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Injecting Some Safety Into Plastic Molding Equipment

March 29, 2019

There’s a lot that can go wrong during the plastic injection molding process — molds can break, tubes can spring leaks, etc. — but one of the more common hazards is also one of the most pedestrian:  mold halves separating during transportation and handling.  But if the hazard is very low-tech, so is the solution: plastic safety straps, which protect both equipment and people.Plastic Straps

The classic mistake made by set-up people is using only one eye-bolt to lift a mold that doesn’t have a safety strap or lifting bar. Whether the eye-bolt is in the ejection half or the injection half, if there is no safety strap when the hoist lifts the mold up, it’s going to tilt dangerously one way or another because an eye-bolt hole is seldom at the mold’s exact center of gravity.  But uneven weight distribution by itself won’t cause the mold-half to fall to the ground: other factors, such as the clearance and lubrication between the bushings and leader pins, and the direction and angle that the mold tilts, play a role in accidents as well.

The second most common way a mold typically comes apart is when one side of the mold hits a platen during assembly.  This can make the other side of the mold smash against the opposing platen.  Other ways a mold can come apart include a racking system that’s difficult to maneuver, a mold cart with a bad wheel, a defective wooden skid, or an incompetent forklift operator and a tight turn.

To review: every mold should have a safety strap, and not just the behemoths.  Small molds, such as MUD inserts, also require safety straps. Plant employees who are handling any sized mold must do so very carefully, because if something goes wrong, it could result in damage to the mold — and to themselves.


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