Have you ever been driving down the highway and had your vehicle start shaking so badly that you feel like it is going to fall apart? We have all experienced tire unbalance — and it’s extremely annoying.
Tire unbalance is typically caused by wear and tear, hitting a pothole, or even a buildup of mud from an off-road experience. The concern with letting this excess vibration continue is that it could lead to serious issues for your vehicle and require expensive repairs.
This unbalance and vibration concern is also true for manufacturing. Companies invest in expensive CNC machinery, high performance tool holders, cutting tools, and rigid fixturing, and still have issues with poor tool life, tool breakage, part chatter, and spindle downtime. This all leads to extra costs and not enough work getting out the door.
Performing regular maintenance, not taking heavy cuts, not maxing out the spindle RPM, and not taking aggressive feed rates are some of the things we see companies do to combat unbalanced tool assemblies to improve tool life and reduce machine downtime. By incorporating balancing to your processes you can change normal practices and put your company in a better position to compete for new business and/or to maintain your existing customers.
All spindle tapers are ground to AT2 taper tolerances and high-performance tool holders typically achieve runout of < 0.003um and balance of G2.5 @ 20,000 RPM — which is great, in theory.
Tool assemblies become unbalanced when you add the moveable parts of a tool such as the cutting tool, pull studs, clamping screws, bearing races, collets, locknuts, etc. So, when you hear a tool salesman say their tool is “balanced by design”, keep in mind that all those moveable parts will, in fact, create your imbalances and your corresponding headaches.
Unbalanced holders will create a centrifugal force causing excessive vibration. This will lead to poor tool life, chipping, and operators slowing down the RPM and/or feed rates. When a tool is balanced, it will minimize the centrifugal force, create less vibration, and increase tool life. We have seen an average tool life increase of over 20% when comparing a balanced holder assembly to an unbalanced holder assembly.
Machine shops invest in skilled operators to determine what parameters cutting tools should operate, through trial and error, from a baseline suggested by the manufacturer. These determinations are generated from their experience where excessive wear, or an audible sound, are the tangibles. By balancing your holders, you will be able to run at higher RPM’s and increase your metal removal rate and throughput. With balancing, we have seen SFM increase 10-30% without seeing any additional wear on the cutting tool.
This is something that seems to get missed when thinking about balanced versus unbalanced assemblies. A dynamic unbalance can be created up to 0.02um due to centrifugal force, compared to that same holder measured statically measuring less than 0.003um — and we all know what introducing runout leads to!
Running extreme cases of unbalanced holders can cause you to achieve only 10% of your machine’s spindle’s life before you start having issues with the bearings. Keep in mind that most OEM will not warranty their machine if you are running unbalanced assemblies greater than G2.5. Your tool holder balanced to G2.5 is good but your tool holder assembly balanced to G2.5 will save you time and money!
At Triumph Tool, we partner with Haimer GmbH for our tool balancing equipment. Haimer GmbH are experts in helping to identify your needs and calculate your ROI. Click below to learn more about tool balancing:
Haimer frequently asked questions – Haimer Balancing Knowledge
Haimer Tool Balancing Product offering – Haimer Balancing Lineup