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FAQ: Why should I invest in a balancing machine?

HAIMER FAQ

Customers and interested people repeatedly contact us in order to find out if investing in a balancing machine is worthwhile for their specific application. On the following page you can find the answers to some of the most frequently asked questions.

Your question was not on this page or maybe it wasn't answered sufficiently? In this case please use the contact form in order to get in touch with us or directly approach your HAIMER representative. We will be happy to advise you personally and help you find the right solution.

“I’m only running tools at 1,500 RPM. Is balancing really necessary?”

Although there is a greater benefit to balancing holders when running at high spindle speeds, there is always a benefit to having balanced tool holders, even at low spindle speeds.

  • We’ve all experienced situations, where we are limited on the speed at which we can run certain cutting tools. Whether it’s because of the sound that the machine tool makes with the increased speeds, or whether it’s the dramatic decrease in cutting tool life with increased speeds, chances are good that this limit we put on the spindle speed, is due to the unbalance within the tool holder assembly. There have been many cases, where after balancing the assembly, we were able to decrease the cycle time, due to the increase in speeds & feeds once the tool holder assembly had been balanced.

“We purchase tool holders that are pre-balanced. Is this good enough?”

Purchasing pre-balanced tool holders is generally a good idea. However: 

  • What happens when you clamp a cutting tool into a balanced tool holder? Cutting tools are sometimes asymmetrical (example: flats on the shank) which will add unbalance to the assembly. 
  • Most tool holder manufacturers stock product in a “Pre-Balanced” condition. A pre-balanced condition means that the tool holders are fully balanced without components such as cutting tools, pull studs, collets, clamping nuts, moveable bearings, data chips, etc… Once these other components are added to the tool holder assembly, the tool holder may need to be re-balanced in order to conform to ISO balance Specifications.

“I don’t need balanced tool holders.”

Modern milling machines operate with high spindle speeds. An unbalance causes centrifugal forces. The centrifugal forces increase squared to the spindle speed. Older machines have spindle speeds of about 2,000 rpm. Even at 10,000 rpm the unbalance in the same exact tool holder causes a centrifugal force that is 25 times higher.

  • The centrifugal force stresses the spindle bearings. The lifetime of the bearings decreases with excessive stress. Consequently, the spindle bearings become damaged and unnecessary repair costs are incurred.
  • The manufacturers of milling machines and spindles specify the use of balanced tools. Often times, if unbalanced tools are used, there will be no warranty on the machine spindle.
  • The direction of the centrifugal force is changing steadily as it rotates with the spindle. This is why centrifugal force causes vibrations.
  • Vibrations shorten the life of the cutting tools. This causes higher cutting tooling costs and a decrease in the quality of the surface -finish.

“Balancing is too complicated.”

It depends. Simple balancing systems often aren’t handled correctly because the operators don’t know the physical background of unbalance and balancing. Sometimes the existing unbalance is raised instead of reduced, since some balancing machines are not adjusted correctly for the specific tool. Overall it is rather difficult to have a specialist just for balancing. However, this is not necessary.

With a good machine, balancing is simple. The operator only has to choose the type of tool he or she wants to balance. From then on the machine tells them what to do. The machine has the expert knowledge and not the operator.

“I only have a few parts to balance. For this purpose a simple machine is sufficient.”

When balancing is not done regularly, the operators have no experience. The risk of incorrect measurement due to improper handling of the machine is very high. Therefore, in such cases, it is important to have a balancing machine that guides the user through the procedure. Plus, it would be unfortunate to have an inferior balancing machine that limits your balancing potential for the future.

“How expensive is a balancing machine?”

It depends on your requirements. A balancing machine is an investment, and an investment must be efficient in order to be justified. Please contact us directly about your needs and requirements for your balancing operations - we will be pleased to help.

“The tool holders that I buy are already balanced.”

Generally a good idea. The manufacturer of tool holders normally can balance quicker and more efficiently. However:

  • What happens when you clamp a cutting tool into a balanced tool holder? The cuttings tools often are unsymmetrical (e.g. side lock shanks). Many tool holders have movable parts which can have different positions after being mounted (e.g. pull studs, clamping screws, bearing races, collets, locknuts). Tool holders for high speed machining should always be balanced when mounted as one complete set-up (tool holder, pull stud, collet, cutting tool, etc.). Once tool holder elements have been modified, the balance level changes.
  • What about the tool holders which are already in your factory? It is nearly impossible to avoid a mixing up of balanced and unbalanced tool holders. One single process with an unbalanced tool at high spindle speed can damage the spindle bearings. This is why the “old” tool holders should be balanced as well.
  • How do you know your tool holders are balanced? After all, when one receives a shipment from a vendor they first check the items in the box and insure that selection and quantity of the items in the box is correct. Why not check that the balance of the tools is correct as well? What balance level does your “pre-balanced” tool holders come to you? Checking the balance of tool holders should always be part of the quality control of incoming goods, particularly if you are paying a premium for “fine-balanced” tools

“A balancing machine is too expensive for me.”

A balancing machine is an investment. An investment must be efficient. The purchasing price has only a small influence on the efficiency of an investment.

A balancing machine is efficient, when: 

  • the process reliability in the production can be improved 
  • the life time of the spindle can be extended. (One single replacement of a spindle costs more than a balancing machine)
  • the frequency of the downtime of the machines is decreased. The most expensive factor in a production is machine standstill
  • the result of the production is improved
  • better surface finish
  • the maximum spindle speeds and feeds can be utilized on your machine
  • quicker throughput
  • the tool life is extended
  • the cutting capacity is improved.

Overall, it is most important that a balancing machine is easy to handle and that it gives you trusting and repeatable results. Ultimately, it should provide the easiest method to find your desired balance level to run at a safe and productive rate in your facility. It is possible to get all of that with a balancing machine that is easy and secure to handle, insuring that you reach the desired results.

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