Handbook Of Shaft Alignment Episode 2 Part 2 pdf

refer to as ‘‘oversized slot’’ shims. If it is necessary to install a shim=spacer thicker than 125 mils, it is recommended that carbon or stainless steel plate be used and that the plate be surface ground on both sides to insure parallel surfaces within 1 mil over a 6 in. distance. The spacer should have 125 rms surface finish or better after grinding. The precut U-shaped shims mentioned above are typically made from stainless steel, which is the recommended material to use to prevent oxidation or corrosion that could occur with carbon steel shims. Brass shims work well unless there is ammonia present. Carbon steel is usually acceptable if you have to make a plate over 125 mils thick. The precut U-shaped shim sizes A through D were meant for use on NEMA motor frame sizes 100 through 400 series. These shims can obviously be used on other machines besides motors. These standard shim sizes work on about 70% of the machinery in industry but they do not work on everything, particularly larger machinery, so it is not uncommon to fabricate custom shims to work in many situations. The rule of thumb is to provide at least 80% contact between each machine foot and its point of contact on a baseplate, frame, or soleplate. Often I have found C-sized shims sitting under a machine foot whose footprint is 6 in. Â 9 in. Just because the shim slot fits the hold down bolt diameter, does not necessarily mean that is the right shim for the job. Therefore, in many cases, special shims need to be fabricated. Shim stock can also be purchased in 6 in. wide rolls in 100 in. and 180 in. lengths and can be aluminum, brass, carbon steel, and stainless steel in usually the following thickness: 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 10, 12, 15, 20, 25, and 31 mils. To fabricate shims over these thickness, you need to use sheet metal that can be purchased in the following gauges: In the event that you have to make your own shims from 6 in. wide rolls, a good pair of tin snips can be used to cut the shims. Making a straight cut is not too difficult on shims up to 20 mils thick. It is difficult to do the cutting, if the thickness exceeds 20 mils thick. Cutting the slot where you make a hemispherical cut gets a little tricky particularly with shims over 15 mils thick. I usually use a permanent felt tip marker for the shim pattern and then start trimming away. I would recommend to wear a pair of leather gloves when cutting the shims. After the shim is cut, I usually have a block of wood and a ball-peen hammer nearby to flatten out the edges I cut. Once I have the shim made, I use the felt-tip marker to write down the thickness of the shim on both sides. If you are having to cut several shims, it is easy to forget who’s who when you pick up the pile of shims. Gauge Thickness (in.) 28 0.015 26 0.018 24 0.024 22 0.030 20 0.036 19 0.042 18 0.048 16 0.060 14 0.075 13 0.090 12 0.105 11 0.120 10 0.135 8 0.165 7 0.187 Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C007 Final Proof page 300 26.9.2006 8:43pm 300 Shaft Alignment Handbook, Third Edition As the slot is the toughest thing to cut, you may want to invest in a punch and die set to make a hole first, then you only have to cut straight lines. If you need to make shims over 25 mils thick, you should be using a hydraulic or mechanical shear for the overall shape of the shim and then drill the hole for the slot and use a band saw to make your cuts to the hole. If you have to make a whole bunch of shims, cut the overall shape, stack them together with the thinner shims in between thicker shims, sandwich the entire pack between two pieces of 1=4in. plate steel, then use an end mill to cut the slot on all of them at the same time. Some ‘‘rules of thumb’’ to follow for shimming machinery are: 1. Excluding the soft foot shims, you should not have more than five to six individual shims (or plates) under a foot to make an alignment correction shim ‘‘pack.’’ 2. The total thickness of the alignment correction shim pack should not exceed half the diameter of the bolt holding that foot down. 7.4.3 LATERAL MOVEMENT Permanently mounted jackscrews or whatever devices may be used to slide equipment sideways should be placed as close as possible to the foot points without interfering with tightening or loosening of foundation bolts. A typical jackscrew arrangement is shown in Figure 7.12. Dial indicators mounted on the baseplate that are used to monitor sideways movement should usually be placed on the opposite side of the machine case from where the movement device (e.g., jackscrew) is located to keep the indicator from inadvertently bump- ing as shown in Figure 7.13. The disadvantage of permanently mounted jackscrews that have been welded to the baseplate or frame is that it will become very difficult to add or remove shim stock as the jackscrew plates are now in the way. The fact of the matter is that the vast majority of rotating machinery do not have jack- screws installed for positioning the machinery. A useful trick in the field to achieve a lateral move is to use a corner foot bolt as a ‘‘pivot’’ point and move one end of a unit at a time when moving sideways as shown in Figure 7.14. FIGURE 7.12 Removable jackscrew for moving a motor sideways. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C007 Final Proof page 301 26.9.2006 8:43pm Correcting Misalignment 301 Start by tightening one of the inboard bolts, usually on the same side as you will be pushing from. After the outboard end has been moved the desired amount, tighten one of the outboard bolts and loosen the inboard bolt that you used as the pivot point. Monitor the movement of the inboard end either by placing a dial indicator at the side of the machine casing at the inboard foot or by using a dial indicator and bracket arrangement attached to one shaft, zero the indicator on one side of the coupling hub then rotate the dial indicator and bracket arrangement 1808 and note the reading as shown in Figure 7.15. Start moving the inboard end in the appropriate direction until the dial indicator on the coupling hub reads one half the original value. Zero the indicator again and rotate the dial indicator and shaft FIGURE 7.13 Monitor the move with an indicator. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C007 Final Proof page 302 26.9.2006 8:43pm 302 Shaft Alignment Handbook, Third Edition assembly back 1808 to the original zeroing point on the other side of the coupling hub and check the reading on the indicator. This assumes that you do not want to have an intentional lateral offset due to movement from off-line to running(OL2R) conditions (refer to Chapter 16). If necessary, continue moving the inboard end to get the dial indicator to read zero when swinging from side to side on the coupling hub. It is also possible to move both ends simultaneously using indicators and jackscrews at each foot. For equipment with inboard First, loosen all but one of the inboard bolts and move the outboard end the amount you decided upon. Next, tighten one of the outboard bolts, loosen the inboard bolt used as a ‘pivot’ point, mount the bracket and indicator onto one of the shafts, rotate the bracket/indicator over to one side, zero the indicator, and rotate to the other side and make a note of the reading. Finally, move the inboard end until the indicator is reading half of the original value (assuming that you want the shafts to be colinear when the units are off-line). Move Pivot here Pivot here Move FIGURE 7.14 Pivoting at the outboard then inboard ends. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C007 Final Proof page 303 26.9.2006 8:43pm Correcting Misalignment 303 to outboard foot distances of 3 ft or less, this seems to work all right with two people on the alignment job. Larger equipment usually requires four or more people to be effective. On new installations it may be desirable to generate a total sideways movement ‘‘map.’’ This will come in handy when calculating the necessary lateral moves to determine whether it is possible to move it as far as the calculation requires. An example of a typical allowable movement map is illustrated in Figure 7.16. Once the map has been established, place each unit in the center of its allowable sideways and axial travel and begin to take your shaft alignment measurements (refer to Chapter 10 through Chapter 15). These movement maps will prove invaluable when aligning multiple element machine drive trains (refer to Chapter 17). 7.4.4 VERTICAL MOVEMENT Lifting equipment is markedly more difficult than sliding it sideways so it is desirable to make the minimum number of moves necessary to achieve the correct vertical position. Lifting jackscrews are rarely found at the corners on rotating machinery casings. If good lateral alignment has been achieved, try to keep as many foot bolts tight or have the jackscrews tightened against the machine element to prevent the unit from moving back out of alignment when shims are added or removed from the feet. Lifting equipment with a couple of foot bolts tightened can be a very delicate and challenging operation and must be performed with extreme caution. The idea is to lift the unit just far enough to slide shims in or out. 7.5 TYPES OF MOVEMENT TOOLS Hammers are probably the most widely used tool for moving machinery sideways. Even if these are the least desirable method, there are preferred techniques when using hammers to move a unit sideways. 1. Use dead blow or soft faced hammers (plastic or rubber) instead of steel hammers. 2. If soft faced hammers are not available, place a piece of wood or plastic between the hammer and the impact point on the piece of machinery to prevent damaging the case. FIGURE 7.15 Monitor the move at the inboard end with a bracket and indicator mounted to the shafts. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C007 Final Proof page 304 26.9.2006 8:43pm 304 Shaft Alignment Handbook, Third Edition 3. Take easy swings at first then begin increasing the force. With practice, you can develop a feel for how the unit moves at each impact. The more force that is used however, the greater chance there is to jolt the dial indicators that are monitoring the unit movement rendering the readings useless. 7.5.1 PRY AND CROWBARS AND WEDGES Pry and crowbars can be found in every mechanic’s toolbox and they invariably end up out at the alignment site just in case they are needed. Consequently, for smaller, light equipment, pry bars end up the most widely used device to lift equipment. A pry bar however, provides very little control in accurately lifting equipment and can slip from its position easily, which can be very painful for your partner who is trying to remove old shims from under the feet with his fingers. A pry bar can also be used to move the equipment sideways assuming there is a leverage device near the feet. The leverage device, however, usually ends up being a piping, electrical conduit, or a long piece of 2 Â4 supported against something else on the machinery frame or foundation. Using hammers and steel wedges to lift equipment is the least desirable method. If there is no alternative, here are some tips when using this technique: Setting the machine cases so they are in the center of their travel. 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 0 50 10 40 20 30 + _ 10 40 20 30 Bolt shank First push the machine cases to one side until the bolts bottom out against the holes. Set up dial indicators at the sides of the feet and zero the indicators. Next push the machine cases the opposite way until the bolts bottom out in the holes again. Make a note of the amount of movement on each of the indicators but do not move them. Finally push the machine cases half way back watching the indicators to see how much you have moved. FIGURE 7.16 Placing the machine in the center of its sideways travel. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C007 Final Proof page 305 26.9.2006 8:43pm Correcting Misalignment 305 1. Place the wedge close to the foot that needs to be lifted without interfering with the process of adding or removing shims. The casing may distort enough to get the necessary shims in or out of that foot area without having to lift the entire unit. 2. Apply a thin film of grease or oil to both sides of the wedge. 3. It is fairly easy to install a wedge but it is quite another thing to get it out from under a heavy piece of machinery. Before installation, provide some means for removal of the wedge. 7.5.2 COMEALONGS AND CHAIN FALLS These devices can be used to both lift and move equipment laterally. The primary problem with this equipment is usually the lack of proper rigging or anchor points for the chain falls or comealongs when moving sideways. There is also the problem of exceeding the capacity of the chain fall when rigged to lift the equipment. The better quality chain falls and comealongs however provide improved control and safety than do hammers and pry bars. 7.5.3 HYDRAULIC JACKS There are many types of hydraulic jacks and kits that can readily be purchased at reasonable prices. When rigged properly, hydraulic jacks provide good control and safety when lifting or sliding equipment and are one of the preferred methods for moving rotating machinery. Figure 7.17 shows a custom-made portable hydraulic lifting and lateral positioning system. FIGURE 7.17 Hydraulic machinery lifting and lateral positioning device. (Courtesy of Murray & Garig Tool Works, Baytown, TX. With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C007 Final Proof page 306 26.9.2006 8:43pm 306 Shaft Alignment Handbook, Third Edition 7.5.4 PERMANENT JACKSCREWS Although jackscrews are the most preferred method for moving machinery, they are not found frequently in industry mainly because of the cost and effort required to install them. A typical jackscrew arrangement is illustrated in Figure 7.18. 7.5.5 PORTABLE JACKSCREWS AND MACHINERY POSITIONERS A considerable amount of imagination has gone into designing these clever devices and could be used in one form or another by most of the industry for machinery alignment applications. If you have more than one of the same type of pump, motor, compressor, etc. it is recom- mended that drop-in puller devices such as shown in Figure 7.19 through Figure 7.24 be used for your specific application. Portable jack bolt kits are also available as shown in Figure 7.25 through Figure 7.27. Another device that can be placed between the baseplate=soleplate and machine casing which has the capacity to adjust for nonparallel surface contact with the added feature of height adjustment are machinery positioners shown in Figure 7.28 and Figure 7.29. 7.6 WHAT TO DO WHEN THINGS ARE NOT WORKING When you are aligning a piece of machinery and everything you try does not seem to be working and in some cases, the alignment seems to be getting worse rather than better. Or perhaps you have improved gross amounts of misalignment but just cannot seem to bring the Be sure the lifting jackscrew is backed out before tightening the foot bolt. FIGURE 7.18 Permanent jackscrews for vertical, lateral, and axial movement. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C007 Final Proof page 307 26.9.2006 8:43pm Correcting Misalignment 307 FIGURE 7.19 Drop-in puller device ready to be inserted into bolt hole on machine case. FIGURE 7.20 Drop-in puller device inserted into hole and ready to pull machine sideways. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C007 Final Proof page 308 26.9.2006 8:43pm 308 Shaft Alignment Handbook, Third Edition units within 1 mil per inch or better. You keep taking 5–10 mils of shim stock out and then putting it back under the same bolting plane you just removed it from or the machinery seems to keep wanting to move out of alignment sideways when you tighten the bolts down. After muttering obscenities to the equipment and tools you are working with, you look up and notice someone walking by looking at you as if you are deranged. What should you do? The ‘‘It’s not working’’ Alignment Troubleshooting List 1. Stop, and mosey off the job site for a few minutes. Go back to your break area and relax. First of all, you have to realize there is something that you have overlooked. It might be FIGURE 7.21 Drop-in puller device ready to be inserted into bolt hole on machine case. FIGURE 7.22 Drop-in puller device inserted into hole and ready to pull machine sideways. Piotrowski / Shaft Alignment Handbook, Third Edition DK4322_C007 Final Proof page 309 26.9.2006 8:43pm Correcting Misalignment 309 [...]... typically only Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C008 Final Proof page 326 6.10 .20 06 12: 13am 326 Shaft Alignment Handbook, Third Edition affects the measurements taken from the top to the bottom of a shaft and will come into play when plotting the shafts in the side view alignment model Usually the amount of bracket sag is the same on both sides of a shaft and therefore the sags... possible alignment solutions to any alignment problem, then you may have also realized that a lot of them are going to be difficult, time consuming, and expensive to do But there are also 319 Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C008 Final Proof page 320 6.10 .20 06 12: 13am 320 Shaft Alignment Handbook, Third Edition FIGURE 8.1 Representing the centerlines of rotation of machinery shafts... Movement Methods, Pumps and Systems, pp 42 45, April 1995 Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C007 Final Proof page 318 26 .9 .20 06 8:43pm Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C008 Final Proof page 319 6.10 .20 06 12: 13am 8 Alignment Modeling Basics So far, we have reviewed the nondestructive techniques to find misalignment, studied good baseplate and foundation... number Therefore the shaft on the right is ‘‘low’’ with respect to the shaft on the left Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C008 Final Proof page 327 6.10 .20 06 12: 13am 327 Alignment Modeling Basics The body of the dial indicator stays at the same distance from the centerline of rotation of the shaft it is attached to FIGURE 8.7 Negative reading indicates that the shaft you are measuring... make it easy to align the shafts within the boundary conditions imposed by the baseplate or foundation and the allowable lateral restrictions between the machinery casing bolts and the holes drilled in the machine cases (a.k.a ‘‘bolt bound’’ conditions) Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C008 Final Proof page 322 6.10 .20 06 12: 13am 322 Shaft Alignment Handbook, Third Edition... / Shaft Alignment Handbook, Third Edition DK4 322 _C008 Final Proof page 324 6.10 .20 06 12: 13am 324 Shaft Alignment Handbook, Third Edition 1 Where the foot and the hold down bolts are located on each machine 2 Where the measurements are taken on the machinery shafts Other critical dimensions that may need to be taken are 1 Where measurements have been taken to observe how the machinery moved from offline... into play in the top view Classically when people initially set up their alignment measurement system the dial indicator is placed on the top of a shaft in the twelve o’clock position, zero the indicator Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C008 Final Proof page 328 6.10 .20 06 12: 13am 328 Shaft Alignment Handbook, Third Edition there and sweep through 908 arcs for the other three... where the centerlines of rotation are by just looking at dial indicator, laser, or optical encoder measurement data Your goal is to position each machine so that both shafts Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C008 Final Proof page 321 6.10 .20 06 12: 13am Alignment Modeling Basics 321 run in the same axis of rotation and you invariably begin to wonder—Is one shaft higher or lower... graph or the model Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C008 Final Proof page 323 6.10 .20 06 12: 13am 323 Alignment Modeling Basics Top t eas w vie le: 4 in 10 s mil Sca up iew v ide S in : 4 10 s mil le Sca FIGURE 8.3 (See color insert following page 322 .) Three-dimensional view of the side and top views 4 Determine the moves for either or both of the machinery casings on the... possible or at least with an accuracy of +1% of the overall length of the drive system 15Љ Motor 15Љ Scale: Pump 5.5Љ 7Љ Side view 5.5Љ 7Љ 10Љ Motor 14.5Љ Up 10Љ Pump 14.5Љ 5Љ FIGURE 8.4 Scaling the machinery feet and measurement positions onto the graph Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C008 Final Proof page 325 6.10 .20 06 12: 13am 325 Alignment Modeling Basics Label which . indicator and shaft FIGURE 7.13 Monitor the move with an indicator. Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C007 Final Proof page 3 02 26.9 .20 06 8:43pm 3 02 Shaft Alignment Handbook, . (Courtesy of Machine Support Inc., Virginia Beach, VA. With permission.) Piotrowski / Shaft Alignment Handbook, Third Edition DK4 322 _C007 Final Proof page 3 12 26.9 .20 06 8:43pm 3 12 Shaft Alignment Handbook, . pile of shims. Gauge Thickness (in.) 28 0.015 26 0.018 24 0. 024 22 0.030 20 0.036 19 0.0 42 18 0.048 16 0.060 14 0.075 13 0.090 12 0.105 11 0. 120 10 0.135 8 0.165 7 0.187 Piotrowski / Shaft Alignment