Systems

Compressed air and pneumatic equipment may operate valves, gates, cylinders, material-handling equipment, or other machine components.

Before servicing pneumatic systems, employees should follow applicable procedures for isolating and relieving hazardous pressure.

Hoses, fittings, and connections should be maintained in safe condition.

Electrical Safety

Injection molding machines, heaters, dryers, robots, conveyors, granulators, and other auxiliary equipment may contain significant electrical hazards.

Employees should:

• Keep electrical enclosures closed.
• Report damaged cords and equipment.
• Avoid unauthorized electrical work.
• Maintain access to electrical panels.
• Keep liquids away from unsuitable electrical equipment.
• Follow electrical safe-work practices.

Only qualified personnel should perform electrical work requiring specialized qualifications.

Hot Surfaces

Barrels, heater bands, nozzles, molds, manifolds, piping, and processed materials may reach temperatures capable of causing serious burns.

Employees should:

• Recognize hot equipment.
• Avoid unnecessary contact.
• Use appropriate tools.
• Wear suitable PPE.
• Allow equipment to cool when required.
• Treat recently operated equipment as potentially hot.

Guards, insulation, shields, or warning methods should be used where appropriate.

Molten Plastic

Molten thermoplastic may cause severe thermal burns.

Employees should:

• Keep exposed skin away from molten material.
• Wear appropriate eye and face protection.
• Use heat-resistant protective equipment where required.
• Maintain distance from potential discharge points.
• Use tools rather than hands to handle hot material.
• Follow established procedures for leaks and spills.

Employees should never assume that partially cooled plastic is safe to touch.

Injection Pressure

Plastic inside an injection molding machine can be under substantial pressure.

Employees should remain clear of nozzles, mold openings, and other locations where pressurized molten material could unexpectedly escape.

Pressure should be appropriately controlled before employees perform servicing or open components that could contain pressurized material.

Purging Operations

Purging is one of the more distinctive hazards of injection molding because heated plastic may be discharged from the injection unit during material changes, startup, shutdown, troubleshooting, or cleaning.

Purging procedures should address:

• Employee positioning
• Discharge direction
• Appropriate guarding or shielding
• Heat-resistant PPE
• Eye and face protection
• Appropriate tools
• Control of nearby personnel
• Ventilation
• Handling of hot purge material
• Fire prevention

Employees should never stand directly in front of a nozzle or other expected discharge path during purging.

Degraded & Decomposed Plastic

Plastic remaining at excessive temperatures or processed improperly may degrade and produce smoke, fumes, pressure, or hazardous decomposition products.

Employees should follow material-specific processing recommendations and established procedures for abnormal conditions.

If unusual smoke, odor, discoloration, pressure, or decomposition is observed:

• Stop or modify the process as appropriate.
• Keep unnecessary employees away.
• Maintain or increase appropriate ventilation when safe.
• Follow established troubleshooting procedures.
• Use required PPE.
• Obtain assistance when necessary.

Employees should not unnecessarily expose themselves to fumes from overheated plastic.

Plastic Resins

Injection molding facilities may process:

• Polyethylene
• Polypropylene
• ABS
• Nylon
• Polycarbonate
• Acetal
• PVC
• Thermoplastic elastomers
• Engineering resins
• Other polymers

The hazards associated with a material may change when it is heated, processed, mixed with additives, or thermally degraded.

Employees should have access to appropriate hazard information for the materials they handle.

Additives, Colorants & Processing Chemicals

Operations may use pigments, masterbatch, release agents, cleaners, lubricants, mold-protection products, solvents, and other chemicals.

Employees should:

• Review labels.
• Follow Safety Data Sheet information.
• Wear appropriate PPE.
• Maintain appropriate ventilation.
• Avoid unnecessary skin contact.
• Store products properly.
• Follow spill procedures.

Chemicals should not be mixed or substituted without appropriate authorization.

Hazard Communication

Hazardous chemicals and materials should be addressed through the facility’s Hazard Communication Program as applicable.

Employees should receive information and training regarding:

• Chemical hazards
• Labels
• Safety Data Sheets
• Protective measures
• PPE
• Storage
• Spill procedures
• Emergency response

Employees should understand that processing a material at elevated temperatures may introduce hazards not encountered when handling the material at room temperature.

Ventilation & Fume Control

Injection molding processes may generate fumes, vapors, smoke, or odors, particularly during purging, overheating, material degradation, or certain processing operations.

The facility should evaluate potential employee exposure and provide appropriate ventilation or other controls where necessary.

Employees should:

• Use ventilation systems as intended.
• Report ventilation problems.
• Avoid unnecessary exposure to process fumes.
• Report unusual or persistent odors.
• Follow procedures for overheated or decomposing material.

Respiratory Protection

Engineering and work-practice controls should be used where feasible to control airborne hazards.

When respiratory protection is required, respirators should be selected and used in accordance with the company’s Respiratory Protection Program.

Employees required to wear respirators should receive applicable medical evaluations, fit testing, and training.

Personal Protective Equipment

PPE should be selected according to the task and anticipated exposure.

Depending on the operation, PPE may include:

• Safety glasses
• Chemical splash goggles
• Face shields
• Heat-resistant gloves
• Chemical-resistant gloves
• Protective sleeves
• Safety footwear
• Hearing protection
• Protective clothing
• Respiratory protection

Employees should understand the limitations and proper use of assigned PPE.

Eye & Face Protection

Eye and face hazards may occur during:

• Purging
• Nozzle cleaning
• Material handling
• Granulating
• Maintenance
• Chemical handling
• Compressed-air use

Appropriate eye protection should be worn based on the hazard.

Face shields may supplement but do not necessarily replace required primary eye protection.

Mold Changes

Mold changes may expose employees to suspended loads, crushing hazards, pinch points, hydraulic connections, hot surfaces, and hazardous energy.

Mold-change procedures should address:

• Machine shutdown
• Lockout/tagout when required
• Mold temperature
• Lifting equipment
• Mold attachment points
• Rigging
• Employee positioning
• Hydraulic and electrical connections
• Mold securement
• Verification before startup

Only appropriately trained employees should participate in mold changes.

Mold Handling

Injection molds may weigh hundreds or thousands of pounds and can cause catastrophic injury if dropped, shifted, or improperly supported.

Employees should:

• Know or determine mold weight.
• Use appropriately rated lifting equipment.
• Use designated lifting points when provided.
• Inspect lifting devices and rigging.
• Keep employees clear of suspended loads.
• Avoid placing body parts beneath or between an unsecured mold and machine.
• Secure molds during storage.

Improvised lifting methods should not be used.

Cranes, Hoists & Lifting Devices

Overhead cranes, jib cranes, gantries, hoists, forklifts, or other lifting equipment may be used for mold handling.

Employees operating lifting equipment should be appropriately trained or qualified for their assigned duties.

Lifting equipment should:

• Have adequate capacity.
• Be inspected as required.
• Be used within rated limits.
• Be positioned appropriately.
• Be maintained in safe condition.

Employees should remain clear of suspended loads.

Rigging

Slings, chains, shackles, eyebolts, lifting rings, and other rigging equipment used during mold changes should be appropriate for the load and lifting configuration.

Rigging should be inspected before use and removed from service when defective.

Employees should avoid shock loading and side loading components unless they are designed for that use.

Robots & Automated Equipment

Injection molding cells may contain robots, pickers, sprue removers, automated conveyors, vision systems, and other automated equipment.

Employees should remain outside safeguarded areas while hazardous automated movement is possible.

Employees should not:

• Reach through guards.
• Climb over barriers.
• Bypass interlocks.
• Enter robot work envelopes without appropriate controls.
• Assume that stopped equipment cannot restart.

Servicing or troubleshooting inside safeguarded areas should follow established energy-control and machine-specific procedures.

Part Removal

Finished parts may be removed manually, mechanically, or robotically.

Employees performing manual removal should:

• Stay clear of mold movement.
• Avoid pinch points.
• Use appropriate tools.
• Follow established machine cycles.
• Avoid defeating safeguards for easier access.

Repeated reaching into hazardous machine areas should be eliminated or controlled wherever practical.

Stuck Parts

Employees should not reach into hazardous machine areas to remove a stuck part while machine movement remains possible.

Safe procedures may require:

• Stopping the machine
• Controlling hazardous energy
• Using appropriate tools
• Allowing hot components to cool
• Obtaining maintenance assistance

Production delays should never justify unsafe entry into a machine.

Granulators & Grinders

Granulators and grinders can expose employees to rotating knives, flying material, noise, dust, and unexpected startup.

Employees should:

• Keep guards and covers secured.
• Avoid reaching into feed openings.
• Use appropriate tools.
• Follow shutdown and lockout/tagout procedures before servicing or clearing jams.
• Wear appropriate PPE.
• Control dust and housekeeping.

Employees should never use hands or feet to force material into operating equipment.

Material Dryers & Hoppers

Resin dryers, hoppers, loaders, and material-handling systems may present heat, electrical, mechanical, dust, and access hazards.

Employees should:

• Follow operating procedures.
• Avoid contact with hot surfaces.
• Maintain guards.
• Use appropriate access equipment.
• Follow energy-control procedures during servicing.
• Keep access platforms and floors clear.

Employees should not climb on machinery or use improvised access methods.

Vacuum Material-Handling Systems

Vacuum loaders and centralized resin systems may contain moving components, electrical equipment, filters, piping, and stored vacuum or pressure.

Employees should follow manufacturer and facility procedures during operation, cleaning, and maintenance.

Systems should be appropriately shut down and isolated before servicing when hazardous energy is present.

Conveyors

Conveyors may transport finished parts, scrap, packaging materials, or raw materials.

Employees should:

• Keep clear of pinch points.
• Maintain guards.
• Avoid walking or climbing on conveyors.
• Use designated crossings.
• Keep clothing and body parts away from moving components.
• Follow lockout/tagout procedures before servicing.

Compressed Air

Compressed air may be used for equipment operation, cleaning, or process functions.

Employees should:

• Inspect hoses and fittings.
• Avoid directing compressed air at themselves or others.
• Use compressed air only for approved purposes.
• Follow applicable pressure limitations and protective measures.
• Control stored pressure before servicing equipment.

Forklifts & Powered Industrial Trucks

Forklifts may be used to move molds, raw materials, finished products, containers, and other loads.

Only trained and authorized employees should operate powered industrial trucks.

Operators should:

• Conduct required inspections.
• Observe rated capacity.
• Maintain visibility.
• Control speed.
• Watch for pedestrians.
• Secure loads.
• Follow facility traffic rules.

Pedestrians should remain alert in forklift operating areas.

Pallet Jacks & Material-Handling Equipment

Employees using powered or manual pallet jacks should:

• Inspect equipment before use.
• Maintain control of loads.
• Keep feet clear of wheels and loads.
• Avoid exceeding equipment capacity.
• Travel at a controlled speed.
• Maintain awareness of pedestrians.

Defective equipment should be removed from service or otherwise controlled.

Manual Material Handling

Employees may handle resin bags, boxes, parts, scrap, tooling, packaging materials, and supplies.

Before lifting, employees should evaluate:

• Weight
• Size
• Grip
• Stability
• Travel path
• Destination

Mechanical assistance or team lifting should be used when appropriate.

Ergonomics

Injection molding work may involve repetitive part handling, trimming, inspection, packing, reaching, lifting, and standing.

Ergonomic improvements may include:

• Adjustable workstations
• Improved material positioning
• Lift tables
• Conveyors
• Carts
• Reduced reaching
• Task rotation
• Appropriate tools
• Automation

Employees should report recurring discomfort or tasks requiring excessive force or awkward posture.

Trimming & Secondary Operations

Finished parts may require trimming, cutting, drilling, welding, assembly, decorating, or other secondary operations.

Employees should use appropriate tools and follow applicable safety procedures.

Potential hazards may include:

• Cuts
• Flying particles
• Moving machinery
• Hot surfaces
• Chemicals
• Fumes
• Noise
• Repetitive motion

Hand & Power Tool Safety

Hand and power tools used for mold work, maintenance, trimming, or production should:

• Be appropriate for the task.
• Be inspected before use.
• Have required guards.
• Be maintained in safe condition.
• Be removed from service when defective.

Employees should use appropriate PPE.

Maintenance & Troubleshooting

Maintenance and troubleshooting may expose employees to hazards not present during normal production.

Before beginning work, employees should identify:

• Hazardous energy
• Machine movement
• Stored pressure
• Hot surfaces
• Electrical hazards
• Elevated components
• Automated equipment
• Chemical hazards

Employees should not place themselves inside hazardous machine areas until appropriate protective measures have been established.

Preventive Maintenance

Injection molding machines and auxiliary equipment should receive preventive maintenance according to manufacturer recommendations and facility procedures.

Maintenance programs may address:

• Guards
• Interlocks
• Emergency stops
• Hydraulic systems
• Electrical systems
• Heater systems
• Ventilation
• Robots
• Conveyors
• Granulators
• Material-handling equipment

Identified safety defects should be corrected promptly.

Equipment Inspection

Employees should inspect equipment as required before or during operation.

Potential inspection items include:

• Guards
• Gates
• Interlocks
• Emergency stops
• Hydraulic leaks
• Electrical damage
• Hoses and fittings
• Abnormal noise
• Abnormal vibration
• Material leaks
• Housekeeping conditions

Employees should report unsafe conditions promptly.

Noise

Granulators, compressors, molding machines, material-handling equipment, and other manufacturing processes may create significant noise.

Where employee exposure warrants evaluation, the facility should assess noise exposure and implement appropriate controls.

Controls may include:

• Equipment maintenance
• Enclosures
• Isolation
• Reduced exposure time
• Hearing protection
• Hearing conservation measures when required

Slips, Trips & Falls

Pellets, plastic scrap, oil, hydraulic fluid, water, packaging materials, cords, and hoses can create walking-surface hazards.

Employees should:

• Clean spills promptly.
• Remove loose pellets.
• Maintain clear aisles.
• Store materials properly.
• Control cords and hoses.
• Report damaged walking surfaces.
• Use designated walkways.

Plastic pellets on smooth floors can create particularly slippery conditions and should be cleaned promptly.

Resin Pellet Control

Spilled resin pellets should be contained and removed promptly.

Employees should:

• Avoid allowing pellets to accumulate around machinery.
• Keep pellets out of walking and vehicle paths.
• Use appropriate cleanup equipment.
• Prevent pellets from entering drains or leaving the facility where practical.
• Report recurring material leaks.

Housekeeping

Good housekeeping helps reduce slips, fires, equipment problems, and material-handling hazards.

Employees should:

• Maintain clear aisles.
• Remove scrap.
• Store tools properly.
• Keep electrical panels accessible.
• Control resin spills.
• Maintain access to emergency equipment.
• Keep combustible materials away from inappropriate heat sources.

Fire Prevention

Injection molding facilities may contain combustible plastics, packaging materials, hydraulic fluids, electrical equipment, heaters, and other potential fire hazards.

Employees should:

• Control ignition sources.
• Maintain good housekeeping.
• Report overheated equipment.
• Store flammable materials appropriately.
• Maintain access to fire protection equipment.
• Follow emergency procedures.

Hot Work

Welding, cutting, grinding, brazing, or other hot work may be necessary during mold repair or equipment maintenance.

Hot work should be performed according to established procedures addressing:

• Combustible materials
• Fire protection
• Ventilation
• PPE
• Fire watch when required
• Hot work authorization or permits where applicable

Chemical Spill Response

Facilities should establish procedures for foreseeable releases involving chemicals, oils, hydraulic fluids, and other materials.

Employees should:

• Identify the material when possible.
• Keep unnecessary personnel away.
• Wear appropriate PPE.
• Stop the source when safe.
• Contain the release when practical.
• Follow cleanup procedures.
• Obtain specialized assistance when necessary.

Employees should not respond beyond their training or available protection.

Waste & Scrap Handling

Injection molding operations may generate:

• Plastic runners
• Sprues
• Rejected parts
• Purge material
• Resin
• Packaging waste
• Used oils
• Solvents
• Contaminated absorbents
• Other industrial waste

Waste should be collected, stored, recycled, or disposed of according to applicable procedures.

Hot purge material should be allowed to cool in a controlled location before ordinary handling or disposal.

Working at Heights

Employees may need access to elevated hoppers, dryers, material systems, platforms, or other equipment.

Employees should use designated platforms, stairs, ladders, or other appropriate access systems.

Employees should not climb on machinery, racking, or other surfaces not designed for employee access.

Ladder Safety

Ladders and portable stepstools should be:

• Appropriate for the task.
• Inspected before use.
• Positioned on stable surfaces.
• Used according to manufacturer instructions.

Employees should avoid overreaching and should not substitute boxes, pallets, or equipment for an appropriate ladder.

Walking-Working Surfaces

Aisles, platforms, stairs, mezzanines, and other walking-working surfaces should be maintained in safe condition.

Employees should report:

• Damaged railings
• Missing covers
• Uneven surfaces
• Poor lighting
• Obstructions
• Slippery conditions

Heat Stress

Employees working around heated molding equipment may experience elevated workplace temperatures.

Heat-illness prevention measures may include:

• Water
• Rest opportunities
• Ventilation
• Cooling
• Acclimatization
• Employee training

Employees should recognize and promptly report symptoms of heat-related illness.

Emergency Procedures

Injection molding facilities should establish procedures for foreseeable emergencies such as:

• Employee injury
• Burns
• Molten-plastic release
• Equipment entanglement
• Hydraulic failure
• Chemical release
• Electrical emergency
• Fire
• Medical emergency
• Severe weather
• Utility failure

Employees should know how to stop equipment and summon emergency assistance.

Burn Response

Thermal burns from molten plastic or hot equipment require prompt attention.

Employees should:

• Move away from the source of exposure.
• Obtain appropriate first aid or medical assistance.
• Follow facility emergency procedures.
• Report the incident promptly.

Employees should not attempt to remove plastic adhered to burned skin unless directed by appropriate medical personnel.

Incident Reporting & Investigation

Employees should promptly report:

• Injuries
• Burns
• Machine incidents
• Near misses
• Equipment malfunctions
• Hydraulic failures
• Chemical exposures
• Electrical incidents
• Guarding deficiencies
• Interlock failures
• Material releases

Incident investigations should evaluate underlying and contributing factors such as:

• Machine design
• Guarding
• Energy control
• Equipment condition
• Employee positioning
• Procedures
• Training
• Maintenance
• Production practices

Corrective actions should address identified causes where practical.

Injection Molding Safety Training

Employee training should correspond to assigned duties and workplace hazards.

Training may include:

• Injection molding machine safety
• Clamping and mold-area hazards
• Machine guarding
• Interlocks and safety devices
• Emergency stops
• Lockout/Tagout
• Stored energy
• Hydraulic and pneumatic safety
• Electrical safety
• Hot surfaces
• Molten plastic
• Purging
• Plastic resins and additives
• Hazard Communication
• Fume and ventilation hazards
• PPE
• Mold changes
• Rigging and lifting
• Robot and automation safety
• Granulator safety
• Forklift safety
• Material handling
• Ergonomics
• Noise
• Housekeeping
• Fire prevention
• Emergency procedures
• Incident reporting

Employees should receive additional training when new machines, molds, materials, automation, chemicals, procedures, or hazards are introduced.

Customized Injection Molding Safety Manuals

Injection molding facilities vary significantly in machine size, clamping force, materials, molds, automation, production processes, auxiliary equipment, maintenance activities, and employee exposures. Operations may range from small molding shops to highly automated facilities with large presses, centralized resin systems, robotics, mold-handling equipment, secondary processing, and extensive material-handling systems.

A customized Injection Molding Safety Manual can be developed around your injection molding machines, molds, plastic resins, purging operations, hydraulic and pneumatic systems, robots, granulators, mold changes, lifting equipment, secondary operations, maintenance activities, and employee exposures.