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Machine Guarding for Plastic Sheet and Roll Stock Extrusion

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1 Machine Guarding for Plastic Sheet and Roll Stock Extrusion
OSHA 10-Hour Outreach Training Program for the Plastics Processing Industry A Presentation of the SPI-OSHA Alliance The 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 Objectives Identify the types of injuries that can occur while operating plastics sheet and roll stock extrusion equipment Describe the possible causes of these injuries Identify ways to safely operate plastic extrusion equipment Recognize the importance of a total safety and health approach This 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 rates OSHA citations National Emphasis Program on Amputations Site-Specific Targeting High workers compensation costs Plastics 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 3089 For Machine Guarding $171, SIC Code 3089 Information 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
Amputations Avulsions Fractures Burns Cuts and bruises Sprains and strains Electric shock These 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 areas Removing or bypassing guards Inadequate temperature monitoring during cleanup Not using LOTO procedures Machine/equipment malfunctions Never 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 job Lack of familiarity with the equipment Inadequate training, comprehension, or both Operating machines with missing or inoperable guards and improper or inadequate machine maintenance Lack of proper PPE Loose clothing around winding equipment Fractures 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 Extruder The 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
Winder Grinder Guarding 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 Tubes Feed 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 extruder Resin in the feed pipe hardened during shutdown Employee heated the feed pipe to soften the plastic for 30 minutes The employee pulled plastic plug at bottom of feed pipe Hot plastic sprayed out causing 2nd & 3rd degree burns We 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 Stack 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 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 Fatality Machine operator was threading plastic film through rolls of film extruder line when he got caught between top and bottom rolls Skull fracture and head trauma resulted in his death Threading 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 Knives Regardless 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 Knives Shown 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 Guarding When 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 Shear The 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 Shear Also considered proximity guarding, the wing guards positioned on either side of this shear prevent employee access during normal production activities.

25 Winder Although 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 Fatality Employee was splicing plastic on new extruder winder rolls to get it started drawstring on hooded sweatshirt got caught in roll employee died by asphyxia Splicing 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 attire Two employees to perform operations – one to perform operation, one to monitor safety Consider coating core itself with adhesive Material accumulator, so material can be stopped during roll-change operation Trip wire and emergency stop devices

27 Grinder Guarding Guarding by: Enclosure over moving components
Anti-kickback flaps in feed throat Proximity guarding – distance from feed chute to rotating knives During 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 belt and pulley Even 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 devices Movable guards with interlocks Fixed barrier or proximity guards Presence-sensing device Locations of guards Over/around moving equipment Around electrical hazards Around thermal hazards Around cut hazards Employers 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 operate Actuated when the interlocked guard is closed or opened Prevents machine from operating when the guard is open Electrical interlock prevents machine operation when the interlocked guard is open Interlocked or fixed guard prevents contact with horizontal movement of hydraulic screen changer You should not tape or defeat these devices Electrical Interlock Switch

33 Interlocked Guard Emergency stop pull cable
Interlocked guard across in-running nip of the chill rolls This picture also shows the emergency stop pull cable Electrical 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 shear The 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 Guards Wing guards This picture shows the discharge side of shear Wing guards on side of shear prevent access through proximity with table in place Guard over moving machine components

37 Fixed Barrier Guards This is a picture of a pull-roll nip barrier guard Fixed 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 mat Light curtain Examples 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 Mat When 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 Curtain Light 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 doing Understand the requirements for guarding machines Implement guarding solutions Today, 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 them The 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 them This 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 Warnings Signs 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!
DANGER White Lettering/Red Background WARNING Black Lettering/Orange Background A 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. CAUTION Black Lettering/Yellow Background

46 High Voltage Place on each electrical cabinet and/or box containing dangerous high voltage.

47 Rotating Screw Some warning signs graphically show the type of injury that the hazard could cause.

48 High Temperature Effective warning signs have both graphical and written information.

49 High Pressure Graphics can give examples of the part of the body that is most likely to receive an injury from the hazard.

50 Crushing Fingers Graphics can give examples of the part of the body that is most likely to receive an injury from the hazard.

51 Amputated Fingers Graphics 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 Tools ANSI B Performance Criteria for Safeguarding ANSI/SPI B Plastics Machinery - Plastics Extrusion Machines - Requirements for the Manufacture, Care and Use ANSI/SPI B Plastic Film and Sheet Winding Machinery - Manufacture, Care, and Use ANSI/SPI B Plastic Sheet Production Machinery - Manufacture, Care and Use ANSI 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 that they 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. CPL Under 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 Steps Potential Hazards Recommended Safe Job Procedures Break 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 Summary Injuries can occur while operating plastics sheet and roll stock extrusion equipment Risk areas can be protected by safety guards and devices Protect yourself and operate plastic extrusion equipment safely Recognize the importance of a total safety and health approach 56

57 Do you have any Questions?

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