The top of the machine, or the area directly above the die space, can allow exposure to the clamp-closing hazard. The need for a guard in this area depends on predictable human error. On machines where would be possible for the operator, standion the floor, to reach over the top of the front or rear guard down into the hazard zone,guard should be provided. If  this guard portable or movable for purposes other than maintenance, then it must be interlocked.

           If, on the other hand, the top access area to the hazard zone is remote from the operator standing on the floor, a top guard may not be required. This might be the case on larg machines or those where the front and rear guards are high enough to prevent the operator from reaching over the top. It must be assumed that if the operator or another person makes a conscious effort to climb onto the machine or another object, he or she is also conscious of the hazard now faced. This conscious effort will generally eliminate pre dictable human error.

           The bottom of the machine, or the area where completed parts drop out, can allow exposure to the clamp-closing hazard. A normal operating practice today is for the operator to sit on a stool and inspect or remove and pack-age parts. These parts are ejected from the mold and drop onto a conveyor or chute that brings them to the operator. The predictable human error is that the operator will reach up into the hazard area, should a part become hung up. To guard against this, the machine should be constructed so that the distance the operator must reach is greater than the normal reaching distance. This meets the design objective of removing the operator from the hazard. If this is not possible, guards should be provided to prevent access. The guard design is critical because part removal is essential to the molding operation. If the guards restrict part removal, they themselves become targets for removal.

            Maintenance ofguards  The guards for the clamp, when properly  designed  and maintained, will normally protect  the operator. The users of the IMM must keep these guards in good repair, reconstruct them when necessary, and keep them installed on the machine.

            Feed openings Material for IMMs is loaded through hoppers into the plasticating barrel. The rotating and reciprocating screw, within the barrel, creates a hazard for anyone inserting a hand into the opening. This hazard must be guarded against. If guarding is not possible, then warning signs should be used. Bridging of the plastic in the feed opening or trapped foreign matter may necessitate work in this area. In that case, the power to the machine should be shut off and a soft metal rod used to remove unwanted parts. Hands should never be inserted into the opening.

            Injection cylinders  Rotating rams and reciprocating cylinders create hazards at the injection end of the machine. Access to this part of the machine is necessary only for maintenance, so fixed permanent guards should be used. Interlocking of these guards is not considered necessary.

             Purging protection During a material change or shutdown, material should  be
purged from the barrel. This should be done with a purging compound compatible with the material being used. Improperly mixed materials can cause violent reactions.

             During normal purging, a shield must be provided to protect the front, top, and rear of  the purging area behind the stationary platen (Fig. 2-63). The material being shot into the  air may splatter onto the operator if the purge shield  is not  available  or not in use. This shield should be interlocked to prevent pushing when it is not in place.

             The machine circuitry should be design so that purging cannot take place  unless the safety gate is closed. This will protect against molten plastic passing through the sprue hole, into the mold area, and out on the operator.