A guest blog from BIG KAISER.
High-speed machining started getting popular in the ‘90s, especially in aerospace where they replaced fabricating processes with machining monolithic parts like wing struts from billets. Machine tools capable of spinning cutting tools at tens of thousands of RPM made it easier to produce these parts quickly.
Like machines, holders adapted. The centrifugal forces they had to manage in order to keep tools cutting correctly became extreme. The toolholding systems available at that time were found not to be as effective as the shallower 1-to-10 taper ratio of the German hollow taper shank, hohl shaft kegel (HSK) in German. The HSK has since been standardized to ISO specifications (12164-1, -2).
HSK is now available in several sizes and forms to fit with small to large machines. For the most part, the market has settled on the form A for general milling. It has been adopted in Japan, North America and Europe and is truly one of the only worldwide-side toolholder standards. Form E or F is for high-speed machining. The forms have different features depending on the standard they follow.
In the end, to achieve efficient tool life, proper finish and productivity in high-speed work, holders need to be as rigid, compact and short as possible to keep the whole assembly stable.
What to know when choosing a high-speed tool holder
When it comes to balancing holders, the quality G2.5 is widely used in the industry and is described in the ISO 1940-1 (issued in 2003) standard. However, this quality class is often over-specified and is in many cases not economically or technically feasible, especially when applied to smaller and lighter tools. Standards often applied to tools are more suited for rigid rotors and are practical in a broader use for balancing.
However, it cannot be applied to a complete system of spindles, tool holders and tools adequately and within technical constraints. For example, a tool to be compliant will have to be balanced to less than 1 gmm/kg at a speed of 25,000 rpm, which in turn corresponds to a mass eccentricity of less than 1 μm. This allowable tolerance is less than the interchange accuracy for even HSK, essentially negating all the costs and time for balancing the tool to such a strict tolerance.
For this reason, all BIG KAISER tool holders are balanced according ISO 16084 (issued in 2017) specifically developed for rotating tool systems. ISO 16084 focuses on the interaction between spindle and tool factoring in the allowable load on the spindle bearings generated by the tool’s imbalance. This load must not exceed one percent of the dynamic load capacity of the spindle bearings.
According to ISO 16084, the allowable unbalance tolerance is specified in [gmm] and is not expressed using a special quality grade [G]. In conclusion, BIG KAISER does not indicate any G-values for balancing quality, but rather the maximum rotational speeds of the individual tool holder.
The BIG Kiaser MEGA holder program includes a variety of styles that can be used up to 40,000 RPM. They guarantee 100 percent concentricity and runout accuracy down to .00004" at the nose. They are built specifically to withstand speed and forces required in today’s high-throughput environment.
For more information on BIG KAISER's approach to balancing tool holders, click here. To learn more about our high-performance tool holders here.
We are very excited to announce that we are now able to offer on-site technical training to YOUR machinists at YOUR location! This is offered at no charge to customers who use any of the manufacturer's whom we represent in California and Nevada.
However, just because you don't purchase things from us, don't feel left out! We also offer on-site topic specter training on any of the following topics for $150/hour.
Each presentation lasts about 2 hours. The presentations last approximately 45-60 minutes with the remaining time for Q&A and discussion about unique applications in your facility.
Training Classes Available:
Advanced Part Manufacturing:
Our most widely used finish boring system, KAISER Series 112, features a high precision boring head with a center-mount boring bar or boring bar/insert holder combo with a predefined fixed offset designed to bore one specific size. And although the KAISER system provides a multitude of standard components to create the ideal combination of boring bar and insert holder – you may not always have the ideal combination at your disposal. Don’t fret – that is the beauty of the system. The total boring range of your assembly is reached through radial adjustment of the bar. However, when doing so, there is still always the consideration of balance while assembling the tool. As logic would tell you, the farther away from the boring head’s centerline you offset the boring bar, the greater the unbalance. This affects not only the performance of the tool, but more importantly, the results. And this is especially true for deep hole boring.
To get the greatest productivity and flexibility from the KAISER 112 boring system, we recommend replacing the fixed bar & insert holder with a radial adjustment bar & insert holder which keeps the bar at centerline at all times. This allows for different boring ranges to be reached, all while keeping the tool as balanced as possible.
In this video, Matt Tegelman, Applications Manager and KAISER Product Manager, walks you through the process of adjusting the fixed boring bars and inserts holders. And if balance is a concern, utilizing the radial adjustable option, Matt demonstrates how to properly center the boring bar on both a tool presetter and in a machine spindle, and finally, how to fine-adjust to the desired diameter.
Watch for more of these brief instructional reference videos here on Cut to the Chase blog in the near future.
Tags: balance, boring tool, deep hole boring, How-To, KAISER, Matt Tegelman, tool presetter
We often run end mill "tests" to determine which one performs best. Obviously, our goal is to "win' the test and get more business for our manufacturer's. This is article is about one our "tricks" and it's also why represent both cutting tool manufacturers and rotary tool manufacturers. We want to insure that the products work together.
As a general rule most cutting tool & tolholder manufacturers prefer to use single angle (ER/DR style) collet chucks for general purpose cutting tool applications under 1/2" (12mm). The rules are a bit different in High Speed Machining, as there are many more things to consider, but the problems of TIR at high speeds, where you can hear and feel the chatter, are still there in general end mill cutting operations at lower RPM. It's all about runout and uneven chip load.
End Mill Holders are prone to runout problems for a couple of reasons:
Depending on the application, end mill holders can be used for holding larger insert style end mills, spade drills, etc. But somewhere between 1/2” and 3/4” there is a line that only you can determine when you need to move from a collet chuck to end mill holder. Generally we recommend using end mill holders only for very specific applications
Using small diameter end mills (1/4" and below) in end mill holders with set screws will have a adverse affect of both surface finish and tool life.
HSK is short for the German words "Hohl Shaft Kegel" or, in English, Hollow Shank Taper.
There are several major differences between "steep taper" toolholders, like NMTB, CAT & BT and HSK.
As machining spindle speeds have increased, BT and CAT tooling systems tend to lose accuracy due to centrifugal forces from running at high RPM. The mouth of the machining center spindle can grow, "bell mouthing". As it grows the BT and CAT tool is under constant drawbar pull, moves up the expanded taper. This causes the Z-axis offset to change. This can also cause the toolholder to stick in the spindle.
The HSK contacts the spindle taper and flange on the spindle face to make a solid union in both the axial and radial planes. In operation, HSK tool holders are resistant to axial movement because the face contact prevents the toolholder from being pulled up into the spindle at high speed.
Cutting tools generally takes higher radial forces because the flange contact and taper contact combine to resist deflection.
Technical Support Blog
At Next Generation Tool we often run into many of the same technical questions from different customers. This section should answer many of your most common questions.
We set up this special blog for the most commonly asked questions and machinist data tables for your easy reference.
If you've got a question that's not answered here, then just send us a quick note via email or reach one of us on our CONTACTS page here on the website
Our technical section is written by several different people. Sometimes, it's from our team here at Next Generation Tooling & at other times it's by one of the innovative manufacturer's we represent in California and Nevada.