AboutAaron Overbeek Expertise I am a Six Sigma Master Black Belt and Lean Champion. My expertise ranges from tacticle (local) implementation to strategic (global) implementation of Lean Six Sigma. Also knowledgable in Best Manufacturing Practices, Quality, Supply Chain, Engineering, and EH&S. I am not a consultant and do not mind follow up questions.
Experience Bachelors of Science in Manufacturing Engineering from the University of Michigan. Lean Champion and Six Sigma Master Black Belt. Member of the American Society of Safety Engineers, Society of Manufacturing Engineers, and ISO audetation.
Director of Operational Excellence and Strategic Sourcing for multi-billion dollar corporation.
Question QUESTION: I have a Toshiba ISC 225 Molding machine. During our last run we had a issue with the machine not closing slowly. it wants to slam shut. We have a repair person that is working on it that is just puzzled he has went through what he thinks is pretty thorough check of everything, cant seem to locate what is causing it to slam shut. Any ideas.
ANSWER: When the mold halves are fully closed you will activate a preset limit indicating the mold is shut and will iniate clamp lock up.
It is important to note that in a many times you will find this limit is set too far from the actual fully closed point. Too large of a setting can allow the machine to apply full pressure to the clamp mechanism before the halves are closed. This can cause slamming of the mold, mold damage, and erratic cycles. Your service rep may not have checked the fluid pressure in the clamp position to identify this problem.
When active, the hydraulic system will apply the preset pressure and volume to the clamp cylinder on a toggle, moving the mechanical linkage into the locked position. On a direct hydraulic machine you should hear a very distinctive “clunk” sound, that is the prefill shifting. When the prefill shifts, oil is applied to the main ram area, and seals off the tank from the main ram. When enough pressure is applied to the ram area to activate a pressure switch that indicates there is enough tonnage to allow the injection cycle to begin the high volume of oil that was being used to build tonnage quickly, is reduced to a lower volume and the pressure continues to build until it reaches the setpoint of full tonnage.
If you do not hear the prefill piston shift at this time and cannot build pressure there is a good chance your trouble lies in the prefill not shifting.
On a toggle machine the pressure is usually limited to around 1,500 psi (check your print). If you have a history of pin breakage, you should check the toggle over pressure that is being achieved during lockup. If you have a history of tie bar breakage check clamp parallelism.
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QUESTION: Thank you for your answer. The machine does clamp fully, it hits the mold slow close or open limit switch the mold just stops and the machine wont work in mold setup either. It is a hydraulic machine.
Answer Do you use magnetic mold clamps? If you do, you could have a faulty platen mounted limit switch. Opening the mold too fast will not release the vacuum slow enough pulling the stationary mold away from the limit switch thus triggering the e-stop. Once the e-stop is hit, you would not be able to the setup mode. Any easy way to check for proper vacuum release is to see if the molded part ever gets stuck in the stationary mold.
If that doesn't work, try slowing down the "fast" cycle of your slow-fast-slow mold opening. A slowdown near the end of travel must be utilized to compensate for the momentum of the mold. Without slowing down the machine it cannot maintain accurate positions and may slam to a stop damaging the machine.
Good luck, if this doesn't work, email me back and I will give you my contact information so we can talk through some other possibilities.
