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Maverick now offers injection molding preventative maintenance packages to the plastics industry! Repair, troubleshooting, and installation of injection mold machines and peripheral equipment.
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Injection Mold Alignment |
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 Proper Alignment is Critical
The critical alignments of any injection-molding machine are platen-to-platen parallelism and tie-bar squareness. Poor alignment results in premature wear on the mold, part flashing, stress on, and potential breakage of tie bars. With long lead times and mold costs as much as $250,000 or more, proper alignment becomes critical.
5 Point Reference
To measure an injection molding machine, five reference points are needed. Three points are chosen on the fixed platen and one each on two tie bars, usually on the lower tie bars closest to the platens. The laser is positioned beside or inside the machine on an instrument stand. One of the vertical laser planes is "bucked in" to three reference points on the fixed platen. Next, the horizontal laser plane is "bucked in" to two tie bars by placing one target on each tie bar. To measure the machine's geometry, the targets that were zeroed to the reference points are used to measure the deviation of a measuring point from the reference point.
Measuring Parallelism of Platens
To measure platen-to-platen parallelism, the laser plane is "bucked in" to the fixed platen. A target is then placed on the opposing or moveable platen and zeroed on one point, usually one corner. Next, the three other corners are measured for deviation from the first corner. The deviation, if any, is a measure of the parallelism of the platens. Since the laser measurement is live, the target can be left on the platen while it is being aligned. If all four corners read zero, then the two platens are parallel. The same method could also be used to check the parallelism of the molds to the platens.
 Measuring Tie-Bar Squareness
Since the laser is comparable to three 100-foot (30.5 meter) long surface plates, each perpendicular to within 1 arc second (like a ceiling and two walls), measuring squareness of the tie bars of even the largest injection molding machines and presses is a simple task.
The process starts by setting up the laser to five points as described above. Then to measure the squareness of, say, the two lower tie bars to the fixed platen in the vertical direction, a target would be zeroed at a point on each tie bar closest to the fixed platen. Since the vertical laser plane has been "bucked in" to the fixed platen, the horizontal plane is perpendicular to the fixed platen. After zeroing the target, it is traversed along the tie bar. A "+" reading indicates the tie bar is sloping "up hill" relative to the platen; a "-" reading means it is sloping "downhill". A bubble level on the target base keeps the target at top-dead center of the (round) tie bar.
To measure "horizontal" squareness of the same tie bar, the target can then be placed on the tie bar horizontally and zeroed to the third (vertical) laser plane. As the target is moved along the tie bar horizontally (again a bubble level on the target base keeps the target at top-dead center), any deviation from the zero point is a measure of horizontal squareness of the tie bar.
The same method is used to measure the squareness of all four tie bars. However, it usually takes two setups to measure all the tie bars for squareness. |
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Last Updated ( Tuesday, 27 September 2005 )
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