1 For the application of this Annex, the machine used for the discontinuous manufacture of molded by injecting material into the mold, which contains one or more cavities in which the product is formed, consisting essentially of the closing unit – molding area and closing mechanism, injection unit, and drive and control systems, as shown in Figure 1 of this Annex, is considered the injection molding machine.
1.1 Applicable definitions:
a) hydraulic injection molding machine: injection molding machine in which the actuation of axles is performed by hydraulic power circuit consisting of electric motor, hydraulic pump and hydraulic cylinder;
b) molding area: area between the plates, where the mold is mounted;
c) closing mechanism: mechanism fixed to the movable plate to move it and apply the closing force;
d) closing force: force exerted by the injection cylinder and screw on the plastic piece that hardens inside the mold of an injection molding machine, which ensures the feeding with additional material as it constricts due to solidification and cooling;
e) injection unit: unit responsible for the plastification and injection of material into the mold by means of a nozzle;
f) injection: mass transfer from the injection cylinder to the mold, cycle process in which a heat-softened material is injected into a mold under pressure, which is maintained until the plastic has sufficiently hardened to be ejected from the mold;
g) power circuit: circuit that provides energy for machine to be operated;
h) Carousel – rotary – injection machine: machine with two or more closing units mounted on movable carousel, in vertical or horizontal position, linked to one or more fixed injection units;
i) multi-station injection molding machine with movable injection unit: machine with movable injection unit linked to two or more fixed closing units;
j) injection molding machine with mold holder table of transverse displacement: machine designed to contain one or more lower parts of the mold fixed to a mold holder table of transverse displacement, which linked to lower part of the mold by means of displacement or rotation movement of the table, to the upper part and to the injection unit;
k) electrical injection molding machine: injection machine in which the axis drives are run by electrical actuators – servomotors;
l) electric engine: any engine that use electrical energy as servomotor or linear engine;
m) engine control unit: unit to control the movement, stopping process and the interruption of the movement of an electric engine, wit or without integrated electronic device, such as frequency converter and contactor;
n) electrical axis: system composed of an electric engine, an engine control unit and additional contactors;
o) stopped state: condition in which there is no movement on any part of the machine with an electric axis;
p) safe stop state: stopped state during which additional measures are taken to prevent unexpected triggers;
q) stop: deceleration of a moving part of the machine until it reaches the stopped state.
r) safe stop during which additional measures are taken to prevent dangerous interruption of movement;
s) monitored safety control input: input of an engine control unit used for interruption of energy supply for the electric axis engine;
t) peripheral equipment: equipment that interacts with injection molding machine, for example, handler to remove parts, equipment to change mold, and clips of automatic clamping clips.
1.2 Specific safety requirements in the danger zones of injection.
1.2.1 Dangers related to the molding area
1.2.1.1 The access to the molding area, where the cycle is commanded or frontal, shall be prevented by means of interlocked movable guards – doors, equipped with two electromechanical safety switches monitored by a safety interface device operating on the control unit so that failure in any of the interlocked devices or in the connection is automatically detected and the start of any subsequent dangerous movement is prevented according to item 12.38 to 12.55 and their sub-items of NR12.
1.2.1.1.1 When magnetic, encoded or optoelectronic safety switches, among others without mechanical actuation, are used, only one switch can be adopted for the interlock and the monitoring must be maintained by the safety interface.
1.2.1.2 In addition to the provisions in sub-item 1.2.1.1 of this Annex, the front guard shall operate in power circuit by means of a check valve, or indirectly, by means of two electromechanical safety switches monitored by safety interface, except for the electrical injection molding machines.
1.2.1.2.1 When magnetic, encoded or optoelectronic safety switches, among others without mechanical actuation, are used, only one switch can be adopted for this function and the monitoring must be maintained by the safety interface.
1.2.1.3 When magnetic, encoded or optoelectronic safety switches, among others without mechanical actuation, are used, only one interlocking device monitored by safety interface can be adopted to meet each one of sub-items 1.2.1.1 and 1.2.1.2 of this Annex.
1.2.1.4 The access to the molding area, where the cycle is not operated, shall be prevented by means of interlocked movable guards, equipped with two electromechanical safety switches monitored by safety interface, which operate in power circuit and turn off the main engine.
1.2.1.4.1 When magnetic, encoded or optoelectronic safety switches, among others without mechanical actuation, are used, only one switch can be adopted for this function and the monitoring must be maintained by the safety interface.
1.2.5.1 There shall be guards in the discharging area so as to prevent body segments reaching the danger zones, according to items 12.38 t 12.55 and sub-items of NR12.
1.2.1.6 The movable guards shall be designed so that it is not possible to stand between the guards and the molding area.
1.2.1.6.1 If staying or accessing the whole body between the guards and the dangerous movement area or
within the molding area is necessary, sub-items 1.2.6.2 to 1.2.6.3.5 of this Annex shall be met.
1.2.1.7 Self-regulating mechanical safety devices shall be installed so as to operate regardless of the position of the plate, opening the guard interrupts the movement of that plate without any adjustment, i.e.; without adjustment to each mold change.
1.2.1.7.1 From the opening of the guard until the effective safety performance, the displacement of movable plate is allowed, from maximum amplitude equal to passed self-regulating mechanical safety device.
1.2.1.7.2 The self-regulating mechanical safety device shall be sized to withstand the starting force of the closing movement of the movable plate, not being its function to withstand the closing force.
1.2.1.8 The interlocked movable guards shall also protect against other movements, and when they are open, they shall:
a) interrupt the cycle; the plastification can continue if the splattering of plasticized material is prevented and the contact force of the nozzle cannot cause dangerous situations;
b) prevent advancing movement of injection piston or screw;
c) prevent advancing movement of injection unit;
d) prevent dangerous movements of ejectors and their mechanisms.
1.2.1.9 Safety devices for machines with electrical axis – electrical injection molding machines
1.2.1.9.1 The electrical injection molding machines shall meet the safety requirements in this Annex, except sub-items 1.2.1.2 and 1.2.1.7.
1.2.1.9.2 For the closing movement of the plate of the electrical injection molding machines, the power circuit shall have serial connection with more than one engine control unit, as follows:
a) an engine speed control unit having more than two serial contactors on its output; or
b) an engine speed control unit with monitored safety control input, having more than one serial contactor on its output; or
c) an engine speed control unit with two input from a Category 3 monitored safety control, and in this case, the use of serial contactors is unnecessary.
1.2.1.9.3 The components of the power circuit shall have automatic monitoring so that it is not possible to start the next cycle movement of the injection in case of failure in one of the components.
1.2.1.9.3.1 The automatic monitoring shall be realized at least once for each movement of the movable guard – door.
1.2.1.9.4 The movable guard of the electrical injection molding machines shall have interlocking device with blocking, which prevents the opening during the dangerous movement.
1.2.1.9.4.1 The interlocking device with blocking shall:
a) meet the provisions of items 12.38 to 12.55 and sub-items of NR12;
b) support a force up to 1000N;
c) keep the movable guard locked in the closed position until the idle state of dangerous movement is reached, and the idle state detection shall be safe against individual failures.
1.2.1.9.5 The electrical injection molding machines shall have a controlled emergency, with power supply to the power circuit necessary to reach the stop, and then, when the stop is reached, the energy is cut off.
1.2.1.9.5.1 The emergency stop shall interrupt all the movements and discharge hydraulic accumulators.
1.2.2 Closing mechanism area
1.2.2.1 The access to the danger zone of the closing mechanism shall be prevented by means of fixed guards or interlocked movable guards – doors.
1.2.2.2 The interlocked movable guard, front or rear, shall have a safety switch monitored by safety interface, which operates in the main circuit and turn off the main engine.
1.2.2.3 The electrical injections in which the shutdown of the respective motor can keep the retained potential energy that pose a risk of unexpected movements in the closing mechanism area shall have additional devices that prevent these movements, such as magnetic brakes.
1.2.3 Plasticizing cylinder and injection nozzle protection
1.2.3.1 The plasticizing cylinder shall have fixed guards to prevent burns resulting from unintended contact with the hot parts of the injection units in which working temperature exceeds 80ºC, and in addition, a label indicating high temperature shall be attached.
1.2.3.2 The injection nozzle shall have interlocked movable guard with a safety switch monitored by safety interface, which interrupt all the movements of the injection unit.
1.2.3.3 The design of the guards shall take into account the extreme positions of the nozzle and the risk of splatter from plasticized material.
1.2.3.4 The moving parts of the injection shall have fixed guards, or interlocked movable guards with a safety switch monitored by safety interface, which interrupt all the movements of the injection unit.
1.2.4 Material feeding area – Funil
1.2.4.1 The access to the plasticizing screw shall be prevented in accordance with the safety distances determined in item A of Annex 1 of NR12.
1.2.4.2 In case of horizontal injection units, a lower opening in the nozzle guard is accepted.
1.2.4.3 The injection units on the molding area shall be equipped with a restraint device to prevent downward movement due to gravity.
1.2.4.3.1 In case of hydraulically driven vertical movement, a check valve shall be installed directly on the cylinder, or as close as possible to the cylinder, using only flanged pipes.
1.2.4.4 Additional measures provided in sub-item 12.113.1 of NR12 shall be adopted in specific maintenance situations, including access to the danger zone.
1.2.5 Discharge area
1.2.5.1 There shall be a guard in the discharge area, so as to prevent body segments reaching the danger zone according to items 12.38 to 12.55 and sub-items, and item A of Annex I of NR12.
1.2.5.1.1 The use of conveyor belts in the discharge area does not exempt the provision in sub-item 1.2.5.1.
1.2.6 Additional safety requirements associated with large machinery
1.2.6.1 The machines are defined as large machinery when:
a) horizontal or vertical distance between the closing rods is greater than 1.2 m; or
b) equivalent vertical or horizontal distance that limits access to the molding area is greater than 1.2m, if there are no rods;
c) a person can stand between the guard of the molding area – door – and the dangerous movement area.
1.2.6.2 Additional safety components, such as mechanical interlocks, shall be installed on the guards of all sides of the machine where the cycle can be initiated to act in each opening movement of the guard and to prevent its movement to “closed” position.
1.2.6.2.1 The components specified in sub-item 1.2.6.2 shall be reactivated separately before another cycle can be started.
1.2.6.2.2 The proper functioning of the additional safety components shall be supervised by safety devices monitored by safety interface, at least once for each movement of the guard – door, such that any failure in these components, safety devices or interconnection is automatically detected to prevent the start of any closing movement of the mold.
1.2.6.3 The large injection machines shall have additional safety devices to detect the presence of a person between the movable guard of the molding area – door – and the molding area, or to detect a person inside the molding area, according to paragraph “c” of item 12.42 of NR12.
1.2.6.3.1 The position of which these devices are reactivated shall permit a clear view of the molding area with the use of visual aids, if necessary.
1.2.6.3.2 When these devices are active, the control circuit of the closing movement shall be interrupted, and if automatic guards – doors – are used, the control circuit of guard closing movement shall be interrupted.
1.2.6.3.3 When a zone monitored by presence sensing devices is invaded, an automatic command shall:
a) interrupt the control circuit of closing movement, and interrupt the control circuit of guard closing movement if guards are used;
b) prevent the injection in the molding area; and
c) prevent the beginning of the next cycle.
1.2.6.3.4 At least one emergency button shall be installed in an accessible position between movable guard of the molding area – door and the molding area, according to items 12.56 to 12.63 and sub-items of NR12.
1.2.6.3.5 At least one emergency button shall be installed in an accessible position inside the molding area according to items 12.56 to 12.63 and sub-items of NR12.
1.2.7 Machines with the movable plate of vertical movement
1.2.7.1 Hydraulic and pneumatic machines with vertical closure shall be equipped with two restraint devices, which can be, for example, hydraulic valves that prevent the accidental downward movement of the plate.
1.2.7.1.1 The valves provided in sub-item 1.2.7.1 shall be installed directly, or as close as possible, on the cylinder, using only flanged pipes.
1.2.7.2 Where the plate has a dimension greater than 800 mm and the opening stroke does not exceed 500 mm, at least one of the restraint devices shall be mechanical.
1.2.7.2.1 When the protection of the molding area is open or when other safety devices are activated, the restraint device shall be activated automatically throughout the stoke of the plate.
1.2.7.2.1.1 When it is not possible to open the movable guard of the molding area before it reaches the maximum opening position, it is allowed that the mechanical restraint device is activated only at the end of the opening stroke.
1.2.7.2.1.2 In the event of failure of one of the other restraint devices, the other device shall prevent the downward movement of the plate.
1.2.7.3 The restraint devices shall be automatically monitored so that in the failure of one of them:
a) the failure is automatically detected; and
b) any downward movement of the plate is prevented.
1.2.8 Carousel machines
1.2.8.1 The access to the dangerous movements of the carousel shall be prevented by fixed guards or interlocked movable guards according to items 12.38 to 12.55 and sub-items of NR12.
1.2.8.2 The access to the molding area shall be prevented according to sub-item 1.2.1.1 of this Annex.
1.2.9 Machines with mold holder table of transversal displacement
1.2.9.1 The access to the dangerous movements of the table shall be prevented by adopting safety systems as provided in items 12.38 to 12.55 and sub-items of NR12 and complementarily by adopting two-hand control devices according to items 12.26, 12.27, 12.28 and 12.29 of NR12.
1.2.9.2 When the vertical movement of the table is possible, accidental downward movement due to gravity shall be prevented.
1.2.10 Multi-station machine with mobile injection unit
1.2.10.1 The access to the danger zones of the injection unit, while moving between the closing units, shall be prevented by fixed guards or interlocked movable guards according to items 12.38 to 12.55 and sub-items of NR12.
1.2.10.2 The access to the molding area shall be prevented according to sub-item 1.2.1.1 of this Annex.
1.2.11 Peripheral equipments.
1.2.11.1 The installation of peripheral equipments shall not reduce the level of safety, observing that:
a) peripheral equipment installation that involves the modification of the machine guards shall not allow access to danger zones;
b) if the opening of a peripheral equipment guard allows access to the danger zone of machine, this guard shall act in the same way as that specified for that zone of the machine zone or, in the case of possibility of whole body access, the provisions of sub-item 1.2.6 of this Annex shall be applied;
c) if the peripheral equipment prevents the access to the danger zone of the machine and can be removed without the use of tools, it shall be interlocked with a control circuit in the same way as the guards specified for that area; and
d) if the opening of a movable guard of the machine allows access to the danger zone of a peripheral equipment, such protection shall meet the safety requirements applicable to the equipment.
Figure 1 – Schematic drawing of horizontal injection molding machine presenting the main danger zones without fixed or movable guards.
Legend:
1: closing mechanism
2: hydraulic extractor
3: discharge area
4: movable plate and fixed plate of the nozzle (molding area)
5: injection nozzle
6: Plasticizing cylinder
7: feeding funil
Source: Fundacentro
