Just because the mold is flashing, does not mean the part weight has increased…
Screw Retraction During Packing or Recovery…
Many older electric molding machines (and a few new ones) have a programming glitch which causes the screw to retract if the packing or back pressure is set too low.
Optimize Your Clamp Movements
Part removal is the easiest part of the injection molding process to optimize and there is no excuse for basic clamp movement optimization.
Situation:
While walking the recent NPE 2015 trade show in Orlando, many of the processes were dialed in beautifully where the mold quickly opens and closes while the part is ejected on the fly. Unfortunately, some machine manufacturers had their molds slowly opening and closing, pausing 1 or 2 seconds before starting ejection, and a couple molds even cycled the ejection system multiple times. Many of these processes lost many seconds of cycle time to clamp movement. This poorly showcases a machine at the show, but loses a lot of productivity at your plant.
My Suggestion:
You should always optimize clamp movements You do not have to slap the mold shut or shake the machine violently as the mold whips open to improve your part removal process. A good basic strategy is as follows:
Mold Opening Fast : This takes place after the initial mold breakaway speed. After the mold components are disengaged, the opening speed should be increased since there are no obstructions. The optimal speed is the fastest speed the machine can safely handle without any awkward movements, machine vibrations.You may need a third, moderate final opening speed if the machine has difficulty maintaining a consistent final mold opening position for robotic part removal.
Final Mold Open : The final mold open position should only be enough to allow proper part ejection.
Eject on the Fly : If a robot is not being used, you should start part ejection before the mold is opened. The fact that the mold is moving away from the part tends to help the part drop downward. This feature typically reduces the total amount of distance the mold has to open when properly set.
Mold Close Fast : Just as with mold open fast, the mold should move quickly when the mold components are not engaged. It is critical that the mold closing speed slows down to a safe speed prior to the mold components making contact for the final mold closing.
Train Anywhere on Any Device
Hello Readers,
This post is to inform all our readers that all our online content is now deliverable on any device with a high-speed internet connection.
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-Andy
High Temperature Materials…
A question recently came in regarding an older post about running high-temperature materials in normal machinery: High Temp Machinery
Question:
We run high temp resin in newer electric presses. i do not believe our injection units were retrofitted with any special materials. the main resin put through our units is PAEK with 30% glass reinforcement, which is a tannish color. we have been experiencing “black streaks” on the part surfaces, and no one in house can seem to figure out the root cause. These streaks are usually dark brown, (despite the symptom name) and really seems to be burnt up resin at the edge of degradation to me… but whether or not our steel can handle the constant high heat cycles has been the main focus of attention. any thoughts from your end that could possibly help us out? we keep the rear zones at about 700*F on these jobs.
My Response:
The most important thing to do first is to compare the actual melt temperature with the manufacturer’s suggested temperature and verify the material is being melted properly. I have seen machines set at 750°F with a resulting melt temperature of only 675°F. In this example, we were able to increase the cooling time and significantly slow down the recovery speed to get the melt temp up to 710°F. This material was still 15° below the recommended temp, but acceptable parts were able to be produced for the while better heater bands were ordered.