Reposted from Easy-Laser®
Efficient manufacturing of today almost always depend on a minimum of downtime. Therefore a spindle crash is a most unwelcome accident. The good thing is that there now are fast methods for checking the machine.
One of the most common things that cause a need for service is spindle crash. And of course this always happens when you really need maximum machine availability! Therefore you want the geometry check of the machine to be as quick as possible. Most technicians would be thrilled to use the Easy-Laser® E940 system for measurement and alignment of the spindle, turret and tailstock back to precise position, because it is so quick to set up on the machine and to use. Here’s how to do:
FIRST CHECK THE STRAIGHTNESS
At first we start to check the straightness of the Z-axis both for tailstock movement and for the turret. Mount the laser transmitter (EHS-unit or D22) in the main spindle and the EHM-unit at the moving part.
If the above measurement is within tolerance, normally 5-10 microns, we can go on with the next measurement.
NEXT STEP, SPINDLE BEARING CHECK
After a crash you want to know the condition of the spindle bearing. Are the bearings still ok, or should they be changed? The E940 includes a vibrometer and software to listen to the bearing following an ISO-standard presentation/documentation, to give you the answer how to proceed with the job.
1. Main spindle to Z-axis (tailstock movement) – analyze the result, which should be within 0.015mm/300mm according to the ISO-standard given from the display unit.
2. Carry on with the main spindle to turret movement.
START MANUFACTURING AGAIN
In a few hours all measurements and necessary alignment has been performed with full documentation according to ISO-standard. Hopefully no severe damage was found, and production can start immediately. The machine is back on track, and so are you!
by Ana Maria Delgado, CRL
Reposted from Easy-Laser®
We had a little chat with Eskil Norberg at the company Maskincentrum, who has many years of experience from measuring and aligning machine tools for the manufacturing industry in Sweden.
Because you must be able to predict the level of precision you can achieve for manufactured parts, especially when it comes to large and complicated items, items that can be tough to measure, and also costly to recover if anything goes wrong.
What does your normal work procedure look like?
We always start with a thorough analysis of the problem, and then continue by choosing the best method and instruments for the specific job.
What type of guarantees do you give before performing a job?
That depends on each individual problem I would say. Normally we guarantee that we can identify the problem, and then present a solution for how to bring the machine to a level where it can produce within tolerance again.
As I said, that depends on the problem, but for example an electronic precision level for levelling, interferometer laser for distance, speed, pitch and yaw measurements. Then a double ball bar for circular interpolation according to ISO 230-4. Easy-Laser® E940 is used for straightness, angles and spindle pointing direction. It has wireless communication which is very convenient and safe for us because the machine can be run with all safety guards on. The system also provides a measurement report directly on site thanks to the built-in documentation possibilities. This is highly appreciated by the client. Then we also use vibration analyzers to check for unbalances, bearing failures and sprocket damages.
Of course. Recently when we aligned with our Easy-Laser® on a machine for the manufacturing of steel beams 6 to 12 meters long [20 to 40 feet] we improved the accuracy of the parts from nearly rejection, i.e. 100% of the tolerance range, down to 10 to 15% of the tolerance range.
First you must understand the effects that follow on the different error conditions in the machine and how they affect the finished products. Always start from the ground up when adjusting the machine, followed by adjustments dependent on previous adjustments. What I try to say is you must adjust in the right order. You should also be aware of how possible electronic compensations affect the machine and its measurement result, so these don’t make the problem worse or maybe disguise any mechanical problem. So, always start from the ground up with the geometry of the machine, that’s my advice. To measure is to know!
by Ana Maria Delgado, CRL
Recently, I&E Central (along with a service partner) used the Easy-Laser E940 Machine Tool system to perform alignment on an automatic lathe similar to the photo above. The lathe has an automatic feeder for 20’ sections of tube stock which are supported alternately by V-rollers, and then clamped by “steady rests” while being machined. The objective of this job was to have the stock in perfect alignment with the rotational center of the spindle when supported by either V-rollers or the steady-rests. In addition, there is a pusher system that advances the stock into the collet. The movement of the pusher needed also to be aligned with the spindle center line. This was a challenging measurement made possible by the availability of a spindle laser which could be directed back through the collet.
A laser transmitter was mounted in the spindle with its beam directed through the collet. The laser was adjusted to the rotational center line, then the spindle was turned at 200 RPM for measurement. In this way the beam precisely marked the rotational center along the entire length of the machine.
The first measurement was the location of the center of each steady rest. A laser detector was mounted on a short piece of stock, which was locked in each steady rest for measurement. A center of circle straightness program was used to measure and adjust the position of each steady rest. These were adjusted “live” so that each steady rest held the stock in line with the spindle rotation.
Once completed, pk-pk deviation in the vertical plane was 0.0095”, in the horizontal plane it was 0.020”, well within the customer’s desired specifications.
The next step was measuring the straightness of travel of the pusher arm relative to the rotational center of the lathe. This was accomplished by grasping a similar piece of stock with the jaws of the pusher, then using the same program to measure and adjust its true position at 4 locations along its travel.
The final adjustment involved adjusting the V-rolls to support the tube stock in line with the center of rotation. This adjustment was actually done without the laser. A full length piece of stock was secured in the collet with the other end supported by the pusher. Each V-roll in turn was adjusted with shims so that it supported the stock precisely on the center-line. The customer tells us that the machine now runs smoother than it ever has.
The measurement and alignment of this machine section was never performed by the customer or any service contractor in that they had no way to make the measurements. The power and flexibility of the Easy-Laser E940 system made this a straightforward job that was completed in 1 day.
Special thanks to Bob Dunn with I&E Central, Inc. for sharing this case study with us!
by Ana Maria Delgado, CRL
Problem: The machine shop of the engineering department of a prestigious Florida university wanted to identify the source of error in their tool room lathe. They had previously observed that when working pieces further away from the spindle chuck, there was an appreciable deviation in accuracy compared with close-to-the-spindle work. The machine shop instructor suspected the problem to lie somewhere in the tailstock and asked us to confirm or refute his suspicions.
Solution: The Easy-Laser E940 Machine Tool laser alignment system was used to perform three types of measurements:
- Z-axis straightness measurement
- A spindle direction measurement
- A spindle-to-tailstock alignment measurement
In addition, the Values program was used to check for play in the tailstock sub-spindle bearings. An additional check was performed to verify whether the tool support returned to its original position when it was unlocked, and then locked again.
After accomplishing the above measurements and checks, it was determined that the straightness of the Z-axis was within tolerance, the spindle direction was ascertained and the alignment between the spindle and tailstock at the furthest distance revealed a small angle. There was no significant play in the sub-spindle bearings and the tool support check was good.
This data allowed the instructor to narrow down the possible corrective actions to take in order to achieve a better alignment and return the lathe to an optimum performance condition.
The ability to perform all of these checks and measurements to a high degree of accuracy allowed the university to quickly and more certainly identify worn components, which will save them a great deal of money in spares costs, as well as ensure that parts and workpieces fabricated on this lathe will turn out as expected, on time and within design tolerances.
by Oliver Gibbs CRL