Presentation on theme: "Machine Guarding for Plastic Sheet and Roll Stock Extrusion"— Presentation transcript:
1 Machine Guarding for Plastic Sheet and Roll Stock Extrusion OSHA 10-Hour Outreach Training Program for thePlastics Processing IndustryA Presentation of the SPI-OSHA AllianceThe Society of the Plastics Industry. Inc. (SPI) and OSHA formed an Alliance in the fall of 2002 in order to help employers in the plastics industry provide safer working environments in their plants. This is a national Alliance, signed with Federal OSHA.As you may know, there are 22 State Plan States that run their own occupational safety and health programs for general industry employers. The rest of the states are covered by Federal OSHA. Although most of the State Plan States have adopted the Federal OSHA Standards, there may be some differences (e.g., California, Michigan). This course is based on Federal OSHA standards.This course on Machine Guarding and Lockout/Tagout (LOTO) was created by a dedicated team, consisting of experts from OSHA and industry. This is a train-the-trainer course—that is, these training modules not only consolidate all the critical information you need on machine guarding and LOTO, but also prepare you to train employees at your worksite.The Alliance would like to hear back from you—not only about how well these tools work for you and how many people you train, but also about ideas you may have for other areas that we can work together on to make a safer workplace in our industry.Please send your comments to Susan Howe, SPI, 1667 K Street, N.W. Suite 1000, Washington, D.C or via at Thank you.Third Edition – September 2008
2 (Screen Capture of Website) Our Alliance developed a Web site to provide you a central resource for safety and health information about the plastics industry.You can link to this site at:This and the other associated pages are a valuable resource for developing your training program, locating information, and learning how-to’s to provide a safer work environment for your employees.
3 (Screen Capture of Website) This site contains links to the machine safety training programs developed by our Alliance.You can link to this site at:
4 Course ObjectivesIdentify the types of injuries that can occur while operating plastics sheet and roll stock extrusion equipmentDescribe the possible causes of these injuriesIdentify ways to safely operate plastic extrusion equipmentRecognize the importance of a total safety and health approachThis course addresses machine guarding and lockout/tagout safety issues relating to plastics extrusion equipment. It does not cover everything you need to know about plant safety.You’re going to hear a common thread running through this course. Machine safety and lockout/tagout programs are only part of the effective safety and health management system at your plant.You should use OSHA's Safety and Health Management eTool, with what you will learn in this course, to develop, refine, or improve your company’s goals for addressing safety and health in your workplace.Additional information on Machine Guarding requirements can be found at the following site:Additional information on Lockout/Tagout requirements can be found at the following site:
5 (Screen Capture of Website) One of the tools developed through our Alliance is a Machine Guarding eTool for Plastics Machinery.OSHA's eTools are "stand-alone," interactive, Web-based training tools on occupational safety and health topics. They are highly illustrated and utilize graphical menus.OSHA's Machine Guarding eTool has modules on saws, presses and plastics machinery.You can access these eTools at the following site:Use the following site to go directly to the Plastics Machinery Machine Guarding eTools:
6 Reasons to Focus on Injuries in the Extrusion Process High injury/illness ratesOSHA citationsNational Emphasis Program on AmputationsSite-Specific TargetingHigh workers compensation costsPlastics is one of the largest manufacturing industries in the US. We directly employ over 1.1 million workers.And plastics processors are the second most frequently cited industry under OSHA's lockout/tagout standard and the third most frequently cited industry under OSHA's machine guarding standards.Citations for the year October September 2007 are listed below.For Lockout/Tagout#Cited #Insp $Penalty Industry Classification$161, SIC Code 3089For Machine Guarding$171, SIC Code 3089Information about OSHA's Site-Specific Targeting Program (SST) is at the end of this presentation, along with reference materials on OSHA’s National Emphasis Program on Amputations.
7 Types of Injuries Cuts and bruises Fatalities Sprains and strains AmputationsAvulsionsFracturesBurnsCuts and bruisesSprains and strainsElectric shockThese are some of the injuries that occur in the plastic processing industry.The focus of these training modules is on the more severe injuries—those in the left column.Fatalities, obviously, are the most severe of all.Amputations can disable and disfigure.Avulsions (degloving) should be considered a near-miss to amputations.Fractures occur when employees are involved in a crushing or caught in injury.Employees receive burns from hot equipment and from hot plastic.
8 Some Causes of Injuries Reaching around, under, over or through guards into hazardous areasRemoving or bypassing guardsInadequate temperature monitoring during cleanupNot using LOTO proceduresMachine/equipment malfunctionsNever attempt to reach around, under, over, or through a guard. If a person standing on the floor can reach over the machine or machine guard into the point of operation, either install new guarding or modify the existing guarding to prevent that from occurring. One common approach is to install a top guard that is either fixed or interlocked, depending on the need for access to the area.Never remove, alter, or attempt to otherwise bypass a safety interlock.Do not remove or open a fixed gate for normal operating tasks.Provide training on the safety hazards and features of the plastics extrusion equipment for all employees who will potentially use it.We will discuss LOTO requirements in the second half of the program.
9 Causes of Injuries (cont’d) Lack of recognition of hazards of the jobLack of familiarity with the equipmentInadequate training, comprehension, or bothOperating machines with missing or inoperable guards and improper or inadequate machine maintenanceLack of proper PPELoose clothing around winding equipmentFractures and crushing injuries can occur at nip points on the rolls during start-up and/or cleaning.The speaker should paraphrase the points listed on the slide.
10 Schematic of ExtruderThe extruder consists of a hopper and feed section, heated barrel, rotating screw, gear reducer and drive motor. Hoppers are used as reservoirs, which contain the resin pellets that will be processed into sheet.Hoppers are located above the feed section - between the gear reducer and the heated barrel. The heated barrel converts the hard resin pellets into molten plastic. Usually the barrel is electrically heated; however, hot oil might be used to melt the resin in the barrel.The rotating screw creates the pressure that drives the molten plastic through the extruder nozzle into the die.
11 Schematic of Extrusion Process Resin is fed into an extruder where it is plasticated into a melt. The extruder, consisting of a heated barrel with an internal rotating screw, pumps the melted resin into a flat sheet die. Sheet exits the die in a semi-viscous state and travels through a series of rolls to cool and size the thickness and width. Sheet is either cut to specified length and width or wound into rolls for subsequent use.As the sheet is forced out of the die, it must be supported because it is hot and in a semi-molten state. Support is supplied by a roll stand. After leaving the roll stand, the sheet cools further as it travels along the conveyor. A set of pull rolls moves the sheet along the conveyor.Upstream from the pull rolls are trim knives, which are used to size the sheet to the final width. Downstream from the pull rolls, a shear will make the final length determination. If continuously wound rolls are required, winders are used in place of the shear.
12 Risk Areas Feed Tubes Roll Stack Trim Knives Pull/Nip Rolls Shear WinderGrinderGuarding for each of these "risk areas" will be demonstrated in the next few slides.Your guarding may look different than what we have demonstrated. But the purpose of this exercise is to illustrate some ways other companies have successfully guarded these points of operation and other danger areas.If you have a creative way of guarding your machine, please share it with us, and we will include it in an update of this module.
13 Feed TubesFeed tubes act to convey the plastic melt from the respective extruder(s) to the feed block.These feed tubes (or feed pipes) must be cleaned from time to time when changing materials, colors, etc.Whether in the form of tubes or pipes or flow channels cut inside a manifold block, the purpose of transferring the plastic melt is the same as are most of the hazards.
14 Accident #1 Third-Degree Skin Burns Two employees were cleaning the feed pipe for a line extruderResin in the feed pipe hardened during shutdownEmployee heated the feed pipe to soften the plastic for 30 minutesThe employee pulled plastic plug at bottom of feed pipeHot plastic sprayed out causing 2nd & 3rd degree burnsWe are providing examples of recent extrusion accidents as a training exercise to help you better understand the types of injuries that are occurring in these "risk areas", and to assist you in designing your machine guarding and safety programs to prevent these accidents.What happened in this accident? The thermocouple had been disconnected so the heater did not shut off, and the temperature gauge was not accurate.Here are some possible solutions:Clean the feed pipe immediately after each material run and before material cools and hardens.Check the thermocouple to ensure proper connection and operation while cleaning.ALWAYS wear appropriate PPE, e.g., face, hand and body protection.
15 Roll StackAs the sheet is forced out of the die, it must be supported because it is hot and in a semi-molten state. Support is provided by a roll stand. Typically, three temperature-controlled rolls are used to allow the sheet to cool and solidify. After leaving the roll stand, the sheet cools further as it travels along the conveyor.The in-running nip on the pictured roll stack is protected by a guard (shown in yellow) that is mounted on a hinge and is also connected to an emergency stop pull cord for added safety.
16 Accident # 2 FatalityMachine operator was threading plastic film through rolls of film extruder line when he got caught between top and bottom rollsSkull fracture and head trauma resulted in his deathThreading plastic film through the rolls of the film extruder line is considered part of normal startup operations. It does require appropriate machine guarding to protect the employee.Here are some possible solutions to prevent this kind of accident:Pre-thread the film extruder line with rope, plastic sheet, or other materials prior to machine start-up. Use this material to pull the plastic sheet through the sheet line.Open all nip points to widest opening to avoid hazards during start-up.
17 Trim Knives pivoting blade guard trim knife This picture shows trim knives with pivoting blade guards that move out of the way when the sheet is present, but move to cover the blades during threading of the sheet and start-up operations to protect maintenance persons and operators from being exposed to the cut hazard(s).
18 Trim KnivesRegardless of the configuration of your trim knives, adequate guarding should be used to protect employees from lacerations during start-up, servicing, and maintenance.
19 Trim KnivesShown here and on the next slide is another approach to shielding employees from the razor sharp blades used for trimming or slitting the extruded sheet and roll stock.
20 Trim Knife GuardingWhen not in use, the entire trim/slitter knife apparatus can be pivoted along with the guard, up and away from the sheet for start-up, servicing, and maintenance.
21 Trim Knife Blade Disposal As the knife blades become dull and replacement is necessary, proper disposal in some form of sharps container similar to the one pictured here will help to prevent cut injuries to employees working on or around the machinery.
22 Pull-Roll Nips Sturdy metal mesh in guard Emergency stop pull cord Sturdy metal mesh composes a portion of the fixed guard. It is important to note that the materials and construction of the guarding must be sufficient to withstand the manufacturing process and adequately protect employees from the hazard. The upper pull roll can be seen behind the guard.As an extra precaution, an emergency stop pull cord has been placed across the full width of the fixed guard and can be easily reached by employees.
23 ShearThe guarding on this shear is considered proximity guarding since it prevents access to the hazard by preventing employees from getting any portion of their body close enough to the point of operation to be injured.
24 ShearAlso considered proximity guarding, the wing guards positioned on either side of this shear prevent employee access during normal production activities.
25 WinderAlthough some machines do have take-up mechanisms or accumulators that will provide a very short amount of time in which to switch out the full roll and start the plastic onto the empty core, many machines require that this operation be performed on-the-fly.
26 Accident #3 FatalityEmployee was splicing plastic on new extruder winder rolls to get it starteddrawstring on hooded sweatshirt got caught in rollemployee died by asphyxiaSplicing plastic on a new roll to get it started is part of normal production operations and may not require LOTO. It does require appropriate machine guarding to protect the employee. You should make that determination in your hazard analysis and include it in the operator work instructions and training.Does this accident involve improper clothing for the job?Was there a company policy about appropriate clothing for the job?If so, did this non-English speaking employee understand the policy?Here are possible solutions:Train employees on proper clothing and attireTwo employees to perform operations – one to perform operation, one to monitor safetyConsider coating core itself with adhesiveMaterial accumulator, so material can be stopped during roll-change operationTrip wire and emergency stop devices
27 Grinder Guarding Guarding by: Enclosure over moving components Anti-kickback flaps in feed throatProximity guarding – distance from feed chute to rotating knivesDuring normal operation the point of operation of the granulator (grinder) is guarded from access by both fixed and interlocked guards.Many accidents associated with this piece of equipment occur during cleaning operations due to direct access to the cutting knives, both rotary and stationery, that must be cleaned and inspected during changeovers of material type or material color.During cleaning the rotor and flywheel, the mechanism must be turned manually to access all of the areas that need cleaning. Inertia of these heavy components lends to injuries including cuts, bruises, and amputations.Proximity Guarding
28 Abrasive Wheel Machinery Work rests on offhand grinding machines must be kept adjusted closely to the wheel with a maximum opening of 1/8-inch to prevent the work piece or tool from being jammed between the wheel and the rest, which may result in wheel breakage or wheel explosion.(a)(4)The purpose of the guarding is to prevent tools from coming between the work rest and the grinding wheel.
29 Abrasive Wheel Machinery The distance between the wheel periphery and the adjustable tongue must never exceed 1/4-inch.(b)(9)If the wheel should break, the upper guard prevents wheel fragments from flying back at the operator.
30 Power-Transmission Apparatus Power-transmission apparatus (shafting, flywheels, pulleys, belts, chain drives, etc.) less than 7 feet from the floor or working platform must be guarded.Unguarded beltand pulleyEven if the apparatus is 7 feet or more from the floor or working platform, if employees need to access the space, it must be guarded or locked out.Some ANSI standards specify 8 feet; consult current standards.
31 Safety Guards and Devices Types of guards and devicesMovable guards with interlocksFixed barrier or proximity guardsPresence-sensing deviceLocations of guardsOver/around moving equipmentAround electrical hazardsAround thermal hazardsAround cut hazardsEmployers are responsible to ensure that machinery is ordered with adequate guarding or retrofitted to protect employees from exposure to mechanical, electrical, and thermal hazards.This module contains a reference section listing some ANSI Voluntary Industry Consensus Standards that you may want to consult as you devise your machine guarding.Newer US-made machines are usually compliant with ANSI machine safety standards, but please note that many older machines have not been retrofitted with updated safeties.In addition, foreign-made machines may not meet all US safety requirements. When purchasing, leasing or using extrusion machines, it is your responsibility to ensure that they are in compliance with all appropriate safety standards.
32 Movable Guards with Interlocks Allows the electrical system to operateActuated when the interlocked guard is closed or openedPrevents machine from operating when the guard is openElectrical interlock prevents machine operation when the interlocked guard is openInterlocked or fixed guard prevents contact with horizontal movement of hydraulic screen changerYou should not tape or defeat these devicesElectrical Interlock Switch
33 Interlocked Guard Emergency stop pull cable Interlocked guard across in-running nip of the chill rollsThis picture also shows the emergency stop pull cableElectrical interlock switch
34 Electrical Interlock Operation This animation shows the operation of an electrical interlock.Proper operation of the electrical interlocks should be verified on a regular basis specified by the machine manufacturer, maintenance department, or safety director.
35 Fixed Barrier Guards Prevent contact with the hazard This is a picture of the front side of a shearThe yellow fixed guard acts as a barrier to prevent exposure to the point of operation.Yellow fixed guard
36 Guard over moving machine components Fixed Barrier GuardsWing guardsThis picture shows the discharge side of shearWing guards on side of shear prevent access through proximity with table in placeGuard over moving machine components
37 Fixed Barrier GuardsThis is a picture of a pull-roll nip barrier guardFixed barrier guards do not have to be interlocked but do have to be designed such that they cannot be removed without the use of tools.
38 Presence Sensing Devices Safety matLight curtainExamples of presence sensing devices include: safety mats, interlocked platforms, photo-electric beams, or other similar devices.Safety Mats:The operation of the safety mat is easy to understand. The safety mat is a simple, normally open switch. When a specified minimum weight is applied to the safety mat the "switch" closes. This sends a signal to the safety mat controller, which in turn, sends a stop signal to the guarded machine.Light curtains:Light curtains have been assuring the safety of operators working at or near dangerous machinery for many years. The light curtain system works by creating an infra red detection plane across the danger area such that any intrusion into the plane results in a stop signal being sent to the machine and the danger being removed. Light curtains are an important tool in safeguarding hazardous machinery and have many advantages to the user in allowing excellent visibility of the working operation and speedy access to equipment which in turn promotes efficient working practice.
39 Presence Sensing Devices Safety MatWhen using the Light Curtain or the Safety Mat it is important that they are spaced far enough away from the point of operation so that the motion can be stopped completely before the employee would be exposed to the hazard.
40 Safety Guards and Devices Light CurtainLight curtain specifications vary and should be chosen to suit the application to ensure adequate protection.
41 How to Protect Yourself Recognize the hazards in the job you are doingUnderstand the requirements for guarding machinesImplement guarding solutionsToday, many companies use the Job Safety Analysis/Job Hazard Analysis Process as an effective means of helping reduce incidents, accidents, and injuries in the workplace. It is an excellent tool to use during new employee orientations and training and can also be used to investigate "near misses" and accidents.Job safety analysis (JSA) is part of many existing accident prevention programs. In general, JSA breaks a job into basic steps, and identifies the hazards associated with each step. The JSA also prescribes controls for each hazard. A JSA is a chart listing these steps, hazards, and controls. There are many commercial vendors of Job Safety Analysis software.You also may want to consider performing a risk assessment such as ANSI B11.TR Risk Assessment and Risk Reduction - A Guide to Estimate, Evaluate and Reduce Risks Associated with Machine Tools.
42 Emergency Stop Button Know: Where they are located What they control When to use themThe control panel on the front of the machine features a Red Emergency Stop Button that Stops all machine function when pressed.Emergency stop buttons may be placed at a variety of locations along the equipment to allow workers to immediately stop operation.In most cases these are not to take the place of normal shutdown controls.
43 Emergency Stop Cable Know: Where they are located What they control When to use themThis picture shows an emergency stop cable on the roll stack.Emergency stop cables may be located at various positions along the machine and/or equipment for use by employees as needed to prevent accidents.As with emergency stop buttons and other safety devices, they are not intended for normal shutdown procedures.
44 Signs and WarningsSigns are posted on a machine to inform us of danger points. We are so used to looking at them that we often do not see them as the machine is running.At the time of initial assignment and periodically afterward, it is good to review the different safety and warning signs on the machine and equipment with employees to maintain an awareness or consciousness of the hazards that they identify.
45 Colors used with Safety Signs have meaning! DANGERWhite Lettering/Red BackgroundWARNINGBlack Lettering/Orange BackgroundA red sign Indicates an imminently hazardous situation which, if not avoided, will result in death or serious injury.An orange sign Indicates a potentially hazardous situation which, if not avoided, could result in death or serious injury.A yellow sign Indicates a potentially hazardous situation which, if not avoided, may result in minor or moderate injury.CAUTIONBlack Lettering/Yellow Background
46 High VoltagePlace on each electrical cabinet and/or box containing dangerous high voltage.
47 Rotating ScrewSome warning signs graphically show the type of injury that the hazard could cause.
48 High TemperatureEffective warning signs have both graphical and written information.
49 High PressureGraphics can give examples of the part of the body that is most likely to receive an injury from the hazard.
50 Crushing FingersGraphics can give examples of the part of the body that is most likely to receive an injury from the hazard.
51 Amputated FingersGraphics can give examples of the part of the body that is most likely to receive an injury from the hazard.
52 References for Extrusion Safety ANSI B11.TR Risk Assessment and Risk Reduction - A Guide to Estimate, Evaluate and Reduce Risks Associated with Machine ToolsANSI B Performance Criteria for SafeguardingANSI/SPI B Plastics Machinery - Plastics Extrusion Machines - Requirements for the Manufacture, Care and UseANSI/SPI B Plastic Film and Sheet Winding Machinery - Manufacture, Care, and UseANSI/SPI B Plastic Sheet Production Machinery - Manufacture, Care and UseANSI Standards are available at the following web site:SPI Guide to Extruded Plastic Sheet Products,
53 OSHA's Site-Specific Targeting (SST) Program OSHA's Site-Specific Targeting (SST) program selects for inspection individual worksites with the nation's highest Days Away from Work Injury and Illness (DAFWII) Case Rate and Days Away, Restricted, or Transferred (DART) Rates. It is based on data reported by more than 80,000 employers surveyed by the agency.See the OSHA Web site for the most current directive and the rates used to target inspections.In order to verify the reliability of claims by establishments thatthey have achieved low DART rates, OSHA inspects a certain percentage of employers with low rates.
54 OSHA National Emphasis Program on Amputations On October 27, 2006, the Occupational Safety and Health Administration (OSHA) revised its national emphasis program aimed at reducing amputations in general industry workplaces. The National Emphasis Program on Amputations targets all types of machinery and equipment that are considered a high risk for causing amputations. The plastics processing industry is among the industries under scrutiny for workplace amputations. The twenty-four states and two territories which operate their own OSHA programs are encouraged, but not required, to adopt a similar emphasis program. State Plan State information is available on OSHA’s Web site. The OSHA directive on this emphasis program is available on OSHA's Web site under Regulations and Compliance, subcategory Compliance Directives, No. CPLUnder this initiative, regional and area OSHA offices will continue to conduct outreach; targeting and selection; and inspections. Area offices will obtain and use additional data to identify and add establishments where serious injuries or fatalities related to these machines have occurred.
55 The Job Safety Analysis Process The Job Safety Analysis (JSA) process is a very effective means of helping reduce incidents, accidents, and injuries in the workplace. It is a multi-step process.Basic Job StepsPotential HazardsRecommended Safe Job ProceduresBreak the job into a sequence of steps. Each of the steps should accompany some major task. That task will consist of a series of movements. Look at each series of movement within that basic task.To complete a JSA effectively, you must identify the hazards or potential hazards associated with each step. Hazards contribute to accidents and injuries. All sources of energy must be identified. It is very important to look at the entire environment to determine every conceivable hazard that might exist.Using the Sequence of Basic Job Steps and Potential Hazards, decide what actions are necessary to eliminate, control, or minimize hazards that could lead to accidents, injuries, damage to the environment, or possible occupational illness. Each safe job procedure or action must correspond to the job steps and identified hazards.Everyone involved in implementing a job or task should be present when the JSA is written. The JSA should be reviewed, approved, and signed by the supervisor before the task is started. Understanding every job step is very important. Whenever a job step changes or a new step is introduced, the JSA must be reviewed and updated. Remember, the key reasons for completing a JSA are to encourage teamwork, to involve everyone performing the job in the process, and to elevate awareness.
56 SummaryInjuries can occur while operating plastics sheet and roll stock extrusion equipmentRisk areas can be protected by safety guards and devicesProtect yourself and operate plastic extrusion equipment safelyRecognize the importance of a total safety and health approach56