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How the Alignment System Works

To measure an injection-molding machine with the L- 743, 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 at a point clos est to the platens. The laser is positioned beside or insi de the machine on an instrument stand. One of the vertical laser planes is bucked in 1 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 tar gets that were zeroed to the reference points are used t o 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 on e point, usually one corner. Next, the three other corners are measured for deviation from the first corner. The d eviation, if any, is a measure of the parallelism o f the platens. Since the laser measurement is live, the target can be left o n 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 L-743 is comparable to three 100-foot (30 .5 meter) long surface plates, each perpendicular to w ithin 1 arc second (like a ceiling and two walls), measur ing squareness of the tie bars of even the largest inje ction molding machines and presses is a simple task.

The process starts by setting up the laser to 5 poi nts as described above. To measure the squareness of the t wo lower tie bars to the fixed platen in the vertical direction, a target would be zeroed at a point on e ach tie bar closest to the fixed platen. Since the vert ical laser plane has been bucked in to the fixed platen, the horizontal plane is perpendicular to the fixed plat en. After zeroing the target, it is traversed along the tie bar. A plus ( +) reading indicates the tie bar is sloping "up hill" relative to the platen; a minus (-) 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 horizo ntally and zeroed to the 3rd (vertical) laser plane . As the target is moved along the tie bar horizontally (again a bubble leve l on the target base keeps the target at top-dead c enter), any deviation from the zero point is a measure of horizontal squa reness of the tie bar.

The same method is used to measure the squareness o f all four tie bars; however, it usually takes two setups to measure all the tie bars for squareness.

Injection Molding Machine Alignment

Side View (Without Removing Mold)

Please note that while this looks like a complex set up, it is the that makes the setup look difficult. The total time to s et up the laser and reference it to the machine should be 13-25 minutes, including t he time to take it out of the box. The total time to completely measure the machi ne for parallelism of the platens and squareness of the tie bars is 35-55 min utes (see timeline below).

Top View

Front View of Platen

Procedure Timeline(minutes)
1. Set the laser on an instrument stand either outside the machine or inside the machine as shown (Laser Position #1). Position the laser so the laser plane (LP) #1 is at a sufficient height to allow measurement of the up per tie bars for squareness. Ensure that there is sufficient room b etween the lower left tie bar and LP#3—75 mm to 300 + mm is the correct range. 5-10
2. Place a single-axis target (A-1519-2.4ZB) in the lo wer left corner of the platen and zero. Mark the s pot for reference purposes, and then move this target to th e upper left side of the platen. Place a second ta rget on the same point in the lower left corner of the platen and ze ro the display. 3-5
3. Adjust the pitch axis of the L-733/743 until the sa me reading appears on both targets. This means the laser is now parallel to these two points (shown on left side of the Front View ). Re-zero both targets. 1-2
4. Move one of the two targets (without changing the z ero point) to the lower right side of the platen. A djust the yaw axis until the target at this location reads zero. Re-measure the other points to ensure that they all read zero. The laser plane is now parallel to the fixed platen.  
5. Mount a target on the lower left tie bar and level using the built-in level vial on the target base. T his keeps the target at top dead center. Adjust the target height until it reads LP #1. Zero the target and mark the reference point. Move the target the lower right tie bar. Repeat thi s procedure with a second target, placing it on the same reference point on the lower left tie bar where the first tar get was zeroed. 3-6
6. Adjust LP#1 using the roll axis in the laser base u ntil both targets read the same number, making the laser plane parallel to the two lower tie bars. 1-2
7. Now the laser is ready to measure parallelism and s quareness of two of the four tie bars. Note: Skip Steps 5 and 6 if tie-bar squareness is not desired  
8. To measure platen parallelism, assuming the moveabl e platen is within 1 meter of the fixed platen, pla ce a target in one corner of the moveable platen. Add or remove r ods from the targets so that the length of the targ et height allows it to read the laser plane. Zero the target (see Side View ). 1-2
9. Move the target to the other three corners and note the readings. Any deviation from zero is a measure ment of out- of-parallel condition of the moveable platen to the fixed platen. Since the readings are live, the tar get (or targets) can be left on the platen while it is being adjuste d to bring it into alignment. 1
10. Since all three laser planes are perpendicular to e ach other, the laser is also now set up to start me asuring tie-bar squareness. Note that the laser cannot measure all four tie bars for squareness with one setup (see S teps 16 and 17).  
11. To measure squareness of the lower tie bar to the p laten in the pitch axis, (as defined by looking int o the end of the tie bar) use the target that set up LP#1 (which sho uld still be reading zero). Move the target the oth er end of the tie bar, where its reading will indicate the squareness . If it reads zero, then it's square to the platen . If not, then the amount shown on the readout is how much either the platen or the tie bar needs to move to bring it int o specification. Again the reading is live, so the t arget can be left in place while the adjustments ar e being made. 1-2
12.Move the target along the tie bar in small incremen ts to measure the tie bar for straightness. Note th e readings as the target is moved.  
13. To measure the tie-bar squareness in the yaw axis ( as defined by looking into the end of the tie bar), set up a target at the 3 o’clock position on the tie bar (see Front View ). The level on the target base can be moved to th e side of the base to keep it at top dead center. 1-3
14. Adjust the target until it picks up LP#3 and zero t he target. As in Step 11, move the target to the ot her end of the tie bar to measure the squareness. If the reading not zero, it is not square. At the same time, the upper tie bar can be measured for squareness in the same yaw axis with t he same setup. 1-3
15. The upper tie bar squareness in the pitch axis can be measured by turning the target up side down, pic king up LP#1 and following Step 11. This also measures the para llelism of the upper tie bar to the lower tie bar i n the pitch axis. Similarly, the upper and lower tie bars can be meas ured for parallelism in the yaw axis by using LP#3. 2-4
16. To measure the two right-hand tie bars, move the la ser to Position #2 and repeat Steps 1-6 to make the laser planes parallel to the same reference. 5-10
17. Repeat Steps 11-15 to measure the squareness of the two right-hand tie bars. 3-5
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